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International Ultraviolet Explorer
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<p>International Ultraviolet Explorer (IUE or Explorer 57, formerly SAS-D) was the first <a href="/facts/Space_telescope/BtI46sDX">space observatory</a> primarily designed to take <a href="/facts/Ultraviolet/kncBUqn5">ultraviolet</a> (UV) <a href="/facts/Electromagnetic_spectrum/24LARvFY">electromagnetic spectrum</a>. The satellite was a collaborative project between <a href="/facts/NASA/TIMCV0yV">NASA</a>, the <a href="/facts/United_Kingdom/kuPAILt2">United Kingdom</a>'s <a href="/facts/Science_and_Engineering_Research_Council/LkjUJeFS">Science and Engineering Research Council</a> (SERC, formerly UKSRC) and the <a href="/facts/European_Space_Agency/L8YRNV0C">European Space Agency</a> (ESA), formerly <a href="/facts/European_Space_Research_Organisation/bbNlK2fW">European Space Research Organisation</a> (ESRO). The mission was first proposed in early 1964, by a group of scientists in the United Kingdom, and was launched on 26 January 1978, 17:36:00 <a href="/facts/Coordinated_Universal_Time/2EnjfSyu">UTC</a> aboard a NASA <a href="/facts/Delta_2000/Xa7fTvwH">Thor-Delta 2914</a> <a href="/facts/Launch_vehicle/g1GCGFJB">launch vehicle</a>. The mission lifetime was initially set for 3 years, but in the end, it lasted 18 years, with the satellite being shut down in 1996. The switch-off occurred for financial reasons, while the telescope was still functioning at near original efficiency. </p><p>It was the first space observatory to be operated in real-time by astronomers who visited the ground stations in the United States and Spain. Astronomers made over 104,000 observations using the IUE, of objects ranging from <a href="/facts/Solar_System/QIcLSazQ">Solar System</a> bodies to distant <a href="/facts/Quasar/HS96328l">quasars</a>. Among the significant scientific results from IUE data were the first large-scale studies of <a href="/facts/Stellar_wind/bn5J6vpx">stellar winds</a>, accurate measurements of the way <a href="/facts/Interstellar_dust/Uy6hlL29">interstellar dust</a> absorbs light, and measurements of the <a href="/facts/Supernova/Pfo2J23l">supernova</a> <a href="/facts/SN_1987A/zHyoUpBC">SN 1987A</a> which showed that it defied stellar evolution theories as they then stood. When the mission ended, it was considered the most successful astronomical satellite ever. </p>