(Courtesy of NASA)
The Compton Gamma Ray Observatory in the Space Shuttle's bay prior to release.
Launched from the Space Shuttle Atlantis in 1991, the Compton Observatory is the second of NASA's "Great Observatories," a family of four orbiting telescopes designed to study the cosmos across the full spectrum of light. The first, the Hubble Space Telescope, was launched in 1990. These four telescopes reflect NASA's ambitious vision for exploring the distant universe.