Editing IRAS (section)

== Mission ==
{{multiple image |align=left |direction=vertical |width=200
 |image1  = IRAS launch USAF-1369th audiovisual squadron-(MAC).jpg
 |caption1= Launch of IRAS in 1983
 |image2  = Comet IRAS-Araki-Alckock-1983.jpg
 |caption2= False color image of [[comet IRAS–Araki–Alcock]] by IRAS
 |image3  = IRAS all-sky infrared survey.jpg
 |caption3= Infrared all-sky survey by IRAS
}}

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&nbsp;micrometers, with resolutions ranging from 30&nbsp;arcseconds at 12&nbsp;micrometers to 2&nbsp;arcminutes at 100&nbsp;micrometers. It discovered about 350,000 sources, many of which are still awaiting identification.  About 75,000 of those are believed to be [[starburst galaxy|starburst galaxies]], still enduring their [[star formation|star-formation]] stage.  Many other sources are normal stars with disks of dust around them, possibly the early stage of [[planetary system]] formation.  New discoveries included a dust disk around [[Vega]] and the first images of the [[Milky Way]]{{'s}} core.

IRAS's life, like that of most infrared satellites that followed, 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, {{convert|73|kg|lb|sp=us}} of [[superfluid]] [[helium]] kept the telescope at a temperature of {{convert|2|K|C F|sigfig=3|lk=on}}, keeping the satellite cool by [[evaporation]]. IRAS was the first use of superfluids in space.<ref>{{cite book
 | last = Rowan-Robinson
 | first = Michael
 | author-link = Michael Rowan-Robinson
 | title = Ripples in the Cosmos
 | publisher = W. H. Freeman and Company
 | date = 1993
 | pages = 75
 | isbn = 0-7167-4503-8}}</ref> The on-board supply of liquid helium was depleted after 10 months on 21 November 1983, causing the telescope temperature to rise, preventing further observations. The spacecraft continues to orbit the Earth.

IRAS was designed to catalog fixed sources, so it scanned the same region of sky several times. Jack Meadows led a team at Leicester University, including [[John K. Davies (astronomer)|John K. Davies]] and [[Simon F. Green]], which searched the rejected sources for moving objects. This led to the discovery of three [[asteroid]]s, including [[3200 Phaethon]] (an [[Apollo asteroid]] and the parent body of the [[Geminids|Geminid]] [[meteor shower]]), six [[comet]]s, and a huge dust trail associated with comet [[10P/Tempel]]. 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.<ref name="springer" />

The Supplemental IRAS Minor Planet Survey (SIMPS) would also later use the archived data to search for more [[minor planet]]s, asteroids.<ref name="SIMPS"> {{cite web
|url= http://www.psi.edu/pds/resource/imps.html
|author= Tedesco
|display-authors= etal
|title= Supplemental IRAS Minor Planet Survey (SIMPS)
|access-date= 29 December 2008
|work= IRAS-A-FPA-3-RDR-IMPS-V6.0
|publisher= [[Planetary Data System]]
|date= 2004
|archive-url= https://web.archive.org/web/20090817051318/http://www.psi.edu/pds/resource/imps.html
|archive-date= 17 August 2009
}} </ref>