Save our satellite say astronomers

The Compton Gamma Ray Observatory will be deliberately destroyed

By BBC News Online science editor Dr David Whitehouse

Nasa engineers are about to begin shutting down the Compton Gamma Ray Observatory (CGRO) in order to crash it back to Earth on 4 June.

Many scientists are upset that the satellite, which cost hundreds of millions of dollars, is being deliberately destroyed.

Artist's impression of a black hole and energetic jet

Nasa officials say that continuing the observatory's mission may be too risky after the failure of one of its three gyroscopes that control its pointing ability.

They say that if another gyroscope fails then the CGRO could not be brought down to Earth in a controlled manner. They fear that it could come down over a populated region.

But some scientists consider that Nasa is overreacting and that the CGRO is irreplaceable.

Pioneering

The CGRO was launched into space in 1991 to detect gamma-rays from space. These are high-energy radiation that comes from the hot, violent and usually remote parts of the Cosmos.

It has carried out pioneering observations into so-called ''gamma ray bursters,'' explosions so powerful that if they occurred close to the Earth could wipe out all life on our planet.

Thankfully they occur on the other side of the Cosmos.

Its detectors are linked directly to the internet and automatically send out alerts to observatories on the ground when a burster is detected.

But space officials are worried about the damage CGRO could cause on the ground as it weighs 17 tonnes. It is the heaviest science satellite ever placed into orbit.

Ed Weiler, Nasa's associate administrator for space science, said that the agency has ''looked at every alternative,'' but decided safety should come first.

Astronomers say that if GRO is deliberately destroyed then the impact on astronomy will last for years before a replacement can be built and put into space.