By Ron Cowen
After 9 years in space, during which it detected some of the highest-energy radiation in the universe, NASA’s Compton Gamma Ray Observatory (GRO) came to a crashing end on June 4.
As planned for several months, controllers fired thrusters on the observatory that gradually lowered its orbit, sending it hurtling though Earth’s upper atmosphere. The charred remains of the 17-ton craft landed in the Pacific Ocean about 3,800 kilometers southeast of Hawaii.
NASA decided that it would end the mission after one of the observatory’s gyroscopes failed last December. With only two gyroscopes remaining on GRO, the minimum required to steer it, NASA said it wanted to bring down the craft while it could still do so in a controlled manner.
To the bitter end, GRO scientists maintained that the craft could operate reliably with just one gyroscope, but the space agency said that strategy would pose too high a risk to human life (SN: 4/22/00, p. 271: Available to subscribers at Observatory on a suicide mission).
Astronomers won’t have another major observatory to detect gamma rays until the planned launch of the Gamma-ray Large Area Space Telescope in 2005.
