Encyclopedia Astronautica

American infrared astronomy satellite. One launch, 2003.08.25. The SIRTF (Space Infrared Telescope Facility) was planned as a 1 meter class, cryogenically cooled space telescope to be operated as an observatory for infrared astronomy.

The main objectives of the mission were: 1) physical studies of the planetary system; 2) detailed study of cold circumstellar dust clouds; 3) a search for the enigmatic brown dwarfs; 4) extension of IRAS studies of forming stars to lower temperatures and luminosities; 5) identification and study of powerful infrared galaxies; and, 6) infrared measurements of all presently catalogued quasars.

The spacecraft was conceived as a long duration facility serviceable by the Shuttle or at a manned space station. Unlike IRAS (Infrared Astronomical Satellite), which swept rapidly across the sky, SIRTF was to be a true observatory, carrying a variety of focal plane instruments. The instruments selected included: 1) a wide field and high resolution camera covering the 2 to 30 micron region with large monolithic detector arrays; 2) an imaging photometer, with small arrays of high sensitivity detectors covering the spectral range from 3 to 700 microns; 3) a spectrometer operating out to 200 microns with resolving power from 50 to >1000. The instrument sensitivity was expected to be increased by a factor of 100 to 1000 over that of IRAS, and the spatial resolution was to be at least a factor of 10 times finer than IRAS.

The Space Infrared Telescope Facility (SIRTF), last of NASA's Great Observatories, was built by Lockheed Martin/Sunnyvale with the Cryogenic Telescope Assembly (CTA) built by Ball; management was by JPL with science operations at the SIRTF Science Center in Pasadena. SIRTF followed on the US/UK/Netherlands IRAS sky survey satellite (1983) and ESA's ISO observatory (1995-98). The US Defense Dept.'s MSX (1996-1997) was another notable IR mission which made a galactic plane survey. The other Great Observatories were the Hubble Space Telescope, the Compton Gamma Ray Observatory, and the Chandra X-ray Observatory.

SIRTF was placed in a solar orbit. The so-called 'Earth-trailing orbit' had the advantage that the infrared-bright Earth was very far away, and didn't block out large interesting pieces of the sky SIRTF might want to look at or interfere with the cryogenic cooling of the telescope.

SIRTF had a 0.85-meter infrared telescope, with a liquid-helium cooled focal plane carrying the three main instruments, IRAC, IRS and MIPS. IRAC (built by Giovanni Fazio's team at the Harvard-Smithsonian) was a near infrared camera imaging in the 3 to 8 micron range. IRS was a spectrograph covering the mid infrared 5 to 40 micron range. The MIPS far infrared Multiband Imaging Photometer covered the 12 to 160 micron range. The spacecraft was 4.45m high and 2.11m in diameter. It had solar arrays which were mounted along one side of the telescope and acted as a sunshield. The telescope observed anywhere on a strip of sky roughly perpendicular to the line joining SIRTF to the Sun, with about 35 percent of the sky visible to SIRTF at any one time. The spacecraft had a dry mass of 851 kg; at launch it carried 50 kg of helium cryogen, 16 kg of nitrogen for attitude control, and a 6 kg telescope cover which was ejected in solar orbit, for a total mass of 923 kg.

AKA: Space Infrared Telescope Facility.
First Launch: 2003.08.25.
Number: 1 .

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Associated Countries
See also
  • Delta The Delta launch vehicle was America's longest-lived, most reliable, and lowest-cost space launch vehicle. Development began in 1955 and it continued in service in the 21st Century despite numerous candidate replacements. More...

Associated Launch Vehicles
  • Delta American orbital launch vehicle. The Delta launch vehicle was America's longest-lived, most reliable, and lowest-cost space launch vehicle. Delta began as Thor, a crash December 1955 program to produce an intermediate range ballistic missile using existing components, which flew thirteen months after go-ahead. Fifteen months after that, a space launch version flew, using an existing upper stage. The addition of solid rocket boosters allowed the Thor core and Able/Delta upper stages to be stretched. Costs were kept down by using first and second-stage rocket engines surplus to the Apollo program in the 1970's. Continuous introduction of new 'existing' technology over the years resulted in an incredible evolution - the payload into a geosynchronous transfer orbit increasing from 68 kg in 1962 to 3810 kg by 2002. Delta survived innumerable attempts to kill the program and replace it with 'more rationale' alternatives. By 2008 nearly 1,000 boosters had flown over a fifty-year career, and cancellation was again announced. More...
  • Delta 7920H American orbital launch vehicle. Version of Delta 7000 using much larger GEM 46 solid rocket motors originally developed for the Delta 3. More...

  • McDowell, Jonathan, Jonathan's Space Home Page (launch records), Harvard University, 1997-present. Web Address when accessed: here.
  • NASA Report, Space Infrared Telescope Facility Launch Press Kit, Web Address when accessed: here.
  • NASA Report, Spitzer Space Telescope Fact Sheet, Web Address when accessed: here.
  • NASA Report, SIRTF: A window on cosmic birth, Web Address when accessed: here.

Associated Launch Sites
  • Cape Canaveral America's largest launch center, used for all manned launches. Today only six of the 40 launch complexes built here remain in use. Located at or near Cape Canaveral are the Kennedy Space Center on Merritt Island, used by NASA for Saturn V and Space Shuttle launches; Patrick AFB on Cape Canaveral itself, operated the US Department of Defense and handling most other launches; the commercial Spaceport Florida; the air-launched launch vehicle and missile Drop Zone off Mayport, Florida, located at 29.00 N 79.00 W, and an offshore submarine-launched ballistic missile launch area. All of these take advantage of the extensive down-range tracking facilities that once extended from the Cape, through the Caribbean, South Atlantic, and to South Africa and the Indian Ocean. More...
  • Cape Canaveral LC17B Delta launch complex. Part of a dual launch pad complex built for the Thor ballistic missile program in 1956. Upgraded over the decades for use with Thor, Delta, Delta II, and Delta III launch vehicles, it remained in use for over half a century. More...

SIRTF Chronology

2003 August 25 - . 05:35 GMT - . Launch Site: Cape Canaveral. Launch Complex: Cape Canaveral LC17B. Launch Pad: SLC17B. LV Family: Delta. Launch Vehicle: Delta 7920H. LV Configuration: Delta 7920H D300.
  • SIRTF - . Mass: 923 kg (2,034 lb). Nation: USA. Agency: NASA. Class: Astronomy. Type: Infrared astronomy satellite. Spacecraft: SIRTF. USAF Sat Cat: 27871 . COSPAR: 2003-038A. Originally to have launched January 9, 2003. Delayed six times. The Space Infrared Telescope Facility (SIRTF) was the last of NASA's 'Great Observatories'. It had a 0.85-meter infrared telescope, with a liquid-helium cooled focal plane carrying the three main instruments. SIRTF was launched by the second Delta II Heavy. The second stage entered a 166 x 167 km x 31.5 deg Earth parking orbit, and after about 33 minutes of coast, passing south of Madagascar, restarted at 0613 UTC to enter a hyperbolic orbit with a perigee of 170 km, an eccentricity of 1.0061, and a velocity of 11.05 km/s. This placed it in a solar orbit of 0.996 x 1.019 AU x 1.14 deg with a year about 4 days longer than Earth's.

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