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Compton Gamma Ray Observatory

Compton Gamma Ray Observatory

he Compton Gamma Ray Observatory, the largest gamma ray observatory ever flown, provided scientists with important observations of high-energy cosmic activity between its launch in 1991 and its de-orbit in 2000.

Named after Nobel prize-winning physicist Arthur Compton, the observatory was launched in April 1991 from the space shuttle Atlantis (mission STS-37). At the time, it was the heaviest satellite ever launched, weighing in at 17,000 kilograms (37,000 pounds). With its successful launch, it became the second of NASA's four Great Observatories, a group of space-based telescopes that also includes the Hubble Space Telescope, the Chandra X-Ray Observatory and the Spitzer Space Telescope. Compton was launched into an orbit 450 kilometers (280 miles) above Earth, completing an orbit every 90 minutes.

Few gamma-wavelength photons are actually emitted from celestial objects, so detecting them is a challenge. The number of gamma-ray interactions that can be detected is directly proportional to the mass of the detector. Therefore, an unusually large group of detectors was necessary for good observations to be made in a reasonable amount of time.

Compton has made a number of important cosmological observations. Near home, it has observed gamma ray emissions coming from thunderclouds in Earth's own atmosphere. After eight productive years, Compton was safely de-orbited in 2000 because of a failed gyro.