{"id":431,"date":"2024-12-18T04:57:14","date_gmt":"2024-12-18T04:57:14","guid":{"rendered":"http:\/\/192.168.10.18\/arslan\/Demo\/GeekyBot\/?p=431"},"modified":"2025-06-18T13:23:47","modified_gmt":"2025-06-18T13:23:47","slug":"space-exploration","status":"publish","type":"post","link":"https:\/\/demo.geekybot.com\/index.php\/space-exploration\/","title":{"rendered":"Space Exploration"},"content":{"rendered":"<div class=\"grey-box w-100 grey-box-top\">\r\n<div class=\"grey-box-content mx-auto w-100\">\r\n<div class=\"page2ref-true topic-content topic-type-REGULAR\" data-student-article=\"true\">\r\n<div class=\"reading-channel\">\r\n<div class=\"topic-header\">\r\n<div class=\"d-flex align-items-top justify-content-between\">\r\n<div class=\"d-flex flex-column\">\r\n<div>\r\n<div>\r\n<h2 class=\"h2\"><strong>Major milestones<\/strong><\/h2>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div class=\"bg-gray-50 p-15 rounded module-spacing recent-news d-flex flex-column float-false\">\r\n<div>\r\n<h2 class=\"font-weight-bold font-14 m-0 d-inline\">News\u00a0<span class=\"text-gray-600\">\u2022<\/span><\/h2>\r\n<div class=\"recent-news-item first-recent-news-item d-inline\"><a class=\"font-14 gtm-ap-news-link\" href=\"https:\/\/www.astronomy.com\/space-exploration\/the-past-present-and-future-of-boeing-in-space\/\" rel=\"nofollow\">The past, present, and future of Boeing in space<\/a>\u00a0<span class=\"font-14 text-gray-600\">\u2022\u00a0Nov. 20, 2024, 12:48 AM ET (Astronomy Magazine)<\/span><\/div>\r\n<\/div>\r\n<\/div>\r\n<section data-level=\"1\">\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237025\" data-level=\"2\" data-has-spy=\"true\">\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"59893\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/32\/69632-050-AA671F9E\/space-shuttle-Endeavour-International-Space-Station-spacecraft-December-9-2000.jpg\" data-href=\"\/media\/1\/557348\/59893\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/32\/69632-050-AA671F9E\/space-shuttle-Endeavour-International-Space-Station-spacecraft-December-9-2000.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/32\/69632-050-AA671F9E\/space-shuttle-Endeavour-International-Space-Station-spacecraft-December-9-2000.jpg?w=300\" alt=\"International Space Station, 2000\" width=\"1254\" height=\"819\" data-width=\"1600\" data-height=\"1044\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/32\/69632-050-AA671F9E\/space-shuttle-Endeavour-International-Space-Station-spacecraft-December-9-2000.jpg\" data-href=\"\/media\/1\/557348\/59893\">International Space Station, 2000<\/a>The International Space Station, imaged from the space shuttle\u00a0<em>Endeavour<\/em>\u00a0on December 9, 2000, after installation of a large solar array (long horizontal panels). Major elements of the partially completed station included (front to back) the American-built connecting node Unity and two Russian-built modules\u2014Zarya, a propulsion and power module, and Zvezda, the initial habitat. A Russian Soyuz TM spacecraft, which carried up the station&#8217;s first three-person crew, is shown docked at the aft end of Zvezda.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">The first artificial\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/Earth-satellite\" data-show-preview=\"true\">Earth satellite<\/a>,\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Sputnik\" data-show-preview=\"true\">Sputnik<\/a>\u00a01, was launched by the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Soviet-Union\" data-show-preview=\"true\">Soviet Union<\/a>\u00a0on October 4, 1957. The first human to go into space,\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Yuri-Gagarin\" data-show-preview=\"true\">Yuri Gagarin<\/a>, was launched, again by the Soviet Union, for a one-orbit journey around\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Earth\" data-show-preview=\"true\">Earth<\/a>\u00a0on April 12, 1961. Within 10 years of that first human flight, American astronauts walked on the surface of the Moon.\u00a0<span id=\"ref838669\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/Apollo-space-program\" data-show-preview=\"true\">Apollo<\/a>\u00a011 crew members\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Neil-Armstrong\" data-show-preview=\"true\">Neil Armstrong<\/a>\u00a0and\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Buzz-Aldrin\" data-show-preview=\"true\">Edwin (\u201cBuzz\u201d) Aldrin<\/a>\u00a0made the first lunar landing on July 20, 1969. A total of 12 Americans on six separate Apollo missions set foot on the Moon between July 1969 and December 1972. Since then, no humans have left Earth orbit, but more than 500 men and women have spent as many as 438 consecutive days in space. Starting in the early 1970s, a series of Soviet (Russian from December 1991)\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/space-station\" data-show-preview=\"true\">space stations<\/a>, the U.S.\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Skylab\" data-show-preview=\"true\">Skylab<\/a>\u00a0station, and numerous\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/space-shuttle\" data-show-preview=\"true\">space shuttle<\/a>\u00a0flights provided Earth-orbiting bases for varying periods of human occupancy and activity. From November 2, 2000, when its first crew took up residence, to its completion in 2011, the\u00a0<span id=\"ref838671\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/International-Space-Station\" data-show-preview=\"true\">International Space Station<\/a>\u00a0(ISS) served as a base for humans living and working in space on a permanent basis. It will continue to be used in this way until at least 2024.<\/p>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"60412\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/72\/22072-004-5D4F9F04\/NASA-rover-Pathfinder-Sojourner-boulder-planet-Chryse-July-4-1997.jpg\" data-href=\"\/media\/1\/557348\/60412\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/72\/22072-004-5D4F9F04\/NASA-rover-Pathfinder-Sojourner-boulder-planet-Chryse-July-4-1997.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/72\/22072-004-5D4F9F04\/NASA-rover-Pathfinder-Sojourner-boulder-planet-Chryse-July-4-1997.jpg?w=300\" alt=\"Sojourner rover examining a boulder on Mars\" width=\"1192\" height=\"596\" data-width=\"600\" data-height=\"300\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/72\/22072-004-5D4F9F04\/NASA-rover-Pathfinder-Sojourner-boulder-planet-Chryse-July-4-1997.jpg\" data-href=\"\/media\/1\/557348\/60412\">Sojourner rover examining a boulder on Mars<\/a>NASA&#8217;s Sojourner robotic rover examining a boulder on Mars&#8217;s Chryse Planitia, as imaged by its parent spacecraft, Pathfinder, after landing on the planet July 4, 1997. Parts of Pathfinder&#8217;s solar arrays and the rover&#8217;s down ramp are in the foreground.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">Since 1957 Earth-orbiting satellites and robotic\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/spacecraft\" data-show-preview=\"true\">spacecraft<\/a>\u00a0journeying away from Earth have gathered valuable\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/data\" data-term=\"data\" data-type=\"EB\">data<\/a>\u00a0about the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Sun\" data-show-preview=\"true\">Sun<\/a>, Earth, other bodies in the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/solar-system\" data-show-preview=\"true\">solar system<\/a>, and the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/universe\" data-show-preview=\"true\">universe<\/a>\u00a0beyond. Robotic spacecraft have landed on the\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Moon\" data-show-preview=\"true\">Moon<\/a>,\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Venus-planet\" data-show-preview=\"true\">Venus<\/a>,\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Mars-planet\" data-show-preview=\"true\">Mars<\/a>,\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Titan-astronomy\" data-show-preview=\"true\">Titan<\/a>, a comet, and four asteroids, have visited all the major planets, and have flown by\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Kuiper-belt\" data-show-preview=\"true\">Kuiper belt<\/a>\u00a0objects and by the nuclei of comets, including\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Halleys-Comet\" data-show-preview=\"true\">Halley\u2019s Comet<\/a>, traveling in the inner solar system. Scientists have used space-derived data to deepen human understanding of the origin and\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/evolution-scientific-theory\" data-show-preview=\"true\">evolution<\/a>\u00a0of galaxies, stars, planets, and other cosmological phenomena.<\/p>\r\n<p class=\"topic-paragraph\">Orbiting satellites also have provided, and continue to provide, important services to the everyday life of many people on Earth. Meteorologic satellites deliver information on short- and long-term weather patterns and their\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/underlying\" data-term=\"underlying\" data-type=\"EB\">underlying<\/a>\u00a0causes. Other Earth-observation satellites remotely sense land and ocean areas, gathering data that improve management of Earth\u2019s resources and that help in understanding global\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/climate-change\" data-show-preview=\"true\">climate change<\/a>. Telecommunications satellites allow essentially instantaneous transfer of voice, images, and data on a global basis. Satellites operated by the\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/United-States\" data-show-preview=\"true\">United States<\/a>,\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Russia\" data-show-preview=\"true\">Russia<\/a>,\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/China\" data-show-preview=\"true\">China<\/a>,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Japan\" data-show-preview=\"true\">Japan<\/a>, India, and Europe give precision\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/navigation-technology\" data-show-preview=\"true\">navigation<\/a>, positioning, and timing information that has become essential to many terrestrial users.\u00a0<span id=\"ref838672\"><\/span>Earth-observation satellites have also become extremely useful to the military authorities of several countries as complements to their land, sea, and air forces and have provided important security-related information to national leaders.<\/p>\r\n<p class=\"topic-paragraph\">As the many benefits of space activity have become evident, other countries have joined the Soviet Union and the United States in developing their own space programs. They include a number of western European countries operating both individually and, after 1975, cooperatively through the\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/European-Space-Agency\" data-show-preview=\"true\">European Space Agency<\/a>, as well as China, Japan,\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Canada\" data-show-preview=\"true\">Canada<\/a>,\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/India\" data-show-preview=\"true\">India<\/a>,\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Israel\" data-show-preview=\"true\">Israel<\/a>,\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Iran\" data-show-preview=\"true\">Iran<\/a>,\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/North-Korea\" data-show-preview=\"true\">North Korea<\/a>,\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/South-Korea\" data-show-preview=\"true\">South Korea<\/a>, and\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Brazil\" data-show-preview=\"true\">Brazil<\/a>. By the second decade of the 21st century, more than 50 countries had space agencies or other government bodies carrying out space activities.<\/p>\r\n<\/section>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref310634\" data-level=\"2\" data-has-spy=\"true\">\r\n<h2 class=\"h2\"><strong>Significant milestones in space exploration<\/strong><\/h2>\r\n<p class=\"topic-paragraph\"><span id=\"ref3323\"><\/span>A list of significant\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/milestones\" data-term=\"milestones\" data-type=\"EB\">milestones<\/a>\u00a0in space exploration is provided in the table.<\/p>\r\n<div class=\"module-spacing\">\u00a0<\/div>\r\n<div class=\"md-drag md-table-wrapper\">\r\n<table><caption>Significant milestones in space exploration<\/caption>\r\n<thead>\r\n<tr>\r\n<th scope=\"col\">date accomplished<\/th>\r\n<th scope=\"col\">event<\/th>\r\n<th scope=\"col\">details<\/th>\r\n<th scope=\"col\">country or agency<\/th>\r\n<\/tr>\r\n<\/thead>\r\n<tbody>\r\n<tr>\r\n<td scope=\"row\">Oct. 4, 1957<\/td>\r\n<td>first artificial Earth satellite<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Sputnik\" data-show-preview=\"true\">Sputnik<\/a>\u00a01<\/td>\r\n<td>U.S.S.R.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Nov. 3, 1957<\/td>\r\n<td>first animal launched into space<\/td>\r\n<td>dog Laika aboard\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Sputnik\" data-show-preview=\"true\">Sputnik<\/a>\u00a02<\/td>\r\n<td>U.S.S.R.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Sept. 14, 1959<\/td>\r\n<td>first spacecraft to hard-land on another celestial object (the\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Moon\" data-show-preview=\"true\">Moon<\/a>)<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Luna-space-probe\" data-show-preview=\"true\">Luna<\/a>\u00a02<\/td>\r\n<td>U.S.S.R.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Oct. 7, 1959<\/td>\r\n<td>first pictures of the far side of the Moon<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Luna-space-probe\" data-show-preview=\"true\">Luna<\/a>\u00a03<\/td>\r\n<td>U.S.S.R.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">April 1, 1960<\/td>\r\n<td>first applications satellite launched<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/TIROS\" data-show-preview=\"true\">TIROS<\/a>\u00a01 (weather observation)<\/td>\r\n<td>U.S.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Aug. 11, 1960<\/td>\r\n<td>first recovery of a payload from Earth orbit<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Discoverer\" data-show-preview=\"true\">Discoverer<\/a>\u00a013 (part of Corona reconnaissance satellite program)<\/td>\r\n<td>U.S.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">April 12, 1961<\/td>\r\n<td>first human to orbit Earth<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Yuri-Gagarin\" data-show-preview=\"true\">Yury Gagarin<\/a>\u00a0on\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Vostok-Soviet-spacecraft\" data-show-preview=\"true\">Vostok<\/a>\u00a01<\/td>\r\n<td>U.S.S.R.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Dec. 14, 1962<\/td>\r\n<td>first data returned from another planet (<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Venus-planet\" data-show-preview=\"true\">Venus<\/a>)<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Mariner\" data-show-preview=\"true\">Mariner<\/a>\u00a02<\/td>\r\n<td>U.S.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">June 16, 1963<\/td>\r\n<td>first woman in space<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Valentina-Tereshkova\" data-show-preview=\"true\">Valentina Tereshkova<\/a>\u00a0on\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Vostok-Soviet-spacecraft\" data-show-preview=\"true\">Vostok<\/a>\u00a06<\/td>\r\n<td>U.S.S.R.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">July 26, 1963<\/td>\r\n<td>first satellite to operate in\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/geostationary-orbit\" data-show-preview=\"true\">geostationary orbit<\/a><\/td>\r\n<td>Syncom 2 (telecommunications satellite)<\/td>\r\n<td>U.S.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">March 18, 1965<\/td>\r\n<td>first space walk<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Aleksei-Leonov\" data-show-preview=\"true\">Aleksey Leonov<\/a>\u00a0on\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Voskhod-spacecraft\" data-show-preview=\"true\">Voskhod<\/a>\u00a02<\/td>\r\n<td>U.S.S.R.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">July 14, 1965<\/td>\r\n<td>first spacecraft pictures of\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Mars-planet\" data-show-preview=\"true\">Mars<\/a><\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Mariner\" data-show-preview=\"true\">Mariner<\/a>\u00a04<\/td>\r\n<td>U.S.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Feb. 3, 1966<\/td>\r\n<td>first spacecraft to soft-land on the Moon<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Luna-space-probe\" data-show-preview=\"true\">Luna<\/a>\u00a09<\/td>\r\n<td>U.S.S.R.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">April 24, 1967<\/td>\r\n<td>first death during a space mission<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Vladimir-Mikhaylovich-Komarov\" data-show-preview=\"true\">Vladimir Komarov<\/a>\u00a0on\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Soyuz\" data-show-preview=\"true\">Soyuz<\/a>\u00a01<\/td>\r\n<td>U.S.S.R.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Dec. 24, 1968<\/td>\r\n<td>first humans to orbit the Moon<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Frank-Borman\" data-show-preview=\"true\">Frank Borman<\/a>,\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Jim-Lovell\" data-show-preview=\"true\">James Lovell<\/a>, and\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/William-A-Anders\" data-show-preview=\"true\">William Anders<\/a>\u00a0on\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/Apollo-space-program\" data-show-preview=\"true\">Apollo<\/a>\u00a08<\/td>\r\n<td>U.S.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">July 20, 1969<\/td>\r\n<td>first human to walk on the Moon<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Neil-Armstrong\" data-show-preview=\"true\">Neil Armstrong<\/a>\u00a0on\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/Apollo-space-program\" data-show-preview=\"true\">Apollo<\/a>\u00a011<\/td>\r\n<td>U.S.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Sept. 24, 1970<\/td>\r\n<td>first return of lunar samples by an unmanned spacecraft<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Luna-space-probe\" data-show-preview=\"true\">Luna<\/a>\u00a016<\/td>\r\n<td>U.S.S.R.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Dec. 15, 1970<\/td>\r\n<td>first soft landing on another planet (Venus)<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Venera\" data-show-preview=\"true\">Venera<\/a>\u00a07<\/td>\r\n<td>U.S.S.R.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">April 19, 1971<\/td>\r\n<td>first\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/space-station\" data-show-preview=\"true\">space station<\/a>\u00a0launched<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Salyut\" data-show-preview=\"true\">Salyut<\/a>\u00a01<\/td>\r\n<td>U.S.S.R.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Nov. 13, 1971<\/td>\r\n<td>first spacecraft to orbit another planet (Mars)<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Mariner\" data-show-preview=\"true\">Mariner<\/a>\u00a09<\/td>\r\n<td>U.S.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Dec. 2, 1971<\/td>\r\n<td>first spacecraft to soft-land on Mars<\/td>\r\n<td>Mars 3<\/td>\r\n<td>U.S.S.R.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Dec. 3, 1973<\/td>\r\n<td>first spacecraft to fly by\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Jupiter-planet\" data-show-preview=\"true\">Jupiter<\/a><\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Pioneer-space-probes\" data-show-preview=\"true\">Pioneer<\/a>\u00a010<\/td>\r\n<td>U.S.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">July 17, 1975<\/td>\r\n<td>first international docking in space<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/Apollo-space-program\" data-show-preview=\"true\">Apollo<\/a>\u00a0and\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Soyuz\" data-show-preview=\"true\">Soyuz<\/a>\u00a0spacecraft during Apollo-Soyuz Test Project<\/td>\r\n<td>U.S., U.S.S.R.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">July 20, 1976<\/td>\r\n<td>first pictures transmitted from the surface of Mars<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Viking-space-probe\" data-show-preview=\"true\">Viking<\/a>\u00a01<\/td>\r\n<td>U.S.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Sept. 1, 1979<\/td>\r\n<td>first spacecraft to fly by\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Saturn-planet\" data-show-preview=\"true\">Saturn<\/a><\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Pioneer-space-probes\" data-show-preview=\"true\">Pioneer<\/a>\u00a011<\/td>\r\n<td>U.S.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">April 12\u201314, 1981<\/td>\r\n<td>first reusable spacecraft launched and returned from space<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/space-shuttle\" data-show-preview=\"true\">space shuttle<\/a>\u00a0Columbia<\/td>\r\n<td>U.S.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Jan. 24, 1986<\/td>\r\n<td>first spacecraft to fly by\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Uranus-planet\" data-show-preview=\"true\">Uranus<\/a><\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Voyager-space-probes\" data-show-preview=\"true\">Voyager<\/a>\u00a02<\/td>\r\n<td>U.S.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">March 13, 1986<\/td>\r\n<td>first spacecraft to make a close flyby of a\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/comet-astronomy\" data-show-preview=\"true\">comet<\/a>\u00a0nucleus<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Giotto\" data-show-preview=\"true\">Giotto<\/a>\u00a0at\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Halleys-Comet\" data-show-preview=\"true\">Halley&#8217;s Comet<\/a><\/td>\r\n<td>European Space Agency<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Aug. 24, 1989<\/td>\r\n<td>first spacecraft to fly by\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Neptune-planet\" data-show-preview=\"true\">Neptune<\/a><\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Voyager-space-probes\" data-show-preview=\"true\">Voyager<\/a>\u00a02<\/td>\r\n<td>U.S.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">April 25, 1990<\/td>\r\n<td>first large optical space telescope launched<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Hubble-Space-Telescope\" data-show-preview=\"true\">Hubble Space Telescope<\/a><\/td>\r\n<td>U.S., European Space Agency<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Dec. 7, 1995<\/td>\r\n<td>first spacecraft to orbit Jupiter<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Galileo-spacecraft\" data-show-preview=\"true\">Galileo<\/a><\/td>\r\n<td>U.S.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Nov. 2, 2000<\/td>\r\n<td>first resident crew to occupy the\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/International-Space-Station\" data-show-preview=\"true\">International Space Station<\/a><\/td>\r\n<td>William Shepherd, Yury Gidzenko, and\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Sergey-Konstantinovich-Krikalyov\" data-show-preview=\"true\">Sergey Krikalyov<\/a><\/td>\r\n<td>U.S., Russia<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Feb. 14, 2000; Feb. 12, 2001<\/td>\r\n<td>first spacecraft to orbit (2000) and land on (2001) an\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/asteroid\" data-show-preview=\"true\">asteroid<\/a><\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Near-Earth-Asteroid-Rendezvous-Shoemaker\" data-show-preview=\"true\">NEAR<\/a>\u00a0at the asteroid\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Eros-asteroid\" data-show-preview=\"true\">Eros<\/a><\/td>\r\n<td>U.S.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">June 21, 2004<\/td>\r\n<td>first privately funded manned spacecraft to achieve suborbital flight above 100 km (62 miles)<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Michael-Melvill\" data-show-preview=\"true\">Mike Melvill<\/a>\u00a0on\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/SpaceShipOne\" data-show-preview=\"true\">SpaceShipOne<\/a><\/td>\r\n<td>Mojave Aerospace Ventures (commercial joint venture)<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">July 1, 2004<\/td>\r\n<td>first spacecraft to orbit Saturn<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/event\/Cassini-Huygens\" data-show-preview=\"true\">Cassini-Huygens<\/a><\/td>\r\n<td>U.S., European Space Agency, Italy<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Jan. 14, 2005<\/td>\r\n<td>first spacecraft to land on the moon of a planet other than Earth (Saturn&#8217;s moon\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Titan-astronomy\" data-show-preview=\"true\">Titan<\/a>)<\/td>\r\n<td>Huygens probe of the Cassini-Huygens spacecraft<\/td>\r\n<td>U.S., European Space Agency, Italy<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">June 13, 2010<\/td>\r\n<td>first spacecraft to return to Earth with samples from an asteroid<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Hayabusa-Japanese-spacecraft\" data-show-preview=\"true\">Hayabusa<\/a><\/td>\r\n<td>Japan<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">March 17, 2011<\/td>\r\n<td>first spacecraft to orbit\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Mercury-planet\" data-show-preview=\"true\">Mercury<\/a><\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Messenger-United-States-spacecraft\" data-show-preview=\"true\">Messenger<\/a><\/td>\r\n<td>U.S.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">August 6, 2104<\/td>\r\n<td>first spacecraft to orbit a comet<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Rosetta-European-Space-Agency-spacecraft\" data-show-preview=\"true\">Rosetta<\/a><\/td>\r\n<td>European Space Agency<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">November 12, 2014<\/td>\r\n<td>first spacecraft to land on a comet<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Rosetta-European-Space-Agency-spacecraft\" data-show-preview=\"true\">Philae<\/a><\/td>\r\n<td>European Space Agency<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">March 6, 2015<\/td>\r\n<td>first spacecraft to orbit a\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/dwarf-planet\" data-show-preview=\"true\">dwarf planet<\/a>\u00a0(<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Ceres-dwarf-planet\" data-show-preview=\"true\">Ceres<\/a>)<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Dawn-United-States-satellite\" data-show-preview=\"true\">Dawn<\/a><\/td>\r\n<td>U.S.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">July 14, 2015<\/td>\r\n<td>first spacecraft to fly by\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Pluto-dwarf-planet\" data-show-preview=\"true\">Pluto<\/a><\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/New-Horizons\" data-show-preview=\"true\">New Horizons<\/a><\/td>\r\n<td>U.S.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">December 21, 2015<\/td>\r\n<td>first rocket stage to return to its launch site<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Falcon-launch-vehicle\" data-show-preview=\"true\">Falcon 9<\/a><\/td>\r\n<td>U.S.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">January 1, 2019<\/td>\r\n<td>farthest object (2014 MU69) explored by a spacecraft<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/New-Horizons\" data-show-preview=\"true\">New Horizons<\/a><\/td>\r\n<td>U.S.<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">January 3, 2019<\/td>\r\n<td>first landing on the Moon&#8217;s far side<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Change-Chinese-lunar-probes\" data-show-preview=\"true\">Chang&#8217;e 4<\/a><\/td>\r\n<td>China<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<\/div>\r\n<\/section>\r\n<\/section>\r\n<\/div>\r\n<div id=\"chatbot-root\">\u00a0<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div class=\"ai-dialog-placeholder\">\u00a0<\/div>\r\n<div data-page-index=\"1\">\u00a0<\/div>\r\n<div class=\"loaded-infinite-scroll-container qa-infinite-scroll-container\">\r\n<div class=\"grey-box w-100 \">\r\n<div class=\"grey-box-content mx-auto w-100\">\r\n<div class=\"page2ref-false topic-content topic-type-REGULAR\">\r\n<div class=\"reading-channel\">\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237026\" data-level=\"1\" data-has-spy=\"true\">\r\n<h1 class=\"h1\"><strong>History of space exploration<\/strong><\/h1>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237027\" data-level=\"2\" data-has-spy=\"true\">\r\n<h2 class=\"h2\"><strong>Prelude to spaceflight<\/strong><\/h2>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237028\" data-level=\"3\" data-has-spy=\"true\">\r\n<h2 class=\"h3\"><strong>Precursors in fiction and fact<\/strong><\/h2>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"190545\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/27\/178727-050-2AFD7411\/Ann-Robinson-Gene-Barry-The-War-of.jpg\" data-href=\"\/media\/1\/557348\/190545\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/27\/178727-050-2AFD7411\/Ann-Robinson-Gene-Barry-The-War-of.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/27\/178727-050-2AFD7411\/Ann-Robinson-Gene-Barry-The-War-of.jpg?w=300\" alt=\"The War of the Worlds\" width=\"1215\" height=\"903\" data-width=\"1600\" data-height=\"1189\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/27\/178727-050-2AFD7411\/Ann-Robinson-Gene-Barry-The-War-of.jpg\" data-href=\"\/media\/1\/557348\/190545\"><em>The War of the Worlds<\/em><\/a>Ann Robinson and Gene Barry in\u00a0<em>The War of the Worlds<\/em>\u00a0(1953), directed by Byron Haskin.<\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">Since ancient times, people around the world have studied the heavens and used their observations and explanations of astronomical phenomena for both religious and practical purposes. Some dreamed of leaving Earth to explore other worlds. For example, the French satirist\u00a0<span id=\"ref838673\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Savinien-Cyrano-de-Bergerac\" data-show-preview=\"true\">Cyrano de Bergerac<\/a>\u00a0in the 17th century wrote\u00a0<em>Histoire comique des \u00e9tats et empires de la lune<\/em>\u00a0(1656) and\u00a0<em>Histoire comique des \u00e9tats et empires du soleil<\/em>\u00a0(1662; together in English as\u00a0<em>A Voyage to the Moon: With Some Account of the Solar World<\/em>, 1754), describing fictional journeys to the\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/moon-natural-satellite\" data-show-preview=\"true\">Moon<\/a>\u00a0and the\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Sun\" data-show-preview=\"true\">Sun<\/a>. Two centuries later the French author\u00a0<span id=\"ref838674\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Jules-Verne\" data-show-preview=\"true\">Jules Verne<\/a>\u00a0and the English novelist and historian\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/H-G-Wells\" data-show-preview=\"true\">H.G. Wells<\/a>\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/infused\" data-term=\"infused\" data-type=\"EB\">infused<\/a>\u00a0their stories with descriptions of outer space and of spaceflight that were consistent with the best understanding of the time. Verne\u2019s\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/From-the-Earth-to-the-Moon-novel-by-Verne\" data-show-preview=\"true\"><em>De la Terre \u00e0 la Lune<\/em><\/a>\u00a0(1865;\u00a0<em>From the Earth to the Moon<\/em>) and Wells\u2019s\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/The-War-of-the-Worlds-novel-by-Wells\" data-show-preview=\"true\"><em>The War of the Worlds<\/em><\/a>\u00a0(1898) and\u00a0<em>The First Men in the Moon<\/em>\u00a0(1901) used sound scientific principles to describe space travel and encounters with alien beings.<\/p>\r\n<p class=\"topic-paragraph\">In order to translate these fictional images of space travel into reality, it was necessary to devise some practical means of countering the influence of Earth\u2019s\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/gravity-physics\" data-show-preview=\"true\">gravity<\/a>. By the beginning of the 20th century, the centuries-old technology of rockets had advanced to the point at which it was reasonable to consider their use to accelerate objects to a\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/velocity\" data-show-preview=\"true\">velocity<\/a>\u00a0sufficient to enter\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/orbit-astronomy\" data-show-preview=\"true\">orbit<\/a>\u00a0around\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Earth\" data-show-preview=\"true\">Earth<\/a>\u00a0and even to escape Earth\u2019s gravity and travel away from the\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/planet\" data-show-preview=\"true\">planet<\/a>.<\/p>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237029\" data-level=\"4\" data-has-spy=\"true\">\r\n<h2 class=\"h4\"><span id=\"ref520277\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Konstantin-Eduardovich-Tsiolkovsky\" data-show-preview=\"true\"><strong>Tsiolkovsky<\/strong><\/a><\/h2>\r\n<p class=\"topic-paragraph\">The first person to study in detail the use of\u00a0<span id=\"ref838684\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/rocket-jet-propulsion-device-and-vehicle\" data-show-preview=\"true\">rockets<\/a>\u00a0for spaceflight was the Russian schoolteacher and mathematician\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Konstantin-Eduardovich-Tsiolkovsky\" data-show-preview=\"true\">Konstantin Tsiolkovsky<\/a>. In 1903 his article \u201cExploration of\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/Cosmic\" data-term=\"Cosmic\" data-type=\"EB\">Cosmic<\/a>\u00a0Space by Means of Reaction Devices\u201d laid out many of the principles of spaceflight. Up to his death in 1935, Tsiolkovsky continued to publish sophisticated studies on the theoretical aspects of\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/spaceflight\" data-show-preview=\"true\">spaceflight<\/a>. He never complemented his writings with practical experiments in rocketry, but his work greatly influenced later space and rocket research in the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Soviet-Union\" data-show-preview=\"true\">Soviet Union<\/a>\u00a0and Europe.<\/p>\r\n<\/section>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237030\" data-level=\"4\" data-has-spy=\"true\">\r\n<h2 class=\"h4\"><span id=\"ref520278\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Robert-Goddard\" data-show-preview=\"true\"><strong>Goddard<\/strong><\/a><\/h2>\r\n<div class=\"assemblies multiple medialist slider js-slider position-relative d-inline-flex align-items-center mw-100\" data-type=\"other\">\r\n<div class=\"slider-container js-slider-container overflow-hidden d-flex rw-slider rw-prev-disabled\">\r\n<div class=\"rw-track d-flex align-items-center\">\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"141793\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/78\/137478-050-5B25BB90\/Robert-Goddard-Worcester-Clark-University-Massachusetts-1924.jpg\" data-href=\"\/media\/1\/557348\/141793\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/78\/137478-050-5B25BB90\/Robert-Goddard-Worcester-Clark-University-Massachusetts-1924.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/78\/137478-050-5B25BB90\/Robert-Goddard-Worcester-Clark-University-Massachusetts-1924.jpg?w=300\" alt=\"Robert Goddard\" width=\"1097\" height=\"834\" data-width=\"1600\" data-height=\"1217\" \/><\/picture><\/a>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">1 of 3<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/78\/137478-050-5B25BB90\/Robert-Goddard-Worcester-Clark-University-Massachusetts-1924.jpg\" data-href=\"\/media\/1\/557348\/141793\">Robert Goddard<\/a>Robert Goddard, Clark University, Worcester, Massachusetts, 1924.<\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"141796\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/81\/137481-050-E5560DA7\/Diagram-Robert-Goddard-rocket-altitude-launch-site-1926.jpg\" data-href=\"\/media\/1\/557348\/141796\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/81\/137481-050-E5560DA7\/Diagram-Robert-Goddard-rocket-altitude-launch-site-1926.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/81\/137481-050-E5560DA7\/Diagram-Robert-Goddard-rocket-altitude-launch-site-1926.jpg?w=300\" alt=\"Robert Goddard\" width=\"1178\" height=\"1673\" data-width=\"1129\" data-height=\"1600\" \/><\/picture><\/a>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">2 of 3<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/81\/137481-050-E5560DA7\/Diagram-Robert-Goddard-rocket-altitude-launch-site-1926.jpg\" data-href=\"\/media\/1\/557348\/141796\">Robert Goddard<\/a>Diagram of Robert Goddard&#8217;s liquid oxygen\u2013gasoline rocket. The rocket\u2014launched in 1926\u2014flew for 2.5 seconds, reached an altitude of 12.5 metres (41 feet), and landed 56 metres (184 feet) away from the launch site.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"107214\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/11\/102511-050-8E5CEFA8\/rocket-Robert-H-Goddard-frame-Auburn-Mass-March-16-1926.jpg\" data-href=\"\/media\/1\/557348\/107214\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/11\/102511-050-8E5CEFA8\/rocket-Robert-H-Goddard-frame-Auburn-Mass-March-16-1926.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/11\/102511-050-8E5CEFA8\/rocket-Robert-H-Goddard-frame-Auburn-Mass-March-16-1926.jpg?w=300\" alt=\"Robert H. Goddard and rocket\" width=\"1108\" height=\"1363\" data-width=\"1303\" data-height=\"1600\" \/><\/picture><\/a>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">3 of 3<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/11\/102511-050-8E5CEFA8\/rocket-Robert-H-Goddard-frame-Auburn-Mass-March-16-1926.jpg\" data-href=\"\/media\/1\/557348\/107214\">Robert H. Goddard and rocket<\/a>Robert H. Goddard and a liquid oxygen\u2013gasoline rocket in its frame; the rocket was first fired on March 16, 1926, at Auburn, Massachusetts.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<button class=\"prev-button js-prev-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20 rw-disabled\" disabled=\"disabled\"><\/button><button class=\"next-button js-next-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20\"><\/button><\/div>\r\n<p class=\"topic-paragraph\">In the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/United-States\" data-show-preview=\"true\">United States<\/a>,\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Robert-Goddard\" data-show-preview=\"true\">Robert Hutchings Goddard<\/a>\u00a0became interested in space exploration after reading works such as\u00a0<em><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/The-War-of-the-Worlds-novel-by-Wells\" data-show-preview=\"true\">The War of the Worlds<\/a><\/em>. Even as a young man, he dedicated himself to working on spaceflight. In his 1904 high-school graduation speech, he stated that \u201cit is difficult to say what is impossible, for the dream of yesterday is the hope of today and the reality of tomorrow.\u201d Goddard received his first two patents for\u00a0<span id=\"ref838676\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/rocket-jet-propulsion-device-and-vehicle\" data-show-preview=\"true\">rocket<\/a>\u00a0technology in 1914, and, with funding from the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/Smithsonian-Institution\" data-show-preview=\"true\">Smithsonian Institution<\/a>, he published a theoretical\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/treatise\" data-term=\"treatise\" data-type=\"MW\">treatise<\/a>,\u00a0<em><span id=\"ref838677\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/A-Method-of-Reaching-Extreme-Altitudes\">A Method of Reaching Extreme Altitudes<\/a><\/em>, in 1919. Goddard\u2019s claim that rockets could be used to send objects as far as the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Moon\" data-show-preview=\"true\">Moon<\/a>\u00a0was widely ridiculed in the public press, including\u00a0<em><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/The-New-York-Times\" data-show-preview=\"true\">The New York Times<\/a><\/em>\u00a0(which published a retraction on July 17, 1969, the day after the launch of the first crewed mission to the Moon). Thereafter, the already shy Goddard conducted much of his work in secret, preferring to patent rather than publish his results. This approach limited his influence on the development of American rocketry, although early rocket developers in\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Germany\" data-show-preview=\"true\">Germany<\/a>\u00a0took notice of his work.<\/p>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"141792\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/76\/137476-050-3B78041A\/Photograph-Charles-A-Lindbergh-Robert-Goddard-rocket-September-23-1935.jpg\" data-href=\"\/media\/1\/557348\/141792\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/76\/137476-050-3B78041A\/Photograph-Charles-A-Lindbergh-Robert-Goddard-rocket-September-23-1935.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/76\/137476-050-3B78041A\/Photograph-Charles-A-Lindbergh-Robert-Goddard-rocket-September-23-1935.jpg?w=300\" alt=\"Robert Goddard: rocket\" width=\"1204\" height=\"1541\" data-width=\"1250\" data-height=\"1600\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/76\/137476-050-3B78041A\/Photograph-Charles-A-Lindbergh-Robert-Goddard-rocket-September-23-1935.jpg\" data-href=\"\/media\/1\/557348\/141792\">Robert Goddard: rocket<\/a>One of Robert Goddard&#8217;s rockets, photograph by Col. Charles A. Lindbergh from atop the launching tower, Roswell, New Mexico, September 23, 1935.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">In the 1920s, as a professor of physics at\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/Clark-University\" data-show-preview=\"true\">Clark University<\/a>\u00a0in Worcester, Massachusetts, Goddard began to experiment with liquid-fueled rockets. His first rocket, launched in Auburn, Massachusetts, on March 16, 1926, rose 12.5 metres (41 feet) and traveled 56 metres (184 feet) from its launching place. The noisy character of his experiments made it difficult for Goddard to continue work in Massachusetts. With support from aviator\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Charles-Lindbergh\" data-show-preview=\"true\">Charles A. Lindbergh<\/a>\u00a0and financial assistance from the philanthropic\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/money\/Daniel-Guggenheim\" data-show-preview=\"true\">Daniel Guggenheim<\/a>\u00a0Fund for the Promotion of Aeronautics, he moved to Roswell,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/New-Mexico\" data-show-preview=\"true\">New Mexico<\/a>, where from 1930 to 1941 he built engines and launched rockets of increasing\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/complexity\" data-term=\"complexity\" data-type=\"EB\">complexity<\/a>.<\/p>\r\n<a class=\"link-module shadow-sm d-block qa-quiz-module\" href=\"https:\/\/www.britannica.com\/quiz\/famous-astronauts-and-cosmonauts\" data-link-module-iframe-link=\"\"><img decoding=\"async\" class=\"rounded-sm mr-15\" src=\"https:\/\/cdn.britannica.com\/14\/188714-131-87D4E380\/moon-Edwin-E-Aldrin-Apollo-11.jpg\" alt=\"Edwin E. Aldrin (Buzz Aldrin) stands on the moon, Apollo 11\" width=\"70\" \/><\/a>\r\n<div class=\"line-clamp clamp-5\">\r\n<div class=\"module-title bg-green\">Britannica Quiz<\/div>\r\n<div class=\"font-weight-semi-bold mt-5\">Famous Astronauts and Cosmonauts<\/div>\r\n<\/div>\r\n<\/section>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237031\" data-level=\"4\" data-has-spy=\"true\">\r\n<h2 class=\"h4\"><span id=\"ref520279\"><\/span><strong><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Hermann-Julius-Oberth\" data-show-preview=\"true\">Oberth<\/a><\/strong><\/h2>\r\n<p class=\"topic-paragraph\">The third widely recognized pioneer of\u00a0<span id=\"ref838686\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/rocket-jet-propulsion-device-and-vehicle\" data-show-preview=\"true\">rocketry<\/a>,\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Hermann-Julius-Oberth\" data-show-preview=\"true\">Hermann Oberth<\/a>, was by birth a Romanian but by nationality a German. Reading Verne\u2019s\u00a0<em>From the Earth to the Moon<\/em>\u00a0as a youth inspired him to study the requirements for interplanetary travel. Oberth\u2019s 1922 doctoral dissertation on rocket-powered flight was rejected by the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/University-of-Heidelberg\" data-show-preview=\"true\">University of Heidelberg<\/a>\u00a0for being too speculative, but it became the basis for his classic 1923 book\u00a0<em><span id=\"ref838691\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Die-Rakete-zu-den-Planetenraumen\">Die Rakete zu den Planetenr\u00e4umen<\/a><\/em>\u00a0(\u201cThe Rocket into Interplanetary Space\u201d). The work explained the mathematical theory of rocketry, applied the theory to rocket design, and discussed the possibility of constructing space stations and of traveling to other planets.<\/p>\r\n<p class=\"topic-paragraph\">In 1929 Oberth published a second influential book,\u00a0<em>Wege zur Raumschiffahrt<\/em>\u00a0(<em><span id=\"ref838692\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Ways-to-Spaceflight\">Ways to Spaceflight<\/a><\/em>). His works led to the creation of a number of rocket clubs in Germany as\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/enthusiasts\" data-term=\"enthusiasts\" data-type=\"EB\">enthusiasts<\/a>\u00a0tried to turn Oberth\u2019s ideas into practical devices. The most important of these groups historically was the Verein f\u00fcr Raumschiffahrt (VfR; \u201cSociety for Spaceship Travel\u201d), which had as a member the young\u00a0<span id=\"ref520283\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Wernher-von-Braun\" data-show-preview=\"true\">Wernher von Braun<\/a>. Although Oberth\u2019s work was crucial in stimulating the development of rocketry in Germany, he himself had only a limited role in that development. Alone among the rocket pioneers, Oberth lived to see his ideas become reality: he was Braun\u2019s guest at the July 16, 1969, launch of\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/Apollo-11\" data-show-preview=\"true\">Apollo 11<\/a>.<\/p>\r\n<\/section>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237032\" data-level=\"4\" data-has-spy=\"true\">\r\n<h2 class=\"h4\"><strong>Other space pioneers<\/strong><\/h2>\r\n<p class=\"topic-paragraph\">Although Tsiolkovsky, Goddard, and Oberth are recognized as the most influential of the first-generation space pioneers, others made contributions in the early decades of the 20th century. For example, the Frenchman\u00a0<span id=\"ref838693\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Robert-Esnault-Pelterie\" data-show-preview=\"true\">Robert Esnault-Pelterie<\/a>\u00a0began work on the\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/theoretical\" data-term=\"theoretical\" data-type=\"EB\">theoretical<\/a>\u00a0aspects of spaceflight as early as 1907 and subsequently published several major books on the topic. He, like Tsiolkovsky in the Soviet Union and Oberth in Germany, was an effective publicist regarding the potential of space exploration. In\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Austria\" data-show-preview=\"true\">Austria<\/a>,\u00a0<span id=\"ref838696\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Eugen-Sanger\" data-show-preview=\"true\">Eugen S\u00e4nger<\/a>\u00a0worked on rocket engines and in the late 1920s proposed developing a \u201crocket plane\u201d that could reach a speed exceeding 10,000 km (more than 6,000 miles) per hour and an altitude of more than 65 km (40 miles). Interested in S\u00e4nger\u2019s work, Nazi Germany in 1936 invited him to continue his investigations in that country.<\/p>\r\n<\/section>\r\n<\/section>\r\n<\/section>\r\n<\/section>\r\n<\/div>\r\n<div id=\"chatbot-root\">\u00a0<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div data-page-index=\"2\">\u00a0<\/div>\r\n<div class=\"loaded-infinite-scroll-container qa-infinite-scroll-container\">\r\n<div class=\"grey-box w-100 \">\r\n<div class=\"grey-box-content mx-auto w-100\">\r\n<div class=\"page2ref-false topic-content topic-type-REGULAR\">\r\n<div class=\"reading-channel\">\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237033\" data-level=\"3\" data-has-spy=\"true\">\r\n<h1 class=\"h3\"><strong>Early rocket development<\/strong><\/h1>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237034\" data-level=\"4\" data-has-spy=\"true\">\r\n<h2 class=\"h4\"><span id=\"ref838699\"><\/span><strong><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Germany\" data-show-preview=\"true\">Germany<\/a><\/strong><\/h2>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"3690\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/09\/4609-050-33F555A7\/Test-launch-rocket-V-2.jpg\" data-href=\"\/media\/1\/557348\/3690\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/09\/4609-050-33F555A7\/Test-launch-rocket-V-2.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/09\/4609-050-33F555A7\/Test-launch-rocket-V-2.jpg?w=300\" alt=\"V-2\" width=\"1134\" height=\"1448\" data-width=\"1045\" data-height=\"1335\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/09\/4609-050-33F555A7\/Test-launch-rocket-V-2.jpg\" data-href=\"\/media\/1\/557348\/3690\">V-2<\/a>Test launch of a V-2 rocket.<\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">It was space exploration that motivated the members of the German VfR to build their rockets, but in the early 1930s their work came to the attention of the German military. In 1932\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Wernher-von-Braun\" data-show-preview=\"true\">Wernher von Braun<\/a>, at age 20, became chief engineer of a rocket-development team for the German army. After\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/biography\/Adolf-Hitler\" data-show-preview=\"true\">Adolf Hitler<\/a>\u00a0came to power in 1933, Braun was named the civilian head of that team, under the military command of\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Walter-Robert-Dornberger\" data-show-preview=\"true\">Walter Robert Dornberger<\/a>. To give Braun\u2019s engineers the needed space and secrecy for their work, the German government erected a development and test centre at Peenem\u00fcnde on the coast of the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Baltic-Sea\" data-show-preview=\"true\">Baltic Sea<\/a>. There they developed, among other devices, the\u00a0<span id=\"ref520282\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/V-2-rocket\" data-show-preview=\"true\">V-2<\/a>\u00a0(originally\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/designated\" data-term=\"designated\" data-type=\"EB\">designated<\/a>\u00a0the A-4)\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/ballistic-missile\" data-show-preview=\"true\">ballistic missile<\/a>. First launched successfully in 1942, the V-2 was used on targets in Europe beginning in September 1944. Although built as a weapon of war, the V-2 later served as the predecessor of many of the rockets used in the early space programs of the United States and the Soviet Union. As\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/event\/World-War-II\" data-show-preview=\"true\">World War II<\/a>\u00a0neared its end in early 1945, Braun and many of his associates chose to surrender to the United States, where they believed they would likely receive support for their\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/rocket-jet-propulsion-device-and-vehicle\" data-show-preview=\"true\">rocket<\/a>\u00a0research and space exploration plans. Later in the year they were taken to the United States, as were their engineering plans and the parts needed to construct a number of V-2s. The German rocket team played a central role in the early development of space launchers for the United States.<\/p>\r\n<\/section>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237035\" data-level=\"4\" data-has-spy=\"true\">\r\n<h2 class=\"h4\"><span id=\"ref520264\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/United-States\" data-show-preview=\"true\"><strong>United States<\/strong><\/a><\/h2>\r\n<p class=\"topic-paragraph\">In 1936, as Braun was developing rockets for the German military, several young American engineers led by graduate student\u00a0<span id=\"ref838700\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Frank-J-Malina\">Frank Malina<\/a>\u00a0began working on rocketry at the Guggenheim Aeronautical Laboratory of the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/California-Institute-of-Technology\" data-show-preview=\"true\">California Institute of Technology<\/a>\u00a0(GALCIT). Malina\u2019s group was supported by the\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/eminent\" data-term=\"eminent\" data-type=\"EB\">eminent<\/a>\u00a0aerodynamicist\u00a0<span id=\"ref838701\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Theodore-von-Karman\" data-show-preview=\"true\">Theodore von K\u00e1rm\u00e1n<\/a>, GALCIT\u2019s director, and it included Chinese engineer\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Qian-Xuesen\" data-show-preview=\"true\">Qian Xuesen<\/a>\u00a0(Ch\u2019ien Hs\u00fceh-sen), who in the 1950s returned home to become one of the pioneers of rocketry in\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/China\" data-show-preview=\"true\">China<\/a>. In 1943 Malina and his associates began calling their group the\u00a0<span id=\"ref838702\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Jet-Propulsion-Laboratory\">Jet Propulsion Laboratory<\/a>\u00a0(JPL), a name that was formally adopted the following year. JPL soon became a centre for missile\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/research-and-development\" data-show-preview=\"true\">research and development<\/a>\u00a0for the U.S. Army. Following World War II, those weapons were adapted for use in early U.S. space experiments. After 1958, when it became part of the newly established\u00a0<span id=\"ref520285\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/NASA\" data-show-preview=\"true\">National Aeronautics and Space Administration<\/a>\u00a0(NASA), JPL adapted itself to being the leading U.S. centre for\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/solar-system\" data-show-preview=\"true\">solar system<\/a>\u00a0exploration.<\/p>\r\n<\/section>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237036\" data-level=\"4\" data-has-spy=\"true\">\r\n<h2 class=\"h4\"><span id=\"ref838661\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Soviet-Union\" data-show-preview=\"true\"><strong>Soviet Union<\/strong><\/a><\/h2>\r\n<p class=\"topic-paragraph\">In the U.S.S.R. the government took an interest in rockets as early as 1921 with the founding of a military facility devoted to rocket research. Over the next decade that centre was expanded and renamed the\u00a0<span id=\"ref838707\"><\/span>Gas Dynamics Laboratory. There in the early 1930s,\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Valentin-Petrovich-Glushko\" data-show-preview=\"true\">Valentin Glushko<\/a>\u00a0carried out pioneering work on rocket engines. Meanwhile, other rocket enthusiasts in the Soviet Union organized into societies that by 1931 had consolidated into an organization known as\u00a0<span id=\"ref838706\"><\/span>GIRD (the abbreviation in Russian for \u201cGroup for the Study of Reactive Motion\u201d), with branches in Moscow and Leningrad. Emerging as leaders of the Moscow branch were the aeronautical engineer\u00a0<span id=\"ref838708\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Sergei-Korolev\" data-show-preview=\"true\">Sergei Korolev<\/a>, who had become interested in\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/spaceflight\" data-show-preview=\"true\">spaceflight<\/a>\u00a0at a young age, and the early space visionary Fridrikh Tsander. Korolyov and a colleague, Mikhail Tikhonravov, on August 17, 1933, launched the first Soviet liquid-fueled rocket. Later that year the Moscow and Leningrad branches of GIRD were combined with the Gas\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/Dynamics\" data-term=\"Dynamics\" data-type=\"MW\">Dynamics<\/a>\u00a0Laboratory to form the military-controlled Rocket Propulsion Research Institute (RNII), which five years later became\u00a0<span id=\"ref838710\"><\/span>Scientific-Research Institute 3 (NII-3). In its early years the organization did not work directly on space technology, but ultimately it played a central role in Soviet rocket development.<\/p>\r\n<p class=\"topic-paragraph\">Korolyov was arrested in 1937 as part of the Soviet leader\u00a0<span id=\"ref838723\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Joseph-Stalin\/Lenins-successor#ref13391\" data-show-preview=\"true\">Joseph Stalin\u2019s great purges<\/a>\u00a0of\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/intellectuals\" data-term=\"intellectuals\" data-type=\"MW\">intellectuals<\/a>\u00a0and was sent to a Siberian prison. After Stalin recognized the imprudence of removing the best technical people from the Soviet war effort, Korolyov was transferred to a prison-based design bureau, where he spent most of World War II working on weapons, although not on large rockets. By the end of the war, Stalin had become interested in\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/ballistic\" data-term=\"ballistic\" data-type=\"MW\">ballistic<\/a>\u00a0missiles, and he sent a team, which included Korolyov, on visits to Germany to investigate the V-2 program. A number of German engineers were relocated to the Soviet Union in the aftermath of the war, but they did not play a central role in postwar Soviet rocket development; most returned to Germany in the early 1950s.<\/p>\r\n<\/section>\r\n<\/section>\r\n<\/div>\r\n<div id=\"chatbot-root\">\u00a0<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div data-page-index=\"3\">\u00a0<\/div>\r\n<div class=\"loaded-infinite-scroll-container qa-infinite-scroll-container\">\r\n<div class=\"grey-box w-100 \">\r\n<div class=\"grey-box-content mx-auto w-100\">\r\n<div class=\"page2ref-false topic-content topic-type-REGULAR\">\r\n<div class=\"reading-channel\">\r\n<section data-level=\"2\">\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237037\" data-level=\"3\" data-has-spy=\"true\">\r\n<h1 class=\"h3\"><strong>Preparing for spaceflight<\/strong><\/h1>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"73049\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/76\/75376-050-6CE7D5D7\/Frank-Malina-steelwork-model-research-rocket-Jet.jpg\" data-href=\"\/media\/1\/557348\/73049\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/76\/75376-050-6CE7D5D7\/Frank-Malina-steelwork-model-research-rocket-Jet.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/76\/75376-050-6CE7D5D7\/Frank-Malina-steelwork-model-research-rocket-Jet.jpg?w=300\" alt=\"Frank Malina and WAC Corporal rocket\" width=\"1109\" height=\"1412\" data-width=\"1256\" data-height=\"1600\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/76\/75376-050-6CE7D5D7\/Frank-Malina-steelwork-model-research-rocket-Jet.jpg\" data-href=\"\/media\/1\/557348\/73049\">Frank Malina and WAC Corporal rocket<\/a>Frank Malina, a cofounder of the Jet Propulsion Laboratory, pictured with an early model of the WAC Corporal research rocket. The surrounding steelwork is the lower section of the vertical launch tower.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">Between 1946 and 1951, the\u00a0<span id=\"ref838725\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/The-United-States-Army\" data-show-preview=\"true\">U.S. Army<\/a>\u00a0conducted test firings of captured German V-2 rockets at White Sands,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/New-Mexico\" data-show-preview=\"true\">New Mexico<\/a>. These sounding-rocket flights reached high\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/altitudes\" data-term=\"altitudes\" data-type=\"EB\">altitudes<\/a>\u00a0(120\u2013200 km [75\u2013125 miles]) before falling back to Earth. Although the primary purpose of the tests was to advance\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/rocket-jet-propulsion-device-and-vehicle\" data-show-preview=\"true\">rocket<\/a>\u00a0technology, the army invited American scientists interested in high-altitude research to put experiments aboard the V-2s. An\u00a0<span id=\"ref838726\"><\/span>Upper Atmosphere Research Panel, chaired by the physicist\u00a0<span id=\"ref838749\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/James-A-Van-Allen\" data-show-preview=\"true\">James Van Allen<\/a>, was formed to coordinate the scientific use of these rocket launchings. The panel had a central role in the early years of American space\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/science\" data-show-preview=\"true\">science<\/a>, which focused on experiments on solar and stellar\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/ultraviolet-radiation\" data-show-preview=\"true\">ultraviolet radiation<\/a>, the aurora, and the nature of the upper atmosphere. As the supply of V-2s dwindled, other U.S.-built sounding rockets such as the WAC Corporal, Aerobee, and\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/Viking-space-probe\" data-show-preview=\"true\">Viking<\/a>\u00a0were put into use. In other countries, particularly the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Soviet-Union\" data-show-preview=\"true\">Soviet Union<\/a>, rocket-based upper-atmosphere research also took place after\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/event\/World-War-II\" data-show-preview=\"true\">World War II<\/a>.<\/p>\r\n<p class=\"topic-paragraph\">In the early 1950s scientists began planning a coordinated international investigation of Earth, to be called the\u00a0<span id=\"ref520284\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/event\/International-Geophysical-Year\" data-show-preview=\"true\">International Geophysical Year<\/a>\u00a0(IGY), that would be held in 1957\u201358 under the\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/auspices\" data-term=\"auspices\" data-type=\"MW\">auspices<\/a>\u00a0of the International Council of Scientific Unions. By this time, progress in rocket development had advanced such that orbiting of an artificial\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/Earth-satellite\" data-show-preview=\"true\">Earth satellite<\/a>\u00a0by 1957 seemed\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/feasible\" data-term=\"feasible\" data-type=\"MW\">feasible<\/a>. At the urging of American scientists, IGY planners in 1954 called for scientifically instrumented satellites to be launched as part of IGY activities. Soon thereafter, the governments of the Soviet Union and the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/United-States\" data-show-preview=\"true\">United States<\/a>\u00a0each announced plans to do so.<\/p>\r\n<p class=\"topic-paragraph\">In the years following World War II, the United States and the U.S.S.R. became political and military competitors in what soon was being called the\u00a0<span id=\"ref838728\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/event\/Cold-War\" data-show-preview=\"true\">Cold War<\/a>. Because the Soviet Union was a closed society, U.S. leaders gave high priority to developing technology that could help gather intelligence on military preparations within the Soviet borders. As orbiting satellites neared realization, the idea of equipping such satellites with cameras and flying them over Soviet territory became more attractive to U.S. planners, and the U.S. Air Force began work on a\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/spy-satellite\" data-show-preview=\"true\">reconnaissance satellite<\/a>\u00a0project. Still unresolved, however, was the question of whether it would violate national\u00a0<span id=\"ref838731\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/sovereignty\" data-show-preview=\"true\">sovereignty<\/a>\u00a0to fly over a country\u2019s territory in orbit, above most of the atmosphere. One reason the U.S. government had committed itself to the IGY\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/satellite\" data-show-preview=\"true\">satellite<\/a>\u00a0program was that it wanted to establish the principle that outer space was not subject to claims of territorial\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/sovereignty\" data-term=\"sovereignty\" data-type=\"MW\">sovereignty<\/a>\u00a0and thus that an orbiting satellite could pass freely over any point on Earth. Such overflights were essential if reconnaissance satellites were to have intelligence value.<\/p>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"73128\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/10\/76510-050-67EEC7D6\/The-Day-the-Earth-Stood-Still-image.jpg\" data-href=\"\/media\/1\/557348\/73128\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/10\/76510-050-67EEC7D6\/The-Day-the-Earth-Stood-Still-image.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/10\/76510-050-67EEC7D6\/The-Day-the-Earth-Stood-Still-image.jpg?w=300\" alt=\"The Day the Earth Stood Still\" width=\"1219\" height=\"1552\" data-width=\"1257\" data-height=\"1600\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/10\/76510-050-67EEC7D6\/The-Day-the-Earth-Stood-Still-image.jpg\" data-href=\"\/media\/1\/557348\/73128\"><em>The Day the Earth Stood Still<\/em><\/a>Still image from the American science-fiction film\u00a0<em>The Day the Earth Stood Still<\/em>\u00a0(1951), in which a humanlike being (right) and his powerful robot servant travel from another world to challenge the peoples of a post-World War II Earth to live in peace. The saucer shape of their spacecraft echoes the most popular form of the unidentified flying objects (UFOs) being widely reported at the time.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">As scientific and military planners contemplated initial space projects and engineers worked on developing the needed launch vehicles, the idea that humans would soon begin the exploration of space entered popular imagination. In Europe since the 1930s, the British Interplanetary Society had been actively promoting the idea that human space travel was soon to happen. American movies such as\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/The-Day-the-Earth-Stood-Still-film-1951\" data-show-preview=\"true\"><em>The Day the Earth Stood Still<\/em><\/a>\u00a0(1951),\u00a0<em>Destination Moon<\/em>\u00a0(1950), and\u00a0<em>When Worlds Collide<\/em>\u00a0(1951) contained vivid images of such journeys. Reports were widespread of sightings of\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/unidentified-flying-object\" data-show-preview=\"true\">unidentified flying objects<\/a>\u00a0(UFOs), which were thought by some to be\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/spacecraft\" data-show-preview=\"true\">spacecraft<\/a>\u00a0from alien worlds.<\/p>\r\n<p class=\"topic-paragraph\">Authors such as\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Isaac-Asimov\" data-show-preview=\"true\">Isaac Asimov<\/a>,\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Robert-A-Heinlein\" data-show-preview=\"true\">Robert A. Heinlein<\/a>, and\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Arthur-C-Clarke\" data-show-preview=\"true\">Arthur C. Clarke<\/a>\u00a0both discussed the reality of space technology in popular writings and constructed believable science-fiction stories based on its use. A central figure in popularization efforts within the United States was\u00a0<span id=\"ref838733\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Wernher-von-Braun\" data-show-preview=\"true\">Wernher von Braun<\/a>. A\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/charismatic\" data-term=\"charismatic\" data-type=\"MW\">charismatic<\/a>\u00a0spokesman for the idea of space travel, Braun, in a series of talks, books, magazine articles, and television appearances during the 1950s, reached millions of people with his ideas for establishing orbiting space stations and human travel to the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Moon\" data-show-preview=\"true\">Moon<\/a>\u00a0and\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Mars-planet\" data-show-preview=\"true\">Mars<\/a>. The efforts of Braun and other popularizers helped create a receptive climate for initial government proposals to undertake space activities and, particularly, to put humans in space.<\/p>\r\n<a class=\"link-module shadow-sm d-block qa-read-more-module\" href=\"https:\/\/www.britannica.com\/story\/will-light-speed-space-travel-ever-be-possible\" data-link-module-iframe-link=\"\"><img decoding=\"async\" class=\"rounded-sm mr-15\" src=\"https:\/\/cdn.britannica.com\/25\/95925-118-033998AE\/Launch-space-shuttle-Discovery-July-2006.jpg\" alt=\"July, 2006, Launch of Space Shuttle Discovery STS-121. See attached for full caption information.\" width=\"70\" \/><\/a>\r\n<div class=\"line-clamp clamp-5\">\r\n<div class=\"module-title bg-navy-dark\">More From Britannica<\/div>\r\n<div class=\"font-weight-semi-bold mt-5\">Will Light-Speed Space Travel Ever Be Possible?<\/div>\r\n<\/div>\r\n<\/section>\r\n<\/section>\r\n<\/div>\r\n<div id=\"chatbot-root\">\u00a0<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div data-page-index=\"4\">\u00a0<\/div>\r\n<div class=\"loaded-infinite-scroll-container qa-infinite-scroll-container\">\r\n<div class=\"grey-box w-100 \">\r\n<div class=\"grey-box-content mx-auto w-100\">\r\n<div class=\"page2ref-false topic-content topic-type-REGULAR\">\r\n<div class=\"reading-channel\">\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237038\" data-level=\"2\" data-has-spy=\"true\">\r\n<h1 class=\"h2\"><strong>From Sputnik to Apollo<\/strong><\/h1>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237039\" data-level=\"3\" data-has-spy=\"true\">\r\n<h2 class=\"h3\"><strong>The first satellites<\/strong><\/h2>\r\n<div class=\"assemblies multiple medialist slider js-slider position-relative d-inline-flex align-items-center mw-100\" data-type=\"other\">\r\n<div class=\"slider-container js-slider-container overflow-hidden d-flex rw-slider rw-prev-disabled\">\r\n<div class=\"rw-track d-flex align-items-center\">\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"155664\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/64\/145464-050-D9934CA4\/Sputnik-1.jpg\" data-href=\"\/media\/1\/557348\/155664\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/64\/145464-050-D9934CA4\/Sputnik-1.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/64\/145464-050-D9934CA4\/Sputnik-1.jpg?w=300\" alt=\"Sputnik 1\" width=\"1113\" height=\"913\" data-width=\"1094\" data-height=\"896\" \/><\/picture><\/a>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">1 of 3<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/64\/145464-050-D9934CA4\/Sputnik-1.jpg\" data-href=\"\/media\/1\/557348\/155664\">Sputnik 1<\/a><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"2908\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/43\/443-050-8C4AD4BD\/Sputnik-3-orbit-composition-measurements-pressure-concentration-May-15-1958.jpg\" data-href=\"\/media\/1\/557348\/2908\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/43\/443-050-8C4AD4BD\/Sputnik-3-orbit-composition-measurements-pressure-concentration-May-15-1958.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/43\/443-050-8C4AD4BD\/Sputnik-3-orbit-composition-measurements-pressure-concentration-May-15-1958.jpg?w=300\" alt=\"Sputnik 3\" width=\"1436\" height=\"1513\" data-width=\"793\" data-height=\"836\" \/><\/picture><\/a>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">2 of 3<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/43\/443-050-8C4AD4BD\/Sputnik-3-orbit-composition-measurements-pressure-concentration-May-15-1958.jpg\" data-href=\"\/media\/1\/557348\/2908\">Sputnik 3<\/a>Sputnik 3, the first multipurpose space-science satellite placed in orbit. Launched May 15, 1958, by the Soviet Union, it made and transmitted measurements of the pressure and composition of Earth&#8217;s upper atmosphere, the concentration of charged particles, and the influx of primary cosmic rays.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"107443\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/86\/104286-050-F7A063C6\/Laika-creature-space-Sputnik-2-November-1957.jpg\" data-href=\"\/media\/1\/557348\/107443\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/86\/104286-050-F7A063C6\/Laika-creature-space-Sputnik-2-November-1957.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/86\/104286-050-F7A063C6\/Laika-creature-space-Sputnik-2-November-1957.jpg?w=300\" alt=\"Laika\" width=\"1298\" height=\"995\" data-width=\"1600\" data-height=\"1229\" \/><\/picture><\/a>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">3 of 3<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/86\/104286-050-F7A063C6\/Laika-creature-space-Sputnik-2-November-1957.jpg\" data-href=\"\/media\/1\/557348\/107443\">Laika<\/a>Laika, the dog who became the first living creature sent into space, aboard Sputnik 2, November 1957.<\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<button class=\"prev-button js-prev-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20 rw-disabled\" disabled=\"disabled\"><\/button><button class=\"next-button js-next-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20\"><\/button><\/div>\r\n<p class=\"topic-paragraph\">Although Soviet plans to orbit a\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/satellite\" data-show-preview=\"true\">satellite<\/a>\u00a0during the IGY had been discussed extensively in technical circles, the October 4, 1957, launch of\u00a0<span id=\"ref838735\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Sputnik\" data-show-preview=\"true\">Sputnik<\/a>\u00a01 came as a surprise, and even a shock, to most people. Prior to the launch,\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/skepticism\" data-term=\"skepticism\" data-type=\"MW\">skepticism<\/a>\u00a0had been widespread about the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Soviet-Union\" data-show-preview=\"true\">U.S.S.R.\u2019s<\/a>\u00a0technical capabilities to develop both a sophisticated scientific satellite and a\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/rocket-jet-propulsion-device-and-vehicle\" data-show-preview=\"true\">rocket<\/a>\u00a0powerful enough to put it into orbit. Under Korolyov\u2019s direction, however, the Soviet Union had been building an\u00a0<span id=\"ref838745\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/ICBM\" data-show-preview=\"true\">intercontinental ballistic missile<\/a>\u00a0(<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/ICBM\" data-show-preview=\"true\">ICBM<\/a>), with engines designed by Glushko, that was capable of delivering a heavy\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/thermonuclear-warhead\" data-show-preview=\"true\">nuclear warhead<\/a>\u00a0to American targets. That ICBM, called the\u00a0<span id=\"ref838738\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/R-7\" data-show-preview=\"true\">R-7<\/a>\u00a0or Semyorka (\u201cNumber 7\u201d), was first successfully tested on August 21, 1957, which cleared the way for its use to launch a satellite. Fearing that development of the\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/elaborate\" data-term=\"elaborate\" data-type=\"EB\">elaborate<\/a>\u00a0scientific satellite intended as the Soviet IGY contribution would keep the U.S.S.R. from being the first into space, Korolyov and his associates, particularly Tikhonravov, designed a much simpler 83.6-kg (184.3-pound) sphere carrying only two\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/radio\" data-show-preview=\"true\">radio<\/a>\u00a0transmitters and four\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/antenna-electronics\" data-show-preview=\"true\">antennas<\/a>. After the success of the R-7 in August, that satellite was rushed into production and became Sputnik 1. A second, larger satellite carrying scientific instruments and the dog\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Laika\" data-show-preview=\"true\">Laika<\/a>, the first living creature in orbit, was launched November 3. The even larger, instrumented\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/spacecraft\" data-show-preview=\"true\">spacecraft<\/a>\u00a0originally intended to be the first Soviet satellite went into orbit in May 1958 as Sputnik 3. (For additional information on Korolyov\u2019s contribution to the Soviet space program,\u00a0<em>see<\/em>\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/money\/Energia-Russian-company\" data-show-preview=\"true\">Energia<\/a>.)<\/p>\r\n<p class=\"topic-paragraph\">After President\u00a0<span id=\"ref838765\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Dwight-D-Eisenhower\" data-show-preview=\"true\">Eisenhower<\/a>, in May 1955, had committed the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/United-States\" data-show-preview=\"true\">United States<\/a>\u00a0to an IGY satellite, the army, navy, and\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/air-force\" data-show-preview=\"true\">air force<\/a>\u00a0competed for the assignment. (No civilian organization existed that was capable of developing the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/launch-vehicle\" data-show-preview=\"true\">launch vehicle<\/a>\u00a0needed.) The mission was assigned to the Naval Research Laboratory rather than to the army\u2019s\u00a0<span id=\"ref838753\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Redstone-rocket\">Redstone<\/a>\u00a0Arsenal, where Braun worked, so that the work would not interfere with Redstone\u2019s higher-priority development of\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/ballistic\" data-term=\"ballistic\" data-type=\"MW\">ballistic<\/a>\u00a0missiles. The navy project, called\u00a0<span id=\"ref838748\"><\/span>Vanguard, would use a new launch vehicle based on modified\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/Viking-space-probe\" data-show-preview=\"true\">Viking<\/a>\u00a0and Aerobee sounding rockets to orbit a small scientific satellite.\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/Vanguard-satellite\" data-show-preview=\"true\">Vanguard<\/a>\u00a0made slow progress over the subsequent two years, but, after Sputnik\u2019s success, the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/White-House-Washington-DC\" data-show-preview=\"true\">White House<\/a>\u00a0pressed to have the satellite launched as quickly as possible. On December 6, 1957, the Vanguard rocket rose only slightly off its launch pad before exploding and sending the satellite not into orbit but onto a Florida beach.<\/p>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"73129\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/09\/76509-050-48FA8213\/William-H-Pickering-James-Van-Allen-model-January-31-1958.jpg\" data-href=\"\/media\/1\/557348\/73129\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/09\/76509-050-48FA8213\/William-H-Pickering-James-Van-Allen-model-January-31-1958.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/09\/76509-050-48FA8213\/William-H-Pickering-James-Van-Allen-model-January-31-1958.jpg?w=300\" alt=\"Explorer 1\" width=\"1238\" height=\"1993\" data-width=\"994\" data-height=\"1600\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/09\/76509-050-48FA8213\/William-H-Pickering-James-Van-Allen-model-January-31-1958.jpg\" data-href=\"\/media\/1\/557348\/73129\">Explorer 1<\/a>(From left) William H. Pickering, James Van Allen, and Wernher von Braun triumphantly raising a full-size model of the first U.S. satellite, Explorer 1, at a press conference following the craft&#8217;s launch on January 31, 1958. A small model of the Jupiter-C launch vehicle stands on a table in front of Braun.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">Braun and his army superiors had not agreed with the decision to assign the satellite mission to the navy. After the launches of the first two Sputniks, they secured permission to attempt their own satellite launch. In anticipation of such a situation, they had kept in touch with JPL and Van Allen and so were able to prepare a satellite quickly. On January 31, 1958, Braun\u2019s Jupiter-C launch vehicle, a modified Redstone\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/ballistic-missile\" data-show-preview=\"true\">ballistic missile<\/a>, carried into orbit\u00a0<span id=\"ref838755\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Explorer-satellites\" data-show-preview=\"true\">Explorer<\/a>\u00a01, the first U.S. satellite. Designed at JPL, Explorer 1 carried Van Allen\u2019s experiment to measure\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/cosmic-ray\" data-show-preview=\"true\">cosmic rays<\/a>. The results from this experiment and similar ones aboard other U.S. and Soviet satellites launched that same year revealed that\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Earth\" data-show-preview=\"true\">Earth<\/a>\u00a0is surrounded by two zones of radiation, now known as the\u00a0<span id=\"ref838758\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/Van-Allen-radiation-belt\" data-show-preview=\"true\">Van Allen radiation belts<\/a>,\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/comprising\" data-term=\"comprising\" data-type=\"MW\">comprising<\/a>\u00a0energetic particles trapped by\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/geomagnetic-field\" data-show-preview=\"true\">Earth\u2019s magnetic field<\/a>.<\/p>\r\n<p class=\"topic-paragraph\">Initial satellite launches were scientific in character, but U.S. government interest in reconnaissance satellites persisted. In February 1958, President Eisenhower authorized the development, under conditions of great secrecy, of such a spacecraft. The project, which came to be called\u00a0<span id=\"ref838767\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Corona-United-States-space-project\">Corona<\/a>, would take pictures over the Soviet Union and return them to Earth by dropping the exposed film in a capsule that would be snatched out of the air as it parachuted back from space. After 12 failures, the first successful\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/Corona\" data-term=\"Corona\" data-type=\"EB\">Corona<\/a>\u00a0mission took place on August 18, 1960; the returned film contained images of many previously unknown Soviet airfields and missile sites.<\/p>\r\n<\/section>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237040\" data-level=\"3\" data-has-spy=\"true\">\r\n<h2 class=\"h3\"><strong>Development of space organizations<\/strong><\/h2>\r\n<\/section>\r\n<\/section>\r\n<\/div>\r\n<div id=\"chatbot-root\">\u00a0<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div data-page-index=\"5\">\u00a0<\/div>\r\n<div class=\"loaded-infinite-scroll-container qa-infinite-scroll-container\">\r\n<div class=\"grey-box w-100 \">\r\n<div class=\"grey-box-content mx-auto w-100\">\r\n<div class=\"page2ref-false topic-content topic-type-REGULAR\">\r\n<div class=\"reading-channel\">\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237041\" data-level=\"4\" data-has-spy=\"true\">\r\n<h1 class=\"h4\"><strong>United States<\/strong><\/h1>\r\n<p class=\"topic-paragraph\">As part of its response to the first\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/Sputnik\" data-show-preview=\"true\">Sputnik<\/a>\u00a0launches, the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/United-States\" data-show-preview=\"true\">United States<\/a>\u00a0government debated how best to organize itself for its space activities. At the time, the military services, particularly the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/air-force\" data-show-preview=\"true\">air force<\/a>\u00a0and the army, hoped that they would have a leading role in space. As an\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/alternative\" data-term=\"alternative\" data-type=\"MW\">alternative<\/a>\u00a0to this rivalry between the services, President Eisenhower in February 1958 created within the Department of Defense the\u00a0<span id=\"ref838768\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Defense-Advanced-Research-Projects-Agency\" data-show-preview=\"true\">Advanced Research Projects Agency<\/a>\u00a0(ARPA, later the\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Defense-Advanced-Research-Projects-Agency\" data-show-preview=\"true\">Defense Advanced Research Projects Agency<\/a>\u00a0[DARPA]) and assigned it responsibility for all U.S. space projects. Soon afterward, he decided to separate civilian from military space efforts and proposed the creation of a\u00a0<span id=\"ref838769\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/NASA\" data-show-preview=\"true\">National Aeronautics and Space Administration<\/a>\u00a0to manage the civilian segment. After approval by Congress, NASA began operation on October 1, 1958. DARPA was not successful in establishing itself as a military space agency. By 1960, after the army had been obliged to relinquish control of JPL and Braun\u2019s\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/rocket-jet-propulsion-device-and-vehicle\" data-show-preview=\"true\">rocket<\/a>\u00a0team to NASA management, the air force had emerged as the leading\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/armed-force\" data-show-preview=\"true\">military service<\/a>\u00a0for space.<\/p>\r\n<p class=\"topic-paragraph\">Eisenhower also decided to create a separate organization to manage the secret\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/spy-satellite\" data-show-preview=\"true\">reconnaissance satellite<\/a>\u00a0program. This effort resulted in the\u00a0<span id=\"ref838772\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/National-Reconnaissance-Office\">National Reconnaissance Office<\/a>\u00a0(NRO), jointly directed by the Department of Defense and the\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Central-Intelligence-Agency\" data-show-preview=\"true\">Central Intelligence Agency<\/a>. The very existence of this organization was kept secret until 1992. The NRO operated the initial Corona program until 1972. It continued to manage the development of successor photointelligence\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/satellite\" data-show-preview=\"true\">satellite<\/a>\u00a0systems of increasing technological sophistication and also developed radar-surveillance and electronic-signals-collection satellites. All were operated under conditions of the highest secrecy.<\/p>\r\n<p class=\"topic-paragraph\">After it received its\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/mandate\" data-term=\"mandate\" data-type=\"MW\">mandate<\/a>\u00a0to send Americans to the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Moon\" data-show-preview=\"true\">Moon<\/a>, NASA grew into a large organization. From its headquarters in Washington, D.C., it operated 10 field centres established throughout the United States to carry out research and technology development and to manage the various universities and industrial contractors involved in the U.S. civilian space program. At the peak of the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/Apollo-space-program\" data-show-preview=\"true\">Apollo<\/a>\u00a0program, NASA had 34,000 employees; by the second decade of the 21st century, this\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/money\/labor-in-economics\" data-show-preview=\"true\">labour force<\/a>\u00a0had shrunk to just over 17,000, but NASA remained by far the largest space agency in the world.<\/p>\r\n<p class=\"topic-paragraph\">The air force had no separate organization for space until 1982, when the\u00a0<span id=\"ref838777\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/The-United-States-Air-Force\" data-show-preview=\"true\">U.S. Air Force<\/a>\u00a0Space Command was created to manage its military space operations, which involved the use of satellites for meteorology, communication, navigation, and early warning of missile attack. The other U.S. military services soon created similar organizations to\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/administer\" data-term=\"administer\" data-type=\"EB\">administer<\/a>\u00a0their smaller space activities. In 1985 these organizations were brought under a unified U.S. Space Command, dominated by the air force, which was responsible for 85 percent of military space activities. Research and development efforts related to military space programs were managed by various government laboratories and carried out primarily by American industry.<\/p>\r\n<\/section>\r\n<\/div>\r\n<div id=\"chatbot-root\">\u00a0<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div data-page-index=\"6\">\u00a0<\/div>\r\n<div class=\"loaded-infinite-scroll-container qa-infinite-scroll-container\">\r\n<div class=\"grey-box w-100 \">\r\n<div class=\"grey-box-content mx-auto w-100\">\r\n<div class=\"page2ref-false topic-content topic-type-REGULAR\">\r\n<div class=\"reading-channel\">\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237042\" data-level=\"4\" data-has-spy=\"true\">\r\n<h1 class=\"h4\"><strong>Soviet Union<\/strong><\/h1>\r\n<p class=\"topic-paragraph\">In contrast to the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/United-States\" data-show-preview=\"true\">United States<\/a>, the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Soviet-Union\" data-show-preview=\"true\">Soviet Union<\/a>\u00a0had no separate publicly acknowledged civilian space agency. For 35 years after\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Sputnik\" data-show-preview=\"true\">Sputnik<\/a>, various design bureaus\u2014state-controlled organizations that actually conceived and developed aircraft and space systems\u2014had great influence within the Soviet system. (For information on the history of specific Soviet aerospace design bureaus,\u00a0<em>see<\/em>\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/money\/Energia-Russian-company\" data-show-preview=\"true\">Energia<\/a>,\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/MiG-Russian-design-bureau\" data-show-preview=\"true\">MiG<\/a>,\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Sukhoy\" data-show-preview=\"true\">Sukhoy<\/a>, and\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Tupolev\" data-show-preview=\"true\">Tupolev<\/a>.) Rivalry between those bureaus and their heads, who were known as chief designers, was a constant reality and posed an obstacle to a\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/coherent\" data-term=\"coherent\" data-type=\"MW\">coherent<\/a>\u00a0Soviet space program. Space policy decisions were made by the Politburo of the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/Central-Committee-Soviet-political-body\" data-show-preview=\"true\">Central Committee<\/a>\u00a0of the\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/communist-party-politics\" data-show-preview=\"true\">Communist Party<\/a>\u00a0as well as the Soviet government\u2019s Council of Ministers. After 1965 the government\u2019s Ministry of General Machine Building was assigned responsibility for managing all Soviet space and missile programs; the Ministry of Defense was also quite influential in shaping space efforts. A separate military branch, the Strategic Missile Forces, was in charge of space launchers and strategic missiles. Various institutes of the Soviet Academy of Sciences, particularly the Institute for Space Research (IKI), proposed and managed scientific missions.<\/p>\r\n<p class=\"topic-paragraph\">Only after the\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/dissolution\" data-term=\"dissolution\" data-type=\"EB\">dissolution<\/a>\u00a0of the U.S.S.R. did\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Russia\" data-show-preview=\"true\">Russia<\/a>\u00a0create a civilian organization for space activities. Formed in February 1992, the\u00a0<span id=\"ref838784\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Roskosmos\" data-show-preview=\"true\">Russian Federal Space Agency<\/a>\u00a0(Roskosmos) has acted as a central focus for the country\u2019s space policy and programs. Although it began as a small organization that dealt with international contacts and the setting of space policies, it quickly took on increasing responsibility for the management of nonmilitary space activities.<\/p>\r\n<\/section>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237043\" data-level=\"4\" data-has-spy=\"true\">\r\n<h2 class=\"h4\"><strong><span id=\"ref838797\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Europe\" data-show-preview=\"true\">Europe<\/a><\/strong><\/h2>\r\n<p class=\"topic-paragraph\">In 1961, within four years of the launch of the first U.S. and Soviet satellites, the government of\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/France\" data-show-preview=\"true\">France<\/a>\u00a0created the\u00a0<span id=\"ref838791\"><\/span>French Space Agency (CNES), which grew to become the largest national organization of its kind in Europe. Gradually other European countries formed government or government-sponsored organizations for space, among them the German Aerospace Center (DLR), the U.K. Space Agency, and the Italian Space Agency (ASI). Still others included space as part of their science or technology ministries.<\/p>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"107220\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/09\/102509-050-B0976D17\/Ariane-5G-launch-vehicle-base-European-Space-Feb-25-2004.jpg\" data-href=\"\/media\/1\/557348\/107220\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/09\/102509-050-B0976D17\/Ariane-5G-launch-vehicle-base-European-Space-Feb-25-2004.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/09\/102509-050-B0976D17\/Ariane-5G-launch-vehicle-base-European-Space-Feb-25-2004.jpg?w=300\" alt=\"Arian 5G launch vehicle\" width=\"1052\" height=\"701\" data-width=\"1600\" data-height=\"1067\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/09\/102509-050-B0976D17\/Ariane-5G-launch-vehicle-base-European-Space-Feb-25-2004.jpg\" data-href=\"\/media\/1\/557348\/107220\">Arian 5G launch vehicle<\/a>An Ariane 5G launch vehicle at the European Space Agency&#8217;s launch base in Kourou, French Guiana, on February 25, 2004.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">In 1964 a\u00a0<span id=\"ref838792\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/European-Space-Research-Organization\">European Space Research Organisation<\/a>\u00a0(ESRO), created at the\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/initiative\" data-term=\"initiative\" data-type=\"MW\">initiative<\/a>\u00a0of European scientists to pool government resources in support of space science, began operations. Ten western European countries and\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Australia\" data-show-preview=\"true\">Australia<\/a>\u00a0joined the organization. In the same year, a parallel\u00a0<span id=\"ref838795\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/European-Launcher-Development-Organization\">European Launcher Development Organisation<\/a>\u00a0(ELDO), which had seven European member states, was established to develop a space\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/launch-vehicle\" data-show-preview=\"true\">launch vehicle<\/a>\u00a0for Europe. Whereas ESRO was successful in mounting a series of science missions, many in collaboration with\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/NASA\" data-show-preview=\"true\">NASA<\/a>, ELDO failed in attempts to design and launch a European\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/rocket-jet-propulsion-device-and-vehicle\" data-show-preview=\"true\">rocket<\/a>. In 1975 a new\u00a0<span id=\"ref838799\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/European-Space-Agency\" data-show-preview=\"true\">European Space Agency<\/a>\u00a0(ESA) was formed from ESRO and ELDO to carry out both of their tasks. As of 2020, ESA had 22 member states\u2014Austria,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Belgium\" data-show-preview=\"true\">Belgium<\/a>, the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Czech-Republic\" data-show-preview=\"true\">Czech Republic<\/a>,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Denmark\" data-show-preview=\"true\">Denmark<\/a>, Estonia, Finland, France,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Germany\" data-show-preview=\"true\">Germany<\/a>,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Greece\" data-show-preview=\"true\">Greece<\/a>,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Hungary\" data-show-preview=\"true\">Hungary<\/a>, Ireland,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Italy\" data-show-preview=\"true\">Italy<\/a>,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Luxembourg\" data-show-preview=\"true\">Luxembourg<\/a>, the Netherlands,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Norway\" data-show-preview=\"true\">Norway<\/a>,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Poland\" data-show-preview=\"true\">Poland<\/a>, Portugal,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Romania\" data-show-preview=\"true\">Romania<\/a>,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Spain\" data-show-preview=\"true\">Spain<\/a>,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Sweden\" data-show-preview=\"true\">Sweden<\/a>,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Switzerland\" data-show-preview=\"true\">Switzerland<\/a>, and the United Kingdom.\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Canada\" data-show-preview=\"true\">Canada<\/a>\u00a0also participated in some ESA projects. With a budget that made it the world\u2019s second largest civilian space agency, ESA carried out a\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/comprehensive\" data-term=\"comprehensive\" data-type=\"MW\">comprehensive<\/a>\u00a0program in space science, applications, and\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/infrastructure\" data-term=\"infrastructure\" data-type=\"MW\">infrastructure<\/a>\u00a0development. In particular, the\u00a0<span id=\"ref838801\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Ariane-European-launch-vehicles\" data-show-preview=\"true\">Ariane<\/a>\u00a0series of expendable launch vehicles was developed under ESA\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/auspices\" data-term=\"auspices\" data-type=\"MW\">auspices<\/a>, with France taking the leading role. These launchers proved to be extremely reliable, and they gave Europe independent access to space and a leading position in the commercial space launch industry.<\/p>\r\n<\/section>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237044\" data-level=\"4\" data-has-spy=\"true\">\r\n<h2 class=\"h4\"><span id=\"ref838802\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Japan\" data-show-preview=\"true\"><strong>Japan<\/strong><\/a><\/h2>\r\n<p class=\"topic-paragraph\">In Japan the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/University-of-Tokyo\" data-show-preview=\"true\">University of Tokyo<\/a>\u00a0created an\u00a0<span id=\"ref838803\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Institute-of-Space-and-Astronautical-Science\">Institute of Space and Astronautical Science<\/a>\u00a0(ISAS) in 1964. This small group undertook the development of scientific\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/spacecraft\" data-show-preview=\"true\">spacecraft<\/a>\u00a0and the vehicles needed to launch them, and it launched Japan\u2019s first\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/satellite\" data-show-preview=\"true\">satellite<\/a>,\u00a0<span id=\"ref838804\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Osumi\" data-show-preview=\"true\">\u014csumi<\/a>, in 1970. In 1981 oversight of ISAS was transferred to the Japanese Ministry of Education. In 1969 the Japanese government founded a\u00a0<span id=\"ref838806\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/National-Space-Development-Agency\">National Space Development Agency<\/a>\u00a0(NASDA), which subsequently undertook a comprehensive program of space technology and satellite development and built a large launch vehicle, called the H-II, for those satellites. In 2001 both ISAS and NASDA came under the control of the Japanese Ministry of Education,\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/Culture\" data-term=\"Culture\" data-type=\"MW\">Culture<\/a>, Sports, Science and Technology. In 2003 ISAS, NASDA, and the National Aerospace Laboratory were merged into a new organization, the\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Japan-Aerospace-Exploration-Agency\" data-show-preview=\"true\">Japan Aerospace Exploration Agency<\/a>\u00a0(JAXA).<\/p>\r\n<div class=\"module-spacing\">\u00a0<\/div>\r\n<\/section>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237045\" data-level=\"4\" data-has-spy=\"true\">\r\n<h2 class=\"h4\"><span id=\"ref838812\"><\/span><strong><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/China\" data-show-preview=\"true\">China<\/a><\/strong><\/h2>\r\n<p class=\"topic-paragraph\">China\u2019s space program evolved largely in secret, under the joint control of the Chinese military and the Commission on Science, Technology, and Industry for the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/Narodna-Odbrana\" data-show-preview=\"true\">National Defense<\/a>. After the communist takeover of 1949,\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Qian-Xuesen\" data-show-preview=\"true\">Qian Xuesen<\/a>, who had worked at GALCIT in the 1940s and helped found JPL, returned to China, where he became the guiding figure in the development of Chinese missiles and launch vehicles, both originally\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/derived\" data-term=\"derived\" data-type=\"EB\">derived<\/a>\u00a0from a Soviet ICBM. China developed a family of\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Long-March-rocket-family\" data-show-preview=\"true\">Chang Zheng<\/a>\u00a0(\u201c<span id=\"ref838814\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Long-March-rocket-family\" data-show-preview=\"true\">Long March<\/a>\u201d) boosters, which are used domestically and serve as competitors in the international commercial space launch market. Its space development has concentrated on applications such as communications satellites and Earth-observation satellites for civilian and military use. In 1993 an independent Chinese Aerospace Corporation, later known as the China Aerospace Science and Technology Corporation, was established to oversee most Chinese space-equipment manufacturers, and the\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/China-National-Space-Administration\" data-show-preview=\"true\">China National Space Administration<\/a>\u00a0was established to manage national space activities.<\/p>\r\n<p class=\"topic-paragraph\">China initiated its own human\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/spaceflight\" data-show-preview=\"true\">spaceflight<\/a>\u00a0program in 1992. The spacecraft, called\u00a0<span id=\"ref838815\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Shenzhou\" data-show-preview=\"true\">Shenzhou<\/a>, that it developed for the effort was modeled on Russia\u2019s time-tested Soyuz design (<em>see below<\/em>\u00a0the section\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/space-exploration\/Mercury#ref237052\" data-show-preview=\"true\">Soyuz<\/a>), but it relied heavily on Chinese-developed technologies and manufacturing. Following four years of uncrewed spacecraft tests, China launched its first\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/indigenous\" data-term=\"indigenous\" data-type=\"MW\">indigenous<\/a>\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/astronaut\" data-show-preview=\"true\">astronaut<\/a>,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/air-force\" data-show-preview=\"true\">air force<\/a>\u00a0pilot\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Yang-Liwei\" data-show-preview=\"true\">Yang Liwei<\/a>, into orbit on October 15, 2003. In so doing, it became the third country\u2014after the former Soviet Union and the United States\u2014to achieve human spaceflight. China has followed its initial human space flight with the step-by-step development of capabilities such as space walking and operating a space laboratory (<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Tiangong\" data-show-preview=\"true\">Tiangong<\/a>) that are required for human operations in\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/low-Earth-orbit\" data-show-preview=\"true\">low Earth orbit<\/a>.<\/p>\r\n<\/section>\r\n<\/div>\r\n<div id=\"chatbot-root\">\u00a0<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div data-page-index=\"7\">\u00a0<\/div>\r\n<div class=\"loaded-infinite-scroll-container qa-infinite-scroll-container\">\r\n<div class=\"grey-box w-100 \">\r\n<div class=\"grey-box-content mx-auto w-100\">\r\n<div class=\"page2ref-false topic-content topic-type-REGULAR\">\r\n<div class=\"reading-channel\">\r\n<section data-level=\"3\">\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237046\" data-level=\"4\" data-has-spy=\"true\">\r\n<h1 class=\"h4\"><strong>International participation<\/strong><\/h1>\r\n<p class=\"topic-paragraph\">A number of international organizations are involved in space activities. The\u00a0<span id=\"ref838827\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/United-Nations\" data-show-preview=\"true\">United Nations<\/a>\u00a0General Assembly established a\u00a0<span id=\"ref838824\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Outer-Space-Committee\">Committee on the Peaceful Uses of Outer Space<\/a>\u00a0in 1959 to discuss scientific, technical, and legal issues related to international space activities; 95 countries were members of the committee in 2020. The committee has provided the forum for the development of five treaties and a number of declarations of principles related to space activities. The most important of them is the 1967\u00a0<span id=\"ref838825\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/event\/Outer-Space-Treaty\" data-show-preview=\"true\">Outer Space Treaty<\/a>, which sets forth the general legal principles governing the uses of space. Other parts of the UN system, most notably the\u00a0<span id=\"ref838829\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/International-Telecommunication-Union\" data-show-preview=\"true\">International Telecommunications Union<\/a>\u00a0(ITU), are engaged in space-related concerns. The ITU is responsible for allocation of radio frequencies and orbital locations for various satellites providing public and commercial services.<\/p>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"118888\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/31\/124931-050-12E839D6\/Intelsat-headquarters-Washington-DC.jpg\" data-href=\"\/media\/1\/557348\/118888\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/31\/124931-050-12E839D6\/Intelsat-headquarters-Washington-DC.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/31\/124931-050-12E839D6\/Intelsat-headquarters-Washington-DC.jpg?w=300\" alt=\"Intelsat\" width=\"1029\" height=\"477\" data-width=\"1600\" data-height=\"742\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/31\/124931-050-12E839D6\/Intelsat-headquarters-Washington-DC.jpg\" data-href=\"\/media\/1\/557348\/118888\">Intelsat<\/a>Intelsat headquarters, Washington, D.C.<\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">At the\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/initiative\" data-term=\"initiative\" data-type=\"MW\">initiative<\/a>\u00a0of the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/United-States\" data-show-preview=\"true\">United States<\/a>, an International Telecommunications Satellite\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/Consortium\" data-term=\"Consortium\" data-type=\"MW\">Consortium<\/a>\u00a0(<span id=\"ref838832\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/money\/Intelsat\" data-show-preview=\"true\">Intelsat<\/a>) was founded in 1964 to develop and operate a global system of communications satellites. By 1969 the organization had established a system of satellites with global coverage; in the late 1980s it provided services to more than 200 countries and territories. Intelsat membership grew to 144 countries before a decision was made in 1999 to change the ownership of the organization from national governments to the private sector. A similar consortium, the\u00a0<span id=\"ref838836\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/International-Maritime-Satellite-Organization\">International Maritime Satellite Organization<\/a>\u00a0(Inmarsat), was established as an intergovernmental organization in 1979 to supply\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/maritime\" data-term=\"maritime\" data-type=\"EB\">maritime<\/a>\u00a0and other mobile communications services via satellite; it also was later transformed into a privately owned entity. In addition, a number of regional organizations have been created to operate communication and meteorologic satellites.<\/p>\r\n<\/section>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237047\" data-level=\"4\" data-has-spy=\"true\">\r\n<h2 class=\"h4\"><strong>Involvement of industry<\/strong><\/h2>\r\n<p class=\"topic-paragraph\">Building the systems and components needed to carry out both government and commercial space programs has required the participation of private industry, and a number of firms have grown to have substantial space involvement. Often these firms have also been major suppliers of\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/aviation\" data-show-preview=\"true\">aviation<\/a>\u00a0and defense products, a reflection of the common technological foundation for what has become known as the\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/aerospace-industry\" data-show-preview=\"true\">aerospace industry<\/a>. Other private firms have specialized in providing space-based services in such areas as telecommunications and\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Earth\" data-show-preview=\"true\">Earth<\/a>\u00a0observation.<\/p>\r\n<\/section>\r\n<\/section>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237048\" data-level=\"3\" data-has-spy=\"true\">\r\n<h2 class=\"h3\"><strong>The first\u00a0<span id=\"ref838841\"><\/span><\/strong><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/manned-spacecraft\"><strong>human spaceflights<\/strong><\/a><\/h2>\r\n<p class=\"topic-paragraph\">During the 1950s space planners in both the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Soviet-Union\" data-show-preview=\"true\">Soviet Union<\/a>\u00a0and the United States anticipated the launching of a human being into orbit as soon as the required\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/launch-vehicle\" data-show-preview=\"true\">launch vehicle<\/a>\u00a0and\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/spacecraft\" data-show-preview=\"true\">spacecraft<\/a>\u00a0could be developed and tested. Much of the initial thinking focused on some form of piloted space plane, which, after being launched atop a\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/rocket-jet-propulsion-device-and-vehicle\" data-show-preview=\"true\">rocket<\/a>, could maneuver in orbit and then return to Earth, gliding to a horizontal landing on a\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/conventional\" data-term=\"conventional\" data-type=\"EB\">conventional<\/a>\u00a0runway.<\/p>\r\n<div class=\"assemblies multiple medialist slider js-slider position-relative d-inline-flex align-items-center mw-100\" data-type=\"other\">\r\n<div class=\"slider-container js-slider-container overflow-hidden d-flex rw-slider rw-prev-disabled\">\r\n<div class=\"rw-track d-flex align-items-center\">\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"59855\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/12\/65012-120-CA2E5A36\/North-American-Aviation-X-15-plane-bomber-Boeing.jpg\" data-href=\"\/media\/1\/557348\/59855\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/12\/65012-120-CA2E5A36\/North-American-Aviation-X-15-plane-bomber-Boeing.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/12\/65012-120-CA2E5A36\/North-American-Aviation-X-15-plane-bomber-Boeing.jpg?w=300\" alt=\"X-15 launched from B-52\" width=\"1183\" height=\"887\" data-width=\"900\" data-height=\"675\" \/><\/picture><\/a>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">1 of 2<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/12\/65012-120-CA2E5A36\/North-American-Aviation-X-15-plane-bomber-Boeing.jpg\" data-href=\"\/media\/1\/557348\/59855\">X-15 launched from B-52<\/a>North American Aviation X-15 rocket-powered plane being air-launched from a Boeing B-52 bomber. Flights of the experimental X-15 in the 1960s set unofficial altitude and speed records for piloted aircraft and contributed to the development of the U.S. crewed spaceflight program.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"117242\" data-asm-type=\"video\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"video\"><a class=\"gtm-assembly-link d-flex justify-content-center\" href=\"https:\/\/www.britannica.com\/video\/air-US-Air-Force-B-52-mother-ship\/-117242\" data-id=\"111225\"><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/25\/111225-138-33D6BFE2\/air-US-Air-Force-B-52-mother-ship.jpg?w=800&amp;h=450&amp;c=crop\" alt=\"launch of an X-15\" width=\"1030\" height=\"584\" \/><\/a>\r\n<div class=\"btn btn-xl btn-white btn-circle position-absolute shadow\">\u00a0<\/div>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">2 of 2<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><span class=\"md-assembly-title font-weight-bold mr-5 d-inline font-sans-serif md-video-caption\">launch of an X-15<\/span>Footage of an X-15 rocket-powered aircraft being launched from a U.S. Air Force B-52 mother ship, c. 1960s. Several pilots were given astronaut&#8217;s wings for their X-15 flights that went over an altitude of 80 km (50 miles).<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<a class=\"font-14 mt-10 d-inline-block\" href=\"https:\/\/www.britannica.com\/science\/space-exploration\/images-videos\">See all videos for this article<\/a><\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<button class=\"prev-button js-prev-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20 rw-disabled\" disabled=\"disabled\"><\/button><button class=\"next-button js-next-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20\"><\/button><\/div>\r\n<p class=\"topic-paragraph\">In the United States the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/air-force\" data-show-preview=\"true\">air force<\/a>\u00a0developed a rocket-powered experimental aircraft, the\u00a0<span id=\"ref838846\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/X-15-aircraft\" data-show-preview=\"true\">X-15<\/a>, which, after being dropped from an in-flight B-52 bomber, could reach altitudes as high as 108 km (67 miles), the edge of outer space. Nevertheless, the X-15 could not achieve the velocity and altitude needed for orbital flight. That was the mission of\u00a0<span id=\"ref838851\"><\/span>Dyna-Soar, another air force project. Dyna-Soar was to be a piloted reusable delta-winged vehicle that would be launched into orbit by a modified\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Titan-rocket\" data-show-preview=\"true\">Titan<\/a>\u00a0ICBM and could carry out either bombing or reconnaissance missions over the Soviet Union or intercept a Soviet satellite in orbit. Although a full-scale vehicle was built and six people were chosen to train as Dyna-Soar crew, the project was canceled in 1963.<\/p>\r\n<div class=\"module-spacing\">\u00a0<\/div>\r\n<p class=\"topic-paragraph\">Rather than base their human\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/spaceflight\" data-show-preview=\"true\">spaceflight<\/a>\u00a0programs on space planes, the Soviet Union and the United States, in their desire to put people into space as quickly as possible, opted for a less technically demanding\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/ballistic\" data-term=\"ballistic\" data-type=\"MW\">ballistic<\/a>\u00a0approach. A person would ride in a capsulelike spacecraft atop a rocket to achieve orbit. At the end of the flight, another rocket (called a retro-rocket) would slow down the spacecraft enough for it to fall back to Earth. To accomplish this feat, the spacecraft would have to survive the intense heat caused by reentering the atmosphere at a high speed and then carry its passenger safely back to Earth\u2019s surface.<\/p>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237049\" data-level=\"4\" data-has-spy=\"true\">\r\n<h2 class=\"h4\"><span id=\"ref838859\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Vostok-Soviet-spacecraft\" data-show-preview=\"true\"><strong>Vostok<\/strong><\/a><\/h2>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"2899\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/34\/434-004-AA460D19\/spacecraft-Vostok-6-woman-cosmonaut-reentry-capsule-June-16-1963.jpg\" data-href=\"\/media\/1\/557348\/2899\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/34\/434-004-AA460D19\/spacecraft-Vostok-6-woman-cosmonaut-reentry-capsule-June-16-1963.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/34\/434-004-AA460D19\/spacecraft-Vostok-6-woman-cosmonaut-reentry-capsule-June-16-1963.jpg?w=300\" alt=\"Vostok 6\" width=\"1140\" height=\"1660\" data-width=\"206\" data-height=\"300\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/34\/434-004-AA460D19\/spacecraft-Vostok-6-woman-cosmonaut-reentry-capsule-June-16-1963.jpg\" data-href=\"\/media\/1\/557348\/2899\">Vostok 6<\/a>Vostok 6 spacecraft, in which the first woman cosmonaut, Valentina Tereshkova, orbited Earth for three days. Launched June 16, 1963, the craft comprised a spherical reentry capsule for its occupant and a conical instrument module.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">Soon after the success of the first Sputniks,\u00a0<span id=\"ref838892\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Sergei-Korolev\" data-show-preview=\"true\">Korolyov<\/a>\u00a0and his associate Tikhonravov began work on the design of an orbital spacecraft that could be used for two purposes. One was to conduct photoreconnaissance missions and then return the exposed film to Earth. The other was to serve as a vehicle for the first human spaceflight missions, in which a human being would replace the reconnaissance camera. The spacecraft was called\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Vostok-Soviet-spacecraft\" data-show-preview=\"true\">Vostok<\/a>\u00a0when it was used to carry a human into space. Vostok had two sections\u2014a spherical capsule in which the person would ride and a conical module that contained the instruments needed for its flight. The spacecraft was large for the time, weighing 4.73 metric tons. The crew capsule was completely covered by a thermal coating to protect it during reentry. Vostok was designed so that the human aboard need not touch any control from launch to touchdown; he would be essentially just a passenger. Nor would he land with the spacecraft. Rather, he would be ejected from it at an\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/altitude\" data-term=\"altitude\" data-type=\"EB\">altitude<\/a>\u00a0of 7 km (4.3 miles) and parachute to dry land while the spacecraft landed nearby with its own parachutes.<\/p>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"19709\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/70\/27070-004-6073A944\/Yury-A-Gagarin-Sergey-P-Korolyov-space-1961.jpg\" data-href=\"\/media\/1\/557348\/19709\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/70\/27070-004-6073A944\/Yury-A-Gagarin-Sergey-P-Korolyov-space-1961.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/70\/27070-004-6073A944\/Yury-A-Gagarin-Sergey-P-Korolyov-space-1961.jpg?w=300\" alt=\"Yuri Gagarin and Sergei Korolev\" width=\"1169\" height=\"869\" data-width=\"403\" data-height=\"300\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/70\/27070-004-6073A944\/Yury-A-Gagarin-Sergey-P-Korolyov-space-1961.jpg\" data-href=\"\/media\/1\/557348\/19709\">Yuri Gagarin and Sergei Korolev<\/a>Yuri Gagarin (left), the first human to travel into space, and Sergei Korolev, Soviet rocket scientist, 1961.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">After a series of five test flights carrying dogs and human dummies, the first person, by that time designated as a\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/astronaut\" data-show-preview=\"true\">cosmonaut<\/a>, lifted into space in Vostok 1 atop a modified\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/R-7\" data-show-preview=\"true\">R-7<\/a>\u00a0rocket on April 12, 1961, from the Soviet launch site at the\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Baikonur\" data-show-preview=\"true\">Baikonur<\/a>\u00a0Cosmodrome in\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Kazakhstan\" data-show-preview=\"true\">Kazakhstan<\/a>. The passenger,\u00a0<span id=\"ref838893\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Yuri-Gagarin\" data-show-preview=\"true\">Yuri Gagarin<\/a>, was a 27-year-old Russian test pilot. After firing of the retro-rocket 78 minutes into the mission, the crew capsule separated from the instrument module\u2014although not without problems\u2014and Gagarin parachuted to a soft landing 108 minutes after his launch. He had reported during the mission \u201cI feel fine\u201d and showed no ill effects from his one-orbit trip around the globe.<\/p>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"219798\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/43\/185243-050-24DED38F\/Valentina-Tereshkova.jpg\" data-href=\"\/media\/1\/557348\/219798\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/43\/185243-050-24DED38F\/Valentina-Tereshkova.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/43\/185243-050-24DED38F\/Valentina-Tereshkova.jpg?w=300\" alt=\"Valentina Tereshkova\" width=\"1260\" height=\"819\" data-width=\"1600\" data-height=\"1042\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/43\/185243-050-24DED38F\/Valentina-Tereshkova.jpg\" data-href=\"\/media\/1\/557348\/219798\">Valentina Tereshkova<\/a><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">There were five additional one-person Vostok missions. In August 1961,\u00a0<span id=\"ref838895\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Gherman-Stepanovich-Titov\" data-show-preview=\"true\">Gherman Titov<\/a>\u00a0at age 25 (still the youngest person ever to fly in space) completed 17 orbits of Earth in Vostok 2. He became ill with space sickness (the equivalent of\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/motion-sickness\" data-show-preview=\"true\">motion sickness<\/a>\u00a0on Earth) during the flight, an incident that caused a one-year delay in Vostok flights while Soviet physicians investigated the possibility that humans could not survive for extended times in the space\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/environment\" data-term=\"environment\" data-type=\"MW\">environment<\/a>. In August 1962, two Vostoks, 3 and 4, were orbited at the same time and came within 6.5 km (4 miles) of one another. This dual mission was repeated in June 1963; aboard the Vostok 6 spacecraft was\u00a0<span id=\"ref838896\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Valentina-Tereshkova\" data-show-preview=\"true\">Valentina Tereshkova<\/a>, the first woman to fly in space.<\/p>\r\n<\/section>\r\n<\/section>\r\n<\/div>\r\n<div id=\"chatbot-root\">\u00a0<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div data-page-index=\"8\">\u00a0<\/div>\r\n<div class=\"loaded-infinite-scroll-container qa-infinite-scroll-container\">\r\n<div class=\"grey-box w-100 \">\r\n<div class=\"grey-box-content mx-auto w-100\">\r\n<div class=\"page2ref-false topic-content topic-type-REGULAR\">\r\n<div class=\"reading-channel\">\r\n<section data-level=\"3\">\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237050\" data-level=\"4\" data-has-spy=\"true\">\r\n<h1 class=\"h4\"><span id=\"ref838898\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/Mercury-space-project\" data-show-preview=\"true\"><strong>Mercury<\/strong><\/a><\/h1>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"138737\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/69\/73169-050-96B763F7\/Friendship-7-John-H-Glenn-Jr-Launch-Feb-20-1962.jpg\" data-href=\"\/media\/1\/557348\/138737\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/69\/73169-050-96B763F7\/Friendship-7-John-H-Glenn-Jr-Launch-Feb-20-1962.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/69\/73169-050-96B763F7\/Friendship-7-John-H-Glenn-Jr-Launch-Feb-20-1962.jpg?w=300\" alt=\"Friendship 7 launch\" width=\"1145\" height=\"1496\" data-width=\"1224\" data-height=\"1600\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/69\/73169-050-96B763F7\/Friendship-7-John-H-Glenn-Jr-Launch-Feb-20-1962.jpg\" data-href=\"\/media\/1\/557348\/138737\"><em>Friendship 7<\/em>\u00a0launch<\/a>Launch of the Mercury spacecraft\u00a0<em>Friendship 7<\/em>\u2014which carried U.S. astronaut John H. Glenn, Jr., the first American to orbit Earth\u2014February 20, 1962.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">The initial U.S. effort to launch a human into space was known as\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/Mercury-space-project\" data-show-preview=\"true\">Project Mercury<\/a>. It was carried out by\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/NASA\" data-show-preview=\"true\">NASA<\/a>, which had been given that responsibility over\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/air-force\" data-show-preview=\"true\">air force<\/a>\u00a0objections. NASA engineers, led by Robert Gilruth and\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Max-Faget\" data-show-preview=\"true\">Maxime Faget<\/a>, designed a small cone-shaped capsule for the mission. Compared with the nearly 5-metric-ton\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/Vostok-Soviet-spacecraft\" data-show-preview=\"true\">Vostok<\/a>, it weighed only 1.94 metric tons. Unlike the Soviet approach, in which a cosmonaut was orbited on the first human\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/spaceflight\" data-show-preview=\"true\">spaceflight<\/a>, NASA planned several suborbital test flights in which an\u00a0<span id=\"ref838899\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/astronaut\" data-show-preview=\"true\">astronaut<\/a>\u00a0would be in space for only a few minutes of his 15-minute up-and-down ride. Only after the Mercury equipment was checked out and the effects of suborbital flight on the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/human-body\" data-show-preview=\"true\">human body<\/a>\u00a0were measured would the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/United-States\" data-show-preview=\"true\">United States<\/a>\u00a0commit to an orbital flight attempt. The Mercury capsule would parachute with its passenger all the way back to\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Earth\" data-show-preview=\"true\">Earth\u2019s<\/a>\u00a0surface, to land in the ocean and be recovered by navy ships. Also in contrast to Vostok, the Mercury capsule was designed to allow the astronaut to control some aspects of its flight while in space.<\/p>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"68861\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/35\/18335-004-D32A11C4\/Alan-B-Shepard-Jr-Freedom-7-deck-May-5-1961.jpg\" data-href=\"\/media\/1\/557348\/68861\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/35\/18335-004-D32A11C4\/Alan-B-Shepard-Jr-Freedom-7-deck-May-5-1961.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/35\/18335-004-D32A11C4\/Alan-B-Shepard-Jr-Freedom-7-deck-May-5-1961.jpg?w=300\" alt=\"Alan B. Shepard and Freedom 7\" width=\"1183\" height=\"844\" data-width=\"550\" data-height=\"392\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/35\/18335-004-D32A11C4\/Alan-B-Shepard-Jr-Freedom-7-deck-May-5-1961.jpg\" data-href=\"\/media\/1\/557348\/68861\">Alan B. Shepard and\u00a0<em>Freedom 7<\/em><\/a>U.S. astronaut Alan B. Shepard, Jr., on the deck of the aircraft carrier USS\u00a0<em>Lake Champlain<\/em>\u00a0on May 5, 1961, after the return of his Mercury spacecraft\u00a0<em>Freedom 7<\/em>\u00a0(in background) from the first crewed suborbital flight.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">The United States used\u00a0<span id=\"ref838900\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/animal\/chimpanzee\" data-show-preview=\"true\">chimpanzees<\/a>, rather than dogs, as test subjects prior to human flights. In what was intended to be the final test flight before a human launch, the chimpanzee\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/animal\/Ham-chimpanzee\" data-show-preview=\"true\">Ham<\/a>\u00a0rode a suborbital\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/trajectory\" data-term=\"trajectory\" data-type=\"EB\">trajectory<\/a>\u00a0on January 31, 1961, using a Redstone\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/rocket-jet-propulsion-device-and-vehicle\" data-show-preview=\"true\">rocket<\/a>\u00a0developed by Braun\u2019s team. Because the flight had experienced minor problems, Braun insisted on one more test flight with an unoccupied dummy\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/spacecraft\" data-show-preview=\"true\">spacecraft<\/a>. If instead, as originally scheduled, that March 1961 flight had carried an astronaut, the United States would have been first with a human in space, although not in orbit.\u00a0<span id=\"ref838901\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Alan-B-Shepard-Jr\" data-show-preview=\"true\">Alan B. Shepard, Jr.<\/a>, made the first crewed Mercury flight atop a Redstone rocket on May 5, 1961. A second suborbital Mercury mission, carrying\u00a0<span id=\"ref838902\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Virgil-I-Grissom\" data-show-preview=\"true\">Virgil I. Grissom<\/a>, followed in July.<\/p>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"138736\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/06\/13706-050-D31BBDFC\/John-H-Glenn-Jr-Friendship-7-preparation-February-20-1962.jpg\" data-href=\"\/media\/1\/557348\/138736\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/06\/13706-050-D31BBDFC\/John-H-Glenn-Jr-Friendship-7-preparation-February-20-1962.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/06\/13706-050-D31BBDFC\/John-H-Glenn-Jr-Friendship-7-preparation-February-20-1962.jpg?w=300\" alt=\"John Glenn and Friendship 7\" width=\"1135\" height=\"764\" data-width=\"1600\" data-height=\"1079\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/06\/13706-050-D31BBDFC\/John-H-Glenn-Jr-Friendship-7-preparation-February-20-1962.jpg\" data-href=\"\/media\/1\/557348\/138736\">John Glenn and\u00a0<em>Friendship 7<\/em><\/a>U.S. astronaut John H. Glenn, Jr., entering the Mercury spacecraft\u00a0<em>Friendship 7<\/em>\u00a0on February 20, 1962, in preparation for launch.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\"><span id=\"ref838903\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/John-Glenn\" data-show-preview=\"true\">John H. Glenn, Jr.<\/a>, became the first American astronaut to orbit Earth in his three-orbit mission on February 20, 1962. His Mercury spacecraft was launched by a modified air force\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Atlas-American-launch-vehicles\" data-show-preview=\"true\">Atlas<\/a>\u00a0ICBM. Three more one-man Mercury orbital flights, carrying astronauts\u00a0<span id=\"ref838904\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Scott-Carpenter\" data-show-preview=\"true\">M. Scott Carpenter<\/a>,\u00a0<span id=\"ref838906\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Wally-Schirra\" data-show-preview=\"true\">Walter M. Schirra, Jr.<\/a>, and\u00a0<span id=\"ref838907\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Gordon-Cooper\" data-show-preview=\"true\">L. Gordon Cooper, Jr.<\/a>, were conducted, the last being a 22-orbit mission in May 1963.<\/p>\r\n<\/section>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237051\" data-level=\"4\" data-has-spy=\"true\">\r\n<h2 class=\"h4\"><strong><span id=\"ref838908\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/Gemini-spacecraft-and-space-program\" data-show-preview=\"true\">Gemini<\/a>\u00a0and Voskhod<\/strong><\/h2>\r\n<p class=\"topic-paragraph\">In 1961 Pres.\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/biography\/John-F-Kennedy\" data-show-preview=\"true\">John F. Kennedy<\/a>\u00a0announced that the United States would send people to the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Moon\" data-show-preview=\"true\">Moon<\/a>\u00a0\u201cbefore this decade is out.\u201d In order to test many of the techniques that would be needed to carry out a lunar mission, particularly rendezvousing and docking two objects in space, the United States in late 1961 decided to develop a two-person spacecraft called\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/Gemini-spacecraft-and-space-program\" data-show-preview=\"true\">Gemini<\/a>. The Gemini spacecraft was much more complex than the\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/rudimentary\" data-term=\"rudimentary\" data-type=\"MW\">rudimentary<\/a>\u00a0Mercury capsule and, at 3.81 metric tons, was twice as heavy. Another converted air force ICBM, a\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Titan-rocket\" data-show-preview=\"true\">Titan<\/a>\u00a0II, was used to launch the Gemini spacecraft.<\/p>\r\n<div class=\"assemblies multiple medialist slider js-slider position-relative d-inline-flex align-items-center mw-100\" data-type=\"other\">\r\n<div class=\"slider-container js-slider-container overflow-hidden d-flex rw-slider rw-prev-disabled\">\r\n<div class=\"rw-track d-flex align-items-center\">\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"8607\" data-asm-type=\"video\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"video\"><a class=\"gtm-assembly-link d-flex justify-content-center\" href=\"https:\/\/www.britannica.com\/video\/Edward-H-White-II-video-space-walk-January-27-1967\/-8607\" data-id=\"23182\"><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/82\/23182-138-1E496691\/Edward-H-White-II-video-space-walk-January-27-1967.jpg?w=800&amp;h=450&amp;c=crop\" alt=\"Witness the first extravehicular activity in space: a space walk performed by astronaut Edward White on the Gemini 4 mission\" width=\"1118\" height=\"631\" \/><\/a>\r\n<div class=\"btn btn-xl btn-white btn-circle position-absolute shadow\">\u00a0<\/div>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">1 of 2<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><span class=\"md-assembly-title font-weight-bold mr-5 d-inline font-sans-serif md-video-caption\">Witness the first extravehicular activity in space: a space walk performed by astronaut Edward White on the Gemini 4 mission<\/span>This video shows the space walk of Edward H. White II, a member of the Gemini 4 mission, launched on June 3, 1965. White was the first American to leave his capsule and perform an extravehicular activity (EVA) in space. He floated outside Gemini 4 for about 20 minutes, moving with the help of a maneuvering gun, which appears in his right hand. White was later one of three Apollo astronauts killed on January 27, 1967, during a training accident.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<a class=\"font-14 mt-10 d-inline-block\" href=\"https:\/\/www.britannica.com\/science\/space-exploration\/images-videos\">See all videos for this article<\/a><\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"10987\" data-asm-type=\"video\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"video\"><a class=\"gtm-assembly-link d-flex justify-content-center\" href=\"https:\/\/www.britannica.com\/video\/rocket-program-engineers-astronauts-Gemini-information-NASA-1967\/-10987\" data-id=\"23189\"><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/89\/23189-138-49E2E75B\/rocket-program-engineers-astronauts-Gemini-information-NASA-1967.jpg?w=800&amp;h=450&amp;c=crop\" alt=\"Watch the launch and booster separation of Gemini spacecraft as it is lifted off the ground by a Titan II rocket\" width=\"1067\" height=\"602\" \/><\/a>\r\n<div class=\"btn btn-xl btn-white btn-circle position-absolute shadow\">\u00a0<\/div>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">2 of 2<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><span class=\"md-assembly-title font-weight-bold mr-5 d-inline font-sans-serif md-video-caption\">Watch the launch and booster separation of Gemini spacecraft as it is lifted off the ground by a Titan II rocket<\/span>The Gemini program was conducted between 1964 and 1967 to give NASA engineers and astronauts information about spacecraft maneuvering, rendezvous, and ground control and about human performance in microgravity, in preparation for the Apollo voyages to the Moon. This video shows a Gemini spacecraft launch and booster separation. A Titan II rocket, a modified version of a rocket designed to carry nuclear warheads, lifts the spacecraft off the ground. Once the craft has cleared the Earth&#8217;s atmosphere, the rocket is jettisoned, and it falls back to Earth. The Gemini craft was an enlarged version of the Mercury capsule and measured 5.8 metres (19 feet) long and 3 metres (10 feet) in diameter.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<a class=\"font-14 mt-10 d-inline-block\" href=\"https:\/\/www.britannica.com\/science\/space-exploration\/images-videos\">See all videos for this article<\/a><\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<button class=\"prev-button js-prev-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20 rw-disabled\" disabled=\"disabled\"><\/button><button class=\"next-button js-next-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20\"><\/button><\/div>\r\n<p class=\"topic-paragraph\">The first crewed Gemini mission lifted into space in March 1965; nine more missions followed, the last in November 1966. On the second mission, in June 1965,\u00a0<span id=\"ref838935\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Edward-H-White-II\" data-show-preview=\"true\">Edward H. White II<\/a>\u00a0became the first American astronaut to operate outside a spacecraft. His 20-minute space walk\u2014also known as extravehicular activity (EVA)\u2014was without incident. Although problems developed on many of the Gemini flights, the program demonstrated that people could live and work in space for as long as 14 days, more than the time needed for a round trip to the Moon. It also showed that astronauts could carry out a\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/rendezvous\" data-term=\"rendezvous\" data-type=\"EB\">rendezvous<\/a>\u00a0in space and could make useful observations of Earth, both visually and photographically.<\/p>\r\n<div class=\"module-spacing\">\u00a0<\/div>\r\n<p class=\"topic-paragraph\">As plans in the United States for multiple-astronaut missions became known, the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Soviet-Union\" data-show-preview=\"true\">Soviet Union<\/a>\u00a0worked to maintain its lead in the space race by modifying the Vostok spacecraft so that it could carry as many as three persons. Korolyov could accomplish this only by having the crew fly without wearing spacesuits. The redesigned spacecraft was known as\u00a0<span id=\"ref838909\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Voskhod-spacecraft\" data-show-preview=\"true\">Voskhod<\/a>. There were two Voskhod missions, one with three people aboard in October 1964 and another with a two-man crew in March 1965. On the second mission, cosmonaut\u00a0<span id=\"ref838910\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Aleksei-Leonov\" data-show-preview=\"true\">Aleksey Leonov<\/a>\u00a0became the first human to leave an orbiting spacecraft, less than three months before White. His 12-minute EVA was full of problems, and his reentry of the Voskhod spacecraft was particularly difficult.<\/p>\r\n<\/section>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237052\" data-level=\"4\" data-has-spy=\"true\">\r\n<h2 class=\"h4\"><span id=\"ref838911\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Soyuz\" data-show-preview=\"true\"><strong>Soyuz<\/strong><\/a><\/h2>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"73144\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/12\/76512-050-93D2365C\/spacecraft-TM-Soyuz-Russian-Atlantis-port-space-September-21-1996.jpg\" data-href=\"\/media\/1\/557348\/73144\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/12\/76512-050-93D2365C\/spacecraft-TM-Soyuz-Russian-Atlantis-port-space-September-21-1996.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/12\/76512-050-93D2365C\/spacecraft-TM-Soyuz-Russian-Atlantis-port-space-September-21-1996.jpg?w=300\" alt=\"Soyuz TM and Mir\" width=\"1135\" height=\"753\" data-width=\"1536\" data-height=\"1023\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/12\/76512-050-93D2365C\/spacecraft-TM-Soyuz-Russian-Atlantis-port-space-September-21-1996.jpg\" data-href=\"\/media\/1\/557348\/73144\">Soyuz TM and Mir<\/a>Russian Soyuz TM spacecraft (the mostly dark structure with extended solar panels) docked to a port on the Mir space station, in an image made from the U.S. space shuttle orbiter\u00a0<em>Atlantis<\/em>, September 21, 1996.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">Korolyov and his associates began work in 1962 on a second-generation spacecraft, to be called\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Soyuz\" data-show-preview=\"true\">Soyuz<\/a>. It was to be a much more complex vehicle than Vostok, holding as many as three people in an orbital crew compartment, with a separate module for crew reentry and a third section containing spacecraft equipment and rocket engines for in-orbit and reentry maneuvers. Soyuz was to be capable not only of flights in Earth orbit but also, in modified versions, of flights around the Moon and even as part of a lunar landing mission.<\/p>\r\n<p class=\"topic-paragraph\">The first launch of Soyuz, with a single cosmonaut,\u00a0<span id=\"ref838912\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Vladimir-Mikhaylovich-Komarov\" data-show-preview=\"true\">Vladimir Komarov<\/a>, aboard, took place on April 23, 1967. Once the spacecraft reached orbit, it suffered a number of problems, which prompted ground controllers to bring Komarov back to Earth as soon as possible. After reentry, however, the spacecraft\u2019s main parachute did not fully\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/deploy\" data-term=\"deploy\" data-type=\"MW\">deploy<\/a>, and the Soyuz hit the ground at high speed. Komarov became the first person to perish during a spaceflight, and the accident dealt a major blow to Soviet hopes of orbiting or landing on the Moon before the United States.<\/p>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"238581\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/41\/194341-050-345CBFEA\/rocket-Soyuz-TMA-10M-Baikonur-Cosmodrome-Kazakhstan-September-25-2013.jpg\" data-href=\"\/media\/1\/557348\/238581\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/41\/194341-050-345CBFEA\/rocket-Soyuz-TMA-10M-Baikonur-Cosmodrome-Kazakhstan-September-25-2013.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/41\/194341-050-345CBFEA\/rocket-Soyuz-TMA-10M-Baikonur-Cosmodrome-Kazakhstan-September-25-2013.jpg?w=300\" alt=\"Soyuz TMA-10M\" width=\"1163\" height=\"1748\" data-width=\"1041\" data-height=\"1564\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/41\/194341-050-345CBFEA\/rocket-Soyuz-TMA-10M-Baikonur-Cosmodrome-Kazakhstan-September-25-2013.jpg\" data-href=\"\/media\/1\/557348\/238581\">Soyuz TMA-10M<\/a>The Soyuz TMA-10M rocket being launched from the Baikonur Cosmodrome in Kazakhstan, September 25, 2013.<\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">After the problems with the Soyuz design were diagnosed and remedied, various models of the spacecraft served as the means of access to space for the Soviet, and then Russian, program of human spaceflight for more than 50 years. Versions of Soyuz have been used both to transport crews to and from the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/International-Space-Station\" data-show-preview=\"true\">International Space Station<\/a>\u00a0and to serve as the crew rescue vehicle\u2014the lifeboat\u2014for the ISS.<\/p>\r\n<\/section>\r\n<\/section>\r\n<\/div>\r\n<div id=\"chatbot-root\">\u00a0<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div data-page-index=\"9\">\u00a0<\/div>\r\n<div class=\"loaded-infinite-scroll-container qa-infinite-scroll-container\">\r\n<div class=\"grey-box w-100 \">\r\n<div class=\"grey-box-content mx-auto w-100\">\r\n<div class=\"page2ref-false topic-content topic-type-REGULAR\">\r\n<div class=\"reading-channel\">\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237053\" data-level=\"3\" data-has-spy=\"true\">\r\n<h1 class=\"h3\"><strong>The race to the\u00a0<span id=\"ref838915\"><\/span><\/strong><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/Moon-exploration\" data-show-preview=\"true\"><strong>Moon<\/strong><\/a><\/h1>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237054\" data-level=\"4\" data-has-spy=\"true\">\r\n<h2 class=\"h4\"><strong>The American commitment<\/strong><\/h2>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"161595\" data-asm-type=\"video\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"video\"><a class=\"gtm-assembly-link d-flex justify-content-center\" href=\"https:\/\/www.britannica.com\/video\/History-human-spaceflight-program-American\/-161595\" data-id=\"152189\"><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/89\/152189-138-61ED6A2A\/History-human-spaceflight-program-American.jpg?w=800&amp;h=450&amp;c=crop\" alt=\"NASA's journey to landing a man on the Moon\" width=\"1314\" height=\"739\" \/><\/a>\r\n<div class=\"btn btn-xl btn-white btn-circle position-absolute shadow\">\u00a0<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><span class=\"md-assembly-title font-weight-bold mr-5 d-inline font-sans-serif md-video-caption\">NASA&#8217;s journey to landing a man on the Moon<\/span>History of the American human spaceflight program in the 1960s.<\/div>\r\n<a class=\"font-14 mt-10 d-inline-block\" href=\"https:\/\/www.britannica.com\/science\/space-exploration\/images-videos\">See all videos for this article<\/a><\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">In the immediate aftermath of Gagarin\u2019s orbital flight, President Kennedy was advised by\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/NASA\" data-show-preview=\"true\">NASA<\/a>\u00a0and by his vice president,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/biography\/Lyndon-B-Johnson\" data-show-preview=\"true\">Lyndon B. Johnson<\/a>, of Braun\u2019s belief that the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Soviet-Union\" data-show-preview=\"true\">Soviet Union<\/a>, using Korolyov\u2019s existing\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/R-7\" data-show-preview=\"true\">R-7<\/a>\u00a0launcher, could well succeed in sending a multiperson\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/spacecraft\" data-show-preview=\"true\">spacecraft<\/a>\u00a0into\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Earth\" data-show-preview=\"true\">Earth<\/a>\u00a0orbit and perhaps even around the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Moon\" data-show-preview=\"true\">Moon<\/a>\u00a0before the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/United-States\" data-show-preview=\"true\">United States<\/a>. The first competition that the United States had a good chance of winning would be that of a crewed lunar landing, because it would require each country to develop a new, more-powerful\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/rocket-jet-propulsion-device-and-vehicle\" data-show-preview=\"true\">rocket<\/a>. On those technical grounds and because a lunar landing would be a very visible demonstration of American strength, Kennedy announced on May 25, 1961, that the United States would commit itself to a lunar landing before 1970. At that time, only one American human\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/spaceflight\" data-show-preview=\"true\">spaceflight<\/a>, Shepard\u2019s 15-minute suborbital journey, had been made.<\/p>\r\n<p class=\"topic-paragraph\">In response to Kennedy\u2019s decision, the United States carried out a warlike, but peaceful, mobilization of financial and human resources. NASA\u2019s budget was increased almost 500 percent in three years, and at its peak the lunar landing program involved more than 34,000 NASA employees and 375,000 employees of industrial and university contractors.<\/p>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"60372\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/88\/70088-050-D36F21E2\/elements-program-Apollo-configurations-journey-Saturn-V.jpg\" data-href=\"\/media\/1\/557348\/60372\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/88\/70088-050-D36F21E2\/elements-program-Apollo-configurations-journey-Saturn-V.jpg\" media=\"(min-width: 680px)\" \/><img decoding=\"async\" src=\"https:\/\/cdn.britannica.com\/88\/70088-050-D36F21E2\/elements-program-Apollo-configurations-journey-Saturn-V.jpg?w=300\" alt=\"Apollo program: launch vehicle and spacecraft modules\" data-width=\"1600\" data-height=\"1144\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/88\/70088-050-D36F21E2\/elements-program-Apollo-configurations-journey-Saturn-V.jpg\" data-href=\"\/media\/1\/557348\/60372\">Apollo program: launch vehicle and spacecraft modules<\/a>Major elements of the U.S. Apollo program, showing the Saturn V launch vehicle and configurations of the Apollo spacecraft modules at launch and during their journey to the Moon.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">By the end of 1962, the basic elements of what was called\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/Apollo-space-program\" data-show-preview=\"true\">Project Apollo<\/a>\u00a0were in place. The\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/launch-vehicle\" data-show-preview=\"true\">launch vehicle<\/a>\u00a0would be a powerful\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Saturn-launch-vehicle\" data-show-preview=\"true\">Saturn<\/a>\u00a0V rocket, 110.6 metres (362.9 feet) tall and power-driven by five huge engines generating a total of 33,000 kilonewtons (7.4 million pounds) of lifting power at takeoff\u2014100 times the takeoff thrust of the Redstone rocket that had launched Shepard. After an intense debate, NASA chose a spacecraft configuration for Apollo that could be sent up in one launch, rather than a larger spacecraft that would need to be assembled in a series of rendezvous in Earth orbit. The Apollo spacecraft would have three sections. A\u00a0<span id=\"ref838932\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Command-Module\">Command Module<\/a>\u00a0would house the three-person crew on liftoff and landing and during the trip to and from the Moon. A\u00a0<span id=\"ref838933\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Service-Module\">Service Module<\/a>\u00a0would carry various equipment and the rocket engine needed to guide the spacecraft into lunar orbit and then send it back to Earth. A\u00a0<span id=\"ref838916\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Lunar-Module\">Lunar Module<\/a>,\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/comprising\" data-term=\"comprising\" data-type=\"MW\">comprising<\/a>\u00a0a descent stage and an ascent stage, would carry two people from lunar orbit to the Moon\u2019s surface and back to the Command Module. The ability of the Lunar Module\u2019s ascent stage to rendezvous and dock in lunar orbit with the Command Module after takeoff from the Moon was critical to the success of the mission. NASA also created a large new launch facility on Merritt Island, near\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Cape-Canaveral\" data-show-preview=\"true\">Cape Canaveral<\/a>, Florida, as the Apollo spaceport.<\/p>\r\n<\/section>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237055\" data-level=\"4\" data-has-spy=\"true\">\r\n<h2 class=\"h4\"><strong>The Soviet response<\/strong><\/h2>\r\n<p class=\"topic-paragraph\">While committing the United States to winning the Moon race, President Kennedy also made several attempts in the early 1960s to convince the Soviet leadership that a cooperative lunar landing program between their two countries would be a better\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/alternative\" data-term=\"alternative\" data-type=\"MW\">alternative<\/a>. No positive reply from the Soviet Union was forthcoming, however. In fact, between 1961 and 1963, there was still vigorous debate within the Soviet Union over the wisdom of undertaking a lunar program, and no final decision had been made on the question.<\/p>\r\n<p class=\"topic-paragraph\">Meanwhile, the separate design bureaus headed by Korolyov and his rival\u00a0<span id=\"ref838918\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Vladimir-Nikolayevich-Chelomey\" data-show-preview=\"true\">Vladimir Chelomey<\/a>\u00a0competed fiercely for a lunar mission assignment, either a flight around the Moon or an actual landing. Finally, in August 1964, Korolyov received the lunar landing assignment, and soon afterward Chelomey was given responsibility for planning a circumlunar flight to be carried out before the 50th anniversary of the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/October-Revolution-Russian-history\" data-show-preview=\"true\">Bolshevik Revolution<\/a>, which would take place in October 1967. In 1965 Soviet leaders decided to\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/combine\" data-term=\"combine\" data-type=\"EB\">combine<\/a>\u00a0the efforts of the two rivals for the circumlunar mission, using a version of Korolyov\u2019s\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/Soyuz\" data-show-preview=\"true\">Soyuz<\/a>\u00a0spacecraft and a new rocket, the UR-500 (also called the\u00a0<span id=\"ref838919\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Proton-Russian-launch-vehicle\" data-show-preview=\"true\">Proton<\/a>), designed by Chelomey.<\/p>\r\n<div class=\"module-spacing\">\u00a0<\/div>\r\n<p class=\"topic-paragraph\">The rocket that Korolyov designed for the lunar landing effort was called the\u00a0<span id=\"ref838924\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/N1\" data-show-preview=\"true\">N1<\/a>. Like the Saturn V, it was huge, standing 112.8 metres (370.1 feet) tall and having a planned takeoff thrust of 44,500 kilonewtons (10 million pounds). Instead of a few large rocket engines in its first stage, however, the N1 had 30 smaller engines. These were developed by\u00a0<span id=\"ref838928\"><\/span>Nikolay Kuznetsov, an aircraft-engine chief designer who had little experience with rocket engines, rather than the more capable Glushko. Korolyov and Valentin Glushko, already personal adversaries for many years, had disagreed on the proper fuel for the N1, and they finally decided that they could no longer work together. Consequently, Korolyov turned to Kuznetsov, who chose the small-engine approach.<\/p>\r\n<p class=\"topic-paragraph\">Indecision, inefficiencies, inadequate budgets, and personal and organizational rivalries in the Soviet system thus posed major obstacles to success in the race to the Moon. To these was added the unexpected death of Korolyov, age 59, during surgery on January 14, 1966. This was a serious setback to the Soviet space program. Korolyov had been a\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/charismatic\" data-term=\"charismatic\" data-type=\"MW\">charismatic<\/a>\u00a0leader and organizer. His successor,\u00a0<span id=\"ref838929\"><\/span>Vasily Mishin, attempted to maintain the program\u2019s momentum, but he was not the effective manager or politically sophisticated operator that Korolyov had been.<\/p>\r\n<\/section>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237056\" data-level=\"4\" data-has-spy=\"true\">\r\n<h2 class=\"h4\"><strong>Interim developments<\/strong><\/h2>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"68867\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/46\/65046-050-C41868E4\/view-Planet-Earth-lunar-horizon-spacecraft-farside-December-1968.jpg\" data-href=\"\/media\/1\/557348\/68867\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/46\/65046-050-C41868E4\/view-Planet-Earth-lunar-horizon-spacecraft-farside-December-1968.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/46\/65046-050-C41868E4\/view-Planet-Earth-lunar-horizon-spacecraft-farside-December-1968.jpg?w=300\" alt=\"Earthrise\" width=\"1093\" height=\"874\" data-width=\"1500\" data-height=\"1200\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/46\/65046-050-C41868E4\/view-Planet-Earth-lunar-horizon-spacecraft-farside-December-1968.jpg\" data-href=\"\/media\/1\/557348\/68867\"><em>Earthrise<\/em><\/a>Earth rising above the lunar horizon, an unprecedented view captured in December 1968 from the Apollo 8 spacecraft as its orbit carried it clear of the far side of the Moon. Taken by astronaut William Anders, this photograph has become known as\u00a0<em>Earthrise<\/em>.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">In the United States, Apollo moved forward as a high-priority program; after the assassination of President Kennedy in November 1963, it became seen as a memorial to the fallen young president. A major setback occurred on January 27, 1967, when astronauts Grissom, White, and\u00a0<span id=\"ref838934\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Roger-B-Chaffee\" data-show-preview=\"true\">Roger Chaffee<\/a>\u00a0were killed after their Apollo 1 Command Module caught fire during a ground test. The first crewed Apollo mission,\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/designated\" data-term=\"designated\" data-type=\"EB\">designated<\/a>\u00a0Apollo 7 and intended to test the redesigned Command Module, was launched into Earth orbit on October 11, 1968. The launcher used was a Saturn IB, a less-powerful rocket than the Saturn V needed to reach the Moon. The mission\u2019s success cleared the way for a bold step\u2014the first launch of a crew atop a Saturn V to the lunar vicinity. On December 21, 1968, the Apollo 8 Command and Service Modules were put on a trajectory that sent them into orbit around the Moon on Christmas Eve, December 24. The three astronauts\u2014<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Frank-Borman\" data-show-preview=\"true\">Frank Borman<\/a>,\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Jim-Lovell\" data-show-preview=\"true\">James A. Lovell, Jr.<\/a>, and\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/William-A-Anders\" data-show-preview=\"true\">William A. Anders<\/a>\u2014sent back close-up images of the lunar surface, read from the biblical book of\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/Genesis-United-States-spacecraft\" data-show-preview=\"true\">Genesis<\/a>, and brought back\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/vivid\" data-term=\"vivid\" data-type=\"EB\">vivid<\/a>\u00a0colour photographs of a blue planet Earth rising over the desolate lunar landscape. By the end of the mission, it was clear that the first lunar landing was only months away.<\/p>\r\n<p class=\"topic-paragraph\">One reason for conducting the Apollo 8 mission was to allow NASA to test most of the systems needed for a lunar landing attempt while waiting to carry out a crewed trial in Earth orbit of the Lunar Module, whose development was behind schedule. Another was the concern that the Soviet Union would beat the United States in sending people to the lunar vicinity. A circumlunar mission indeed had been part of Soviet plans, but the Soyuz 1 accident had made the October 1967\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/deadline\" data-term=\"deadline\" data-type=\"EB\">deadline<\/a>\u00a0infeasible. During 1968 a number of test flights of a circumlunar mission were made, using the Proton launcher and a version of the Soyuz spacecraft designated\u00a0<span id=\"ref838936\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Zond\" data-show-preview=\"true\">Zond<\/a>. In September Zond 5 carried a biological payload, including two tortoises, around the Moon and safely back to Earth, but two months later the Zond 6 spacecraft depressurized and then crashed on landing, ending any hope for a quick follow-on launch with a human crew. Plans to send cosmonauts around the Moon in a Zond spacecraft were postponed indefinitely in March 1969, but two more scientifically successful uncrewed circumlunar missions, Zond 7 and Zond 8, were carried out in 1969 and 1970, respectively.<\/p>\r\n<p class=\"topic-paragraph\">The Soviet lunar landing program went forward rather fitfully after 1964. The missions were intended to employ the N1 launch vehicle and another variation of the Soyuz spacecraft, designated L3, that included a lunar landing module designed for one\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/astronaut\" data-show-preview=\"true\">cosmonaut<\/a>. Although an L3 spacecraft was constructed and three cosmonauts trained for its use, the N1 rocket was never successfully launched. After four failed attempts between 1969 and 1972\u2014including a spectacular launch pad explosion in July 1969\u2014the N1 program was finally canceled in May 1974, and Soviet hopes for human missions to the Moon thus ended.<\/p>\r\n<\/section>\r\n<\/section>\r\n<\/div>\r\n<div id=\"chatbot-root\">\u00a0<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div data-page-index=\"10\">\u00a0<\/div>\r\n<div class=\"loaded-infinite-scroll-container qa-infinite-scroll-container\">\r\n<div class=\"grey-box w-100 \">\r\n<div class=\"grey-box-content mx-auto w-100\">\r\n<div class=\"page2ref-false topic-content topic-type-REGULAR\">\r\n<div class=\"reading-channel\">\r\n<section data-level=\"2\">\r\n<section data-level=\"3\">\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237057\" data-level=\"4\" data-has-spy=\"true\">\r\n<h1 class=\"h4\"><strong>The Apollo lunar landings and Apollo-Soyuz<\/strong><\/h1>\r\n<div class=\"assemblies multiple medialist slider js-slider position-relative d-inline-flex align-items-center mw-100\" data-type=\"other\">\r\n<div class=\"slider-container js-slider-container overflow-hidden d-flex rw-slider rw-prev-disabled\">\r\n<div class=\"rw-track d-flex align-items-center\">\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"8519\" data-asm-type=\"video\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"video\"><a class=\"gtm-assembly-link d-flex justify-content-center\" href=\"https:\/\/www.britannica.com\/video\/famous-Neil-Armstrong-space-films-clips-arrival-July-20-1969\/-8519\" data-id=\"23183\"><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/83\/23183-138-3E257FAE\/famous-Neil-Armstrong-space-films-clips-arrival-July-20-1969.jpg?w=800&amp;h=450&amp;c=crop\" alt=\"Witness Neil Armstrong take humankind's first steps on the lunar surface during NASA's Apollo 11 mission\" width=\"1117\" height=\"630\" \/><\/a>\r\n<div class=\"btn btn-xl btn-white btn-circle position-absolute shadow\">\u00a0<\/div>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">1 of 5<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><span class=\"md-assembly-title font-weight-bold mr-5 d-inline font-sans-serif md-video-caption\">Witness Neil Armstrong take humankind&#8217;s first steps on the lunar surface during NASA&#8217;s Apollo 11 mission<\/span>Perhaps the most famous of all space films, these clips document the arrival of the first human beings on the Moon during the afternoon of July 20, 1969. They comprise footage of the landing of the Apollo 11 spacecraft, taken with a 16-mm camera mounted in Edwin Aldrin&#8217;s window, and Neil Armstrong&#8217;s first steps on the Moon, recorded by a television camera whose signal was transmitted back to NASA Mission Control in Houston. In the audio can be heard one of the most famous misstatements in history: Armstrong had planned to say \u201cThat&#8217;s one small step for a man, one giant leap for mankind,\u201d but he forgot the \u201ca\u201d in the excitement of the moment.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<a class=\"font-14 mt-10 d-inline-block\" href=\"https:\/\/www.britannica.com\/science\/space-exploration\/images-videos\">See all videos for this article<\/a><\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"2881\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/15\/415-050-5342912B\/Edwin-Aldrin-Apollo-11-mission-surface-Neil-July-20-1969.jpg\" data-href=\"\/media\/1\/557348\/2881\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/15\/415-050-5342912B\/Edwin-Aldrin-Apollo-11-mission-surface-Neil-July-20-1969.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/15\/415-050-5342912B\/Edwin-Aldrin-Apollo-11-mission-surface-Neil-July-20-1969.jpg?w=300\" alt=\"Buzz Aldrin on the Moon\" width=\"1059\" height=\"2648\" data-width=\"591\" data-height=\"1477\" \/><\/picture><\/a>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">2 of 5<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/15\/415-050-5342912B\/Edwin-Aldrin-Apollo-11-mission-surface-Neil-July-20-1969.jpg\" data-href=\"\/media\/1\/557348\/2881\">Buzz Aldrin on the Moon<\/a>Apollo 11 astronaut Buzz Aldrin, photographed July 20, 1969, during the first crewed mission to the Moon&#8217;s surface. Reflected in Aldrin&#8217;s faceplate is the Lunar Module and astronaut Neil Armstrong, who took the picture.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"8518\" data-asm-type=\"video\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"video\"><a class=\"gtm-assembly-link d-flex justify-content-center\" href=\"https:\/\/www.britannica.com\/video\/video-mission-Apollo-Moon-astronauts-half-parts\/-8518\" data-id=\"23184\"><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/84\/23184-138-6179D68E\/video-mission-Apollo-Moon-astronauts-half-parts.jpg?w=800&amp;h=450&amp;c=crop\" alt=\"Watch an Apollo mission lift off from the Moon to rendezvous with the Command and Service modules\" width=\"1139\" height=\"646\" \/><\/a>\r\n<div class=\"btn btn-xl btn-white btn-circle position-absolute shadow\">\u00a0<\/div>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">3 of 5<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><span class=\"md-assembly-title font-weight-bold mr-5 d-inline font-sans-serif md-video-caption\">Watch an Apollo mission lift off from the Moon to rendezvous with the Command and Service modules<\/span>This video shows an Apollo mission taking off from the Moon. The Lunar Module consisted of two parts. The lower half, or descent stage, contained the landing engine and gear and was left behind to save weight and fuel. The upper half, or ascent stage, carried the astronauts to a rendezvous with the orbiting Command and Service modules, which took them back to Earth. The liftoff was recorded with a camera on the mission&#8217;s Lunar Roving Vehicle.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<a class=\"font-14 mt-10 d-inline-block\" href=\"https:\/\/www.britannica.com\/science\/space-exploration\/images-videos\">See all videos for this article<\/a><\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"100556\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/41\/100241-050-5EB51C16\/farside-Moon-Apollo-11-mission-1969.jpg\" data-href=\"\/media\/1\/557348\/100556\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/41\/100241-050-5EB51C16\/farside-Moon-Apollo-11-mission-1969.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/41\/100241-050-5EB51C16\/farside-Moon-Apollo-11-mission-1969.jpg?w=300\" alt=\"far side of the Moon\" width=\"1094\" height=\"904\" data-width=\"1600\" data-height=\"1326\" \/><\/picture><\/a>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">4 of 5<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/41\/100241-050-5EB51C16\/farside-Moon-Apollo-11-mission-1969.jpg\" data-href=\"\/media\/1\/557348\/100556\">far side of the Moon<\/a>The far side of the Moon, photographed during the Apollo 11 mission, 1969.<\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"138452\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/18\/418-050-613974C9\/Eagle-Grumman-lunar-module-Apollo-11-footpads-July-20-1969.jpg\" data-href=\"\/media\/1\/557348\/138452\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/18\/418-050-613974C9\/Eagle-Grumman-lunar-module-Apollo-11-footpads-July-20-1969.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/18\/418-050-613974C9\/Eagle-Grumman-lunar-module-Apollo-11-footpads-July-20-1969.jpg?w=300\" alt=\"Apollo 11 lunar module Eagle, 1969\" width=\"1237\" height=\"1130\" data-width=\"1600\" data-height=\"1462\" \/><\/picture><\/a>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">5 of 5<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/18\/418-050-613974C9\/Eagle-Grumman-lunar-module-Apollo-11-footpads-July-20-1969.jpg\" data-href=\"\/media\/1\/557348\/138452\">Apollo 11 lunar module\u00a0<em>Eagle<\/em>, 1969<\/a>Apollo 11 lunar module\u00a0<em>Eagle<\/em>\u00a0with its four landing-gear footpads deployed. This photograph was taken from the command module\u00a0<em>Columbia<\/em>\u00a0as the two spacecraft moved apart above the Moon.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<button class=\"prev-button js-prev-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20 rw-disabled\" disabled=\"disabled\"><\/button><button class=\"next-button js-next-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20\"><\/button><\/div>\r\n<p class=\"topic-paragraph\">In contrast to the Soviet lunar landing efforts, during 1969 all went well for the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/Apollo-space-program\" data-show-preview=\"true\">Apollo<\/a>\u00a0program. In March the Apollo 9 crew successfully tested the Lunar Module in\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Earth\" data-show-preview=\"true\">Earth<\/a>\u00a0orbit, and in May the Apollo 10 crew carried out a full dress rehearsal for the landing, coming within 15,200 metres (50,000 feet) of the lunar surface. On July 16, 1969, astronauts\u00a0<span id=\"ref838937\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Neil-Armstrong\" data-show-preview=\"true\">Armstrong<\/a>,\u00a0<span id=\"ref838938\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Buzz-Aldrin\" data-show-preview=\"true\">Aldrin<\/a>, and\u00a0<span id=\"ref838939\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Michael-Collins-American-astronaut\" data-show-preview=\"true\">Michael Collins<\/a>\u00a0set off on the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/Apollo-11\" data-show-preview=\"true\">Apollo 11<\/a>\u00a0mission, the first lunar landing attempt. While Collins remained in lunar orbit in the Command Module, Armstrong piloted the Lunar Module, nicknamed\u00a0<em>Eagle<\/em>, away from boulders on the lunar surface and to a successful landing on a flat lava plain called the Sea of Tranquillity at 4:18\u00a0<span class=\"text-smallcaps\">PM<\/span>\u00a0U.S. Eastern Daylight Time on July 20. He reported to mission control, \u201cHouston, Tranquillity Base here. The Eagle has landed.\u201d Six and a half hours later, Armstrong, soon followed by Aldrin, left the Lunar Module and took the first human step on the surface of another\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/celestial\" data-term=\"celestial\" data-type=\"EB\">celestial<\/a>\u00a0body. As he did so, he noted, \u201cThat\u2019s one small step for [a] man, one giant leap for mankind.\u201d (In the excitement of the moment, Armstrong apparently skipped the \u201ca\u201d in the statement he had prepared.) Concluding 2.5 hours of activity on the lunar surface, the two men returned to the Lunar Module with 21.7 kg (47.8 pounds) of lunar samples. Twelve hours later, they blasted off the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Moon\" data-show-preview=\"true\">Moon<\/a>\u00a0in the Lunar Module\u2019s ascent stage and rejoined Collins in the Command Module. The crew returned to Earth on July 24, splashing down in the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Pacific-Ocean\" data-show-preview=\"true\">Pacific Ocean<\/a>, where they were greeted by U.S. Pres.\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/biography\/Richard-Nixon\" data-show-preview=\"true\">Richard Nixon<\/a>.<\/p>\r\n<div class=\"assemblies multiple medialist slider js-slider position-relative d-inline-flex align-items-center mw-100\" data-type=\"other\">\r\n<div class=\"slider-container js-slider-container overflow-hidden d-flex rw-slider rw-prev-disabled\">\r\n<div class=\"rw-track d-flex align-items-center\">\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"2882\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/16\/416-050-5EA533A7\/spacecraft-liftoff-Apollo-15-rocket-Florida-Cape-July-26-1971.jpg\" data-href=\"\/media\/1\/557348\/2882\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/16\/416-050-5EA533A7\/spacecraft-liftoff-Apollo-15-rocket-Florida-Cape-July-26-1971.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/16\/416-050-5EA533A7\/spacecraft-liftoff-Apollo-15-rocket-Florida-Cape-July-26-1971.jpg?w=300\" alt=\"Apollo 15 liftoff\" width=\"1133\" height=\"1949\" data-width=\"865\" data-height=\"1489\" \/><\/picture><\/a>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">1 of 3<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/16\/416-050-5EA533A7\/spacecraft-liftoff-Apollo-15-rocket-Florida-Cape-July-26-1971.jpg\" data-href=\"\/media\/1\/557348\/2882\">Apollo 15 liftoff<\/a>Apollo 15 spacecraft during liftoff from Cape Kennedy, Florida, U.S., atop a Saturn V three-stage rocket, July 26, 1971. A camera mounted at the mobile launch tower&#8217;s 110-metre (360-foot) level recorded this photograph.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"2880\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/13\/413-050-80F3ECDE\/James-B-Irwin-Apollo-15-back-Lunar-July-26-1971.jpg\" data-href=\"\/media\/1\/557348\/2880\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/13\/413-050-80F3ECDE\/James-B-Irwin-Apollo-15-back-Lunar-July-26-1971.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/13\/413-050-80F3ECDE\/James-B-Irwin-Apollo-15-back-Lunar-July-26-1971.jpg?w=300\" alt=\"Apollo 15\" width=\"1222\" height=\"900\" data-width=\"1111\" data-height=\"819\" \/><\/picture><\/a>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">2 of 3<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/13\/413-050-80F3ECDE\/James-B-Irwin-Apollo-15-back-Lunar-July-26-1971.jpg\" data-href=\"\/media\/1\/557348\/2880\">Apollo 15<\/a>Apollo 15 astronaut James B. Irwin standing in back of the Lunar Roving Vehicle; the Lunar Module (LM) is at left with the modular equipment storage assembly (MESA) in front of it. Apollo 15 was launched July 26, 1971.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"138455\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/19\/419-050-0CE86370\/modules-Service-Command-Apollo-15-lunar-orbit.jpg\" data-href=\"\/media\/1\/557348\/138455\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/19\/419-050-0CE86370\/modules-Service-Command-Apollo-15-lunar-orbit.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/19\/419-050-0CE86370\/modules-Service-Command-Apollo-15-lunar-orbit.jpg?w=300\" alt=\"Apollo 15 Command and Service modules, 1971\" width=\"1056\" height=\"1538\" data-width=\"692\" data-height=\"1008\" \/><\/picture><\/a>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">3 of 3<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/19\/419-050-0CE86370\/modules-Service-Command-Apollo-15-lunar-orbit.jpg\" data-href=\"\/media\/1\/557348\/138455\">Apollo 15 Command and Service modules, 1971<\/a>Apollo 15 Command and Service modules in lunar orbit with the Moon&#8217;s surface in the background, as photographed from the Lunar Module. The Scientific Instrument Module (SIM) bay can be seen on the front of the Service Module.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<button class=\"prev-button js-prev-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20 rw-disabled\" disabled=\"disabled\"><\/button><button class=\"next-button js-next-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20\"><\/button><\/div>\r\n<p class=\"topic-paragraph\">The successful Apollo 12 mission followed in November 1969. The\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/Apollo-13-mission\" data-show-preview=\"true\">Apollo 13<\/a>\u00a0mission, launched in April 1970, experienced an explosion of the oxygen tank in its Service Module on the outbound trip to the Moon. The crew survived this accident only through the\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/improvised\" data-term=\"improvised\" data-type=\"EB\">improvised<\/a>\u00a0use of the Lunar Module as living quarters in order to preserve the remaining capabilities of the Command Module for reentering Earth\u2019s atmosphere after they had returned from their circumlunar journey. Four more Apollo missions followed. On each of the final three, the crew had a small cartlike rover that allowed them to travel several kilometres from their landing site. The final mission,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/event\/Apollo-17\" data-show-preview=\"true\">Apollo 17<\/a>, which was conducted in December 1972, included geologist\u00a0<span id=\"ref838942\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Harrison-Schmitt\" data-show-preview=\"true\">Harrison Schmitt<\/a>, the only trained scientist to set foot on the Moon.<\/p>\r\n<div class=\"assemblies multiple medialist slider js-slider position-relative d-inline-flex align-items-center mw-100\" data-type=\"other\">\r\n<div class=\"slider-container js-slider-container overflow-hidden d-flex rw-slider rw-prev-disabled\">\r\n<div class=\"rw-track d-flex align-items-center\">\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"8517\" data-asm-type=\"video\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"video\"><a class=\"gtm-assembly-link d-flex justify-content-center\" href=\"https:\/\/www.britannica.com\/video\/payload-vehicle-missions-Lunar-Roving-Vehicle-astronauts\/-8517\" data-id=\"23185\"><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/85\/23185-138-97F99E9D\/payload-vehicle-missions-Lunar-Roving-Vehicle-astronauts.jpg?w=800&amp;h=450&amp;c=crop\" alt=\"Watch the Lunar Roving Vehicle transport two astronauts on the Moon during the Apollo 15, 16, and 17 missions\" width=\"1067\" height=\"602\" \/><\/a>\r\n<div class=\"btn btn-xl btn-white btn-circle position-absolute shadow\">\u00a0<\/div>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">1 of 2<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><span class=\"md-assembly-title font-weight-bold mr-5 d-inline font-sans-serif md-video-caption\">Watch the Lunar Roving Vehicle transport two astronauts on the Moon during the Apollo 15, 16, and 17 missions<\/span>The Lunar Roving Vehicle, used on the Apollo 15, 16, and 17 missions. Built by Boeing largely of aluminum alloy, the vehicle was designed to carry two astronauts and their tools, instruments, and lunar samples up to a total payload of 490 kg (1,080 pounds), which was more than twice its own weight; nevertheless, it could be folded into a space 1.5 metres (5 feet) wide and 0.5 metre (20 inches) thick for stowage in the Lunar Module. Each steel-mesh wheel was driven by a small electric motor, which gave the rover a maximum speed of 12 km (8 miles) per hour on clear ground. Its large dish antenna transmitted a TV signal from a front-mounted colour camera directly to Earth.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<a class=\"font-14 mt-10 d-inline-block\" href=\"https:\/\/www.britannica.com\/science\/space-exploration\/images-videos\">See all videos for this article<\/a><\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"60514\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/14\/414-050-80F443C9\/geologist-astronaut-Apollo-17-foot-split-boulder-mission-December-13-1972.jpg\" data-href=\"\/media\/1\/557348\/60514\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/14\/414-050-80F443C9\/geologist-astronaut-Apollo-17-foot-split-boulder-mission-December-13-1972.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/14\/414-050-80F443C9\/geologist-astronaut-Apollo-17-foot-split-boulder-mission-December-13-1972.jpg?w=300\" alt=\"Apollo 17 astronaut Harrison Schmitt on the Moon, 1972\" width=\"1100\" height=\"876\" data-width=\"1109\" data-height=\"883\" \/><\/picture><\/a>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">2 of 2<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/14\/414-050-80F443C9\/geologist-astronaut-Apollo-17-foot-split-boulder-mission-December-13-1972.jpg\" data-href=\"\/media\/1\/557348\/60514\">Apollo 17 astronaut Harrison Schmitt on the Moon, 1972<\/a>Apollo 17 geologist-astronaut Harrison Schmitt at the foot of a huge split boulder, December 13, 1972, during the mission&#8217;s third extravehicular exploration of the Taurus-Littrow Valley landing site on the Moon.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<button class=\"prev-button js-prev-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20 rw-disabled\" disabled=\"disabled\"><\/button><button class=\"next-button js-next-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20\"><\/button><\/div>\r\n<p class=\"topic-paragraph\">The\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/United-States\" data-show-preview=\"true\">United States<\/a>\u00a0had won the race to the Moon, but that race had been motivated primarily by political considerations. No equally compelling reason to continue to travel to the Moon or to send humans to\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Mars-planet\" data-show-preview=\"true\">Mars<\/a>\u00a0was put forth in the following years. Proposals by U.S. presidents in 1989 and 2004 to restart human exploration beyond Earth orbit received insufficient political support to be\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/implemented\" data-term=\"implemented\" data-type=\"MW\">implemented<\/a>. No human has traveled beyond near-Earth orbit since Apollo 17 in December 1972. U.S. plans have called for a return to the Moon in the 2020s.<\/p>\r\n<p class=\"topic-paragraph\">An Apollo\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/spacecraft\" data-show-preview=\"true\">spacecraft<\/a>\u00a0was used for the last time in 1975. Three years earlier, as a sign of improved U.S.-Soviet relations, the two countries had agreed to carry out a joint mission in which an Apollo spacecraft carrying three astronauts would dock in orbit with a\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/Soyuz\" data-show-preview=\"true\">Soyuz<\/a>\u00a0vehicle having two cosmonauts aboard. The\u00a0<span id=\"ref838943\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Apollo-Soyuz-Test-Project\">Apollo-Soyuz Test Project<\/a>, which took place in July 1975, featured a \u201chandshake in space\u201d between Apollo commander\u00a0<span id=\"ref838944\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Thomas-Stafford\" data-show-preview=\"true\">Thomas P. Stafford<\/a>\u00a0and Soyuz commander\u00a0<span id=\"ref838945\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Aleksei-Leonov\" data-show-preview=\"true\">Aleksey Leonov<\/a>.<\/p>\r\n<\/section>\r\n<\/section>\r\n<\/section>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237058\" data-level=\"2\" data-has-spy=\"true\">\r\n<h2 class=\"h2\"><strong>Orbiting space platforms<\/strong><\/h2>\r\n<\/section>\r\n<\/div>\r\n<div id=\"chatbot-root\">\u00a0<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div data-page-index=\"11\">\u00a0<\/div>\r\n<div class=\"loaded-infinite-scroll-container qa-infinite-scroll-container\">\r\n<div class=\"grey-box w-100 \">\r\n<div class=\"grey-box-content mx-auto w-100\">\r\n<div class=\"page2ref-false topic-content topic-type-REGULAR\">\r\n<div class=\"reading-channel\">\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237059\" data-level=\"3\" data-has-spy=\"true\">\r\n<h1 class=\"h3\"><span id=\"ref838946\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/space-station\" data-show-preview=\"true\"><strong>Space stations<\/strong><\/a><\/h1>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"2897\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/32\/432-050-386E80F5\/Soyuz-10-launch-Baikonur-Cosmodrome-Kazakhstan-cosmonauts-April-23-1971.jpg\" data-href=\"\/media\/1\/557348\/2897\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/32\/432-050-386E80F5\/Soyuz-10-launch-Baikonur-Cosmodrome-Kazakhstan-cosmonauts-April-23-1971.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/32\/432-050-386E80F5\/Soyuz-10-launch-Baikonur-Cosmodrome-Kazakhstan-cosmonauts-April-23-1971.jpg?w=300\" alt=\"Soyuz 10\" width=\"1121\" height=\"538\" data-width=\"1439\" data-height=\"691\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/32\/432-050-386E80F5\/Soyuz-10-launch-Baikonur-Cosmodrome-Kazakhstan-cosmonauts-April-23-1971.jpg\" data-href=\"\/media\/1\/557348\/2897\">Soyuz 10<\/a>Soyuz 10 before being positioned for launch at the Baikonur Cosmodrome in Kazakhstan. Carrying three cosmonauts, Soyuz 10 was launched April 23, 1971, to the Salyut 1 space station, which had been put into orbit four days earlier. Equipment malfunction prevented the cosmonauts from entering and occupying the station.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">By 1969, even though the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Soviet-Union\" data-show-preview=\"true\">U.S.S.R.<\/a>\u00a0was still moving forward with its lunar landing program, it had begun to shift its\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/emphasis\" data-term=\"emphasis\" data-type=\"EB\">emphasis<\/a>\u00a0in human\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/spaceflight\" data-show-preview=\"true\">spaceflight<\/a>\u00a0to the development of Earth-orbiting stations in which\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/astronaut\" data-show-preview=\"true\">cosmonaut<\/a>\u00a0crews could carry out extended observations and experiments on missions that lasted weeks or months rather than a few days. The first Soviet\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/space-station\" data-show-preview=\"true\">space station<\/a>, called\u00a0<span id=\"ref838947\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Salyut\" data-show-preview=\"true\">Salyut<\/a>\u00a01, was launched April 19, 1971. The first crew to occupy the station\u2014<span id=\"ref838948\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Georgy-Timofeyevich-Dobrovolsky\" data-show-preview=\"true\">Georgy Dobrovolsky<\/a>,\u00a0<span id=\"ref838949\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Viktor-Ivanovich-Patsayev\" data-show-preview=\"true\">Viktor Patsayev<\/a>, and\u00a0<span id=\"ref838950\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Vladislav-Nikolayevich-Volkov\" data-show-preview=\"true\">Vladislav Volkov<\/a>\u2014spent 23 days aboard carrying out scientific studies but perished when their\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/Soyuz\" data-show-preview=\"true\">Soyuz<\/a>\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/spacecraft\" data-show-preview=\"true\">spacecraft<\/a>\u00a0depressurized during reentry.<\/p>\r\n<div class=\"assemblies multiple medialist slider js-slider position-relative d-inline-flex align-items-center mw-100\" data-type=\"other\">\r\n<div class=\"slider-container js-slider-container overflow-hidden d-flex rw-slider rw-prev-disabled\">\r\n<div class=\"rw-track d-flex align-items-center\">\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"66789\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/22\/71322-050-1AB5E6E7\/space-station-orbit-astronauts-Skylab-4-crew-February-8-1974.jpg\" data-href=\"\/media\/1\/557348\/66789\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/22\/71322-050-1AB5E6E7\/space-station-orbit-astronauts-Skylab-4-crew-February-8-1974.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/22\/71322-050-1AB5E6E7\/space-station-orbit-astronauts-Skylab-4-crew-February-8-1974.jpg?w=300\" alt=\"Skylab in orbit\" width=\"1114\" height=\"858\" data-width=\"1600\" data-height=\"1235\" \/><\/picture><\/a>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">1 of 2<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/22\/71322-050-1AB5E6E7\/space-station-orbit-astronauts-Skylab-4-crew-February-8-1974.jpg\" data-href=\"\/media\/1\/557348\/66789\">Skylab in orbit<\/a>U.S. Skylab space station in orbit over a cloud-covered Earth, photographed February 8, 1974, by the departing third crew of astronauts from their Skylab 4 Command Module. The makeshift gold-coloured sun shield and underlying parasol on the main part of the station were installed by the first two crews to cover damage done to Skylab&#8217;s protective shielding during launch. The launch mishap also tore off one of the station&#8217;s lateral solar arrays.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"60378\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/94\/70094-050-750F3494\/space-station-Skylab-modules-Service-Apollo-Command.jpg\" data-href=\"\/media\/1\/557348\/60378\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/94\/70094-050-750F3494\/space-station-Skylab-modules-Service-Apollo-Command.jpg\" media=\"(min-width: 680px)\" \/><img decoding=\"async\" src=\"https:\/\/cdn.britannica.com\/94\/70094-050-750F3494\/space-station-Skylab-modules-Service-Apollo-Command.jpg?w=300\" alt=\"Skylab\" data-width=\"1338\" data-height=\"1600\" \/><\/picture><\/a>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">2 of 2<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/94\/70094-050-750F3494\/space-station-Skylab-modules-Service-Apollo-Command.jpg\" data-href=\"\/media\/1\/557348\/60378\">Skylab<\/a>U.S. space station Skylab (occupied 1973\u201374), shown with docked Apollo Command and Service modules.<\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<button class=\"prev-button js-prev-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20 rw-disabled\" disabled=\"disabled\"><\/button><button class=\"next-button js-next-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20\"><\/button><\/div>\r\n<p class=\"topic-paragraph\">With similar objectives for a long-term crewed platform in space, the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/United-States\" data-show-preview=\"true\">United States<\/a>\u00a0converted the third stage of a\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/Saturn-launch-vehicle\" data-show-preview=\"true\">Saturn<\/a>\u00a0V\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/rocket-jet-propulsion-device-and-vehicle\" data-show-preview=\"true\">rocket<\/a>\u00a0into an orbital workshop for solar and biomedical studies. This first U.S. space station, called\u00a0<span id=\"ref838951\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Skylab\" data-show-preview=\"true\">Skylab<\/a>, was launched May 14, 1973. Over a period of eight and a half months, three three-person crews using\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/Apollo-space-program\" data-show-preview=\"true\">Apollo<\/a>\u00a0spacecraft for transport spent time aboard Skylab, with the final crew staying for 84 days. Skylab was abandoned in February 1974 and reentered\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Earth\" data-show-preview=\"true\">Earth\u2019s<\/a>\u00a0atmosphere in July 1979, with some portions of the station surviving reentry and landing in\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Australia\" data-show-preview=\"true\">Australia<\/a>.<\/p>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"2898\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/33\/433-050-5914B26C\/spacecraft-Soyuz-T-5-Salyut-7-space-station-June-24.jpg\" data-href=\"\/media\/1\/557348\/2898\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/33\/433-050-5914B26C\/spacecraft-Soyuz-T-5-Salyut-7-space-station-June-24.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/33\/433-050-5914B26C\/spacecraft-Soyuz-T-5-Salyut-7-space-station-June-24.jpg?w=300\" alt=\"Soyuz T-5 and Salyut 7\" width=\"1022\" height=\"1376\" data-width=\"963\" data-height=\"1295\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/33\/433-050-5914B26C\/spacecraft-Soyuz-T-5-Salyut-7-space-station-June-24.jpg\" data-href=\"\/media\/1\/557348\/2898\">Soyuz T-5 and Salyut 7<\/a>Soyuz T-5 spacecraft (foreground) docked with the Salyut 7 space station, as photographed in orbit from Soyuz T-6. Salyut 7 was launched on April 19, 1982. Soyuz T-5, carrying the station&#8217;s primary two-man crew, was launched nearly a month later, on May 13. Soyuz T-6, launched on June 24, carried three additional crew members, including a French guest cosmonaut, to the orbiting station.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">Because of budgetary cuts, the United States did not launch a planned second Skylab. In contrast, the Soviet Union orbited and successfully occupied five more Salyut stations in a program that continued through the mid-1980s. Two of these stations had a military reconnaissance mission, but the others were devoted to scientific studies, particularly biomedical research. The Soviet Union also launched guest cosmonauts from allied countries for short stays aboard Salyut 6 and 7.<\/p>\r\n<p class=\"topic-paragraph\">These early stations were a reflection of a long-held belief among space\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/visionaries\" data-term=\"visionaries\" data-type=\"EB\">visionaries<\/a>, dating back to Tsiolkovsky at the start of the 20th century, that living and working in space, first in Earth orbit and then on the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Moon\" data-show-preview=\"true\">Moon<\/a>,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Mars-planet\" data-show-preview=\"true\">Mars<\/a>, and other locations, were an important part of the human future. It also was thought that increasingly complex orbital outposts would be the first steps in a long-term process of space development and colonization. The early focus of the United States and the U.S.S.R. on sending people to the Moon for political reasons deviated from this vision, which has since returned to dominate space thinking.<\/p>\r\n<div class=\"assemblies multiple medialist slider js-slider position-relative d-inline-flex align-items-center mw-100\" data-type=\"other\">\r\n<div class=\"slider-container js-slider-container overflow-hidden d-flex rw-slider rw-prev-disabled\">\r\n<div class=\"rw-track d-flex align-items-center\">\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"68868\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/18\/73218-050-126F8312\/space-station-Mir-Russian-Atlantis-Cook-Strait-March-23-1996.jpg\" data-href=\"\/media\/1\/557348\/68868\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/18\/73218-050-126F8312\/space-station-Mir-Russian-Atlantis-Cook-Strait-March-23-1996.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/18\/73218-050-126F8312\/space-station-Mir-Russian-Atlantis-Cook-Strait-March-23-1996.jpg?w=300\" alt=\"Mir\" width=\"1067\" height=\"1031\" data-width=\"1600\" data-height=\"1550\" \/><\/picture><\/a>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">1 of 2<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/18\/73218-050-126F8312\/space-station-Mir-Russian-Atlantis-Cook-Strait-March-23-1996.jpg\" data-href=\"\/media\/1\/557348\/68868\">Mir<\/a>Russian space station Mir\u2014in the background is Cook Strait near New Zealand&#8217;s South Island\u2014as photographed March 23, 1996, from the space shuttle orbiter\u00a0<em>Atlantis<\/em>\u00a0prior to docking of the two spacecraft.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"60376\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/92\/70092-050-7482A08E\/space-station-Soviet-Russian-Mir-completion-module-1996.jpg\" data-href=\"\/media\/1\/557348\/60376\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/92\/70092-050-7482A08E\/space-station-Soviet-Russian-Mir-completion-module-1996.jpg\" media=\"(min-width: 680px)\" \/><img decoding=\"async\" src=\"https:\/\/cdn.britannica.com\/92\/70092-050-7482A08E\/space-station-Soviet-Russian-Mir-completion-module-1996.jpg?w=300\" alt=\"Mir\" data-width=\"1600\" data-height=\"1560\" \/><\/picture><\/a>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">2 of 2<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/92\/70092-050-7482A08E\/space-station-Soviet-Russian-Mir-completion-module-1996.jpg\" data-href=\"\/media\/1\/557348\/60376\">Mir<\/a>Soviet\/Russian space station Mir after completion in 1996. The date shown for each module is its year of launch. Docked to the station are a Soyuz TM crewed spacecraft and an uncrewed Progress resupply ferry.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<button class=\"prev-button js-prev-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20 rw-disabled\" disabled=\"disabled\"><\/button><button class=\"next-button js-next-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20\"><\/button><\/div>\r\n<p class=\"topic-paragraph\">The Soviet Union followed its Salyut station series with the February 1986 launch of the core element of the\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/modular\" data-term=\"modular\" data-type=\"EB\">modular<\/a>\u00a0<span id=\"ref838952\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Mir-Soviet-Russian-space-station\" data-show-preview=\"true\">Mir<\/a>\u00a0space station. Additional modules carrying scientific equipment and expanding the living space were attached to Mir in subsequent years. In 1994\u201395\u00a0<span id=\"ref838953\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Valery-Vladimirovich-Polyakov\" data-show-preview=\"true\">Valery Polyakov<\/a>, a medical doctor, spent 438 continuous days aboard the station. More than 100 different people from 12 countries visited Mir, including seven American astronauts in the 1995\u201398 period. The station, which was initially scheduled to operate for only five years, supported human habitation until mid-2000 (continuously between 1989 and 1999), although it experienced a number of accidents and other serious problems. In March 2001 it made a controlled atmospheric reentry, with the surviving pieces falling into the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Pacific-Ocean\" data-show-preview=\"true\">Pacific Ocean<\/a>.<\/p>\r\n<div class=\"module-spacing\">\u00a0<\/div>\r\n<p class=\"topic-paragraph\">The United States did not follow up on Skylab until 1984, when Pres.\u00a0<span id=\"ref838956\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Ronald-Reagan\" data-show-preview=\"true\">Ronald Reagan<\/a>\u00a0approved a space station program and invited U.S. allies to participate. By 1988, 11 countries\u2014Canada,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Japan\" data-show-preview=\"true\">Japan<\/a>, and 9 countries from Europe\u2014had decided to join what was known as Space Station Freedom. Progress in developing the station was slow, however, and in 1993 newly elected Pres.\u00a0<span id=\"ref838955\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Bill-Clinton\" data-show-preview=\"true\">Bill Clinton<\/a>\u00a0ordered a sweeping redesign of the program. The United States and its existing partners invited\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Russia\" data-show-preview=\"true\">Russia<\/a>, which had\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/inherited\" data-term=\"inherited\" data-type=\"EB\">inherited<\/a>\u00a0most of the Soviet Union\u2019s space efforts after the U.S.S.R.\u2019s collapse in 1991, to participate in the multinational program, renamed the\u00a0<span id=\"ref838954\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/International-Space-Station\" data-show-preview=\"true\">International Space Station<\/a>\u00a0(ISS). Three additional countries joined during the 1990s and thereby made the 16-country project the largest-ever cooperative technological undertaking. The first two elements of the ISS were launched and connected in space in late 1998. Between 2000 and 2011, U.S., European, Japanese, and Russian modules were added to the ISS, along with Canadian robotic equipment and U.S.-provided trusses, solar panels, and associated hardware. An initial three-person crew began its stay aboard the ISS in November 2000, and the station has been continuously occupied since then. When ISS assembly was completed in 2011, the program\u2019s focus shifted to scientific and technological utilization of the orbiting laboratory, which is planned to remain in service until at least 2024.<\/p>\r\n<\/section>\r\n<\/div>\r\n<div id=\"chatbot-root\">\u00a0<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div data-page-index=\"12\">\u00a0<\/div>\r\n<div class=\"loaded-infinite-scroll-container qa-infinite-scroll-container\">\r\n<div class=\"grey-box w-100 \">\r\n<div class=\"grey-box-content mx-auto w-100\">\r\n<div class=\"page2ref-false topic-content topic-type-REGULAR\">\r\n<div class=\"reading-channel\">\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref310635\" data-level=\"3\" data-has-spy=\"true\">\r\n<h1 class=\"h3\"><strong>International space endurance records<\/strong><\/h1>\r\n<p class=\"topic-paragraph\"><span id=\"ref3324\"><\/span>A list of human endurance records in space is provided in the table.<\/p>\r\n<div class=\"md-drag md-table-wrapper\">\r\n<table><caption>International space endurance records<\/caption>\r\n<thead>\r\n<tr>\r\n<th scope=\"col\">cosmonaut\/astronaut<\/th>\r\n<th scope=\"col\">primary habitat<\/th>\r\n<th scope=\"col\">month and year launched<\/th>\r\n<th scope=\"col\">days in space<\/th>\r\n<\/tr>\r\n<\/thead>\r\n<tbody>\r\n<tr>\r\n<td scope=\"row\"><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Yuri-Gagarin\" data-show-preview=\"true\">Yury A. Gagarin<\/a><\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Vostok-Soviet-spacecraft\" data-show-preview=\"true\">Vostok<\/a>\u00a01<\/td>\r\n<td>April 1961<\/td>\r\n<td>0.07<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\"><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Gherman-Stepanovich-Titov\" data-show-preview=\"true\">Gherman S. Titov<\/a><\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Vostok-Soviet-spacecraft\" data-show-preview=\"true\">Vostok<\/a>\u00a02<\/td>\r\n<td>August 1961<\/td>\r\n<td>1.05<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\"><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Andriyan-Nikolayev\" data-show-preview=\"true\">Andriyan G. Nikolayev<\/a><\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Vostok-Soviet-spacecraft\" data-show-preview=\"true\">Vostok<\/a>\u00a03<\/td>\r\n<td>August 1962<\/td>\r\n<td>3.93<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\"><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Valery-Bykovsky\" data-show-preview=\"true\">Valery F. Bykovsky<\/a><\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Vostok-Soviet-spacecraft\" data-show-preview=\"true\">Vostok<\/a>\u00a05<\/td>\r\n<td>June 1963<\/td>\r\n<td>4.97<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\"><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Gordon-Cooper\" data-show-preview=\"true\">L. Gordon Cooper, Jr.<\/a> <a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Pete-Conrad\" data-show-preview=\"true\">Charles Conrad, Jr.<\/a><\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/Gemini-spacecraft-and-space-program\" data-show-preview=\"true\">Gemini<\/a>\u00a05<\/td>\r\n<td>August 1965<\/td>\r\n<td>7.92<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\"><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Frank-Borman\" data-show-preview=\"true\">Frank Borman<\/a> <a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Jim-Lovell\" data-show-preview=\"true\">James A. Lovell, Jr.<\/a><\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/Gemini-spacecraft-and-space-program\" data-show-preview=\"true\">Gemini<\/a>\u00a07<\/td>\r\n<td>December 1965<\/td>\r\n<td>13.75<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\"><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Andriyan-Nikolayev\" data-show-preview=\"true\">Andriyan G. Nikolayev<\/a> Vitaly I. Sevastyanov<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Soyuz\" data-show-preview=\"true\">Soyuz<\/a>\u00a09<\/td>\r\n<td>June 1970<\/td>\r\n<td>17.71<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Georgy T. Dobrovolsky <a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Viktor-Ivanovich-Patsayev\" data-show-preview=\"true\">Viktor I. Patsayev<\/a> <a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Vladislav-Nikolayevich-Volkov\" data-show-preview=\"true\">Vladislav N. Volkov<\/a><\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Salyut\" data-show-preview=\"true\">Salyut<\/a>\u00a01<\/td>\r\n<td>June 1971<\/td>\r\n<td>23.76<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\"><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Pete-Conrad\" data-show-preview=\"true\">Charles Conrad, Jr.<\/a> Paul J. Weitz Joseph P. Kerwin<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Skylab\" data-show-preview=\"true\">Skylab<\/a><\/td>\r\n<td>May 1973<\/td>\r\n<td>28.04<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\"><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Alan-Bean\" data-show-preview=\"true\">Alan L. Bean<\/a> Jack R. Lousma Owen K. Garriott<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Skylab\" data-show-preview=\"true\">Skylab<\/a><\/td>\r\n<td>July 1973<\/td>\r\n<td>59.49<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Gerald P. Carr William R. Pogue Edward G. Gibson<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Skylab\" data-show-preview=\"true\">Skylab<\/a><\/td>\r\n<td>November 1973<\/td>\r\n<td>84.04<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Yury V. Romanenko Georgy M. Grechko<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Salyut\" data-show-preview=\"true\">Salyut<\/a>\u00a06<\/td>\r\n<td>December 1977<\/td>\r\n<td>96.42<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Vladimir V. Kovalyonok Aleksandr S. Ivanchenkov<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Salyut\" data-show-preview=\"true\">Salyut<\/a>\u00a06<\/td>\r\n<td>June 1978<\/td>\r\n<td>139.6<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Vladimir A. Lyakhov Valery V. Ryumin<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Salyut\" data-show-preview=\"true\">Salyut<\/a>\u00a06<\/td>\r\n<td>February 1979<\/td>\r\n<td>175.06<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Leonid I. Popov Valery V. Ryumin<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Salyut\" data-show-preview=\"true\">Salyut<\/a>\u00a06<\/td>\r\n<td>April 1980<\/td>\r\n<td>184.84<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Anatoly N. Berezovoy Valentin V. Lebedev<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Salyut\" data-show-preview=\"true\">Salyut<\/a>\u00a07<\/td>\r\n<td>May 1982<\/td>\r\n<td>211.38<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Leonid D. Kizim Vladimir A. Solovyov Oleg Y. Atkov<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Salyut\" data-show-preview=\"true\">Salyut<\/a>\u00a07<\/td>\r\n<td>February 1984<\/td>\r\n<td>236.95<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Yury V. Romanenko<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Mir-Soviet-Russian-space-station\" data-show-preview=\"true\">Mir<\/a><\/td>\r\n<td>February 1987<\/td>\r\n<td>326.48<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Vladimir G. Titov Musa K. Manarov<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Mir-Soviet-Russian-space-station\" data-show-preview=\"true\">Mir<\/a><\/td>\r\n<td>December 1987<\/td>\r\n<td>365.95<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Valery V. Polyakov<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Mir-Soviet-Russian-space-station\" data-show-preview=\"true\">Mir<\/a><\/td>\r\n<td>January 1994<\/td>\r\n<td>437.75<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<\/div>\r\n<\/section>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref310636\" data-level=\"3\" data-has-spy=\"true\">\r\n<h2 class=\"h3\">Summary of space stations launched since 1971<\/h2>\r\n<p class=\"topic-paragraph\"><span id=\"ref3325\"><\/span>A summary of space stations launched since 1971 is provided in the table.<\/p>\r\n<div class=\"md-drag md-table-wrapper\">\r\n<table><caption>Space stations (1971 onward)<\/caption>\r\n<thead>\r\n<tr>\r\n<th scope=\"col\">station, or major module for modular station<\/th>\r\n<th scope=\"col\">country of origin, or country of launch for ISS* modules<\/th>\r\n<th scope=\"col\">date launched<\/th>\r\n<th scope=\"col\">date reentered<\/th>\r\n<th scope=\"col\">occupancy, total days (and number of major expeditions)<\/th>\r\n<th scope=\"col\">comments<\/th>\r\n<\/tr>\r\n<\/thead>\r\n<tfoot>\r\n<tr>\r\n<td colspan=\"6\">*International Space Station.<\/td>\r\n<\/tr>\r\n<\/tfoot>\r\n<tbody>\r\n<tr>\r\n<td scope=\"row\"><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Salyut\" data-show-preview=\"true\">Salyut<\/a>\u00a01<\/td>\r\n<td>U.S.S.R.<\/td>\r\n<td>April 19, 1971<\/td>\r\n<td>October 11, 1971<\/td>\r\n<td>23 (1)<\/td>\r\n<td>first space station, equipped for scientific studies; abandoned after its first crew died returning to Earth<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\"><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Salyut\" data-show-preview=\"true\">Salyut<\/a>\u00a02<\/td>\r\n<td>U.S.S.R.<\/td>\r\n<td>April 3, 1973<\/td>\r\n<td>May 28, 1973<\/td>\r\n<td>0<\/td>\r\n<td>military reconnaissance platform; suffered explosion after achieving orbit and was never occupied<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Cosmos 557<\/td>\r\n<td>U.S.S.R.<\/td>\r\n<td>May 11, 1973<\/td>\r\n<td>May 22, 1973<\/td>\r\n<td>0<\/td>\r\n<td>scientific station; crippled after achieving orbit and was never occupied<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\"><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Skylab\" data-show-preview=\"true\">Skylab<\/a><\/td>\r\n<td>U.S.<\/td>\r\n<td>May 14, 1973<\/td>\r\n<td>July 11, 1979<\/td>\r\n<td>171 (3)<\/td>\r\n<td>first U.S. space station; successfully supported solar studies and biomedical experiments on the effects of weightlessness<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\"><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Salyut\" data-show-preview=\"true\">Salyut<\/a>\u00a03<\/td>\r\n<td>U.S.S.R.<\/td>\r\n<td>June 25, 1974<\/td>\r\n<td>January 24, 1975<\/td>\r\n<td>16 (1)<\/td>\r\n<td>military reconnaissance platform<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\"><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Salyut\" data-show-preview=\"true\">Salyut<\/a>\u00a04<\/td>\r\n<td>U.S.S.R.<\/td>\r\n<td>December 26, 1974<\/td>\r\n<td>February 3, 1977<\/td>\r\n<td>93 (2)<\/td>\r\n<td>scientific station; operated until its systems were exhausted<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\"><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Salyut\" data-show-preview=\"true\">Salyut<\/a>\u00a05<\/td>\r\n<td>U.S.S.R.<\/td>\r\n<td>June 22, 1976<\/td>\r\n<td>August 8, 1977<\/td>\r\n<td>67 (2)<\/td>\r\n<td>military reconnaissance platform<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\"><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Salyut\" data-show-preview=\"true\">Salyut<\/a>\u00a06<\/td>\r\n<td>U.S.S.R.<\/td>\r\n<td>September 29, 1977<\/td>\r\n<td>July 29, 1982<\/td>\r\n<td>684 (6)<\/td>\r\n<td>first second-generation Salyut, operated as highly successful scientific station; resident crews hosted a series of international visitors<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\"><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Salyut\" data-show-preview=\"true\">Salyut<\/a>\u00a07<\/td>\r\n<td>U.S.S.R.<\/td>\r\n<td>April 19, 1982<\/td>\r\n<td>February 2, 1991<\/td>\r\n<td>815 (5)<\/td>\r\n<td>problem-plagued follow-up to Salyut 6 that had to be repeatedly rescued<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\"><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Mir-Soviet-Russian-space-station\" data-show-preview=\"true\">Mir<\/a>\u00a0(modular)<\/td>\r\n<td>U.S.S.R.\/Russia<\/td>\r\n<td>\u2014<\/td>\r\n<td>March 23, 2001<\/td>\r\n<td>occupied March 14, 1986, to June 15, 2000 (continuously from September 7, 1989, to August 28, 1999)<\/td>\r\n<td>first space station assembled in orbit using individually launched, specialized modules; successfully applied lessons learned from Salyut program<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Mir base block<\/td>\r\n<td>\u2014<\/td>\r\n<td>February 20, 1986<\/td>\r\n<td>\u2014<\/td>\r\n<td>\u2014<\/td>\r\n<td>habitat module<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Kvant 1<\/td>\r\n<td>\u2014<\/td>\r\n<td>March 31, 1987<\/td>\r\n<td>\u2014<\/td>\r\n<td>\u2014<\/td>\r\n<td>astrophysics observatory with X-ray telescopes<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Kvant 2<\/td>\r\n<td>\u2014<\/td>\r\n<td>November 26, 1989<\/td>\r\n<td>\u2014<\/td>\r\n<td>\u2014<\/td>\r\n<td>supplementary life-support systems and large air lock<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Kristall<\/td>\r\n<td>\u2014<\/td>\r\n<td>May 31, 1990<\/td>\r\n<td>\u2014<\/td>\r\n<td>\u2014<\/td>\r\n<td>microgravity materials-processing laboratory<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Spektr<\/td>\r\n<td>\u2014<\/td>\r\n<td>May 20, 1995<\/td>\r\n<td>\u2014<\/td>\r\n<td>\u2014<\/td>\r\n<td>module with apparatus for NASA research<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Priroda<\/td>\r\n<td>\u2014<\/td>\r\n<td>April 23, 1996<\/td>\r\n<td>\u2014<\/td>\r\n<td>\u2014<\/td>\r\n<td>module with NASA apparatus and Earth-sciences sensors<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\"><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/International-Space-Station\" data-show-preview=\"true\">International Space Station<\/a>\u00a0(modular)<\/td>\r\n<td>international consortium, primarily U.S. and Russia<\/td>\r\n<td>\u2014<\/td>\r\n<td>\u2014<\/td>\r\n<td>permanently occupied since November 2, 2000<\/td>\r\n<td>modular, expandable station intended to serve world&#8217;s space agencies for first quarter of 21st century<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Zarya<\/td>\r\n<td>Russia<\/td>\r\n<td>November 20, 1998<\/td>\r\n<td>\u2014<\/td>\r\n<td>\u2014<\/td>\r\n<td>U.S.-funded, Russian-built module supplying initial solar power and attitude-control system<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Unity<\/td>\r\n<td>U.S.<\/td>\r\n<td>December 4, 1998<\/td>\r\n<td>\u2014<\/td>\r\n<td>\u2014<\/td>\r\n<td>U.S.-built connecting node<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Zvezda<\/td>\r\n<td>Russia<\/td>\r\n<td>July 2, 2000<\/td>\r\n<td>\u2014<\/td>\r\n<td>\u2014<\/td>\r\n<td>Russian-built habitat module and control centre<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Destiny<\/td>\r\n<td>U.S.<\/td>\r\n<td>February 7, 2001<\/td>\r\n<td>\u2014<\/td>\r\n<td>\u2014<\/td>\r\n<td>U.S.-built NASA microgravity laboratory<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Quest<\/td>\r\n<td>U.S.<\/td>\r\n<td>July 12, 2001<\/td>\r\n<td>\u2014<\/td>\r\n<td>\u2014<\/td>\r\n<td>U.S.-built air lock, allowing station-based space walks for U.S. and Russian astronauts<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Pirs<\/td>\r\n<td>Russia<\/td>\r\n<td>September 14, 2001<\/td>\r\n<td>\u2014<\/td>\r\n<td>\u2014<\/td>\r\n<td>Russian-built docking compartment, providing Soyuz docking port and additional air lock for Russian space walks<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Harmony<\/td>\r\n<td>U.S.<\/td>\r\n<td>October 23, 2007<\/td>\r\n<td>\u2014<\/td>\r\n<td>\u2014<\/td>\r\n<td>U.S.-built connecting node<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Columbus<\/td>\r\n<td>U.S.<\/td>\r\n<td>February 7, 2008<\/td>\r\n<td>\u00a0<\/td>\r\n<td>\u00a0<\/td>\r\n<td><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/European-Space-Agency\" data-show-preview=\"true\">European Space Agency<\/a>-built microgravity laboratory<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Kibo<\/td>\r\n<td>U.S.<\/td>\r\n<td>March 11, 2008; May 31, 2008<\/td>\r\n<td>\u00a0<\/td>\r\n<td>\u00a0<\/td>\r\n<td>Japanese-built microgravity laboratory<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Dextre<\/td>\r\n<td>U.S.<\/td>\r\n<td>March 11, 2008<\/td>\r\n<td>\u00a0<\/td>\r\n<td>\u00a0<\/td>\r\n<td>Canadian-built robot<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Mini-Research Module-2<\/td>\r\n<td>Russia<\/td>\r\n<td>November 10, 2009<\/td>\r\n<td>\u2014<\/td>\r\n<td>\u2014<\/td>\r\n<td>Russian-built docking compartment, providing Soyuz docking port and additional air lock for Russian space walks<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Tranquility<\/td>\r\n<td>U.S.<\/td>\r\n<td>February 8, 2010<\/td>\r\n<td>\u2014<\/td>\r\n<td>\u2014<\/td>\r\n<td>U.S.-built connecting node<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Mini-Research Module-1<\/td>\r\n<td>U.S.<\/td>\r\n<td>May 14, 2010<\/td>\r\n<td>\u2014<\/td>\r\n<td>\u2014<\/td>\r\n<td>Russian-built docking compartment<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Permanent Multipurpose Module Leonardo<\/td>\r\n<td>U.S.<\/td>\r\n<td>February 24, 2011<\/td>\r\n<td>\u2014<\/td>\r\n<td>\u2014<\/td>\r\n<td>Italian-built module<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Bigelow Expandable Activity Module<\/td>\r\n<td>U.S.<\/td>\r\n<td>April 8, 2016<\/td>\r\n<td>\u2014<\/td>\r\n<td>\u2014<\/td>\r\n<td>Module built by Bigelow Aerospace to test expandable module technology<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\"><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Tiangong\" data-show-preview=\"true\">Tiangong<\/a>\u00a01<\/td>\r\n<td>China<\/td>\r\n<td>September 29, 2011<\/td>\r\n<td>April 2, 2018<\/td>\r\n<td>21 (2)<\/td>\r\n<td>first Chinese space station<\/td>\r\n<\/tr>\r\n<tr>\r\n<td scope=\"row\">Tiangong 2<\/td>\r\n<td>China<\/td>\r\n<td>September 15, 2016<\/td>\r\n<td>\u2014<\/td>\r\n<td>29 (1)<\/td>\r\n<td>second Chinese space station<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n<\/div>\r\n<\/section>\r\n<\/div>\r\n<div id=\"chatbot-root\">\u00a0<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div data-page-index=\"13\">\u00a0<\/div>\r\n<div class=\"loaded-infinite-scroll-container qa-infinite-scroll-container\">\r\n<div class=\"grey-box w-100 \">\r\n<div class=\"grey-box-content mx-auto w-100\">\r\n<div class=\"page2ref-false topic-content topic-type-REGULAR\">\r\n<div class=\"reading-channel\">\r\n<section data-level=\"1\">\r\n<section data-level=\"2\">\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237060\" data-level=\"3\" data-has-spy=\"true\">\r\n<h1 class=\"h3\">The\u00a0<span id=\"ref838957\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/space-shuttle\" data-show-preview=\"true\">space shuttle<\/a><\/h1>\r\n<div class=\"assemblies multiple medialist slider js-slider position-relative d-inline-flex align-items-center mw-100\" data-type=\"other\">\r\n<div class=\"slider-container js-slider-container overflow-hidden d-flex rw-slider rw-prev-disabled\">\r\n<div class=\"rw-track d-flex align-items-center\">\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"59926\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/17\/27117-004-03C5864D\/Discovery-space-shuttle-orbiter-image-mission-Florida-January-24-1985.jpg\" data-href=\"\/media\/1\/557348\/59926\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/17\/27117-004-03C5864D\/Discovery-space-shuttle-orbiter-image-mission-Florida-January-24-1985.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/17\/27117-004-03C5864D\/Discovery-space-shuttle-orbiter-image-mission-Florida-January-24-1985.jpg?w=300\" alt=\"Discovery liftoff, 1985\" width=\"1084\" height=\"1665\" data-width=\"293\" data-height=\"450\" \/><\/picture><\/a>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">1 of 2<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/17\/27117-004-03C5864D\/Discovery-space-shuttle-orbiter-image-mission-Florida-January-24-1985.jpg\" data-href=\"\/media\/1\/557348\/59926\"><em>Discovery<\/em>\u00a0liftoff, 1985<\/a>U.S. space shuttle orbiter\u00a0<em>Discovery<\/em>\u00a0lifting off from the Kennedy Space Center in Florida on its third mission, January 24, 1985. Also visible in the image are its attached external tank (orange) and one of its two solid-fuel boosters.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"111641\" data-asm-type=\"video\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"video\"><a class=\"gtm-assembly-link d-flex justify-content-center\" href=\"https:\/\/www.britannica.com\/video\/launch-flight-space-shuttle-Columbia-John-Young-1981\/-111641\" data-id=\"21901\"><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/01\/21901-138-EF4C4BB5\/launch-flight-space-shuttle-Columbia-John-Young-1981.jpg?w=800&amp;h=450&amp;c=crop\" alt=\"Witness the liftoff and landing of NASA's Columbia space shuttle crewed by astronauts John Young and Bob Crippen\" width=\"1161\" height=\"653\" \/><\/a>\r\n<div class=\"btn btn-xl btn-white btn-circle position-absolute shadow\">\u00a0<\/div>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">2 of 2<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><span class=\"md-assembly-title font-weight-bold mr-5 d-inline font-sans-serif md-video-caption\">Witness the liftoff and landing of NASA&#8217;s\u00a0<em>Columbia<\/em>\u00a0space shuttle crewed by astronauts John Young and Bob Crippen<\/span>Liftoff and landing of\u00a0<em>Columbia<\/em>, the first space shuttle, April 12\u201314, 1981.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<a class=\"font-14 mt-10 d-inline-block\" href=\"https:\/\/www.britannica.com\/science\/space-exploration\/images-videos\">See all videos for this article<\/a><\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<button class=\"prev-button js-prev-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20 rw-disabled\" disabled=\"disabled\"><\/button><button class=\"next-button js-next-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20\"><\/button><\/div>\r\n<p class=\"topic-paragraph\">After the success of the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/Apollo-11\" data-show-preview=\"true\">Apollo 11<\/a>\u00a0mission,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/NASA\" data-show-preview=\"true\">NASA<\/a>\u00a0proposed an ambitious plan for a series of large space stations to be developed during the 1970s and a new reusable space\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/transportation\" data-term=\"transportation\" data-type=\"EB\">transportation<\/a>\u00a0system to send people and supplies to those stations, lunar bases, and crewed missions to\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Mars-planet\" data-show-preview=\"true\">Mars<\/a>\u00a0in the 1980s. This plan was quickly rejected, as there was no interest in an ambitious and expensive post-Apollo space program among the political leadership or the general public. In 1972 NASA received presidential approval to develop a partially reusable transport vehicle called a\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/space-shuttle\" data-show-preview=\"true\">space shuttle<\/a>. This vehicle was intended to carry people and as much as 29,500 kg (65,000 pounds) of cargo into\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/low-Earth-orbit\" data-show-preview=\"true\">low Earth orbit<\/a>\u00a0at low cost. On the basis of those expectations, the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/United-States\" data-show-preview=\"true\">United States<\/a>\u00a0planned to use the shuttle as its sole\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/launch-vehicle\" data-show-preview=\"true\">launch vehicle<\/a>\u00a0once it entered operation and to operate a shuttle\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/fleet\" data-term=\"fleet\" data-type=\"EB\">fleet<\/a>\u00a0with a launch rate as high as 60 per year. In the absence of a\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/space-station\" data-show-preview=\"true\">space station<\/a>, plans also called for having the shuttle serve double duty as a space platform to conduct in-orbit research for periods as long as two weeks. To that end, Europe pledged to contribute a pressurized laboratory, known as\u00a0<span id=\"ref838958\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Spacelab\" data-show-preview=\"true\">Spacelab<\/a>, that would be carried in the shuttle\u2019s payload bay.<\/p>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"60377\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/93\/70093-050-AA168D21\/space-shuttle-orbiter-liquid-propellant-tank-rocket-boosters.jpg\" data-href=\"\/media\/1\/557348\/60377\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/93\/70093-050-AA168D21\/space-shuttle-orbiter-liquid-propellant-tank-rocket-boosters.jpg\" media=\"(min-width: 680px)\" \/><img decoding=\"async\" src=\"https:\/\/cdn.britannica.com\/93\/70093-050-AA168D21\/space-shuttle-orbiter-liquid-propellant-tank-rocket-boosters.jpg?w=300\" alt=\"U.S. space shuttle\" data-width=\"1187\" data-height=\"1600\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/93\/70093-050-AA168D21\/space-shuttle-orbiter-liquid-propellant-tank-rocket-boosters.jpg\" data-href=\"\/media\/1\/557348\/60377\">U.S. space shuttle<\/a>U.S. space shuttle, composed of a winged orbiter, an external liquid-propellant tank, and two solid-fuel rocket boosters.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">The space shuttle design had three major components. A reusable winged orbiter carried crew and cargo and glided to a landing on a runway at the end of its mission. A large external tank carried the liquid-oxygen and liquid-hydrogen propellants for the orbiter\u2019s three powerful engines. The tank was used only during the first eight minutes of flight; once the fuel was exhausted, the tank was\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/discarded\" data-term=\"discarded\" data-type=\"EB\">discarded<\/a>\u00a0and burned up on reentry. Two solid-fuel rockets assisted in accelerating the vehicle during the first two minutes of flight; they were then detached and parachuted into the ocean, where they were recovered for future use. A fleet of four operational orbiters, named\u00a0<em><span id=\"ref838960\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Columbia-space-shuttle\">Columbia<\/a><\/em>,\u00a0<em><span id=\"ref838961\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Challenger-space-shuttle\">Challenger<\/a><\/em>,\u00a0<em><span id=\"ref838962\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Atlantis-space-shuttle\">Atlantis<\/a><\/em>, and\u00a0<em><span id=\"ref838963\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Discovery-space-shuttle\">Discovery<\/a><\/em>, was built in order to allow multiple shuttle flights each year. Facilities in Florida originally constructed for the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/Apollo-space-program\" data-show-preview=\"true\">Apollo<\/a>\u00a0program were remodeled for shuttle use, and construction on a facility at Vandenberg Air Force Base in California for launching the shuttle into north-south polar orbits was begun.<\/p>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"100201\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/21\/21521-050-02D43180\/Sally-Ride-Challenger-space-flight-June-1983.jpg\" data-href=\"\/media\/1\/557348\/100201\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/21\/21521-050-02D43180\/Sally-Ride-Challenger-space-flight-June-1983.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/21\/21521-050-02D43180\/Sally-Ride-Challenger-space-flight-June-1983.jpg?w=300\" alt=\"Sally Ride\" width=\"1111\" height=\"752\" data-width=\"1600\" data-height=\"1085\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/21\/21521-050-02D43180\/Sally-Ride-Challenger-space-flight-June-1983.jpg\" data-href=\"\/media\/1\/557348\/100201\">Sally Ride<\/a>Sally Ride, the first U.S. female astronaut to fly into space, aboard the space shuttle Challenger during her maiden flight in June 1983.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">After several years of technical and budgetary delays to the program, the first space shuttle flight took place on April 12, 1981; aboard were astronauts\u00a0<span id=\"ref838964\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/John-W-Young\" data-show-preview=\"true\">John W. Young<\/a>, a veteran of the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/Gemini-spacecraft-and-space-program\" data-show-preview=\"true\">Gemini<\/a>\u00a0and Apollo programs, and\u00a0<span id=\"ref838965\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Robert-Crippen\" data-show-preview=\"true\">Robert Laurel Crippen<\/a>. With additional shuttle flights, it became evident that\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/projections\" data-term=\"projections\" data-type=\"EB\">projections<\/a>\u00a0of the vehicle\u2019s operational costs and performance had been extremely optimistic. Major refurbishment was required between each launch; the highest flight rate achieved was in 1985, when the shuttle was launched nine times. Each launch cost hundreds of millions of dollars, rather than the tens of millions that had been promised in 1972. Although the space shuttle was a remarkable technological achievement as a first-generation reusable launch vehicle, the plans to use it as the only launcher for American payloads proved to be a major policy mistake, and the cost of its operation acted as a barrier to undertaking other ambitious space efforts.<\/p>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"73155\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/11\/76511-050-9E25BC4B\/Challenger-accident-destruction-liftoff-crew-space-teacher-January-28-1986.jpg\" data-href=\"\/media\/1\/557348\/73155\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/11\/76511-050-9E25BC4B\/Challenger-accident-destruction-liftoff-crew-space-teacher-January-28-1986.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/11\/76511-050-9E25BC4B\/Challenger-accident-destruction-liftoff-crew-space-teacher-January-28-1986.jpg?w=300\" alt=\"Challenger explosion, 1986\" width=\"1141\" height=\"924\" data-width=\"1600\" data-height=\"1296\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/11\/76511-050-9E25BC4B\/Challenger-accident-destruction-liftoff-crew-space-teacher-January-28-1986.jpg\" data-href=\"\/media\/1\/557348\/73155\"><em>Challenger<\/em>\u00a0explosion, 1986<\/a>U.S. space shuttle\u00a0<em>Challenger<\/em>\u00a0just seconds after its explosive destruction on January 28, 1986. The accident, which occurred a little more than a minute after liftoff, killed the orbiter&#8217;s seven-person crew, including the first teacher to be launched into space.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">The optimism surrounding the space shuttle program was publicly shattered on January 28, 1986, when the\u00a0<em>Challenger<\/em>\u00a0orbiter was destroyed in a\u00a0<span id=\"ref1253025\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/event\/Challenger-disaster\" data-show-preview=\"true\">catastrophic explosion<\/a>\u00a073 seconds after liftoff. Its seven-person crew perished; among them was schoolteacher\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Christa-Corrigan-McAuliffe\" data-show-preview=\"true\">Christa McAuliffe<\/a>, on board as the first teacher in space. The launch had taken place in unusually cold weather, and a sealing ring within a segment joint of one of the solid\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/rocket-jet-propulsion-device-and-vehicle\" data-show-preview=\"true\">rocket<\/a>\u00a0boosters failed. The solid rocket broke loose and hit the external tank, rupturing it. The flame from the leaking booster ignited the shuttle\u2019s fuel, causing the explosion.<\/p>\r\n<p class=\"topic-paragraph\">After the accident, the shuttle fleet was grounded until September 1988. A replacement orbiter,\u00a0<em><span id=\"ref838970\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Endeavour-United-States-space-shuttle\">Endeavour<\/a><\/em>, was built, but, upon the resumption of flights, the shuttle fleet was operated with much greater\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/assurances\" data-term=\"assurances\" data-type=\"MW\">assurances<\/a>\u00a0for the safety of its crew. This limited the flight rate to six to eight missions per year; the 100th shuttle flight was not achieved until October 2000.<\/p>\r\n<div class=\"module-spacing\">\u00a0<\/div>\r\n<p class=\"topic-paragraph\">Both before and after the\u00a0<em>Challenger<\/em>\u00a0accident, the space shuttle demonstrated impressive capabilities in space operations, including the repair and redeployment of damaged satellites\u2014most striking being the in-orbit repair of the\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Hubble-Space-Telescope\" data-show-preview=\"true\">Hubble Space Telescope<\/a>\u00a0in 1993. Four more missions to upgrade Hubble were carried out between 1997 and 2009. Beginning in 1998, the space shuttle was used to carry components of the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/International-Space-Station\" data-show-preview=\"true\">ISS<\/a>\u00a0into orbit, along with the crews to assemble those components. It also was used to ferry people and supplies to and from the space station, the role for which it was first\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/conceived\" data-term=\"conceived\" data-type=\"EB\">conceived<\/a>. There were a total of 37 shuttle missions associated with assembling and outfitting the ISS.<\/p>\r\n<p class=\"topic-paragraph\">The shuttle program suffered its second fatal disaster on February 1, 2003, when the orbiter\u00a0<em><span id=\"ref1253026\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/event\/Columbia-disaster\" data-show-preview=\"true\">Columbia<\/a><\/em>\u00a0broke up over Texas at an altitude of about 60 km (40 miles) as it was returning from an orbital mission. All seven crew members died, including Ilan Ramon, the first Israeli\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/astronaut\" data-show-preview=\"true\">astronaut<\/a>\u00a0to go into space. The shuttle fleet was once again grounded during the ensuing investigation into the cause of the accident, and flights to keep the ISS in operation were conducted by Russian\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/spacecraft\" data-show-preview=\"true\">spacecraft<\/a>.<\/p>\r\n<p class=\"topic-paragraph\">As part of the rethinking of U.S. space plans in the wake of the\u00a0<em>Columbia<\/em>\u00a0accident, it was decided to retire the space shuttle from service once assembly of the ISS had been completed. This decision was announced by Pres.\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/biography\/George-W-Bush\" data-show-preview=\"true\">George W. Bush<\/a>\u00a0in January 2004. The final space shuttle flight took place in July 2011, and the remaining three orbiters were then retired to museums around the United States.<\/p>\r\n<p class=\"topic-paragraph\">Between 1981 and 2011, space shuttles flew 135 missions, traveled 872,906,379 km (542,398,878 miles), and launched 355 different people (306 men and 49 women) from 16 countries into orbit. Including repeat fliers, a total of 852 people went into space on the shuttle, with two of them, U.S. astronauts\u00a0<span id=\"ref1253027\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Jerry-Ross\" data-show-preview=\"true\">Jerry Ross<\/a>\u00a0and\u00a0<span id=\"ref1253028\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Franklin-Chang-Diaz\" data-show-preview=\"true\">Franklin Chang-D\u00edaz<\/a>, each making seven separate trips to orbit.<\/p>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"60529\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/31\/60831-004-AB602BEB\/cargo-transporter-Antonov-An-225-Mriya-Buran-orbiter-1988.jpg\" data-href=\"\/media\/1\/557348\/60529\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/31\/60831-004-AB602BEB\/cargo-transporter-Antonov-An-225-Mriya-Buran-orbiter-1988.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/31\/60831-004-AB602BEB\/cargo-transporter-Antonov-An-225-Mriya-Buran-orbiter-1988.jpg?w=300\" alt=\"Buran orbiter\" width=\"1155\" height=\"570\" data-width=\"550\" data-height=\"272\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/31\/60831-004-AB602BEB\/cargo-transporter-Antonov-An-225-Mriya-Buran-orbiter-1988.jpg\" data-href=\"\/media\/1\/557348\/60529\">Buran orbiter<\/a>Buran orbiter, part of the Soviet space shuttle project, atop an Antonov An-225 cargo transporter, 1989.<\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">In the 1980s the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Soviet-Union\" data-show-preview=\"true\">Soviet Union<\/a>\u00a0also developed a space shuttle, called\u00a0<span id=\"ref838973\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Buran-Russian-spacecraft\" data-show-preview=\"true\">Buran<\/a>, and a very powerful rocket, called\u00a0<span id=\"ref838974\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Energia-Soviet-launch-vehicle\" data-show-preview=\"true\">Energia<\/a>, to launch it and other heavy\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/payloads\" data-term=\"payloads\" data-type=\"EB\">payloads<\/a>.\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/money\/Energia-Russian-company\" data-show-preview=\"true\">Energia<\/a>\u00a0was launched only twice, once in 1987 with a military payload and once the next year carrying Buran on a successful uncrewed test flight into orbit and back. Use of the two vehicles was abandoned as the Soviet Union faced increasing economic problems.<\/p>\r\n<\/section>\r\n<\/section>\r\n<\/section>\r\n<\/div>\r\n<div id=\"chatbot-root\">\u00a0<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div data-page-index=\"14\">\u00a0<\/div>\r\n<div class=\"loaded-infinite-scroll-container qa-infinite-scroll-container\">\r\n<div class=\"grey-box w-100 \">\r\n<div class=\"grey-box-content mx-auto w-100\">\r\n<div class=\"page2ref-false topic-content topic-type-REGULAR\">\r\n<div class=\"reading-channel\">\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237061\" data-level=\"1\" data-has-spy=\"true\">\r\n<h1 class=\"h1\">Human beings in space: debate and consequences<\/h1>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"207761\" data-asm-type=\"video\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"video\"><a class=\"gtm-assembly-link d-flex justify-content-center\" href=\"https:\/\/www.britannica.com\/video\/outer-space-smells-some-causes\/-207761\" data-id=\"187038\"><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/38\/187038-138-E22DC8DB\/outer-space-smells-some-causes.jpg?w=800&amp;h=450&amp;c=crop\" alt=\"Explaining the smelly secrets of outer space\" width=\"1118\" height=\"629\" \/><\/a>\r\n<div class=\"btn btn-xl btn-white btn-circle position-absolute shadow\">\u00a0<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><span class=\"md-assembly-title font-weight-bold mr-5 d-inline font-sans-serif md-video-caption\">Explaining the smelly secrets of outer space<\/span>What does outer space smell like? Learn about some reported smells of outer space and the chemical causes of these.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<a class=\"font-14 mt-10 d-inline-block\" href=\"https:\/\/www.britannica.com\/science\/space-exploration\/images-videos\">See all videos for this article<\/a><\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">By the early 2020s more than 500 people, coming from more than 40 different countries and more than 10 percent of whom were women, had flown in space. As of that same time, only\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Russia\" data-show-preview=\"true\">Russia<\/a>,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/China\" data-show-preview=\"true\">China<\/a>, and the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/United-States\" data-show-preview=\"true\">United States<\/a>\u00a0had the capability of carrying out human spaceflights. With the retirement of the space shuttle in 2011, the United States lost its independent human\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/spaceflight\" data-show-preview=\"true\">spaceflight<\/a>\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/capability\" data-term=\"capability\" data-type=\"EB\">capability<\/a>. Such capability was not regained until 2020, when a new private commercial\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/spacecraft\" data-show-preview=\"true\">spacecraft<\/a>, SpaceX\u2019s Crew\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/Dragon-spacecraft\" data-show-preview=\"true\">Dragon<\/a>, was ready for use.<\/p>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237062\" data-level=\"2\" data-has-spy=\"true\">\r\n<h2 class=\"h2\">Risks and benefits<\/h2>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"126945\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/98\/78098-050-7998488E\/Astronauts-John-Grunsfeld-space-shuttle-Richard-Linnehan-March-8-2002.jpg\" data-href=\"\/media\/1\/557348\/126945\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/98\/78098-050-7998488E\/Astronauts-John-Grunsfeld-space-shuttle-Richard-Linnehan-March-8-2002.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/98\/78098-050-7998488E\/Astronauts-John-Grunsfeld-space-shuttle-Richard-Linnehan-March-8-2002.jpg?w=300\" alt=\"astronauts John Grunsfeld and Richard Linnehan with the Hubble Space Telescope, 2002\" width=\"1152\" height=\"1160\" data-width=\"1592\" data-height=\"1600\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/98\/78098-050-7998488E\/Astronauts-John-Grunsfeld-space-shuttle-Richard-Linnehan-March-8-2002.jpg\" data-href=\"\/media\/1\/557348\/126945\">astronauts John Grunsfeld and Richard Linnehan with the Hubble Space Telescope, 2002<\/a>Astronauts John Grunsfeld and Richard Linnehan near the Hubble Space Telescope, temporarily hosted in the space shuttle\u00a0<em>Columbia<\/em>&#8216;s cargo bay, March 8, 2002.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">Human spaceflight is both risky and expensive. From the crash landing of the first crewed Soyuz spacecraft in 1967 to the breakup of the shuttle orbiter\u00a0<em>Columbia<\/em>\u00a0in 2003, 18 people died during spaceflights. Providing the systems to support people while in orbit adds significant additional costs to a space mission, and ensuring that the launch, flight, and reentry are carried out as safely as possible also requires highly reliable and thus costly equipment, including both spacecraft and launchers.<\/p>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"138783\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/81\/77681-050-7E199C9F\/Examples-approaches-Hubble-Space-Telescope-space-artist-2002.jpg\" data-href=\"\/media\/1\/557348\/138783\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/81\/77681-050-7E199C9F\/Examples-approaches-Hubble-Space-Telescope-space-artist-2002.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/81\/77681-050-7E199C9F\/Examples-approaches-Hubble-Space-Telescope-space-artist-2002.jpg?w=300\" alt=\"Opportunity, artist's conception\" width=\"1128\" height=\"902\" data-width=\"1250\" data-height=\"1000\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/81\/77681-050-7E199C9F\/Examples-approaches-Hubble-Space-Telescope-space-artist-2002.jpg\" data-href=\"\/media\/1\/557348\/138783\">Opportunity, artist&#8217;s conception<\/a>The U.S. robotic rover Opportunity traversing the Martian surface, as depicted in an artist&#8217;s conception.<\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">From the start of human spaceflight efforts, some have argued that the benefits of sending humans into space do not justify either the risks or the costs. They contend that robotic missions can produce equal or even greater scientific results with lower expenditures and that human presence in space has no other valid justification. Those who support human spaceflight cite the still unmatched ability of\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/human-intelligence-psychology\" data-show-preview=\"true\">human intelligence<\/a>, flexibility, and reliability in carrying out certain experiments in orbit, in repairing and maintaining robotic spacecraft and automated instruments in space, and in acting as explorers in initial journeys to other places in the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/solar-system\" data-show-preview=\"true\">solar system<\/a>. They also argue that astronauts serve as excellent role models for younger people and act as\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/vicarious\" data-term=\"vicarious\" data-type=\"MW\">vicarious<\/a>\u00a0representatives of the many who would like to fly in space themselves. In addition is the long-held view that eventually some humans will leave\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Earth\" data-show-preview=\"true\">Earth<\/a>\u00a0to establish permanent outposts and larger settlements on the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Moon\" data-show-preview=\"true\">Moon<\/a>,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Mars-planet\" data-show-preview=\"true\">Mars<\/a>, or other locations.<\/p>\r\n<\/section>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237063\" data-level=\"2\" data-has-spy=\"true\">\r\n<h2 class=\"h2\">Selecting people for spaceflights<\/h2>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"73158\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/07\/76507-050-628A8ECC\/astronaut-scuba-diver-microgravity-simulation-tank-assembly-September-2000.jpg\" data-href=\"\/media\/1\/557348\/73158\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/07\/76507-050-628A8ECC\/astronaut-scuba-diver-microgravity-simulation-tank-assembly-September-2000.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/07\/76507-050-628A8ECC\/astronaut-scuba-diver-microgravity-simulation-tank-assembly-September-2000.jpg?w=300\" alt=\"astronaut spacewalk training\" width=\"1046\" height=\"697\" data-width=\"1536\" data-height=\"1024\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/07\/76507-050-628A8ECC\/astronaut-scuba-diver-microgravity-simulation-tank-assembly-September-2000.jpg\" data-href=\"\/media\/1\/557348\/73158\">astronaut spacewalk training<\/a>Space-suited U.S. astronaut (centre), assisted by a scuba diver, practicing in-space assembly routines in a water-filled microgravity simulation tank at the Yuri Gagarin Cosmonaut Training Centre (Star City) near Moscow. The rehearsal was part of preparations for a space shuttle mission to the International Space Station in September 2000.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">Most of the individuals who have gone into space are highly trained\u00a0<span id=\"ref838977\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/astronaut\" data-show-preview=\"true\">astronauts<\/a>\u00a0and cosmonauts, the two\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/designations\" data-term=\"designations\" data-type=\"MW\">designations<\/a>\u00a0having originated in the United States and the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Soviet-Union\" data-show-preview=\"true\">Soviet Union<\/a>, respectively. (Both\u00a0<em>taikonaut<\/em>\u00a0and\u00a0<em>yuhangyuan<\/em>\u00a0have sometimes been used to describe the astronauts in China\u2019s crewed space program.) Those governments interested in sending some of their citizens into space select candidates from many applicants on the basis of their backgrounds and physical and psychological characteristics. The candidates undergo rigorous training before being chosen for an initial spaceflight and then prepare in detail for each mission assigned. Training centres with specialized facilities exist in the United States, at\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/NASA\" data-show-preview=\"true\">NASA\u2019s<\/a>\u00a0Johnson Space Center in Houston, Texas; in Russia, at the Yuri Gagarin Cosmonaut Training Centre (commonly called Star City), outside Moscow; in\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Germany\" data-show-preview=\"true\">Germany<\/a>, at\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/European-Space-Agency\" data-show-preview=\"true\">ESA\u2019s<\/a>\u00a0European Astronaut Centre in Cologne; in\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Japan\" data-show-preview=\"true\">Japan<\/a>, at JAXA\u2019s Tsukuba Space Center, near Tokyo; and in China, at Space City, near Beijing.<\/p>\r\n<p class=\"topic-paragraph\">Astronauts and cosmonauts who undertook multiple spaceflights traditionally fell into one of two categories. The first consisted of pilots, often with military backgrounds, who had\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/extensive\" data-term=\"extensive\" data-type=\"EB\">extensive<\/a>\u00a0experience in flying high-performance aircraft. They were responsible for piloting space vehicles such as the\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/space-shuttle\" data-show-preview=\"true\">space shuttle<\/a>\u00a0and\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Soyuz\" data-show-preview=\"true\">Soyuz<\/a>. The other category included scientists and engineers who are not necessarily pilots. They had primary responsibility for carrying out the scientific and engineering activities scheduled for a particular mission. They were known in the U.S. space program as\u00a0<span id=\"ref838981\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/mission-specialist\">mission specialists<\/a>\u00a0and in the Russian space program as flight engineers. With the development of long-duration\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/space-station\" data-show-preview=\"true\">space stations<\/a>\u00a0such as\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Mir-Soviet-Russian-space-station\" data-show-preview=\"true\">Mir<\/a>\u00a0and the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/International-Space-Station\" data-show-preview=\"true\">ISS<\/a>, the distinction between pilot and nonpilot astronauts and cosmonauts has become less clear, because all members of a space station crew carry out station operations and experiments.<\/p>\r\n<div class=\"module-spacing\">\u00a0<\/div>\r\n<p class=\"topic-paragraph\">A third category of individuals who have gone into space was called variously\u00a0<span id=\"ref838989\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/payload-specialist\">payload specialists<\/a>\u00a0or guest cosmonauts. These individuals include scientists and engineers who accompany their experiments into orbit; individuals selected to go into space for political reasons, such as members of the U.S.\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/Congress\" data-term=\"Congress\" data-type=\"EB\">Congress<\/a>\u00a0or persons from countries allied with the Soviet Union or the United States; and a few nontechnical people\u2014for example, the rare journalist or teacher or the private individual willing to pay substantial amounts of money for a spaceflight. These people are intensively trained for their particular flight but usually go into space only once. The first orbital spaceflight with a crew of private individuals, one of whom had chartered the spacecraft, Inspiration4, launched in 2021. At some future time, the costs and risks of human spaceflight may become low enough to accommodate a booming business of\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/space-tourism\" data-show-preview=\"true\">space tourism<\/a>, in which many people would be able to experience spaceflight. Until then, access to orbit will be restricted to a comparatively small number of people. However, several firms have planned for paying customers brief suborbital flights that would provide a few minutes of\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/weightlessness\" data-show-preview=\"true\">weightlessness<\/a>\u00a0and dramatic views of Earth as they are launched on a trajectory carrying them just below 100 km (62 miles) in altitude, the generally recognized border between airspace and outer space.<\/p>\r\n<\/section>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237064\" data-level=\"2\" data-has-spy=\"true\">\r\n<h2 class=\"h2\">Biomedical, psychological, and sociological aspects<\/h2>\r\n<p class=\"topic-paragraph\">Human beings have evolved to live in the\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/environment\" data-term=\"environment\" data-type=\"MW\">environment<\/a>\u00a0of Earth\u2019s surface. The space environment\u2014with its very low level of\u00a0<span id=\"ref838992\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/gravity-physics\" data-show-preview=\"true\">gravity<\/a>, lack of atmosphere, wide temperature variations, and often high levels of\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/ionizing-radiation\" data-show-preview=\"true\">ionizing radiation<\/a>\u00a0from the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Sun\" data-show-preview=\"true\">Sun<\/a>, from particles trapped in the Van Allen radiation belts, and from cosmic rays\u2014is an unnatural place for humans. An understanding of the effects on the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/human-body\" data-show-preview=\"true\">human body<\/a>\u00a0of spaceflight, particularly long-duration flights away from Earth to destinations such as Mars, is incomplete.<\/p>\r\n<p class=\"topic-paragraph\">Many of those going into space experience space sickness (<em>see<\/em>\u00a0<span id=\"ref838990\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/motion-sickness\" data-show-preview=\"true\">motion sickness<\/a>), which may cause vomiting, nausea, and stomach discomfort, among other\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/symptoms\" data-term=\"symptoms\" data-type=\"EB\">symptoms<\/a>. The condition is thought to arise from a contradiction experienced in the brain between external information coming from the eyes and internal information coming from the balance organs in the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/inner-ear\" data-show-preview=\"true\">inner ear<\/a>, which are normally stimulated continually by gravity. Space sickness usually disappears within two or three days as the brain adapts to the space environment, although symptoms may reappear temporarily when the space traveler returns to Earth\u2019s gravity.<\/p>\r\n<p class=\"topic-paragraph\">The virtual absence of gravity causes loss of tissue mass in the calf and thigh\u00a0<span id=\"ref838994\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/muscle\" data-show-preview=\"true\">muscles<\/a>, which are used on Earth\u2019s surface to counter the effect of gravity. Muscles that are less involved with gravity, such as those used to bend the legs or arms, are less affected. Some loss of muscle mass in the heart has been observed in astronauts on long-duration missions. In the absence of gravity, blood that normally pools in the body\u2019s lower extremities initially shifts to the upper regions. As a result, the face appears puffy, the person experiences sinus congestion and headaches, and blood production decreases as the body attempts to\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/compensate\" data-term=\"compensate\" data-type=\"EB\">compensate<\/a>. In addition, in the space environment, some weight-bearing bones in the body atrophy.<\/p>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"68871\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/21\/73221-050-8758A5B4\/Yury-V-Usachyov-Russian-cycle-ergometer-service-April-25-2001.jpg\" data-href=\"\/media\/1\/557348\/68871\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/21\/73221-050-8758A5B4\/Yury-V-Usachyov-Russian-cycle-ergometer-service-April-25-2001.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/21\/73221-050-8758A5B4\/Yury-V-Usachyov-Russian-cycle-ergometer-service-April-25-2001.jpg?w=300\" alt=\"Yuri Usachyov exercising at the International Space Station\" width=\"1189\" height=\"1700\" data-width=\"1119\" data-height=\"1600\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/21\/73221-050-8758A5B4\/Yury-V-Usachyov-Russian-cycle-ergometer-service-April-25-2001.jpg\" data-href=\"\/media\/1\/557348\/68871\">Yuri Usachyov exercising at the International Space Station<\/a>Russian cosmonaut Yuri V. Usachyov exercising on a cycle ergometer in the Zvezda service module of the International Space Station, April 25, 2001.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">Although the changes in muscle, bone, and blood production do not pose problems for astronauts in space, they do so on their return to Earth. For example, in normal gravity, a person with decreased bone mass runs a greater risk of breaking a bone during normal strenuous activity. Countermeasures, particularly various forms of exercise while in space, have been developed to prevent these effects from causing health problems later on Earth. Even so, people recovering from long-duration flights require varying amounts of time to readjust to Earth conditions. Light-headedness usually disappears within one or two days; lack of balance and symptoms of motion sickness, in three to five days; anemia, in one to two weeks; muscle atrophy, in three to five weeks; and bone atrophy, in one to three years or more.<\/p>\r\n<p class=\"topic-paragraph\">Except for the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/Apollo-space-program\" data-show-preview=\"true\">Apollo<\/a>\u00a0trips to the Moon, all human spaceflights have taken place in near-Earth orbit. In this location,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/geomagnetic-field\" data-show-preview=\"true\">Earth\u2019s magnetic field<\/a>\u00a0shields humans from potentially dangerous exposure to ionizing radiation from recurrent major disturbances on the Sun and interplanetary cosmic rays. The Apollo missions, which were all less than two weeks long, were timed to avoid exposure to anticipated high levels of\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/solar-radiation\" data-show-preview=\"true\">solar radiation<\/a>. If, however, humans were sent on journeys to\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/Mars\" data-term=\"Mars\" data-type=\"EB\">Mars<\/a>\u00a0or other destinations that would take months or even years, such measures would be inadequate. Exposure to high levels of solar radiation or cosmic rays could cause potentially fatal tumours and other health problems (<em>see<\/em>\u00a0<span id=\"ref838996\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/radiation-injury\" data-show-preview=\"true\">radiation injury<\/a>). Space engineers will need to devise adequate radiation shielding for interplanetary crewed spacecraft and will require accurate predictions of\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/radiation-damage\" data-show-preview=\"true\">radiation damage<\/a>\u00a0to the body to ensure that risks remain within acceptable limits.\u00a0<span id=\"ref1263726\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/medical-research\">Biomedical advances<\/a>\u00a0are also necessary to develop methods for the early detection and mitigation of radiation damage. Nevertheless, the effects of radiation may remain a major obstacle to long human voyages in space.<\/p>\r\n<p class=\"topic-paragraph\">In addition to the biomedical issues associated with human spaceflight are a number of psychological and sociological issues, particularly for long-duration missions aboard a space station or to distant destinations. To be in space is to be in an extreme and isolated environment. Mission planners will have to consider issues relating to crew size and composition\u2014particularly if the crews are mixtures of men and women and come from several nations with different cultures\u2014if interpersonal conflicts are to be\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/avoided\" data-term=\"avoided\" data-type=\"EB\">avoided<\/a>\u00a0and effective teamwork achieved.<\/p>\r\n<\/section>\r\n<\/section>\r\n<\/div>\r\n<div id=\"chatbot-root\">\u00a0<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div data-page-index=\"15\">\u00a0<\/div>\r\n<div class=\"loaded-infinite-scroll-container qa-infinite-scroll-container\">\r\n<div class=\"grey-box w-100 \">\r\n<div class=\"grey-box-content mx-auto w-100\">\r\n<div class=\"page2ref-false topic-content topic-type-REGULAR\">\r\n<div class=\"reading-channel\">\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237065\" data-level=\"1\" data-has-spy=\"true\">\r\n<h1 class=\"h1\">Science in space<\/h1>\r\n<p class=\"topic-paragraph\">In the decades following the first\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/Sputnik\" data-show-preview=\"true\">Sputnik<\/a>\u00a0and\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/Explorer-satellites\" data-show-preview=\"true\">Explorer<\/a>\u00a0satellites, the ability to put their instruments into outer space gave scientists the opportunity to acquire new information about the natural\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/universe\" data-show-preview=\"true\">universe<\/a>, information that in many cases would have been unobtainable any other way. Space\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/science\" data-show-preview=\"true\">science<\/a>\u00a0added a new dimension to the quest for knowledge, complementing and extending what had been gained from centuries of theoretical speculations and ground-based observations.<\/p>\r\n<p class=\"topic-paragraph\">After Gagarin\u2019s 1961 flight, space missions involving human crews carried out a range of significant research, from on-site geologic investigations on the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Moon\" data-show-preview=\"true\">Moon<\/a>\u00a0to a wide variety of observations and experiments aboard orbiting\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/spacecraft\" data-show-preview=\"true\">spacecraft<\/a>. In particular, the presence in space of humans as experimenters and, in some cases, as experimental subjects\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/facilitated\" data-term=\"facilitated\" data-type=\"MW\">facilitated<\/a>\u00a0studies in biomedicine and\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/materials-science\" data-show-preview=\"true\">materials science<\/a>. Nevertheless, most space science was, and continues to be, performed by robotic spacecraft in\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Earth\" data-show-preview=\"true\">Earth<\/a>\u00a0orbit, in other locations from which they observe the universe, or on missions to various bodies in the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/solar-system\" data-show-preview=\"true\">solar system<\/a>. In general, such missions are far less expensive than those involving humans and can carry sophisticated automated instruments to gather a wide variety of relevant data.<\/p>\r\n<p class=\"topic-paragraph\">In addition to the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/United-States\" data-show-preview=\"true\">United States<\/a>\u00a0and the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Soviet-Union\" data-show-preview=\"true\">Soviet Union<\/a>, several other countries achieved the\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/capability\" data-term=\"capability\" data-type=\"EB\">capability<\/a>\u00a0of developing and operating scientific spacecraft and thus carrying out their own space science missions. They include\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Japan\" data-show-preview=\"true\">Japan<\/a>,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/China\" data-show-preview=\"true\">China<\/a>,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Canada\" data-show-preview=\"true\">Canada<\/a>,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/India\" data-show-preview=\"true\">India<\/a>, and a number of European countries such as the United Kingdom,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/France\" data-show-preview=\"true\">France<\/a>,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Italy\" data-show-preview=\"true\">Italy<\/a>, and\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Germany\" data-show-preview=\"true\">Germany<\/a>, acting alone and through cooperative organizations, particularly the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/European-Space-Agency\" data-show-preview=\"true\">European Space Agency<\/a>. Furthermore, many other countries became involved in space activities through the participation of their scientists in specific missions. Bilateral or multilateral cooperation between various countries in carrying out space science missions grew to be the usual way of proceeding.<\/p>\r\n<p class=\"topic-paragraph\">Scientific research in space can be divided into five general areas: (1) solar and space physics, including study of the magnetic and electromagnetic fields in space and the various energetic particles also present, with particular attention to their interactions with Earth, (2) exploration of the planets, moons, asteroids, comets, meteoroids, and dust in the solar system, (3) study of the origin,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/evolution-scientific-theory\" data-show-preview=\"true\">evolution<\/a>, and current state of the varied objects in the universe beyond the solar system, (4) research on nonliving and living materials, including humans, in the very low\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/gravity-physics\" data-show-preview=\"true\">gravity<\/a>\u00a0levels of the space\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/environment\" data-term=\"environment\" data-type=\"MW\">environment<\/a>, and (5) study of Earth from space.<\/p>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237066\" data-level=\"2\" data-has-spy=\"true\">\r\n<h2 class=\"h2\">Solar and\u00a0<span id=\"ref838998\"><\/span>space physics<\/h2>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"73159\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/10\/76810-004-DE63D1C8\/image-oval-Earth-North-Polar-ultraviolet-light-February-1996.jpg\" data-href=\"\/media\/1\/557348\/73159\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/10\/76810-004-DE63D1C8\/image-oval-Earth-North-Polar-ultraviolet-light-February-1996.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/10\/76810-004-DE63D1C8\/image-oval-Earth-North-Polar-ultraviolet-light-February-1996.jpg?w=300\" alt=\"auroral oval\" width=\"1113\" height=\"898\" data-width=\"550\" data-height=\"444\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/10\/76810-004-DE63D1C8\/image-oval-Earth-North-Polar-ultraviolet-light-February-1996.jpg\" data-href=\"\/media\/1\/557348\/73159\">auroral oval<\/a>Earth&#8217;s full North Polar auroral oval, in an image taken in ultraviolet light by the U.S. Polar spacecraft over northern Canada, April 6, 1996. In the colour-coded image, which simultaneously shows dayside and nightside auroral activity, the most intense levels of activity are red, and the lowest levels are blue. Polar, launched in February 1996, was designed to further scientists&#8217; understanding of how plasma energy contained in the solar wind interacts with Earth&#8217;s magnetosphere.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">The first scientific discovery made with instruments orbiting in space was the existence of the\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/Van-Allen-radiation-belt\" data-show-preview=\"true\">Van Allen radiation belts<\/a>, discovered by Explorer 1 in 1958. Subsequent space missions investigated Earth\u2019s\u00a0<span id=\"ref839002\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/magnetosphere\" data-show-preview=\"true\">magnetosphere<\/a>, the surrounding region of space in which the planet\u2019s magnetic field exerts a controlling effect (<em>see<\/em>\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Earth\/The-interior#ref54200\" data-show-preview=\"true\">Earth: The magnetic field and magnetosphere<\/a>). Of particular and ongoing interest has been the interaction of the flux of charged particles emitted by the Sun, called the\u00a0<span id=\"ref838999\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/solar-wind\" data-show-preview=\"true\">solar wind<\/a>, with the magnetosphere. Early space science investigations showed, for example, that luminous atmospheric displays known as\u00a0<span id=\"ref839001\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/aurora-atmospheric-phenomenon\" data-show-preview=\"true\">auroras<\/a>\u00a0are the result of this interaction, and scientists came to understand that the magnetosphere is an extremely complex phenomenon.<\/p>\r\n<div class=\"module-spacing\">\u00a0<\/div>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"252765\" data-asm-type=\"video\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"video\"><a class=\"gtm-assembly-link d-flex justify-content-center\" href=\"https:\/\/www.britannica.com\/video\/solar-probe-touches-the-sun\/-252765\" data-id=\"220877\"><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/77\/220877-138-20426640\/solar-probe-touches-the-sun.jpg?w=800&amp;h=450&amp;c=crop\" alt=\"NASA's Parker Solar Probe spacecraft\" width=\"1255\" height=\"706\" \/><\/a>\r\n<div class=\"btn btn-xl btn-white btn-circle position-absolute shadow\">\u00a0<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><span class=\"md-assembly-title font-weight-bold mr-5 d-inline font-sans-serif md-video-caption\">NASA&#8217;s Parker Solar Probe spacecraft<\/span>NASA&#8217;s Parker Solar Probe spacecraft has traveled closer to the Sun than any other mission in history to investigate its highly charged magnetic field.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<a class=\"font-14 mt-10 d-inline-block\" href=\"https:\/\/www.britannica.com\/science\/space-exploration\/images-videos\">See all videos for this article<\/a><\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">The focus of inquiry in space physics was later extended to understanding the characteristics of the\u00a0<span id=\"ref839003\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Sun\" data-show-preview=\"true\">Sun<\/a>, both as an average star and as the primary source of energy for the rest of the solar system, and to exploring space between the Sun and Earth and other planets (<em>see<\/em>\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/interplanetary-medium\" data-show-preview=\"true\">interplanetary medium<\/a>). The magnetospheres of other planets, particularly\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Jupiter-planet\" data-show-preview=\"true\">Jupiter<\/a>\u00a0with its strong magnetic field, also came under study. Scientists sought a better understanding of the internal\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/dynamics\" data-term=\"dynamics\" data-type=\"MW\">dynamics<\/a>\u00a0and overall behaviour of the Sun, the underlying causes of variations in solar activity, and the way in which those variations\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/propagate\" data-term=\"propagate\" data-type=\"MW\">propagate<\/a>\u00a0through space and ultimately affect Earth\u2019s magnetosphere and upper atmosphere. The concept of\u00a0<span id=\"ref839005\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/space-weather\" data-show-preview=\"true\">space weather<\/a>\u00a0was advanced to describe the changing conditions in the Sun-Earth region of the solar system. Variations in space weather can cause geomagnetic storms that interfere with the operation of satellites and even systems on the ground such as power grids.<\/p>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"68872\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/08\/4508-050-F44CF1B4\/Sun-astronauts-mission-NASA-Skylab-4-image.jpg\" data-href=\"\/media\/1\/557348\/68872\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/08\/4508-050-F44CF1B4\/Sun-astronauts-mission-NASA-Skylab-4-image.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/08\/4508-050-F44CF1B4\/Sun-astronauts-mission-NASA-Skylab-4-image.jpg?w=300\" alt=\"solar flare photographed by Skylab\" width=\"1093\" height=\"882\" data-width=\"1600\" data-height=\"1294\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/08\/4508-050-F44CF1B4\/Sun-astronauts-mission-NASA-Skylab-4-image.jpg\" data-href=\"\/media\/1\/557348\/68872\">solar flare photographed by Skylab<\/a>A spectacular flare on the Sun, photographed in extreme ultraviolet light on December 19, 1973, by the third astronaut crew aboard the U.S. space station Skylab.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">To carry out the investigations required for addressing these scientific questions, the United States, Europe, the Soviet Union, and Japan developed a variety of space missions, often in a coordinated fashion. In the United States, early studies of the Sun were undertaken by a series of\u00a0<span id=\"ref839006\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Orbiting-Solar-Observatory\">Orbiting Solar Observatory<\/a>\u00a0satellites (launched 1962\u201375) and the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/astronaut\" data-show-preview=\"true\">astronaut<\/a>\u00a0crews of the\u00a0<span id=\"ref839007\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Skylab\" data-show-preview=\"true\">Skylab<\/a>\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/space-station\" data-show-preview=\"true\">space station<\/a>\u00a0in 1973\u201374, using that facility\u2019s\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/Apollo-space-program\" data-show-preview=\"true\">Apollo<\/a>\u00a0Telescope Mount. These were followed by the Solar Maximum Mission\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/satellite\" data-show-preview=\"true\">satellite<\/a>\u00a0(launched 1980). ESA developed the\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Ulysses-space-probe\" data-show-preview=\"true\">Ulysses<\/a>\u00a0mission (1990) to explore the Sun\u2019s polar regions. Solar-terrestrial interactions were the focus of many of the Explorer series of spacecraft (1958\u201375) and the\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Orbiting-Geophysical-Observatory\" data-show-preview=\"true\">Orbiting Geophysical Observatory<\/a>\u00a0satellites (1964\u201369).<\/p>\r\n<p class=\"topic-paragraph\">In the 1980s\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/NASA\" data-show-preview=\"true\">NASA<\/a>, ESA, and Japan\u2019s Institute of Space and Astronautical Science undertook a cooperative venture to develop a\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/comprehensive\" data-term=\"comprehensive\" data-type=\"MW\">comprehensive<\/a>\u00a0series of space missions, named the\u00a0<span id=\"ref839010\"><\/span>International Solar-Terrestrial Physics Program, that would be aimed at full investigation of the Sun-Earth connection. This program was responsible for the U.S. Wind (1994) and Polar (1996) spacecraft, the European\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Solar-and-Heliospheric-Observatory\" data-show-preview=\"true\">Solar and Heliospheric Observatory<\/a>\u00a0(SOHO; 1995) and Cluster (2000) missions, and the Japanese Geotail satellite (1992).<\/p>\r\n<p class=\"topic-paragraph\">Among many other missions, NASA has launched a number of satellites, including Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics (TIMED, 2001); the Japanese-U.S.-U.K. collaboration\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Hinode\" data-show-preview=\"true\">Hinode<\/a>\u00a0(2006); and\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Solar-Terrestrial-Relations-Observatory\" data-show-preview=\"true\">Solar Terrestrial Relations Observatory<\/a>\u00a0(STEREO, 2006), part of its Solar Terrestrial Probes program. The\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Solar-Dynamics-Observatory\" data-show-preview=\"true\">Solar Dynamics Observatory<\/a>\u00a0(2010); the twin Van Allen Probes (2012); and the Parker Solar Probe (2018), which made the closest flybys of the Sun, were part of another NASA program called Living with a Star. A two-satellite European\/Chinese mission called Double Star (2003\u201304) studied the impact of the Sun on Earth\u2019s environment.<\/p>\r\n<\/section>\r\n<\/section>\r\n<\/div>\r\n<div id=\"chatbot-root\">\u00a0<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div data-page-index=\"16\">\u00a0<\/div>\r\n<div class=\"loaded-infinite-scroll-container qa-infinite-scroll-container\">\r\n<div class=\"grey-box w-100 \">\r\n<div class=\"grey-box-content mx-auto w-100\">\r\n<div class=\"page2ref-false topic-content topic-type-REGULAR\">\r\n<div class=\"reading-channel\">\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237067\" data-level=\"2\" data-has-spy=\"true\">\r\n<h1 class=\"h2\"><span id=\"ref839011\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/interplanetary-exploration\">Solar system exploration<\/a><\/h1>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"2891\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/26\/426-050-94D87925\/Luna-9-spacecraft-soft-land-Moon-surface-Soviet-January-31-1966.jpg\" data-href=\"\/media\/1\/557348\/2891\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/26\/426-050-94D87925\/Luna-9-spacecraft-soft-land-Moon-surface-Soviet-January-31-1966.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/26\/426-050-94D87925\/Luna-9-spacecraft-soft-land-Moon-surface-Soviet-January-31-1966.jpg?w=300\" alt=\"Luna 9\" width=\"1097\" height=\"1104\" data-width=\"864\" data-height=\"869\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/26\/426-050-94D87925\/Luna-9-spacecraft-soft-land-Moon-surface-Soviet-January-31-1966.jpg\" data-href=\"\/media\/1\/557348\/2891\">Luna 9<\/a>The first spacecraft to soft-land on the Moon was Luna 9. It was launched by the Soviet Union on January 31, 1966, and returned photographs of the lunar surface for three days.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">From the start of space activity, scientists recognized that\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/spacecraft\" data-show-preview=\"true\">spacecraft<\/a>\u00a0could gather scientifically valuable\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/data\" data-term=\"data\" data-type=\"EB\">data<\/a>\u00a0about the various planets, moons, and smaller bodies in the\u00a0<span id=\"ref839012\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/solar-system\" data-show-preview=\"true\">solar system<\/a>. Both the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/United-States\" data-show-preview=\"true\">United States<\/a>\u00a0and the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Soviet-Union\" data-show-preview=\"true\">U.S.S.R.<\/a>\u00a0attempted to send robotic missions to the\u00a0<span id=\"ref839014\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Moon\" data-show-preview=\"true\">Moon<\/a>\u00a0in the late 1950s. The first four U.S.\u00a0<span id=\"ref839013\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Pioneer-space-probes\" data-show-preview=\"true\">Pioneer<\/a>\u00a0spacecraft, Pioneer 0\u20133, launched in 1958, were not successful in returning data about the Moon. The fifth mission, Pioneer 4 (1959), was the first U.S. spacecraft to escape\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Earth\" data-show-preview=\"true\">Earth\u2019s<\/a>\u00a0gravitational pull; it flew by the Moon at twice the planned distance but returned some useful data. Three Soviet missions,\u00a0<span id=\"ref839015\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Luna-space-probe\" data-show-preview=\"true\">Luna<\/a>\u00a01\u20133, explored the vicinity of the Moon in 1959, confirming that it had no appreciable\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/magnetic-field\" data-show-preview=\"true\">magnetic field<\/a>\u00a0and sending back the first-ever images of its far side. Luna 1 was the first spacecraft to fly past the Moon, beating Pioneer 4 by two months. Luna 2, in making a hard landing on the lunar surface, was the first spacecraft to strike another\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/celestial\" data-term=\"celestial\" data-type=\"EB\">celestial<\/a>\u00a0object. Later, in the 1960s and early 1970s, Luna and Lunokhod spacecraft soft-landed on the Moon, and some gathered soil samples and returned them to Earth.<\/p>\r\n<div class=\"assemblies multiple medialist slider js-slider position-relative d-inline-flex align-items-center mw-100\" data-type=\"other\">\r\n<div class=\"slider-container js-slider-container overflow-hidden d-flex rw-slider rw-prev-disabled\">\r\n<div class=\"rw-track d-flex align-items-center\">\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"7942\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/14\/8814-050-38D2201A\/lander-Viking-2-one-spacecraft-Mars-cameras-1976.jpg\" data-href=\"\/media\/1\/557348\/7942\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/14\/8814-050-38D2201A\/lander-Viking-2-one-spacecraft-Mars-cameras-1976.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/14\/8814-050-38D2201A\/lander-Viking-2-one-spacecraft-Mars-cameras-1976.jpg?w=300\" alt=\"Viking 2 on Mars\" width=\"1096\" height=\"877\" data-width=\"1600\" data-height=\"1280\" \/><\/picture><\/a>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">1 of 3<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/14\/8814-050-38D2201A\/lander-Viking-2-one-spacecraft-Mars-cameras-1976.jpg\" data-href=\"\/media\/1\/557348\/7942\">Viking 2 on Mars<\/a>Viking 2 lander (foreground) on Mars, photographed by one of the spacecraft&#8217;s own cameras, 1976.<\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"17692\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/51\/21151-050-4F23F248\/pancake-domes-edge-Alpha-Regio-highland-area.jpg\" data-href=\"\/media\/1\/557348\/17692\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/51\/21151-050-4F23F248\/pancake-domes-edge-Alpha-Regio-highland-area.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/51\/21151-050-4F23F248\/pancake-domes-edge-Alpha-Regio-highland-area.jpg?w=300\" alt=\"Alpha Regio, Venus\" width=\"1061\" height=\"849\" data-width=\"1600\" data-height=\"1280\" \/><\/picture><\/a>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">2 of 3<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/51\/21151-050-4F23F248\/pancake-domes-edge-Alpha-Regio-highland-area.jpg\" data-href=\"\/media\/1\/557348\/17692\">Alpha Regio, Venus<\/a>Merged pancake domes on the eastern edge of the Alpha Regio highland area of Venus, in an oblique view generated by computer from radar data gathered by the Magellan spacecraft. The volcanic features, each about 25 km (15 miles) in diameter and about 750 metres (0.5 mile) high, are thought to have been formed from the extrusion of extremely viscous lava onto the surface. The vertical scale of the image is exaggerated to bring out topological detail; colour is simulated from surface images taken by Soviet Venera landers.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"60533\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/00\/4300-050-299CEC0B\/nucleus-image-photographs-Comet-Halley-board-Multicolour-14-1986.jpg\" data-href=\"\/media\/1\/557348\/60533\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/00\/4300-050-299CEC0B\/nucleus-image-photographs-Comet-Halley-board-Multicolour-14-1986.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/00\/4300-050-299CEC0B\/nucleus-image-photographs-Comet-Halley-board-Multicolour-14-1986.jpg?w=300\" alt=\"Comet Halley nucleus\" width=\"1085\" height=\"1107\" data-width=\"1153\" data-height=\"1175\" \/><\/picture><\/a>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">3 of 3<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/00\/4300-050-299CEC0B\/nucleus-image-photographs-Comet-Halley-board-Multicolour-14-1986.jpg\" data-href=\"\/media\/1\/557348\/60533\">Comet Halley nucleus<\/a>Composite image of the nucleus of Comet Halley produced from 68 photographs taken on March 13\u201314, 1986, by the Halley Multicolour Camera onboard the Giotto spacecraft.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<button class=\"prev-button js-prev-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20 rw-disabled\" disabled=\"disabled\"><\/button><button class=\"next-button js-next-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20\"><\/button><\/div>\r\n<p class=\"topic-paragraph\">In the 1960s the United States became the first country to send a spacecraft to the vicinity of other planets;\u00a0<span id=\"ref839016\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Mariner\" data-show-preview=\"true\">Mariner<\/a>\u00a02 flew by\u00a0<span id=\"ref839017\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Venus-planet\" data-show-preview=\"true\">Venus<\/a>\u00a0in December 1962, and Mariner 4 flew past\u00a0<span id=\"ref839018\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Mars-planet\" data-show-preview=\"true\">Mars<\/a>\u00a0in July 1965. Among significant accomplishments of planetary missions in succeeding decades were the U.S.\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Viking-space-probe\" data-show-preview=\"true\">Viking<\/a>\u00a0landings on Mars in 1976 and the Soviet\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Venera\" data-show-preview=\"true\">Venera<\/a>\u00a0explorations of the atmosphere and surface of Venus from the mid-1960s to the mid-1980s. In the years since, the United States has continued an active program of solar system exploration, as did the Soviet Union until its\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/dissolution\" data-term=\"dissolution\" data-type=\"EB\">dissolution<\/a>\u00a0in 1991.\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Japan\" data-show-preview=\"true\">Japan<\/a>\u00a0launched missions to the Moon, Mars,\u00a0<span id=\"ref839020\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Halleys-Comet\" data-show-preview=\"true\">Halley\u2019s Comet<\/a>, and Venus and returned samples from the asteroids Itokawa and Ryugu. Europe\u2019s first independent solar system mission,\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Giotto\" data-show-preview=\"true\">Giotto<\/a>, also flew by Halley. After the turn of the 21st century, it sent missions to the Moon, Venus, and Mars and an orbiter-lander,\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Rosetta-European-Space-Agency-spacecraft\" data-show-preview=\"true\">Rosetta-Philae<\/a>, to a comet.\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/India\" data-show-preview=\"true\">India<\/a>\u00a0and\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/China\" data-show-preview=\"true\">China<\/a>\u00a0sent the\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Chandrayaan\" data-show-preview=\"true\">Chandrayaan-1<\/a>\u00a0(2008) and two\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Change-Chinese-lunar-probes\" data-show-preview=\"true\">Chang\u2019e<\/a>\u00a0(2007, 2010) missions, respectively, to orbit the Moon. China\u2019s Chang\u2019e 3 mission landed a small rover, Yutu, on the Moon in 2013, and Chang\u2019e 4 made the first landing on the far side of the Moon in 2019. India\u2019s\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/Mars-Orbiter-Mission\" data-show-preview=\"true\">Mars Orbiter Mission<\/a>\u00a0entered orbit around that planet in 2014. China placed the Tianwen-1 lander and the Zhurong rover on\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/Mars\" data-term=\"Mars\" data-type=\"EB\">Mars<\/a>\u00a0in 2021, and that same year Hope, an orbiter from the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/United-Arab-Emirates\" data-show-preview=\"true\">United Arab Emirates<\/a>, entered Mars orbit.\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/NASA\" data-show-preview=\"true\">NASA\u2019s<\/a>\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Dawn-United-States-satellite\" data-show-preview=\"true\">Dawn<\/a>\u00a0mission (2007) orbited the large asteroid\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Vesta-asteroid\" data-show-preview=\"true\">Vesta<\/a>\u00a0from 2011 to 2012 and entered orbit around the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/dwarf-planet\" data-show-preview=\"true\">dwarf planet<\/a>\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Ceres-dwarf-planet\" data-show-preview=\"true\">Ceres<\/a>\u00a0in 2015.<\/p>\r\n<div class=\"assemblies multiple medialist slider js-slider position-relative d-inline-flex align-items-center mw-100\" data-type=\"other\">\r\n<div class=\"slider-container js-slider-container overflow-hidden d-flex rw-slider rw-prev-disabled\">\r\n<div class=\"rw-track d-flex align-items-center\">\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"12218\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/58\/1858-004-B7D081B9\/Io-flyby-artist-spacecraft-rendering-probe-Galileo.jpg\" data-href=\"\/media\/1\/557348\/12218\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/58\/1858-004-B7D081B9\/Io-flyby-artist-spacecraft-rendering-probe-Galileo.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/58\/1858-004-B7D081B9\/Io-flyby-artist-spacecraft-rendering-probe-Galileo.jpg?w=300\" alt=\"Galileo flying by Io\" width=\"1138\" height=\"1070\" data-width=\"266\" data-height=\"250\" \/><\/picture><\/a>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">1 of 3<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/58\/1858-004-B7D081B9\/Io-flyby-artist-spacecraft-rendering-probe-Galileo.jpg\" data-href=\"\/media\/1\/557348\/12218\">Galileo flying by Io<\/a>U.S. spacecraft Galileo making a flyby of Jupiter&#8217;s moon Io, in an artist&#8217;s rendering. At the stage of the mission being depicted, the atmospheric probe has already been deployed; its former point of attachment is the circular structure at Galileo&#8217;s nearer end, along the main axis. Projecting from the central body are a probe relay antenna; a scan platform holding four optical instruments; a long boom (continuing out of view) with plasma, particle, and magnetic-field detectors; and two shorter booms carrying power generators that convert the heat from radioactive isotope decay into electricity. The high-gain antenna, which failed to unfurl fully during the mission, and its large circular sun shield are at the farther end of the craft.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"60063\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/18\/69718-004-49685B48\/space-probe-NEAR-Near-Earth-Asteroid-Rendezvous-February-2001.jpg\" data-href=\"\/media\/1\/557348\/60063\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/18\/69718-004-49685B48\/space-probe-NEAR-Near-Earth-Asteroid-Rendezvous-February-2001.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/18\/69718-004-49685B48\/space-probe-NEAR-Near-Earth-Asteroid-Rendezvous-February-2001.jpg?w=300\" alt=\"Near Earth Asteroid Rendezvous\" width=\"1112\" height=\"786\" data-width=\"550\" data-height=\"388\" \/><\/picture><\/a>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">2 of 3<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/18\/69718-004-49685B48\/space-probe-NEAR-Near-Earth-Asteroid-Rendezvous-February-2001.jpg\" data-href=\"\/media\/1\/557348\/60063\">Near Earth Asteroid Rendezvous<\/a>U.S. Near Earth Asteroid Rendezvous (NEAR) space probe in orbit around an asteroid, in an artist&#8217;s conception. Launched February 17, 1996, NEAR rendezvoused with the asteroid Eros, which it studied for a year in orbit before touching down on its surface in February 2001.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"73162\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/93\/73393-050-028995CC\/hemispheres-images-pair-mosaics-Eros-orbit-asteroid-February-23-2000.jpg\" data-href=\"\/media\/1\/557348\/73162\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/93\/73393-050-028995CC\/hemispheres-images-pair-mosaics-Eros-orbit-asteroid-February-23-2000.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/93\/73393-050-028995CC\/hemispheres-images-pair-mosaics-Eros-orbit-asteroid-February-23-2000.jpg?w=300\" alt=\"Eros asteroid\" width=\"1133\" height=\"1239\" data-width=\"742\" data-height=\"812\" \/><\/picture><\/a>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">3 of 3<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/93\/73393-050-028995CC\/hemispheres-images-pair-mosaics-Eros-orbit-asteroid-February-23-2000.jpg\" data-href=\"\/media\/1\/557348\/73162\">Eros asteroid<\/a>Opposite hemispheres of the asteroid Eros, shown in a pair of mosaics made from images taken by the U.S. Near Earth Asteroid Rendezvous (NEAR) Shoemaker spacecraft on February 23, 2000, from orbit around the asteroid.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<button class=\"prev-button js-prev-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20 rw-disabled\" disabled=\"disabled\"><\/button><button class=\"next-button js-next-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20\"><\/button><\/div>\r\n<p class=\"topic-paragraph\">Early on, scientists planned to conduct solar system exploration in three stages: initial reconnaissance from spacecraft flying by a planet, comet, or asteroid; detailed surveillance from a spacecraft orbiting the object; and on-site research after landing on the object or, in the case of a giant gas planet, by sending a\u00a0<span id=\"ref839041\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/space-probe\">probe<\/a>\u00a0into its atmosphere. All three of those stages have been carried out for the Moon, Venus, Mars, Jupiter,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/Saturn-launch-vehicle\" data-show-preview=\"true\">Saturn<\/a>, a comet, and several asteroids. Several Soviet and U.S. robotic spacecraft have landed on Venus and the Moon, and the United States has landed spacecraft on the surface of Mars. A long-term detailed\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/surveillance\" data-term=\"surveillance\" data-type=\"EB\">surveillance<\/a>\u00a0of\u00a0<span id=\"ref839023\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Jupiter-planet\" data-show-preview=\"true\">Jupiter<\/a>\u00a0and its moons began in 1995 when the U.S.\u00a0<span id=\"ref839025\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Galileo-spacecraft\" data-show-preview=\"true\">Galileo<\/a>\u00a0spacecraft took up orbit around the planet, at the same time releasing a probe into the turbulent Jovian atmosphere. In 2001 the U.S.\u00a0<span id=\"ref839027\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Near-Earth-Asteroid-Rendezvous-Shoemaker\" data-show-preview=\"true\">Near Earth Asteroid Rendezvous<\/a>\u00a0(NEAR) spacecraft landed on the\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/asteroid\" data-show-preview=\"true\">asteroid<\/a>\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Eros-asteroid\" data-show-preview=\"true\">Eros<\/a>\u00a0and transmitted information from its surface for more than two weeks.<\/p>\r\n<p class=\"topic-paragraph\">Among the rocky inner planets, only\u00a0<span id=\"ref839028\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Mercury-planet\" data-show-preview=\"true\">Mercury<\/a>\u00a0was for some time relatively neglected. In the first half century of space exploration,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/Mercury-space-project\" data-show-preview=\"true\">Mercury<\/a>\u00a0was visited just once; the U.S.\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Mariner\" data-show-preview=\"true\">Mariner<\/a>\u00a010 probe made three flybys of the planet in 1974\u201375. In 2004 the U.S.\u00a0<span id=\"ref839030\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Messenger-United-States-spacecraft\" data-show-preview=\"true\">Messenger<\/a>\u00a0spacecraft was launched to Mercury for a series of flybys beginning in 2008 and entered orbit around the planet in 2011. A joint European-Japanese\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/probe\" data-term=\"probe\" data-type=\"EB\">probe<\/a>, BepiColombo, was launched toward Mercury in 2018 and is scheduled to enter orbit there in 2025.<\/p>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"15101\" data-asm-type=\"video\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"video\"><a class=\"gtm-assembly-link d-flex justify-content-center\" href=\"https:\/\/www.britannica.com\/video\/Voyager-1-planets-spacecraft-Voyagers-animation-paths-August-1989\/-15101\" data-id=\"23176\"><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/76\/23176-138-B22115C3\/Voyager-1-planets-spacecraft-Voyagers-animation-paths-August-1989.jpg?w=800&amp;h=450&amp;c=crop\" alt=\"Follow Voyager flight paths past gas giants Jupiter, Saturn, Uranus, and Neptune and beyond Pluto\" width=\"1225\" height=\"695\" \/><\/a>\r\n<div class=\"btn btn-xl btn-white btn-circle position-absolute shadow\">\u00a0<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><span class=\"md-assembly-title font-weight-bold mr-5 d-inline font-sans-serif md-video-caption\">Follow Voyager flight paths past gas giants Jupiter, Saturn, Uranus, and Neptune and beyond Pluto<\/span>This animation shows the paths of the Voyager 1 and 2 spacecraft, which were designed to explore the outer planets of the solar system. The twin probes, each carrying 10 instruments, provided a wealth of new information about interplanetary space and the four giant gas planets and their moons. The Voyagers were launched in late 1977. In 1979 they reached Jupiter. Passing through the planet&#8217;s gravitational field, they gathered enough energy to \u201cslingshot\u201d around the planet and head for Saturn. Voyager 1 reached Saturn in November 1980, then headed out of the solar system. Voyager 2 continued on to Uranus, reaching the planet in January 1986. Changing course again and heading for Neptune, the spacecraft arrived at the outermost gas giant in August 1989. It then continued out of the solar system. In the first years of the 21st century, each craft was still sending back information about the outer reaches of the solar system and had traveled well beyond the orbit of Pluto.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<a class=\"font-14 mt-10 d-inline-block\" href=\"https:\/\/www.britannica.com\/science\/space-exploration\/images-videos\">See all videos for this article<\/a><\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">As of 2020, the exploration of the two outer giant gas planets\u2014<span id=\"ref839035\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Uranus-planet\" data-show-preview=\"true\">Uranus<\/a>\u00a0and\u00a0<span id=\"ref839040\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Neptune-planet\" data-show-preview=\"true\">Neptune<\/a>\u2014remained at the first stage. In a series of U.S. missions launched in the 1970s,\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Pioneer-space-probes\" data-show-preview=\"true\">Pioneer<\/a>\u00a010 flew by\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Jupiter-planet\" data-show-preview=\"true\">Jupiter<\/a>, whereas Pioneer 11 and\u00a0<span id=\"ref839042\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Voyager-space-probes\" data-show-preview=\"true\">Voyager<\/a>\u00a01 and 2 flew by both Jupiter and Saturn. Voyager 2 then went on to travel past Uranus and Neptune. On August 25, 2012,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/Voyager-1\" data-show-preview=\"true\">Voyager 1<\/a>\u00a0became the first space probe to enter interstellar space when it crossed the\u00a0<span id=\"ref1196972\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/heliopause\" data-show-preview=\"true\">heliopause<\/a>, the outer limit of the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Sun\" data-show-preview=\"true\">Sun\u2019s<\/a>\u00a0magnetic field and\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/solar-wind\" data-show-preview=\"true\">solar wind<\/a>. The Voyagers were expected to still be returning data through 2020. The U.S.\u00a0<span id=\"ref839044\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/event\/Cassini-Huygens\" data-show-preview=\"true\">Cassini<\/a>\u00a0spacecraft, launched in 1997, began a long-term surveillance mission in the Saturnian system in 2004; the following year its European-built Huygens probe descended to the surface of\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Titan-astronomy\" data-show-preview=\"true\">Titan<\/a>, Saturn\u2019s largest moon. In 2017 the Cassini mission ended when it burned up in Saturn\u2019s atmosphere. In 2011 the United States launched the\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Juno-spacecraft\" data-show-preview=\"true\">Juno<\/a>\u00a0mission, which studied the origin and\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/evolution-scientific-theory\" data-show-preview=\"true\">evolution<\/a>\u00a0of Jupiter after it arrived at the giant planet in 2016. Thus, every significant body in the solar system, even the dwarf planet\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Pluto-dwarf-planet\" data-show-preview=\"true\">Pluto<\/a>\u00a0and its largest moon,\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Charon-astronomy\" data-show-preview=\"true\">Charon<\/a>, has been visited at least once by a spacecraft. (The U.S.\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/New-Horizons\" data-show-preview=\"true\">New Horizons<\/a>\u00a0spacecraft, launched in 2006, flew by Pluto and Charon in 2015 and by a much smaller\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Kuiper-belt\" data-show-preview=\"true\">Kuiper belt<\/a>\u00a0object, Arrokoth, in 2019.)<\/p>\r\n<div class=\"module-spacing\">\u00a0<\/div>\r\n<p class=\"topic-paragraph\">These exploratory missions sought information on the origin and evolution of the solar system and on the various objects that it\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/comprises\" data-term=\"comprises\" data-type=\"MW\">comprises<\/a>, including chemical composition; surface topography; data on magnetic fields, atmospheres, and volcanic activity; and, particularly for Mars, evidence of water in the present or past and perhaps even of\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/extraterrestrial-life\" data-show-preview=\"true\">extraterrestrial life<\/a>\u00a0in some form.<\/p>\r\n<p class=\"topic-paragraph\">What has been learned to date confirms that Earth and the rest of the solar system formed at about the same time from the same cloud of gas and dust surrounding the Sun. The four outer\u00a0<span id=\"ref839046\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/giant-planet\">giant gas planets<\/a>\u00a0are roughly similar in size and chemical\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/composition\" data-term=\"composition\" data-type=\"MW\">composition<\/a>, but each has a set of moons that differ widely in their characteristics, and in some ways they and their satellites resemble miniature solar systems. The four rocky inner planets had a common origin but followed very different evolutionary paths and today have very different surfaces, atmospheres, and internal activity. Ongoing comparative study of the evolution of Venus, Mars, and Earth could provide important insights into Earth\u2019s future and its continued ability to support life.<\/p>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"68875\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/94\/73394-004-B1C1C342\/wall-Gullies-Martian-valley-liquid-image-channels-July-12-1999.jpg\" data-href=\"\/media\/1\/557348\/68875\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/94\/73394-004-B1C1C342\/wall-Gullies-Martian-valley-liquid-image-channels-July-12-1999.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/94\/73394-004-B1C1C342\/wall-Gullies-Martian-valley-liquid-image-channels-July-12-1999.jpg?w=300\" alt=\"Nirgal Vallis gullies on Mars\" width=\"1190\" height=\"837\" data-width=\"550\" data-height=\"387\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/94\/73394-004-B1C1C342\/wall-Gullies-Martian-valley-liquid-image-channels-July-12-1999.jpg\" data-href=\"\/media\/1\/557348\/68875\">Nirgal Vallis gullies on Mars<\/a>Gullies along the south-facing wall of the Martian valley Nirgal Vallis, in an image taken July 12, 1999, from the Mars Global Surveyor spacecraft. The kilometre-long channels, which appear to have been cut by liquid that emerged near the top of the wall, have been cited by some scientists as evidence for the flow of water on Mars in geologically recent times, but the interpretation is controversial.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">The question of whether life has ever existed elsewhere in the solar system continues to\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/intrigue\" data-term=\"intrigue\" data-type=\"EB\">intrigue<\/a>\u00a0both scientists and the general public. The United States sent two\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Viking-space-probe\" data-show-preview=\"true\">Viking<\/a>\u00a0spacecraft to land on the surface of Mars in 1976. Each contained three experiments intended to search for traces of organic material that might indicate the presence of past or present\u00a0<span id=\"ref839052\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/extraterrestrial-life\" data-show-preview=\"true\">life-forms<\/a>; none of the experiments produced positive results. Twenty years later, a team of scientists studying a meteorite of Martian origin found in Antarctica announced the discovery of possible microscopic fossils resulting from past organic life. Their claim was not universally accepted, but it led to an\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/accelerated\" data-term=\"accelerated\" data-type=\"EB\">accelerated<\/a>\u00a0program of Martian exploration focused on the search for evidence of the action of liquid water, thought necessary for life to have evolved. Beginning in 2001, the United States sent a series of \u201cfollow the water\u201d missions to orbit or land on Mars, including\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/2001-Mars-Odyssey\" data-show-preview=\"true\">2001 Mars Odyssey<\/a>\u00a0(2001), two\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Mars-Exploration-Rover\" data-show-preview=\"true\">Mars Exploration Rovers<\/a>, Spirit and Opportunity (2003),\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Mars-Reconnaissance-Orbiter\" data-show-preview=\"true\">Mars Reconnaissance Orbiter<\/a>\u00a0(2005), the\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Curiosity-United-States-robotic-vehicle\" data-show-preview=\"true\">Curiosity<\/a>\u00a0rover (2011), the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/Mars-Atmosphere-and-Volatile-Evolution\" data-show-preview=\"true\">MAVEN<\/a>\u00a0orbiter (2013), the InSight lander (2018), and the Perseverance rover and Ingenuity helicopter (2020). Europe launched the\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Mars-Express\" data-show-preview=\"true\">Mars Express<\/a>\u00a0mission in 2003 and the ExoMars Trace Gas Orbiter in 2016. A major long-term goal of the Mars exploration program is to return samples of the Martian surface to Earth for laboratory analysis, and\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/Perseverance\" data-term=\"Perseverance\" data-type=\"EB\">Perseverance<\/a>\u00a0collected samples in 2021 for a future sample return mission.<\/p>\r\n<p class=\"topic-paragraph\">There are indications that water may be present in the outer solar system. The Galileo mission provided images and other data related to Jupiter\u2019s moon\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Europa-satellite-of-Jupiter\" data-show-preview=\"true\">Europa<\/a>\u00a0that suggest the presence of a liquid water ocean beneath its icy crust. Future missions are needed to confirm the existence of this ocean and search for evidence of organic or biological processes in it. The\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/event\/Cassini-Huygens\" data-show-preview=\"true\">Cassini-Huygens<\/a>\u00a0mission confirmed the presence of lakes of liquid methane on Saturn\u2019s moon Titan and suggested the likely existence of liquid water underneath the surface of another moon,\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Enceladus\" data-show-preview=\"true\">Enceladus<\/a>.<\/p>\r\n<\/section>\r\n<\/div>\r\n<div id=\"chatbot-root\">\u00a0<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div data-page-index=\"17\">\u00a0<\/div>\r\n<div class=\"loaded-infinite-scroll-container qa-infinite-scroll-container\">\r\n<div class=\"grey-box w-100 \">\r\n<div class=\"grey-box-content mx-auto w-100\">\r\n<div class=\"page2ref-false topic-content topic-type-REGULAR\">\r\n<div class=\"reading-channel\">\r\n<section data-level=\"1\">\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237068\" data-level=\"2\" data-has-spy=\"true\">\r\n<h1 class=\"h2\">Exploring the\u00a0<span id=\"ref839056\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/universe\" data-show-preview=\"true\">universe<\/a><\/h1>\r\n<p class=\"topic-paragraph\">Until the dawn of\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/spaceflight\" data-show-preview=\"true\">spaceflight<\/a>, astronomers were limited in their ability to observe objects beyond the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/solar-system\" data-show-preview=\"true\">solar system<\/a>\u00a0to those portions of the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/electromagnetic-spectrum\" data-show-preview=\"true\">electromagnetic spectrum<\/a>\u00a0that can penetrate\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Earth\" data-show-preview=\"true\">Earth\u2019s<\/a>\u00a0atmosphere. These portions include the visible region, parts of the ultraviolet region, and most of the radio-frequency region. The ability to place instruments on a\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/spacecraft\" data-show-preview=\"true\">spacecraft<\/a>\u00a0operating above the atmosphere (<em>see<\/em>\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/satellite-observatory\" data-show-preview=\"true\">satellite observatory<\/a>) opened the possibility of observing the universe in all regions of the spectrum. Even operating in the visible region, a space-based observatory could\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/avoid\" data-term=\"avoid\" data-type=\"EB\">avoid<\/a>\u00a0the problems caused by\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/atmospheric-turbulence\" data-show-preview=\"true\">atmospheric turbulence<\/a>\u00a0and airglow.<\/p>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"73163\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/78\/75378-050-94C43B64\/Cats-Eye-Nebula-images-data-superimposition-observatories.jpg\" data-href=\"\/media\/1\/557348\/73163\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/78\/75378-050-94C43B64\/Cats-Eye-Nebula-images-data-superimposition-observatories.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/78\/75378-050-94C43B64\/Cats-Eye-Nebula-images-data-superimposition-observatories.jpg?w=300\" alt=\"Cat's Eye Nebula\" width=\"1103\" height=\"544\" data-width=\"1600\" data-height=\"790\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/78\/75378-050-94C43B64\/Cats-Eye-Nebula-images-data-superimposition-observatories.jpg\" data-href=\"\/media\/1\/557348\/73163\">Cat&#8217;s Eye Nebula<\/a>Two computer-coloured images of the Cat&#8217;s Eye Nebula (NGC 6543) made from data gathered by Earth-orbiting observatories. The left image was made in X-rays by the Chandra X-Ray Observatory; the right image is a superimposition of the Chandra image (rendered in purple tones) and a colour-enhanced image processed from visible-light observations made by the Hubble Space Telescope (in yellows, greens, and reds). The combined image reveals the position of hot, X-ray-emitting gas relative to the cooler material that is emitting in visible wavelengths. The Cat&#8217;s Eye, a planetary nebula, comprises expanding shells of gas that have been blown off by its central star, which is nearing the end of its life.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">Beginning in the 1960s, a number of countries launched\u00a0<span id=\"ref839066\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/satellite-observatory\" data-show-preview=\"true\">satellites<\/a>\u00a0to explore cosmic phenomena in the gamma-ray, X-ray, ultraviolet, visible, and infrared regions. More recently, space-based radio\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/astronomy\" data-show-preview=\"true\">astronomy<\/a>\u00a0has been pursued. In the last decades of the 20th century, the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/United-States\" data-show-preview=\"true\">United States<\/a>\u00a0embarked on the development of a series of long-duration orbital facilities collectively called the\u00a0<span id=\"ref839059\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Great-Observatories\" data-show-preview=\"true\">Great Observatories<\/a>. They include the\u00a0<span id=\"ref839061\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Hubble-Space-Telescope\" data-show-preview=\"true\">Hubble Space Telescope<\/a>, launched in 1990 for observations in the visible and ultraviolet regions; the\u00a0<span id=\"ref839063\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Compton-Gamma-Ray-Observatory\" data-show-preview=\"true\">Compton Gamma Ray Observatory<\/a>, launched in 1991; the\u00a0<span id=\"ref839064\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Chandra-X-Ray-Observatory\" data-show-preview=\"true\">Chandra X-Ray Observatory<\/a>, launched in 1999; and the\u00a0<span id=\"ref839065\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Spitzer-Space-Telescope\" data-show-preview=\"true\">Spitzer Space Telescope<\/a>, launched in 2003. Europe and\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Japan\" data-show-preview=\"true\">Japan<\/a>\u00a0have also been active in space-based astronomy and\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/astrophysics\" data-show-preview=\"true\">astrophysics<\/a>. Europe\u2019s\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Herschel-space-telescope\" data-show-preview=\"true\">Herschel<\/a>\u00a0infrared observatory, launched in 2009, studied the origin and\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/evolution-scientific-theory\" data-show-preview=\"true\">evolution<\/a>\u00a0of stars and galaxies. A\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/optical-telescope\" data-show-preview=\"true\">telescope<\/a>\u00a0aboard Japan\u2019s\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Akari\" data-show-preview=\"true\">Akari<\/a>\u00a0spacecraft, launched in 2006, also observed the universe in the infrared spectrum.<\/p>\r\n<p class=\"topic-paragraph\">The results of these space investigations have made major contributions to an understanding of the origin, evolution, and likely future of the universe, galaxies, stars, and planetary systems. For example, the U.S.\u00a0<span id=\"ref839068\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Cosmic-Background-Explorer\" data-show-preview=\"true\">Cosmic Background Explorer<\/a>\u00a0(COBE)\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/satellite\" data-show-preview=\"true\">satellite<\/a>, launched in 1989, mapped the microwave background radiation left over from the early universe, providing strong support for the theory that the universe was created in a\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/primordial\" data-term=\"primordial\" data-type=\"MW\">primordial<\/a>\u00a0explosion, known as the\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/big-bang-model\" data-show-preview=\"true\">big bang<\/a>. Precision measurements of this\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/cosmic-microwave-background\" data-show-preview=\"true\">cosmic microwave background<\/a>\u00a0by the American\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Wilkinson-Microwave-Anisotropy-Probe\" data-show-preview=\"true\">Wilkinson Microwave Anisotropy Probe<\/a>\u00a0(WMAP, 2001) and the European\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Planck\" data-show-preview=\"true\">Planck<\/a>\u00a0spacecraft (2009) enabled astronomers to determine the age, size, and shape of the universe. The U.S. satellite\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Kepler-satellite\" data-show-preview=\"true\">Kepler<\/a>\u00a0(2009) discovered thousands of planetary candidates of startling\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/diversity\" data-term=\"diversity\" data-type=\"MW\">diversity<\/a>\u00a0orbiting distant suns. The European satellites\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Hipparcos\" data-show-preview=\"true\">Hipparcos<\/a>\u00a0(1989) and\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Gaia-European-Space-Agency-satellite\" data-show-preview=\"true\">Gaia<\/a>\u00a0(2013) precisely mapped the position of more than a billion stars. The striking images of cosmic objects obtained by the Hubble Space Telescope not only added significantly to scientific knowledge but also shaped the public\u2019s perception of the cosmos, perhaps as significantly as did the astronomer\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Galileo-Galilei\" data-show-preview=\"true\">Galileo<\/a>\u2019s observations of the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Moon\" data-show-preview=\"true\">Moon<\/a>\u00a0and\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Jupiter-planet\" data-show-preview=\"true\">Jupiter<\/a>\u00a0nearly four centuries earlier. Working as complements to ground-based observatories of increasing sensitivity, space-based observatories helped create a revolution in modern astronomy.<\/p>\r\n<\/section>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237069\" data-level=\"2\" data-has-spy=\"true\">\r\n<h2 class=\"h2\"><span id=\"ref839074\"><\/span>Microgravity research<\/h2>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"162922\" data-asm-type=\"video\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"video\"><a class=\"gtm-assembly-link d-flex justify-content-center\" href=\"https:\/\/www.britannica.com\/video\/Description-weightlessness-astronauts\/-162922\" data-id=\"153024\"><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/24\/153024-138-8CC3024E\/Description-weightlessness-astronauts.jpg?w=800&amp;h=450&amp;c=crop\" alt=\"How astronauts prepare for weightlessness in space\" width=\"1099\" height=\"618\" \/><\/a>\r\n<div class=\"btn btn-xl btn-white btn-circle position-absolute shadow\">\u00a0<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><span class=\"md-assembly-title font-weight-bold mr-5 d-inline font-sans-serif md-video-caption\">How astronauts prepare for weightlessness in space<\/span>Description of weightlessness and how astronauts prepare for it.<\/div>\r\n<a class=\"font-14 mt-10 d-inline-block\" href=\"https:\/\/www.britannica.com\/science\/space-exploration\/images-videos\">See all videos for this article<\/a><\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">A spacecraft orbiting Earth is essentially in a continuous state of\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/freefall-physics\" data-show-preview=\"true\">free fall<\/a>. All objects associated with the spacecraft, including any crew and other contents, are accelerating\u2014i.e., falling freely\u2014at the same rate in Earth\u2019s gravitational field (<em>see<\/em>\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Earth\/Basic-planetary-data#ref54194\" data-show-preview=\"true\">Earth: Basic planetary data<\/a>). As a result, these objects do not \u201cfeel\u201d the presence of Earth\u2019s\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/gravity-physics\" data-show-preview=\"true\">gravity<\/a>\u00a0but instead experience a state of\u00a0<span id=\"ref839083\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/weightlessness\" data-show-preview=\"true\">weightlessness<\/a>, or zero gravity. True zero gravity, however, is experienced only at the centre of mass of a freely falling object. With increasing distance from the centre of mass, the influence of gravity increases in both directions perpendicular to the object\u2019s flight path. These constant but tiny accelerations make necessary the use of the term\u00a0<em><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/microgravity\" data-show-preview=\"true\">microgravity<\/a><\/em>\u00a0to describe the space\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/environment\" data-term=\"environment\" data-type=\"MW\">environment<\/a>. (It is possible to create a similar absence of gravity\u2019s effects only briefly on Earth or in an aircraft.) Human activity or the operation of equipment in a spacecraft causes vibrations that impart additional accelerations and so raise gravity levels, which can make it difficult to carry out highly sensitive experiments under sufficiently low microgravity conditions. Although spacecraft designers cannot totally eliminate gravitational effects, they hope to reduce them in some parts of the\u00a0<span id=\"ref839084\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/International-Space-Station\" data-show-preview=\"true\">International Space Station<\/a>\u00a0to one microgravity\u2014one-millionth of Earth\u2019s gravity\u2014by isolating those areas from vibrations and other disturbances as much as possible.<\/p>\r\n<p class=\"topic-paragraph\">The opportunity to carry out experiments in the absence of gravity has interested scientists from the beginning of activities in orbit. In addition to concern about the effects of the weightlessness on humans sent into space (<em>see above<\/em>\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/space-exploration\/Human-beings-in-space-debate-and-consequences#ref237064\" data-show-preview=\"true\">Biomedical, psychological, and sociological aspects<\/a>), scientists are interested in its effects on the reproductive and developmental cycles of plants and animals other than humans. The overall goal is to use space-based research to add to the general understanding of a wide range of biological processes.<\/p>\r\n<div class=\"module-spacing\">\u00a0<\/div>\r\n<p class=\"topic-paragraph\"><span id=\"ref839087\"><\/span>Life-sciences experiments were carried out on the\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Skylab\" data-show-preview=\"true\">Skylab<\/a>,\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Salyut\" data-show-preview=\"true\">Salyut<\/a>, and\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Mir-Soviet-Russian-space-station\" data-show-preview=\"true\">Mir<\/a>\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/space-station\" data-show-preview=\"true\">space stations<\/a>\u00a0and\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/constitute\" data-term=\"constitute\" data-type=\"MW\">constitute<\/a>\u00a0a significant portion of work aboard the ISS. Such research also was conducted on\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/space-shuttle\" data-show-preview=\"true\">space shuttle<\/a>\u00a0missions, particularly within the\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Spacelab\" data-show-preview=\"true\">Spacelab<\/a>\u00a0facility. In addition, the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Soviet-Union\" data-show-preview=\"true\">Soviet Union<\/a>\u00a0and the United States launched a number of robotic satellites dedicated to life-sciences research. Together these experiments have involved a wide range of nonhuman organisms, from bacteria, plants, and invertebrate animals to fish, birds, frogs, turtles, and mammals such as rats and monkeys. Human crew members also have served as experimental subjects for research on such topics as the functioning of the neurological system and the process of aging. In October 1998, the U.S. senator and former\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/Mercury-space-project\" data-show-preview=\"true\">Mercury<\/a>\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/astronaut\" data-show-preview=\"true\">astronaut<\/a>\u00a0<span id=\"ref839088\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/John-Glenn\" data-show-preview=\"true\">John H. Glenn, Jr.<\/a>, at age 77 returned to space on a shuttle mission dedicated to life-sciences research, which included studies of similarities between the aging process and the body\u2019s response to weightlessness. The hope is that the results of biomedical experiments conducted in microgravity can be used to improve human health and\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/well-being\" data-term=\"well-being\" data-type=\"EB\">well-being<\/a>\u00a0on Earth.<\/p>\r\n<div class=\"assemblies multiple medialist slider js-slider position-relative d-inline-flex align-items-center mw-100\" data-type=\"other\">\r\n<div class=\"slider-container js-slider-container overflow-hidden d-flex rw-slider rw-prev-disabled\">\r\n<div class=\"rw-track d-flex align-items-center\">\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"161938\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/91\/150091-050-2E62E690\/composite-drop-heptane-fuel-grayscale-video-stills.jpg\" data-href=\"\/media\/1\/557348\/161938\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/91\/150091-050-2E62E690\/composite-drop-heptane-fuel-grayscale-video-stills.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/91\/150091-050-2E62E690\/composite-drop-heptane-fuel-grayscale-video-stills.jpg?w=300\" alt=\"microgravity: combustion\" width=\"1095\" height=\"821\" data-width=\"1600\" data-height=\"1200\" \/><\/picture><\/a>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">1 of 2<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/91\/150091-050-2E62E690\/composite-drop-heptane-fuel-grayscale-video-stills.jpg\" data-href=\"\/media\/1\/557348\/161938\">microgravity: combustion<\/a>A 3-mm-wide drop of heptane fuel burning in microgravity. The image is a composite of grayscale video stills that have been coloured to show the movement of soot away from the burning droplet (bright yellow, middle).<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"60020\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/08\/408-050-B2AF8C0F\/Ulf-Merbold-German-orbit-materials-processing-experiment-payload-November-28-1983.jpg\" data-href=\"\/media\/1\/557348\/60020\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/08\/408-050-B2AF8C0F\/Ulf-Merbold-German-orbit-materials-processing-experiment-payload-November-28-1983.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/08\/408-050-B2AF8C0F\/Ulf-Merbold-German-orbit-materials-processing-experiment-payload-November-28-1983.jpg?w=300\" alt=\"Spacelab 1\" width=\"1178\" height=\"817\" data-width=\"1000\" data-height=\"695\" \/><\/picture><\/a>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">2 of 2<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/08\/408-050-B2AF8C0F\/Ulf-Merbold-German-orbit-materials-processing-experiment-payload-November-28-1983.jpg\" data-href=\"\/media\/1\/557348\/60020\">Spacelab 1<\/a>West German physicist-astronaut Ulf Merbold conducting a materials-processing experiment aboard Spacelab, carried into orbit in the payload bay of the space shuttle orbiter\u00a0<em>Columbia<\/em>. The shuttle mission was launched November 28, 1983.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<button class=\"prev-button js-prev-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20 rw-disabled\" disabled=\"disabled\"><\/button><button class=\"next-button js-next-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20\"><\/button><\/div>\r\n<p class=\"topic-paragraph\">The microgravity environment also offers unique conditions for experiments designed to explore the behaviour of materials. Among the areas of inquiry are biotechnology, combustion\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/science\" data-show-preview=\"true\">science<\/a>, fluid physics, fundamental physics, and\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/materials-science\" data-show-preview=\"true\">materials science<\/a>. Experiments in the microgravity environment on various materials, including metals, alloys, electronic and photonic materials, composites, colloids, glasses and ceramics, and polymers, have resulted in a greater understanding of the role of gravity in similar laboratory and manufacturing processes on Earth. The microgravity environment offers the potential for producing biological materials, including highly ordered protein crystals for crystallographic analysis and even materials resembling human tissues, that are difficult or impossible to make on Earth. Although microgravity research is still largely at the basic level, scientists and engineers hope that additional work\u2014another major focus for the ISS\u2014will lead to practical knowledge of great usefulness to manufacturing processes on Earth.<\/p>\r\n<\/section>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237070\" data-level=\"2\" data-has-spy=\"true\">\r\n<h2 class=\"h2\">Observing Earth<\/h2>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"73169\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/74\/3174-050-C19F6FD0\/ocean-surface-Gravity-map-Earth-Seasat-orbit-1978.jpg\" data-href=\"\/media\/1\/557348\/73169\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/74\/3174-050-C19F6FD0\/ocean-surface-Gravity-map-Earth-Seasat-orbit-1978.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/74\/3174-050-C19F6FD0\/ocean-surface-Gravity-map-Earth-Seasat-orbit-1978.jpg?w=300\" alt=\"gravity map of Earth's oceans\" width=\"1128\" height=\"628\" data-width=\"1600\" data-height=\"892\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/74\/3174-050-C19F6FD0\/ocean-surface-Gravity-map-Earth-Seasat-orbit-1978.jpg\" data-href=\"\/media\/1\/557348\/73169\">gravity map of Earth&#8217;s oceans<\/a>Gravity map of Earth&#8217;s ocean surface, computed from radar-altimetry measurements made from orbit by the U.S. satellite Seasat in 1978. Because the ocean surface is deformed by the varying gravitational attraction of the underlying marine topography, such maps sensitively mirror seafloor features and have been valuable in identifying previously uncharted seamounts, ridges, and fracture zones.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">Satellites, space stations, and space shuttle missions have provided a new perspective for scientists to collect data about Earth itself. In addition to practical applications (<em>see below<\/em>\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/space-exploration\/Space-applications#ref237071\" data-show-preview=\"true\">Space applications<\/a>), Earth observation from space has made significant contributions to fundamental knowledge. An early and continuing example is the use of satellites to make various geodetic measurements, which has allowed precise determinations of Earth\u2019s shape, internal structure, and rotational motion and the tidal and other periodic motions of the oceans. Fields as\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/diverse\" data-term=\"diverse\" data-type=\"MW\">diverse<\/a>\u00a0as archaeology, seismology, and oceanography likewise have benefited from observations and measurements made from orbit.<\/p>\r\n<p class=\"topic-paragraph\">Scientists have begun to use observations from space as part of\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/comprehensive\" data-term=\"comprehensive\" data-type=\"MW\">comprehensive<\/a>\u00a0efforts in fields such as oceanography and ecology to understand and model the causes, processes, and effects of global\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/climate-change\" data-show-preview=\"true\">climate change<\/a>, including the influence of human activities. The goal is to obtain comprehensive sets of data over meaningful time spans about key physical, chemical, and biological processes that are shaping the planet\u2019s future. This is a coordinated international effort, in which the United States, Europe, Japan, and other countries are providing satellites to obtain the needed observations.<\/p>\r\n<\/section>\r\n<\/section>\r\n<\/div>\r\n<div id=\"chatbot-root\">\u00a0<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div data-page-index=\"18\">\u00a0<\/div>\r\n<div class=\"loaded-infinite-scroll-container qa-infinite-scroll-container\">\r\n<div class=\"grey-box w-100 \">\r\n<div class=\"grey-box-content mx-auto w-100\">\r\n<div class=\"page2ref-false topic-content topic-type-REGULAR\">\r\n<div class=\"reading-channel\">\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237071\" data-level=\"1\" data-has-spy=\"true\">\r\n<h1 class=\"h1\">Space applications<\/h1>\r\n<div class=\"assemblies multiple medialist slider js-slider position-relative d-inline-flex align-items-center mw-100\" data-type=\"other\">\r\n<div class=\"slider-container js-slider-container overflow-hidden d-flex rw-slider rw-prev-disabled\">\r\n<div class=\"rw-track d-flex align-items-center\">\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"241523\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/15\/204715-050-D9EF63AC\/Launch-rocket-SpaceX-Falcon-Heavy-Kennedy-Space-February-6-2018.jpg\" data-href=\"\/media\/1\/557348\/241523\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/15\/204715-050-D9EF63AC\/Launch-rocket-SpaceX-Falcon-Heavy-Kennedy-Space-February-6-2018.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/15\/204715-050-D9EF63AC\/Launch-rocket-SpaceX-Falcon-Heavy-Kennedy-Space-February-6-2018.jpg?w=300\" alt=\"SpaceX: Falcon Heavy rocket\" width=\"1104\" height=\"1354\" data-width=\"1304\" data-height=\"1600\" \/><\/picture><\/a>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">1 of 2<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/15\/204715-050-D9EF63AC\/Launch-rocket-SpaceX-Falcon-Heavy-Kennedy-Space-February-6-2018.jpg\" data-href=\"\/media\/1\/557348\/241523\">SpaceX: Falcon Heavy rocket<\/a>Launch of the SpaceX Falcon Heavy rocket from the Kennedy Space Center, Cape Canaveral, Florida, February 6, 2018.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<div class=\"position-relative rw-slide col-100 px-20\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"68876\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/47\/73347-050-C10C7514\/orbits-characteristics-satellite-shape-inclination-Earth-terms.jpg\" data-href=\"\/media\/1\/557348\/68876\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/47\/73347-050-C10C7514\/orbits-characteristics-satellite-shape-inclination-Earth-terms.jpg\" media=\"(min-width: 680px)\" \/><img decoding=\"async\" src=\"https:\/\/cdn.britannica.com\/47\/73347-050-C10C7514\/orbits-characteristics-satellite-shape-inclination-Earth-terms.jpg?w=300\" alt=\"satellite orbits\" data-width=\"1600\" data-height=\"1100\" \/><\/picture><\/a>\r\n<div class=\"position-absolute top-10 left-10 assembly-slide-tag rounded-lg\">2 of 2<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/47\/73347-050-C10C7514\/orbits-characteristics-satellite-shape-inclination-Earth-terms.jpg\" data-href=\"\/media\/1\/557348\/68876\">satellite orbits<\/a>Basic characteristics of orbits in which a satellite can be placed around Earth, categorized by inclination, shape, and altitude. A given orbit can be described in terms of combinations of these characteristics.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<button class=\"prev-button js-prev-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20 rw-disabled\" disabled=\"disabled\"><\/button><button class=\"next-button js-next-button position-absolute btn btn-circle shadow btn-lg btn-blue-dark m-20\"><\/button><\/div>\r\n<p class=\"topic-paragraph\">Space visionaries in the early 20th century recognized that putting satellites into orbit could furnish direct and\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/tangible\" data-term=\"tangible\" data-type=\"MW\">tangible<\/a>\u00a0benefits to people on Earth. For example,\u00a0<span id=\"ref839095\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Arthur-C-Clarke\" data-show-preview=\"true\">Arthur C. Clarke<\/a>\u00a0in 1945 described a way in which three satellites in orbit about 35,800 km (22,250 miles) above the Equator could relay communications around the globe. In this orbit, called a\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/geostationary-orbit\" data-show-preview=\"true\">geostationary orbit<\/a>, the satellites would have an orbital period equal to Earth\u2019s rotational period and thus appear from the ground to be stationary in the sky. (For additional information on\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/satellite\" data-show-preview=\"true\">satellite<\/a>\u00a0orbits,\u00a0<em>see<\/em>\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/spaceflight#ref219235\" data-show-preview=\"true\">spaceflight: Earth orbit<\/a>.) A report for the U.S. Army Air Forces in 1946 by Project RAND (the\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/predecessor\" data-term=\"predecessor\" data-type=\"EB\">predecessor<\/a>\u00a0of the RAND Corporation) identified the benefits of being able to observe Earth from space, which included distinguishing the impact sites of bombs dropped by U.S. aircraft and improving weather forecasting.<\/p>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"139721\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/73\/136573-050-0DE6044A\/US-Department-of-Defense-Space-Test-Program.jpg\" data-href=\"\/media\/1\/557348\/139721\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/73\/136573-050-0DE6044A\/US-Department-of-Defense-Space-Test-Program.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/73\/136573-050-0DE6044A\/US-Department-of-Defense-Space-Test-Program.jpg?w=300\" alt=\"Space Test Program's Standard Interface Vehicle (STP-SIV)\" width=\"1112\" height=\"856\" data-width=\"1600\" data-height=\"1234\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/73\/136573-050-0DE6044A\/US-Department-of-Defense-Space-Test-Program.jpg\" data-href=\"\/media\/1\/557348\/139721\">Space Test Program&#8217;s Standard Interface Vehicle (STP-SIV)<\/a>The U.S. Department of Defense&#8217;s Space Test Program&#8217;s Standard Interface Vehicle (STP-SIV), manufactured by Ball Aerospace.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">Space development, the practical application of the capabilities of\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/spacecraft\" data-show-preview=\"true\">spacecraft<\/a>\u00a0and of the data collected from space, has evolved in parallel with space exploration. There are two general categories of space applications. One provides benefits that are considered public goods\u2014i.e., that cannot easily be marketed to individual purchasers\u2014and thus are usually provided by governments, using public funds. Examples of public-good space applications include meteorology; navigation, position location, and timing; and military and national security uses. The other category of applications provides goods or services that can be sold to purchasers at a profit. These applications are the basis for the commercial development of space by the private sector. Examples of existing commercial space applications include various forms of telecommunications and\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/data-transmission\" data-show-preview=\"true\">data transmission<\/a>\u00a0via satellites, remote sensing of Earth\u2019s surface, and commercial space transportation. Other applications, such as\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/space-tourism\" data-show-preview=\"true\">space tourism<\/a>, space-based power generation, the manufacture of high-value materials in a microgravity\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/environment\" data-term=\"environment\" data-type=\"MW\">environment<\/a>, and the commercial development of extraterrestrial resources, may appear in the future.<\/p>\r\n<p class=\"topic-paragraph\">Many space applications have both civilian and military uses, and thus similar systems have been developed by both sectors. How to manage and use these dual-purpose systems effectively is a continuing policy issue.<\/p>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237072\" data-level=\"2\" data-has-spy=\"true\">\r\n<h2 class=\"h2\"><span id=\"ref839100\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/meteorology\" data-show-preview=\"true\">Meteorology<\/a><\/h2>\r\n<p class=\"topic-paragraph\">Meteorologists initially thought that\u00a0<span id=\"ref839105\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/weather-satellite\" data-show-preview=\"true\">satellites<\/a>\u00a0would be used primarily to observe cloud patterns and thus provide warnings of impending storms. They did not expect space observations to be central to improved weather forecasting overall. Nevertheless, as the technology of space-based instrumentation became more\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/sophisticated\" data-term=\"sophisticated\" data-type=\"EB\">sophisticated<\/a>, satellites were called upon to provide three-dimensional profiles of additional variables in the atmosphere, including temperature, moisture content, and wind speed. These data have become critical to modern\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/weather-forecasting\" data-show-preview=\"true\">weather forecasting<\/a>.<\/p>\r\n<p class=\"topic-paragraph\">Meteorological satellites are placed in one of two different kinds of orbit. Satellites in geostationary orbit provide continuous images of cloud patterns over large areas of Earth\u2019s surface. From changes in those patterns, meteorologists can deduce wind speeds and locate developing storms. Satellites in lower orbits aligned in a north-south direction, called\u00a0<span id=\"ref839109\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/polar-orbit\">polar orbits<\/a>, can obtain more detailed data about changing atmospheric conditions. They also provide repetitive global coverage as Earth rotates beneath their orbit. In the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/United-States\" data-show-preview=\"true\">United States<\/a>, military and civilian agencies each have developed independent polar-orbiting\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/weather-satellite\" data-show-preview=\"true\">meteorological satellite<\/a>\u00a0systems;\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/China\" data-show-preview=\"true\">China<\/a>, Europe, and\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Russia\" data-show-preview=\"true\">Russia<\/a>\u00a0also have\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/deployed\" data-term=\"deployed\" data-type=\"MW\">deployed<\/a>\u00a0their own polar-orbiting satellites. The United States, Europe, Russia, China,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/India\" data-show-preview=\"true\">India<\/a>, and\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Japan\" data-show-preview=\"true\">Japan<\/a>\u00a0have orbited geostationary meteorological satellites.<\/p>\r\n<div class=\"module-spacing\">\u00a0<\/div>\r\n<p class=\"topic-paragraph\">Although the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/research-and-development\" data-show-preview=\"true\">research and development<\/a>\u00a0activity needed to produce meteorological satellites has been carried out by various space agencies, control over satellite operation usually has been handed over to organizations with general responsibility for weather forecasting. In the United States the\u00a0<span id=\"ref839113\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/National-Oceanic-and-Atmospheric-Administration\" data-show-preview=\"true\">National Oceanographic and Atmospheric Administration<\/a>\u00a0(NOAA) operates geostationary and polar-orbiting satellites for short- and long-term forecasting; the Department of Defense (DOD) also has developed similar satellites for military use. In Europe an intergovernmental organization called\u00a0<span id=\"ref839104\"><\/span>Eumetsat was created in 1986 to operate Europe\u2019s meteorological satellites and provide their observations to national weather services. Agencies around the world cooperate in the exchange of\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/data\" data-term=\"data\" data-type=\"EB\">data<\/a>\u00a0from their satellites. Meteorological satellites are an excellent example of both the ability of space systems to provide extremely valuable benefits to humanity and the need for international cooperation to maximize those benefits.<\/p>\r\n<\/section>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237073\" data-level=\"2\" data-has-spy=\"true\">\r\n<h2 class=\"h2\">Positioning, navigation, and timing<\/h2>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"73033\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/13\/73213-050-5CE17A6B\/orbit-satellite-Navstar-Global-Positioning-System-artist.jpg\" data-href=\"\/media\/1\/557348\/73033\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/13\/73213-050-5CE17A6B\/orbit-satellite-Navstar-Global-Positioning-System-artist.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/13\/73213-050-5CE17A6B\/orbit-satellite-Navstar-Global-Positioning-System-artist.jpg?w=300\" alt=\"GPS satellite\" width=\"1139\" height=\"1139\" data-width=\"1434\" data-height=\"1434\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/13\/73213-050-5CE17A6B\/orbit-satellite-Navstar-Global-Positioning-System-artist.jpg\" data-href=\"\/media\/1\/557348\/73033\">GPS satellite<\/a>U.S. Navstar Global Positioning System (GPS) satellite in orbit over Earth, shown in an artist&#8217;s conception.<\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">In 1957 scientists tracking the first satellite,\u00a0<span id=\"ref839117\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Sputnik\" data-show-preview=\"true\">Sputnik<\/a>\u00a01, found that they could plot the satellite\u2019s orbit very precisely by analyzing the Doppler shift (<em>see<\/em>\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/Doppler-effect\" data-show-preview=\"true\">Doppler effect<\/a>) in the frequency of its transmitted signal with respect to a fixed location on Earth. They understood that if this process could be reversed\u2014i.e., if the orbits of several satellites were precisely known\u2014it would be possible to identify one\u2019s location on Earth by using information from those satellites.<\/p>\r\n<p class=\"topic-paragraph\">This realization, coupled with the need to establish the position of submarines carrying\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/ballistic\" data-term=\"ballistic\" data-type=\"MW\">ballistic<\/a>\u00a0missiles, led the United States and the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Soviet-Union\" data-show-preview=\"true\">Soviet Union<\/a>\u00a0each to develop satellite-based navigation systems in the 1960s and early \u201970s. Those systems, however, did not provide highly accurate information and were unwieldy to use. The two countries then developed second-generation products\u2014the U.S. Navstar\u00a0<span id=\"ref839119\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/GPS\" data-show-preview=\"true\">Global Positioning System<\/a>\u00a0(GPS) and the Soviet\u00a0<span id=\"ref839121\"><\/span>Global Navigation Satellite System (GLONASS)\u2014that did much to solve the problems of their predecessors. The original purpose of the systems was the support of military activities, and they have continued to operate under military control while serving a wide variety of civilian uses.<\/p>\r\n<p class=\"topic-paragraph\">GPS requires a minimum of 24 satellites, with four satellites distributed in each of six orbits. Deployment of the full\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/complement\" data-term=\"complement\" data-type=\"EB\">complement<\/a>\u00a0of satellites was completed in 1994 and included provision for continual replenishment and updating and the maintenance of several spare satellites in orbit. Each satellite carries four atomic clocks accurate to one nanosecond. Because the satellites\u2019 orbits are maintained very precisely by ground controllers and the time signals from each satellite are highly accurate, users with a GPS receiver can determine their distance from each of a minimum of four satellites and, from this information, pinpoint their exact location in three dimensions with an accuracy of approximately 3 metres (10 feet) horizontally and 5 metres (16 feet) vertically.<\/p>\r\n<p class=\"topic-paragraph\">GLONASS, which became operational in 1995, functions on the same general principles as GPS. The fully\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/deployed\" data-term=\"deployed\" data-type=\"EB\">deployed<\/a>\u00a0system consists of 24 satellites distributed in three orbits. Because of Russia\u2019s economic difficulties, however, GLONASS for some years was not well maintained, and replacement satellite deployment was slow. However, with improved economic conditions, the Russian government gave high priority to achieving and maintaining a fully operational GLONASS system.<\/p>\r\n<p class=\"topic-paragraph\">Notwithstanding the military origin of GPS and GLONASS, civilian users have proliferated. They range from wilderness campers, farmers, golfers, and recreational sailors to surveyors, car-rental firms, bus and truck fleets, and the world\u2019s airlines. The timing information from GPS satellites is also used by the Internet and other computer networks to manage the flow of information. Users have found ways to increase the accuracy of position location to a few centimetres by\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/combining\" data-term=\"combining\" data-type=\"EB\">combining<\/a>\u00a0GPS signals with ground-based enhancements or with GLONASS signals, and affordable GPS receivers make the system widely accessible.<\/p>\r\n<p class=\"topic-paragraph\">The United States regards GPS as a global utility to be offered free of charge to all users and has stated its intent to maintain and upgrade the system into the indefinite future. Concern has been expressed, however, that important worldwide civilian activities such as\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/air-traffic-control\" data-show-preview=\"true\">air traffic control<\/a>\u00a0should not depend on a system controlled by one country\u2019s military forces. In response, Europe began in the late 1990s to develop its own navigation satellite system, called\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/Galileo-spacecraft\" data-show-preview=\"true\">Galileo<\/a>, to be operated under civilian control. Galileo became operational in 2016. In the early 21st century China began to develop its own global navigation system, called Beidou (\u201cCompass\u201d). Initially consisting of three satellites in geostationary orbit over China, Beidou began operation in 2000. A full global version of Beidou was completed in 2020. Japan and India developed systems for regional use, the Quasi-Zenith Satellite System (QZSS) and Navigation with Indian\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/Constellation\" data-term=\"Constellation\" data-type=\"EB\">Constellation<\/a>\u00a0(NavIC), respectively, which both became operational in 2018.<\/p>\r\n<\/section>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237074\" data-level=\"2\" data-has-spy=\"true\">\r\n<h2 class=\"h2\">Military and national security uses of space<\/h2>\r\n<p class=\"topic-paragraph\">Those countries and organizations with armed forces deployed abroad were quick to recognize the great usefulness of space-based systems in military operations. The United States, Russia, the United Kingdom,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/France\" data-show-preview=\"true\">France<\/a>, China, the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/North-Atlantic-Treaty-Organization\" data-show-preview=\"true\">North Atlantic Treaty Organization<\/a>\u00a0(NATO), and, to a lesser degree, other European countries have deployed increasingly sophisticated space systems\u2014including satellites for communications, meteorology, and positioning and navigation\u2014that are dedicated to military uses. In addition, the United States and Russia have developed satellites to provide early warning of hostile missile launches. Many of these satellites have been designed to meet unique military requirements, such as the ability to operate in a wartime environment, when an opponent may try to interfere with their functioning.<\/p>\r\n<p class=\"topic-paragraph\">To date, military space systems have served primarily to\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/enhance\" data-term=\"enhance\" data-type=\"MW\">enhance<\/a>\u00a0the effectiveness of ground-, air-, and sea-based military forces. Commanders rely on satellites to communicate with troops on the front lines, and, in extreme circumstances, national authorities could use them to issue the commands to launch nuclear weapons. Meteorological satellites assist in planning air strikes, and positioning satellites are used to guide weapons to their targets with high accuracy.<\/p>\r\n<p class=\"topic-paragraph\">Despite the substantial military use of space, no country has deployed a space system capable of attacking a satellite in orbit or of delivering a weapon to a target on Earth. Nevertheless, as more countries\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/acquire\" data-term=\"acquire\" data-type=\"EB\">acquire<\/a>\u00a0military space capabilities and as regional and local conflicts persist around the world, it is not clear whether space will continue to be treated as a weapons-free sanctuary.<\/p>\r\n<p class=\"topic-paragraph\">In addition to recognizing the value of space systems in warfare, national leaders in the United States and the Soviet Union realized early on that the ability to gather information about surface-based activities such as weapons development and deployment and troop movements would assist them in planning their own national security activities. As a result, both countries deployed a variety of space systems for collecting intelligence. They include reconnaissance satellites that provide high-resolution images of Earth\u2019s surface in close to real time for use in identifying threatening activities, planning military operations, and monitoring arms-control agreements. Other satellites collect electronic signals such as telephone, radio, and Internet messages and other emissions, which can be used to determine the type of activities that are taking place in a particular location. Most national-security space activity is carried out in a highly secret manner. As the value to national security of such satellite systems has become evident, other countries, such as France,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Germany\" data-show-preview=\"true\">Germany<\/a>,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Italy\" data-show-preview=\"true\">Italy<\/a>, China, India, Japan, and\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Israel\" data-show-preview=\"true\">Israel<\/a>, have developed similar\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/capabilities\" data-term=\"capabilities\" data-type=\"EB\">capabilities<\/a>, and still others have begun planning their own systems.<\/p>\r\n<\/section>\r\n<\/section>\r\n<\/div>\r\n<div id=\"chatbot-root\">\u00a0<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div data-page-index=\"19\">\u00a0<\/div>\r\n<div class=\"loaded-infinite-scroll-container qa-infinite-scroll-container\">\r\n<div class=\"grey-box w-100 \">\r\n<div class=\"grey-box-content mx-auto w-100\">\r\n<div class=\"page2ref-false topic-content topic-type-REGULAR\">\r\n<div class=\"reading-channel\">\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237075\" data-level=\"2\" data-has-spy=\"true\">\r\n<h1 class=\"h2\"><span id=\"ref839137\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/satellite-communication\" data-show-preview=\"true\">Satellite<\/a>\u00a0telecommunications<\/h1>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"2900\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/35\/435-050-7DAECBE7\/communications-satellite-American-Telstar-1-television-signals-July-10-1962.jpg\" data-href=\"\/media\/1\/557348\/2900\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/35\/435-050-7DAECBE7\/communications-satellite-American-Telstar-1-television-signals-July-10-1962.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/35\/435-050-7DAECBE7\/communications-satellite-American-Telstar-1-television-signals-July-10-1962.jpg?w=300\" alt=\"Telstar 1\" width=\"1177\" height=\"2268\" data-width=\"615\" data-height=\"1185\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/35\/435-050-7DAECBE7\/communications-satellite-American-Telstar-1-television-signals-July-10-1962.jpg\" data-href=\"\/media\/1\/557348\/2900\">Telstar 1<\/a>Telstar 1, launched July 10, 1962, relayed the first transatlantic television signals.<\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">Although some early space experiments explored the use of large orbiting satellites as passive reflectors of signals from point to point on\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Earth\" data-show-preview=\"true\">Earth<\/a>, most work in the late 1950s and early \u201960s focused on the technology by which a signal sent from the ground would be received by\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/satellite\" data-show-preview=\"true\">satellite<\/a>, electronically processed, and relayed to another ground station. American Telephone and Telegraph, recognizing the commercial potential of\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/satellite-communication\" data-show-preview=\"true\">satellite communications<\/a>, in 1962 paid\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/NASA\" data-show-preview=\"true\">NASA<\/a>\u00a0to launch its first\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Telstar-communications-satellite\" data-show-preview=\"true\">Telstar<\/a>\u00a0satellite. Because that satellite, which operated in a fairly low orbit, was in range of any one receiving\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/antenna\" data-term=\"antenna\" data-type=\"EB\">antenna<\/a>\u00a0for only a few minutes, a large network of such satellites would have been necessary for an operational system. Engineers from the American firm Hughes Aircraft, led by\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/biography\/Harold-Rosen\" data-show-preview=\"true\">Harold Rosen<\/a>, developed a design for a satellite that would operate in\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/geostationary-orbit\" data-show-preview=\"true\">geostationary orbit<\/a>. Aided by research support from NASA, the first successful geostationary satellite,\u00a0<span id=\"ref839138\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Syncom-2\">Syncom 2<\/a>, was launched in 1963; it demonstrated the feasibility of the Hughes concept prior to commercial use.<\/p>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"126832\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/20\/128720-050-583BAC1B\/Intelsat-I-Engineers-Stanley-R-Peterson-world-April-6-1965.jpg\" data-href=\"\/media\/1\/557348\/126832\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/20\/128720-050-583BAC1B\/Intelsat-I-Engineers-Stanley-R-Peterson-world-April-6-1965.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/20\/128720-050-583BAC1B\/Intelsat-I-Engineers-Stanley-R-Peterson-world-April-6-1965.jpg?w=300\" alt=\"Early Bird, or Intelsat I\" width=\"1120\" height=\"866\" data-width=\"1600\" data-height=\"1238\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/20\/128720-050-583BAC1B\/Intelsat-I-Engineers-Stanley-R-Peterson-world-April-6-1965.jpg\" data-href=\"\/media\/1\/557348\/126832\">Early Bird, or Intelsat I<\/a>Engineers Stanley R. Peterson (left) and Ray Bowerman checking out Early Bird, or Intelsat I, the world&#8217;s first commercial communications satellite, which was launched April 6, 1965.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">The\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/United-States\" data-show-preview=\"true\">United States<\/a>\u00a0also took the lead in creating the organizational framework for communications satellites. Establishment of the Communications Satellite Corporation (<span id=\"ref839139\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/money\/Comsat\" data-show-preview=\"true\">Comsat<\/a>) was authorized in 1962 to operate American communications satellites, and two years later an international agency, the International Telecommunications Satellite Organization (<span id=\"ref839145\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/money\/Intelsat\" data-show-preview=\"true\">Intelsat<\/a>), was formed at the proposal of the United States to develop a global network. Comsat, the original manager of Intelsat, decided to base the Intelsat network on geostationary satellites. The first commercial\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/communications-satellite\" data-show-preview=\"true\">communications satellite<\/a>,\u00a0<span id=\"ref839146\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Intelsat-I\">Intelsat 1<\/a>, also known as Early Bird, was launched in 1965. Intelsat completed its initial global network with the stationing of a satellite over the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Indian-Ocean\" data-show-preview=\"true\">Indian Ocean<\/a>\u00a0in mid-1969, in time to televise the first\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Moon\" data-show-preview=\"true\">Moon<\/a>\u00a0landing around the world.<\/p>\r\n<p class=\"topic-paragraph\">The original use of communications satellites was to\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/relay\" data-term=\"relay\" data-type=\"EB\">relay<\/a>\u00a0voice, video, and data from one relatively large antenna to a second, distant one, from which the communication then would be distributed over terrestrial networks. This point-to-point application introduced international communications to many new areas of the world, and in the 1970s it also was employed domestically within a number of countries, especially the United States. As undersea fibre-optic cables improved in\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/carrying-capacity\" data-show-preview=\"true\">carrying capacity<\/a>\u00a0and signal quality, they became economically and technologically competitive with communications satellites, and the latter responded with comparable technological advances that allowed these space-based systems to meet the challenge. A number of companies in the United States and Europe manufacture communications satellites and\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/vie\" data-term=\"vie\" data-type=\"EB\">vie<\/a>\u00a0for customers on a global basis. Other firms operate these satellites, often producing significant profits.<\/p>\r\n<p class=\"topic-paragraph\">Other space-based communications applications have appeared, the most prominent being the broadcast of signals, primarily television programming, directly to small antennas serving individual households. A similar use is the broadcast of audio programming to small antennas in locations ranging from rural villages in the developing world to individual automobiles in the United States. International private satellite networks emerged as rivals to the originally government-owned Intelsat, which after 2001 was transformed into a private-sector organization.<\/p>\r\n<p class=\"topic-paragraph\">Yet another service that has been devised for satellites is communication with and between mobile users. In 1979 the International\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/Maritime\" data-term=\"Maritime\" data-type=\"EB\">Maritime<\/a>\u00a0Satellite Organization (Inmarsat) was formed to relay messages to ships at sea. Beginning in the late 1990s, with the growth of personal mobile communications such as\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/cell-phone\" data-show-preview=\"true\">cellular telephone<\/a>\u00a0services, several attempts were made to establish satellite-based systems for this purpose. Typically employing constellations of many satellites in\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/low-Earth-orbit\" data-show-preview=\"true\">low Earth orbit<\/a>, they experienced difficulty competing with ground-based cellular systems. This led these companies to concentrate on specialized applications, such as offering communications services in remote areas where there are no ground-based competitors.<\/p>\r\n<div class=\"module-spacing\">\u00a0<\/div>\r\n<p class=\"topic-paragraph\">In the late 2010s\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/megaconstellation\" data-show-preview=\"true\">megaconstellations<\/a>\u00a0arose that would supply Internet service via satellite to the entire world. The first such launches happened in 2019 with the first 6 in the 1,000-satellite OneWeb\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/constellation\" data-term=\"constellation\" data-type=\"EB\">constellation<\/a>\u00a0and the first 60 in\u00a0<span id=\"ref1303785\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/SpaceX\" data-show-preview=\"true\">SpaceX<\/a>\u2019s almost 30,000-satellite Starlink constellation.\u00a0<span id=\"ref1303784\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/money\/Amazoncom\" data-show-preview=\"true\">Amazon<\/a>\u00a0has planned its own constellation, Project Kuiper, which would have 3,236 satellites. These megaconstellations would increase the number of satellites in low Earth orbit by a factor of 10, which has raised concerns among regulators about a corresponding increase in\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/space-debris\" data-show-preview=\"true\">space debris<\/a>\u00a0and among astronomers about satellite tracks interfering in\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/optical-telescope\" data-show-preview=\"true\">telescope<\/a>\u00a0images.<\/p>\r\n<p class=\"topic-paragraph\">The first commercial space application was satellite communications, and it has remained the most successful one. One estimate of revenues associated with the industry for the year 2017 included $15.5 billion from satellite manufacturing, $119.8 billion from selling the associated ground systems, $128.7 billion from the users of satellite communication systems, and $4.6 billion for launching the satellites, for a total of $268.6 billion. As of 2020 there were more than 400 commercial geostationary communications satellites around the world, operated by about 60 different owners.<\/p>\r\n<\/section>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237076\" data-level=\"2\" data-has-spy=\"true\">\r\n<h2 class=\"h2\"><span id=\"ref839156\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/detection-system\"><strong>Remote sensing<\/strong><\/a><\/h2>\r\n<p class=\"topic-paragraph\"><em>Remote sensing<\/em>\u00a0is a term applied to the use of satellites to observe various\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/characteristics\" data-term=\"characteristics\" data-type=\"EB\">characteristics<\/a>\u00a0of Earth\u2019s land and water surfaces in order to obtain information valuable in mapping, mineral exploration, land-use planning, resource management, and other activities. Remote sensing is carried out from orbit with multispectral sensors; i.e., observations are made in several discrete regions of the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/electromagnetic-spectrum\" data-show-preview=\"true\">electromagnetic spectrum<\/a>\u00a0that include visible light and usually other wavelengths. From multispectral imagery, analysts are able to derive information on such varied areas of interest as crop condition and type, pollution patterns, and sea conditions.<\/p>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"181766\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/66\/166866-004-FA7707A7\/Landsat-satellite-images-mining-area-deforestation-Brazil-1992.jpg\" data-href=\"\/media\/1\/557348\/181766\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/66\/166866-004-FA7707A7\/Landsat-satellite-images-mining-area-deforestation-Brazil-1992.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/66\/166866-004-FA7707A7\/Landsat-satellite-images-mining-area-deforestation-Brazil-1992.jpg?w=300\" alt=\"satellite imagery of deforestation\" width=\"1136\" height=\"549\" data-width=\"600\" data-height=\"290\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/66\/166866-004-FA7707A7\/Landsat-satellite-images-mining-area-deforestation-Brazil-1992.jpg\" data-href=\"\/media\/1\/557348\/181766\">satellite imagery of deforestation<\/a>Colour-coded Landsat satellite images of Brazil&#8217;s Caraj\u00e1s mining area, documenting extensive deforestation between 1986 (left) and 1992 (right). Areas of cleared land appear bluish green.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">Because many applications of remote sensing have a public-good character, a commercial remote-sensing industry has been slow to develop. In addition, the secrecy surrounding intelligence-gathering satellites during the\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/event\/Cold-War\" data-show-preview=\"true\">Cold War<\/a>\u00a0era set\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/stringent\" data-term=\"stringent\" data-type=\"EB\">stringent<\/a>\u00a0limits on the capabilities that could be offered on a commercial basis. Since then, however, very high resolution images (about 0.5 metre [1.5 feet]) have been gathered by several commercial systems. The United States launched the first remote-sensing satellite, NASA\u2019s\u00a0<span id=\"ref839159\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Landsat\" data-show-preview=\"true\">Landsat<\/a>\u00a01 (originally called Earth Resources Technology Satellite), in 1972. The goals of the Landsat program, which by 2020 had included seven successful satellites, were to demonstrate the value of multispectral observation and to prepare the system for transfer to private operators. Despite two decades of attempts at such a transfer, Landsat has remained a U.S. government program. In 1986\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/France\" data-show-preview=\"true\">France<\/a>\u00a0launched the first of its\u00a0<span id=\"ref839161\"><\/span>SPOT remote-sensing satellites and created a marketing organization, Spot Image, to promote use of its imagery. Six\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/subsequent\" data-term=\"subsequent\" data-type=\"EB\">subsequent<\/a>\u00a0SPOT satellites have been launched. Both Landsat\u2019s and SPOT\u2019s multispectral images offered a moderate ground resolution of 10\u201330 metres (about 33\u2013100 feet).\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Japan\" data-show-preview=\"true\">Japan<\/a>\u00a0and\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/India\" data-show-preview=\"true\">India<\/a>\u00a0also launched multispectral remote-sensing satellites.<\/p>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"139713\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/75\/136575-050-057D2945\/satellite-WorldView-2-launch-Vandenberg-Air-Force-Base-October-8-2009.jpg\" data-href=\"\/media\/1\/557348\/139713\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/75\/136575-050-057D2945\/satellite-WorldView-2-launch-Vandenberg-Air-Force-Base-October-8-2009.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/75\/136575-050-057D2945\/satellite-WorldView-2-launch-Vandenberg-Air-Force-Base-October-8-2009.jpg?w=300\" alt=\"WorldView-2 satellite\" width=\"1136\" height=\"1712\" data-width=\"1063\" data-height=\"1600\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/75\/136575-050-057D2945\/satellite-WorldView-2-launch-Vandenberg-Air-Force-Base-October-8-2009.jpg\" data-href=\"\/media\/1\/557348\/139713\">WorldView-2 satellite<\/a>WorldView-2 satellite prior to its October 8, 2009, launch from Vandenberg Air Force Base, California.<\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">Since the 1990s, with the end of the Cold War, some of the technology used in reconnaissance satellites has been declassified. In addition, technological developments in India and several countries in Europe enabled those countries to develop both optical and\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/radar\" data-show-preview=\"true\">radar<\/a>\u00a0Earth-observation satellites with high ground resolution and to market imagery on a commercial basis. Among major customers for high-resolution imagery are governments that lack their own reconnaissance satellites; the U.S. government has also purchased significant amounts of such imagery from U.S. commercial firms rather than obtaining it from government-operated satellites. The global availability of imagery previously available only to the leaders of a few countries is troubling to some observers, who express concern that it could lead to increased military threats. Others suggest that this\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/widespread\" data-term=\"widespread\" data-type=\"EB\">widespread<\/a>\u00a0availability will contribute to a more stable world.<\/p>\r\n<\/section>\r\n<\/div>\r\n<div id=\"chatbot-root\">\u00a0<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div data-page-index=\"20\">\u00a0<\/div>\r\n<div class=\"loaded-infinite-scroll-container qa-infinite-scroll-container\">\r\n<div class=\"grey-box w-100 \">\r\n<div class=\"grey-box-content mx-auto w-100\">\r\n<div class=\"page2ref-false topic-content topic-type-REGULAR\">\r\n<div class=\"reading-channel\">\r\n<section data-level=\"1\">\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237077\" data-level=\"2\" data-has-spy=\"true\">\r\n<h1 class=\"h2\">Commercial space transportation<\/h1>\r\n<p class=\"topic-paragraph\">The prosperity of the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/communications-satellite\" data-show-preview=\"true\">communications satellite<\/a>\u00a0business was accompanied by a willingness of the private sector to pay substantial sums for the launch of its satellites. Initially, most commercial communications satellites went into space on U.S.-government-operated vehicles. When the\u00a0<span id=\"ref839167\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/space-shuttle\" data-show-preview=\"true\">space shuttle<\/a>\u00a0was declared operational in 1982, it became the sole American\u00a0<span id=\"ref839168\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/launch-vehicle\" data-show-preview=\"true\">launch vehicle<\/a>\u00a0providing such services. After the 1986\u00a0<em>Challenger<\/em>\u00a0accident, however, the shuttle was prohibited from launching commercial payloads. This created an opportunity for the U.S. private sector to employ existing expendable launch vehicles such as the\u00a0<span id=\"ref839169\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Delta-launch-vehicle\" data-show-preview=\"true\">Delta<\/a>,\u00a0<span id=\"ref839170\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Atlas-American-launch-vehicles\" data-show-preview=\"true\">Atlas<\/a>, and\u00a0<span id=\"ref839171\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Titan-rocket\" data-show-preview=\"true\">Titan<\/a>\u00a0as commercial launchers. In the 1990s, an American commercial space\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/transportation\" data-term=\"transportation\" data-type=\"EB\">transportation<\/a>\u00a0industry emerged. Whereas the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Titan-astronomy\" data-show-preview=\"true\">Titan<\/a>\u00a0was not a commercial success, the other two vehicles found a few commercial customers. However, the business was not profitable, and American firms no longer compete for commercial launch contracts, with the exception of Space Exploration Technologies (<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/SpaceX\" data-show-preview=\"true\">SpaceX<\/a>), which has marketed launch services using its\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Falcon-launch-vehicle\" data-show-preview=\"true\">Falcon<\/a>\u00a09 booster to customers around the world.<\/p>\r\n<p class=\"topic-paragraph\">Europe followed a different path to commercial space transport. After deciding in the early 1970s to develop the\u00a0<span id=\"ref839174\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Ariane-European-launch-vehicles\" data-show-preview=\"true\">Ariane<\/a>\u00a0launcher, it created under French leadership a marketing organization called Arianespace to seek commercial launch contracts for the vehicle. In the mid-1980s both the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Soviet-Union\" data-show-preview=\"true\">U.S.S.R.<\/a>\u00a0and\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/China\" data-show-preview=\"true\">China<\/a>\u00a0initiated efforts to attract commercial customers for their launch vehicles. As the industry developed in the 1990s, American companies initiated joint ventures with\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Russia\" data-show-preview=\"true\">Russia<\/a>\u00a0and\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Ukraine\" data-show-preview=\"true\">Ukraine<\/a>\u00a0to market those countries\u2019 launchers; in the 2000s these companies ended their involvement in marketing Russian launchers. China continued to market its\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/Long-March-rocket-family\" data-show-preview=\"true\">Long March<\/a>\u00a0series of launch vehicles for commercial use, and other countries, such as\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/India\" data-show-preview=\"true\">India<\/a>\u00a0and\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Japan\" data-show-preview=\"true\">Japan<\/a>, hoped to market their\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/indigenous\" data-term=\"indigenous\" data-type=\"MW\">indigenous<\/a>\u00a0launchers on a commercial basis. The main competition for launching large communications satellites to\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/geostationary-orbit\" data-show-preview=\"true\">geosynchronous orbit<\/a>, the most lucrative commercial opportunity, was between companies in Russia, China, and Europe.<\/p>\r\n<p class=\"topic-paragraph\">However, in the 2010s, SpaceX\u2019s partially reusable Falcon 9\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/rocket-jet-propulsion-device-and-vehicle\" data-show-preview=\"true\">rocket<\/a>\u00a0came to dominate the commercial launch industry with its low prices. The Russian space agency Roscosmos discontinued flights of its\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/Proton-Russian-launch-vehicle\" data-show-preview=\"true\">Proton<\/a>\u00a0launch vehicle because of price competition, and the American company United Launch Alliance, a\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/money\/joint-venture\" data-show-preview=\"true\">joint venture<\/a>\u00a0between Lockheed Martin and Boeing, which used the Delta IV and Atlas V rockets, lost its monopoly on U.S. military launches when the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/air-force\" data-show-preview=\"true\">air force<\/a>\u00a0awarded a contract to SpaceX. In 2018, out of 41 commercial launches, the Falcon 9 did 16.<\/p>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"238342\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/30\/194330-050-19BEDE9E\/astronauts-NASA-supply-spacecraft-Kate-Rubins-SpaceX.jpg\" data-href=\"\/media\/1\/557348\/238342\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/30\/194330-050-19BEDE9E\/astronauts-NASA-supply-spacecraft-Kate-Rubins-SpaceX.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/30\/194330-050-19BEDE9E\/astronauts-NASA-supply-spacecraft-Kate-Rubins-SpaceX.jpg?w=300\" alt=\"SpaceX Dragon at the International Space Station\" width=\"1193\" height=\"795\" data-width=\"1600\" data-height=\"1065\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/30\/194330-050-19BEDE9E\/astronauts-NASA-supply-spacecraft-Kate-Rubins-SpaceX.jpg\" data-href=\"\/media\/1\/557348\/238342\">SpaceX Dragon at the International Space Station<\/a>NASA astronauts Kate Rubins (left) and Jeff Williams retrieving the SpaceX Dragon supply spacecraft from aboard the International Space Station, 2016.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">In 2008 in the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/United-States\" data-show-preview=\"true\">United States<\/a>,\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/NASA\" data-show-preview=\"true\">NASA<\/a>\u00a0contracted on a commercial basis for the transportation of cargo to the International Space Station (ISS) rather than manage such launches itself. In 2010 this approach was extended to transporting astronauts to the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/space-station\" data-show-preview=\"true\">space station<\/a>. The first demonstration of commercial cargo delivery to the ISS took place in May 2012, with the flight of a SpaceX\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Dragon-spacecraft\" data-show-preview=\"true\">Dragon<\/a>\u00a0capsule; operational cargo flights began later that year. Commercial missions carrying crew to orbit began in 2020.<\/p>\r\n<p class=\"topic-paragraph\">In 2017 the revenues of the commercial space transportation industry were estimated to be $5.5 billion. Analysts forecast an average of 42 commercial launches per year in the ensuing decade.<\/p>\r\n<div class=\"module-spacing\">\u00a0<\/div>\r\n<\/section>\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237078\" data-level=\"2\" data-has-spy=\"true\">\r\n<h2 class=\"h2\"><strong>New commercial applications<\/strong><\/h2>\r\n<p class=\"topic-paragraph\">Space advocates have identified a number of possible opportunities for the future commercial use of space. For their economic feasibility, many depend on lowering the cost of transportation to space, an objective that to date has eluded both governments and private\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/entrepreneurs\" data-term=\"entrepreneurs\" data-type=\"MW\">entrepreneurs<\/a>. Access to\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/low-Earth-orbit\" data-show-preview=\"true\">low Earth orbit<\/a>\u00a0has typically cost tens of thousands of dollars per kilogram of payload\u2014a significant barrier to further space development. However, one company,\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/SpaceX\" data-show-preview=\"true\">SpaceX<\/a>, lowered this cost by a factor of 10 with its Falcon 9 rocket and promises to reduce it still further with its planned Falcon Heavy.<\/p>\r\n<p class=\"topic-paragraph\">The\u00a0<span id=\"ref839176\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/International-Space-Station\" data-show-preview=\"true\">ISS<\/a>\u00a0originally was expected to be the scene of significant commercially funded research and other activity as its laboratories began to operate. This was projected to include both industry-funded microgravity research in ISS laboratories and less-conventional undertakings such as hosting fare-paying passengers, filming movies on the facility, and allowing commercial\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/endorsements\" data-term=\"endorsements\" data-type=\"EB\">endorsements<\/a>\u00a0of goods used aboard the station. Commercial success for the ISS was predicted to lead to the development of new, privately financed facilities in low Earth orbit, including research, manufacturing, and residential outposts, and perhaps to privately financed transportation systems for access to those facilities. Because of delays in completing the station\u2014particularly after the grounding of the shuttle fleet following the\u00a0<em>Columbia<\/em>\u00a0accident in 2003\u2014such commercial demand for access to the station did not emerge. However, with the ISS planned to operate until at least 2024, it is possible that the private sector may use the ISS more if early research results demonstrate the facility\u2019s benefits.<\/p>\r\n<p class=\"topic-paragraph\">Another potential commercial application is the transport of fare-paying passengers into space, known as\u00a0<span id=\"ref839177\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/space-tourism\" data-show-preview=\"true\">space tourism<\/a>. Various surveys have suggested a willingness among many in the general public to spend considerable sums for the opportunity to experience space travel. Although a very limited number of wealthy individuals have purchased trips into\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Earth\" data-show-preview=\"true\">Earth<\/a>\u00a0orbit to visit the ISS at a very high price, large-scale development of the space tourism market will not be possible until less-expensive, highly reliable transportation systems to orbit have been developed.<\/p>\r\n<p class=\"topic-paragraph\">One variant of space tourism is to take fare-paying passengers to the edge of space\u2014generally set at 100 km (62 miles) altitude\u2014for brief suborbital flights that offer a few minutes of\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/weightlessness\" data-show-preview=\"true\">weightlessness<\/a>\u00a0and a broad view of Earth. In 2004, in response to a prize competition initiated in the late 1990s, a privately funded\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/spacecraft\" data-show-preview=\"true\">spacecraft<\/a>, named\u00a0<span id=\"ref839178\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/SpaceShipOne\" data-show-preview=\"true\">SpaceShipOne<\/a>, became the first of its kind to carry human beings (in this case, test pilots) on such flights. This achievement could herald the beginning of a commercial suborbital travel business. Even so, the speed reached by SpaceShipOne was just over three times the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/speed-of-sound-physics\" data-show-preview=\"true\">speed of sound<\/a>, roughly one-seventh of the speed required for entering a practical low-Earth orbit. Frequent commercial flights into orbit appear to be some years in the future.<\/p>\r\n<p class=\"topic-paragraph\">However, several companies, such as Virgin Galactic with its SpaceShipTwo, hope to begin commercial suborbital flights. In addition to carrying space tourists, such flights could provide opportunities for research and technology development. One 2012 estimate suggested that there could be daily suborbital flights within 10 years of the first commercial suborbital flight.<\/p>\r\n<p class=\"topic-paragraph\">As an\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/alternative\" data-term=\"alternative\" data-type=\"MW\">alternative<\/a>\u00a0to existing sources of energy, suggestions have been made for space-based systems that capture large amounts of\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/solar-energy\" data-show-preview=\"true\">solar energy<\/a>\u00a0and transmit it in the form of microwaves or laser beams to Earth. Achieving this objective would require the deployment of a number of large structures in space and the development of an environmentally acceptable form of energy transmission to create a cost-effective competitor to Earth-based energy-supply systems.<\/p>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"73170\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/35\/76835-050-55D9A3AF\/mosaic-images-region-spacecraft-orbit-Moon-Clementine-1994.jpg\" data-href=\"\/media\/1\/557348\/73170\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/35\/76835-050-55D9A3AF\/mosaic-images-region-spacecraft-orbit-Moon-Clementine-1994.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/35\/76835-050-55D9A3AF\/mosaic-images-region-spacecraft-orbit-Moon-Clementine-1994.jpg?w=300\" alt=\"Moon's south polar region\" width=\"1121\" height=\"1203\" data-width=\"1490\" data-height=\"1600\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/35\/76835-050-55D9A3AF\/mosaic-images-region-spacecraft-orbit-Moon-Clementine-1994.jpg\" data-href=\"\/media\/1\/557348\/73170\">Moon&#8217;s south polar region<\/a>The Moon&#8217;s south polar region in a mosaic of images made by the U.S. Clementine spacecraft from lunar orbit in 1994. The mosaic, which is centered on the south pole and combines the illumination received over more than two of the Moon&#8217;s solar days (each about 29 Earth days), reveals the existence of appreciable permanently shadowed areas where water ice could exist. Ice deposits, if they could be mined economically, would constitute an important resource for a future crewed lunar outpost.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">Resources available on the\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/place\/Moon\" data-show-preview=\"true\">Moon<\/a>\u00a0and other bodies of the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/solar-system\" data-show-preview=\"true\">solar system<\/a>, particularly asteroids, represent additional potential objectives for commercial development. For example, over billions of years the\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/solar-wind\" data-show-preview=\"true\">solar wind<\/a>\u00a0has deposited large amounts of the isotope\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/helium-chemical-element\" data-show-preview=\"true\">helium<\/a>-3 in the soil of the lunar surface. Scientists and engineers have suggested that helium-3 could be\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off eb\" href=\"https:\/\/www.britannica.com\/dictionary\/extracted\" data-term=\"extracted\" data-type=\"EB\">extracted<\/a>\u00a0and transported to Earth, where it is rare, for use in\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/nuclear-fusion\" data-show-preview=\"true\">nuclear fusion<\/a>\u00a0reactors. In addition, there is evidence to suggest that the Moon\u2019s polar regions contain ice, which could supply a crewed lunar outpost with drinking water, breathable oxygen, and hydrogen for spacecraft fuel. Significant quantities of potentially valuable resources such as water, carbon, nitrogen, and rare metals may also exist on some\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/science\/asteroid\" data-show-preview=\"true\">asteroids<\/a>, and space mining of those resources has been proposed.<\/p>\r\n<\/section>\r\n<\/section>\r\n<\/div>\r\n<div id=\"chatbot-root\">\u00a0<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div data-page-index=\"21\">\u00a0<\/div>\r\n<div class=\"loaded-infinite-scroll-container qa-infinite-scroll-container\">\r\n<div class=\"grey-box w-100 \">\r\n<div class=\"grey-box-content mx-auto w-100\">\r\n<div class=\"page2ref-false topic-content topic-type-REGULAR\">\r\n<div class=\"reading-channel\">\r\n<div class=\"md-sentinel--spy-target\">\u00a0<\/div>\r\n<section id=\"ref237079\" data-level=\"1\" data-has-spy=\"true\">\r\n<h1 class=\"h1\">Issues for the future<\/h1>\r\n<p class=\"topic-paragraph\">Space exploration and development have been stimulated by a complex mixture of motivations, including scientific inquiry, intense competition between national governments and\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/ideologies\" data-term=\"ideologies\" data-type=\"MW\">ideologies<\/a>, and commercial profit. Underlying them has been a vision of the outward movement of humans from\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Earth\" data-show-preview=\"true\">Earth<\/a>, ultimately leading to permanent settlements in space or on other celestial bodies. In reality, however, only 27 people have traveled beyond Earth orbit, all of them\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/Apollo-space-program\" data-show-preview=\"true\">Apollo<\/a>\u00a0astronauts during the primarily politically inspired race to the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/place\/Moon\" data-show-preview=\"true\">Moon<\/a>. Twenty-four of these astronauts visited the Moon, 12 of them\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/story\/how-many-people-have-been-to-the-moon\" data-show-preview=\"true\">walked on its surface<\/a>, and additional astronauts are scheduled to do so by 2025 as part of the\u00a0<a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/topic\/Artemis-program\" data-show-preview=\"true\">Artemis<\/a>\u00a0space program.<\/p>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"238344\" data-asm-type=\"image\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"image\"><a class=\"gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media\" href=\"https:\/\/cdn.britannica.com\/38\/194338-050-5A11BFB0\/NanoRacks-CubeSats-Deployer-set-nanosatellites-research-spacecraft-2014.jpg\" data-href=\"\/media\/1\/557348\/238344\"><picture><source srcset=\"https:\/\/cdn.britannica.com\/38\/194338-050-5A11BFB0\/NanoRacks-CubeSats-Deployer-set-nanosatellites-research-spacecraft-2014.jpg?w=300\" media=\"(min-width: 680px)\" \/><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/38\/194338-050-5A11BFB0\/NanoRacks-CubeSats-Deployer-set-nanosatellites-research-spacecraft-2014.jpg?w=300\" alt=\"nanosatellite\" width=\"1248\" height=\"832\" data-width=\"1041\" data-height=\"693\" \/><\/picture><button class=\"magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10\" aria-label=\"Zoom in\"><\/button><\/a><\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><a class=\"gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link\" href=\"https:\/\/cdn.britannica.com\/38\/194338-050-5A11BFB0\/NanoRacks-CubeSats-Deployer-set-nanosatellites-research-spacecraft-2014.jpg\" data-href=\"\/media\/1\/557348\/238344\">nanosatellite<\/a>A NanoRacks CubeSats Deployer releasing a set of CubeSats\u2014small research spacecraft, classed as nanosatellites, to be used to conduct Earth observations and advanced electronics testing\u2014from the International Space Station, 2014.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">Scientists will continue to seek answers to leading questions about the physical and biological\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/universe\" data-show-preview=\"true\">universe<\/a>\u00a0through the deployment of increasingly advanced instruments on orbiting satellites and space probes. The principal space-faring countries appear willing to continue their substantial support for space\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/science\" data-show-preview=\"true\">science<\/a>. The availability of government funding will set the pace of scientific progress.<\/p>\r\n<div class=\"assemblies\">\r\n<div class=\"w-100\">\r\n<figure class=\"md-assembly m-0 mb-md-0 card card-borderless print-false\" data-assembly-id=\"194489\" data-asm-type=\"video\">\r\n<div class=\"md-assembly-wrapper card-media\" data-type=\"video\"><a class=\"gtm-assembly-link d-flex justify-content-center\" href=\"https:\/\/www.britannica.com\/video\/space-debris-danger-efforts-objects-spacecraft-satellites\/-194489\" data-id=\"179616\"><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/cdn.britannica.com\/16\/179616-138-C4B19C3E\/space-debris-danger-efforts-objects-spacecraft-satellites.jpg?w=800&amp;h=450&amp;c=crop\" alt=\"Protecting satellites from space debris\" width=\"1200\" height=\"675\" \/><\/a>\r\n<div class=\"btn btn-xl btn-white btn-circle position-absolute shadow\">\u00a0<\/div>\r\n<\/div>\r\n<figcaption class=\"card-body\">\r\n<div class=\"md-assembly-caption text-muted font-14 font-serif line-clamp\"><span class=\"md-assembly-title font-weight-bold mr-5 d-inline font-sans-serif md-video-caption\">Protecting satellites from space debris<\/span>Learn about space debris, including efforts to eliminate the danger it poses to satellites, spacecraft, and other objects.<button class=\"js-more-btn btn btn-unstyled font-12 bg-white js-content\" aria-label=\"Toggle more\/less fact data\"><span class=\"link-blue\">(more)<\/span><\/button><\/div>\r\n<a class=\"font-14 mt-10 d-inline-block\" href=\"https:\/\/www.britannica.com\/science\/space-exploration\/images-videos\">See all videos for this article<\/a><\/figcaption>\r\n<\/figure>\r\n<\/div>\r\n<\/div>\r\n<p class=\"topic-paragraph\">The various applications of space capability hold the greatest promise for significant change. If other commercial ventures equal or surpass the success of the\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/satellite\" data-show-preview=\"true\">satellite<\/a>\u00a0communications sector, space could become a major centre of business activity. If governments decide to expand the activity in space of their armed forces, space could become another major military theatre\u2014like the land, the sea, and the air on Earth\u2014for waging war and\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/deploying\" data-term=\"deploying\" data-type=\"MW\">deploying<\/a>\u00a0weapons. If observing Earth from space becomes crucial for effective planetary management, an assortment of increasingly varied and specialized observation satellites could be launched. Thus, outer space could become a much busier area of human activity in the 21st century than it was in the 20th century. At some point, it even may become necessary to establish a space traffic-control system\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/analogous\" data-term=\"analogous\" data-type=\"MW\">analogous<\/a>\u00a0to traffic-control systems on Earth. Already, debris from exploding upper\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/technology\/rocket-jet-propulsion-device-and-vehicle\" data-show-preview=\"true\">rocket<\/a>\u00a0stages, dead satellites, accidental collisions of space objects, and at least one test of an antisatellite weapon are threats to the use of the space\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/environment\" data-term=\"environment\" data-type=\"MW\">environment<\/a>, and governments and private operators are taking steps to avoid creating additional\u00a0<span id=\"ref1263727\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/technology\/space-debris\" data-show-preview=\"true\">space debris<\/a>.<\/p>\r\n<p class=\"topic-paragraph\">The development of space as an arena for multiple government and private activities will pose significant policy and legal challenges. The legal framework for space activities is based on the 1967\u00a0<span id=\"ref839180\"><\/span><a class=\"md-crosslink \" href=\"https:\/\/www.britannica.com\/event\/Outer-Space-Treaty\" data-show-preview=\"true\">Outer Space Treaty<\/a>\u00a0and four subsequent\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/topic\/United-Nations\" data-show-preview=\"true\">United Nations<\/a>\u00a0treaties\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/implementing\" data-term=\"implementing\" data-type=\"MW\">implementing<\/a>\u00a0its provisions. These agreements were negotiated at a time when governments were the principal players in space and commercial space activities were in their infancy. Whether they form an adequate and appropriate framework for current and future space activities requires review. One suggestion is to create a voluntary code of conduct setting out the principles for responsible use of space.<\/p>\r\n<p class=\"topic-paragraph\">The Outer Space Treaty prohibits the deployment of weapons of mass destruction in outer space and on celestial bodies. Other treaties have limited some military activities in space, but there is no general framework regulating the military uses of space. The wisdom of developing space weapons\u2014or, alternatively, of limiting their development and keeping space a weapons-free environment\u2014is an issue for discussion and debate.<\/p>\r\n<div class=\"module-spacing\">\u00a0<\/div>\r\n<p class=\"topic-paragraph\">To date, the benefits of space exploration and development have\u00a0<a class=\"md-dictionary-link md-dictionary-tt-off mw\" href=\"https:\/\/www.merriam-webster.com\/dictionary\/accrued\" data-term=\"accrued\" data-type=\"MW\">accrued<\/a>\u00a0mainly to those countries that have financed space activities. The contributions of space to the economic and\u00a0<a class=\"md-crosslink autoxref \" href=\"https:\/\/www.britannica.com\/science\/social-learning\" data-show-preview=\"true\">social development<\/a>\u00a0of large regions of Earth have been limited. The Outer Space Treaty identifies space as \u201cthe common heritage of mankind.\u201d How to ensure that the benefits of this common heritage are more equitably distributed will be a continuing challenge.<\/p>\r\n<h3>Disclaimer<\/h3>This content has been reposted from <a href=\"https:\/\/www.britannica.com\/science\/space-exploration\/Commercial-space-transportation\" target=\"_blank\" rel=\"noreferrer noopener\">Britannica.com\/<\/a> for informational purposes only.<\/section>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>","protected":false},"excerpt":{"rendered":"<p>Major milestones News\u00a0\u2022 The past, present, and future of Boeing in space\u00a0\u2022\u00a0Nov. 20, 2024, 12:48 AM ET (Astronomy Magazine) \u00a0 [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":3097,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_bbp_topic_count":0,"_bbp_reply_count":0,"_bbp_total_topic_count":0,"_bbp_total_reply_count":0,"_bbp_voice_count":0,"_bbp_anonymous_reply_count":0,"_bbp_topic_count_hidden":0,"_bbp_reply_count_hidden":0,"_bbp_forum_subforum_count":0,"footnotes":""},"categories":[126,109],"tags":[305,307,304,303,309,306,308],"class_list":["post-431","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-education","category-technology","tag-astronauts","tag-human-spaceflight","tag-nasa","tag-space-exploration","tag-space-science","tag-space-technology","tag-space-telescopes"],"_links":{"self":[{"href":"https:\/\/demo.geekybot.com\/index.php\/wp-json\/wp\/v2\/posts\/431","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/demo.geekybot.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/demo.geekybot.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/demo.geekybot.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/demo.geekybot.com\/index.php\/wp-json\/wp\/v2\/comments?post=431"}],"version-history":[{"count":5,"href":"https:\/\/demo.geekybot.com\/index.php\/wp-json\/wp\/v2\/posts\/431\/revisions"}],"predecessor-version":[{"id":1577,"href":"https:\/\/demo.geekybot.com\/index.php\/wp-json\/wp\/v2\/posts\/431\/revisions\/1577"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/demo.geekybot.com\/index.php\/wp-json\/wp\/v2\/media\/3097"}],"wp:attachment":[{"href":"https:\/\/demo.geekybot.com\/index.php\/wp-json\/wp\/v2\/media?parent=431"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/demo.geekybot.com\/index.php\/wp-json\/wp\/v2\/categories?post=431"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/demo.geekybot.com\/index.php\/wp-json\/wp\/v2\/tags?post=431"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}