IRAS

Infobox Space telescope
name = Infrared Astronomical Satellite (IRAS)


caption = IRAS beside some of its all-sky images
organization = NASA / NIVR /
SERC
major_contractors = Ball Aerospace / Fokker Space / Hollandse Signaal
alt_names =
nssdc_id =
location = in orbit, deactivated
orbit_type = sun-synchronous polar orbit
height = 900 km
period = 100 minutes
velocity =
accel_gravity =
launch_date = 25 January 1983
launch_location = SLC-2 West, Vandenberg AFB, California
launch_vehicle = Delta 3910
mission_length = 10 months
wavelength = infrared
mass = 1083 kg
style = Ritchey-Chrétien
diameter = 0.57 m
area = ~1 m²
focal_length = 5.5 m, "f"/9.6
coolant = 475 L (75 kg) of superfluid He
instrument_1_name = Main array
instrument_1_characteristics = 62 detectors
instrument_2_name = Low Resolution Spectrometer (LRS)
instrument_2_characteristics = nowrap|8 to 22 µm slitless spectrometer
instrument_3_name = Chopped Photometric Channel (CPC)
instrument_3_characteristics = low-quality mapping
website = [http://lambda.gsfc.nasa.gov/product/iras IRAS website] The Infrared Astronomical Satellite (IRAS) was the first-ever space-based observatory to perform a survey of the entire sky at infrared wavelengths.

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).

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 micrometre 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. The observatory also made headlines briefly with the discovery of an "unknown object" that was at first described as "possibly as large as the giant planet Jupiter and possibly so close to Earth that it would be part of this solar system." [cite news|url=http://web.ipac.caltech.edu/staff/tchester/iras/washington_post_mystery_object.html|title=Mystery Heavenly Body Discovered|publisher=Washington Post|publisherlink=Washington Post|accessdate=2008-01-28|author=Thomas O'Toole|page=A1|date=30 December 1983] However, further analysis revealed that, of several unidentified objects, nine were distant galaxies and the tenth was "intergalactic cirrus".cite web|url=http://web.ipac.caltech.edu/staff/tchester/iras/no_tenth_planet_yet.html|publisher=Thomas J. Chester (CalTech)|title=No Tenth Planet Yet From IRAS|accessdate=2008-01-28|author=Thomas J. Chester] None were found to be Solar System bodies.

IRAS's life, like most of infrared satellites that followed after IRAS, was limited by its cooling system: to effectively work in the infrared domain, the telescope must be cooled to impressively low temperatures. In IRAS' case, 475 liters 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 fluid helium depleted after 10 months on November 22 1983, causing the telescope temperature to rise, preventing further observations.

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 the periodic comets 126P/IRAS and 161P/Hartley-IRAS and comet IRAS-Araki-Alcock (C/1983 H1), which made a close approach to the Earth in 1983.

Several space infrared telescopes have continued and greatly expanded the study of the infrared Universe, such as the Infrared Space Observatory launched in 1995, the Spitzer Space Telescope launched in 2003, and the AKARI Space Telescope launched in 2006.

References

ee also

*Infrared astronomy
*Telescope
*Space Telescope

External links

* [http://irsa.ipac.caltech.edu/IRASdocs/iras.html Caltech IRAS page]
* [http://wikisky.org/?img_source=IRAS IRAS survey on WikiSky]