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The Infrared Astronomical Satellite (IRAS) was the first-ever space-based observatory to perform a survey of the entire sky at infrared wavelengths.〔(IRAS Explanatory Supplement II. Satellite Description ) IPAC IRAS archive〕 Launched on January 25, 1983,〔 its mission lasted ten months.〔 The telescope was a joint project of the United States (NASA), the Netherlands (NIVR), and the United Kingdom (SERC). Over 250,000 infrared sources were observed at 12, 25, 60, and 100 micrometer wavelengths.〔 Support for the processing and analysis of data from IRAS was contributed from the Infrared Processing and Analysis Center at the California Institute of Technology. Currently, the Infrared Science Archive at IPAC holds the IRAS archive.〔http://www.ipac.caltech.edu/project/15〕〔(IRAS data archive at IRSA )〕 == Mission == IRAS was the first observatory to perform an all-sky survey at infrared wavelengths. It mapped 96% of the sky four times, at 12, 25, 60 and 100 micrometres wavelengths, with resolutions ranging from 30 arcseconds at wavelength 12 micrometers to 2 arcminutes at wavelength 100 micrometers. It discovered about 350,000 sources, many of which are still awaiting identification. About 75,000 of those are believed to be starburst galaxies, still enduring their star-formation stage. Many other sources are normal stars with disks of dust around them, possibly the early stage of a planetary system formation. New discoveries included a dust disk around Vega and the first images of the Milky Way Galaxy's core. IRAS's life, like that of most of infrared satellites that followed after, was limited by its cooling system. To effectively work in the infrared domain, a telescope must be cooled to cryogenic temperatures. In IRAS's case, 73 kilograms of superfluid helium kept the telescope at a temperature of 2 kelvins (about -271 °C), keeping the satellite cool by evaporation. The on-board supply of liquid helium was depleted after 10 months on November 22, 1983, causing the telescope temperature to rise, preventing further observations. The spacecraft continues to orbit close to the earth. IRAS was designed to catalogue fixed sources, so it scanned the same region of sky several times. Jack Meadows led a team at Leicester University, including John Davies and Simon Green, which searched the rejected sources for moving objects. This led to the discovery of three asteroids, including 3200 Phaethon (an Apollo asteroid and the parent body of the Geminid meteor shower), six comets, and a huge dust trail associated with comet Tempel-2. The comets included 126P/IRAS, 161P/Hartley-IRAS, and comet IRAS-Araki-Alcock (C/1983 H1), which made a close approach to the Earth in 1983. Out of the six comets IRAS found, four were long period and two were short period comets.〔(Lutz D. Schmadel - Dictionary of minor planet names (2003) - Page 315 (Google Books) )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「IRAS」の詳細全文を読む スポンサード リンク
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