The Great Observatories program is NASA's series of artificial satellites that consist of four large, powerful space-based astronomical telescopes. Each of the four missions was designed to examine a specific wavelength/energy region of the electromagnetic spectrum (gamma rays, X-rays, visible and ultraviolet light, infrared light) using very different technologies. Dr. Charles Pellerin, NASA's Director, Astrophysics invented and developed the program. The four Great Observatories were launched between 1990 and 2003, and three remain operational as of 2017.
Great Observatories Edit
- The Hubble Space Telescope (HST) primarily observes visible light and near-ultraviolet. It was launched in 1990 aboard Discovery during STS-31. 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 some of the best results to date.
- 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 de-orbited 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 into an elliptical high-earth orbit, 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 into an earth-trailing solar orbit; it was called the Space Infrared Telescope Facility (SIRTF) before launch. Depletion of its onboard liquid helium coolant in 2009 reduced its functionality significantly, leaving it with only two short-wavelength imaging modules.