Great Observatories Program - Great Observatories

Great Observatories

• The Hubble Space Telescope (HST) primarily observes visible light and near-ultraviolet. A servicing mission in 1997 added capability in the near-infrared range and one last mission in 2009 was to fix and extend the life of Hubble which resulted in fantastic results to date. It was launched in 1990 aboard Discovery during STS-31.

• The Compton Gamma Ray Observatory (CGRO) primarily observed gamma rays, though it extended into hard x-rays as well. It was launched in 1991 aboard Atlantis during STS-37 and was deorbited in 2000 after failure of a gyroscope.

• The Chandra X-ray Observatory (CXO) primarily observes soft x-rays. It was launched in 1999 aboard Columbia during STS-93 and was initially named the Advanced X-ray Astronomical Facility (AXAF).

• The Spitzer Space Telescope (SST) observes the infrared spectrum. It was launched in 2003 aboard a Delta II rocket and was called the Space Infrared Telescope Facility (SIRTF) before launch.

Of these satellites, only the Compton Gamma Ray Observatory is not currently operating; one of its gyroscopes failed, and NASA ordered it to be de-orbited on June 4, 2000. Parts that survived reentry splashed into the Pacific Ocean. Hubble was originally intended to be retrieved and returned to Earth by the Space Shuttle, but the retrieval plan was later abandoned. On October 31, 2006 NASA Administrator Michael D. Griffin gave the go-ahead for a final refurbishment mission. The 11-day STS-125 mission by Atlantis, launched on 11 May 2009, installed fresh batteries, replaced all gyroscopes, and installed the Wide Field Camera 3 and the Cosmic Origins Spectrograph.

Spitzer was the only one of the Great Observatories not launched by the Space Shuttle. It was originally intended to be so launched, but after the Challenger disaster, the Centaur LH2/LOX upper stage that would have been required to push it into a heliocentric orbit was banned from Shuttle use. Titan and Atlas rockets were canceled for cost reasons. After redesign and lightening, it was launched by a Delta II rocket instead.