 Infrared Astronomical Satellite in space simulator at JPL | |||||||||
| Mission type | Infraredspace observatory | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Operator | |||||||||
| COSPAR ID | 1983-004A | ||||||||
| SATCATno. | 13777 | ||||||||
| Website | irsa | ||||||||
| Mission duration | Final: 9 months, 26 days | ||||||||
| Spacecraft properties | |||||||||
| Manufacturer | |||||||||
| Launch mass | 1,083 kg (2,388 lb) | ||||||||
| Dimensions | 3.60 × 3.24 × 2.05 m (11.8 × 10.6 × 6.7 ft)[1] | ||||||||
| Start of mission | |||||||||
| Launch date | 25 January 1983, 21:17 (1983-01-25UTC21:17) UTC[3] | ||||||||
| Rocket | Delta 3910 | ||||||||
| Launch site | VandenbergSLC-2W | ||||||||
| Entered service | 9 February 1983[2] | ||||||||
| End of mission | |||||||||
| Disposal | Decommissioned | ||||||||
| Deactivated | 21 November 1983 (1983-11-22)[3] | ||||||||
| Orbital parameters | |||||||||
| Reference system | Geocentric | ||||||||
| Regime | Sun-synchronous | ||||||||
| Semi-major axis | 7,270.69 km (4,517.80 mi) | ||||||||
| Eccentricity | 0.001857 | ||||||||
| Perigee altitude | 879.05 km (546.22 mi) | ||||||||
| Apogee altitude | 906.05 km (562.99 mi) | ||||||||
| Inclination | 98.95 deg | ||||||||
| Period | 102.8 min | ||||||||
| Mean motion | 14.00 rev/day | ||||||||
| Epoch | 19 November 2016, 04:15:30 UTC[4] | ||||||||
| Main telescope | |||||||||
| Type | Ritchey–Chrétien[5] | ||||||||
| Diameter | 57 cm (22 in)[5] | ||||||||
| Focal length | 545 cm (215 in),f/9.56[5] | ||||||||
| Collecting area | 2,019 cm2 (312.9 sq in)[5] | ||||||||
| Wavelengths | Long-wavelength to far-infrared | ||||||||
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TheInfrared Astronomical Satellite (Dutch:Infrarood Astronomische Satelliet) (IRAS) was the firstspace telescope to perform asurvey of the entirenight sky atinfraredwavelengths.[6] Launched on 25 January 1983,[3] its mission lasted ten months.[7] 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.[7]
Support for the processing and analysis of data from IRAS was contributed from theInfrared Processing and Analysis Center at theCalifornia Institute of Technology. Currently, theInfrared Science Archive at IPAC holds the IRAS archive.[8][9]
The success of IRAS led to interest in the 1985Infrared Telescope (IRT) mission on the Space Shuttle, and the planned Shuttle Infrared Telescope Facility which eventually transformed into the Space Infrared Telescope Facility, SIRTF, which in turn was developed into theSpitzer Space Telescope, launched in 2003.[10] The success of early infrared space astronomy led to further missions, such as theInfrared Space Observatory (1990s) and theHubble Space Telescope'sNICMOS instrument.
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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 micrometers, with resolutions ranging from 30 arcseconds at 12 micrometers to 2 arcminutes at 100 micrometers. It discovered about 350,000 sources, many of which are still awaiting identification. About 75,000 of those are believed to bestarburst galaxies, still enduring theirstar-formation stage. Many other sources are normal stars with disks of dust around them, possibly the early stage ofplanetary system formation. New discoveries included a dust disk aroundVega and the first images of theMilky 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, 73 kilograms (161 lb) ofsuperfluidhelium kept the telescope at a temperature of 2 K (−271 °C; −456 °F), keeping the satellite cool byevaporation. IRAS was the first use of superfluids in space.[11] 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, includingJohn K. Davies andSimon F. Green, which searched the rejected sources for moving objects. This led to the discovery of threeasteroids, including3200 Phaethon (anApollo asteroid and the parent body of theGeminidmeteor shower), sixcomets, and a huge dust trail associated with comet10P/Tempel. The comets included126P/IRAS,161P/Hartley–IRAS, andcomet 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.[7]
The Supplemental IRAS Minor Planet Survey (SIMPS) would also later use the archived data to search for moreminor planets, asteroids.[12]
Overall, over a quarter million discrete targets were observed during its operations, both inside and beyond theSolar System.[7] In addition, new objects were discovered including asteroids and comets.[7]The observatory made headlines briefly with the announcement on 10 December 1983 of the discovery of an "unknown object" at first described as "possibly as large as the giant planetJupiter and possibly so close toEarth that it would be part of this solar system".[13][14] Further analysis revealed that, of several unidentified objects, nine were distant galaxies and the tenth was "intergalactic cirrus".[15] None were found to be Solar System bodies.[15][16]
During its mission, IRAS (and later the Spitzer Space Telescope) detected odd infrared signatures around several stars. This led to the systems being targeted by the Hubble Space Telescope's NICMOS instrument between 1999 and 2006, but nothing was detected. In 2014, using new image processing techniques on the Hubble data, researchers discoveredplanetary disks around these stars.[17]
IRAS discovered six comets, out of total of 22 discoveries and recoveries of all comets that year.[7][18] This was a lot for this period, before the launch ofSOHO in 1995, which would allow the discovery of many more comets in the next decade (it would detect 1000 comets in ten years).[19]
| 3200 Phaethon | 11 October 1983 | list |
| 3728 IRAS | 23 August 1983 | list |
| (10714) 1983 QG | 31 August 1983 | list |
| (100004) 1983 VA | 1 November 1983 | list |
Several infrared space telescopes have continued and greatly expanded the study of the infrared Universe, such as theInfrared Space Observatory launched in 1995, theSpitzer Space Telescope launched in 2003, and theAkari Space Telescope launched in 2006.
A next generation of infrared space telescopes began when NASA'sWide-field Infrared Survey Explorer launched on 14 December 2009 aboard aDelta II rocket fromVandenberg Air Force Base. Known as WISE, the telescope provided results hundreds of times more sensitive than IRAS at the shorter wavelengths; it also had an extended mission dubbedNEOWISE beginning in October 2010 after its coolant supply ran out.
A planned mission is NASA'sNear-Earth Object Surveillance Mission (NEOSM), which is a successor to the NEOWISE mission.
On 29 January 2020, 23:39:35 UTC,[21] IRAS was expected to pass as closely as 12 meters[22] from the U.S. Air Force's Gravity Gradient Stabilization Experiment (GGSE-4) of 1967, another un-deorbited satellite left aloft; the 14.7-kilometer per second pass[23] had an estimated risk of collision of 5%. Further complications arose from the fact that GGSE-4 was outfitted with an 18 meter long stabilization boom that was in an unknown orientation and may have struck the satellite even if the spacecraft's main body did not.[24] Initial observations from amateur astronomers seemed to indicate that both satellites had survived the pass, with the California-based debris tracking organization LeoLabs later confirming that they had detected no new tracked debris following the incident.[25][26]
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