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. Last Updated: 07/27/2016

Satellite May Crash From Orbit

The largest U.S. scientific satellite, the 17-ton Compton Gamma Ray Observatory, is in danger of premature death.

After nine years in orbit, its instruments are still producing floods of data about the most violent phenomena in the distant universe, and probably could keep going for years. But one of the spacecraft's three gyroscopes, which help keep the craft level, has failed. Flight controllers may have to destroy the $600 million Compton observatory before it loses another gyroscope and becomes a possible hazard to populated areas when it eventually dives through the atmosphere at the end of its useful life.

So the National Aeronautics and Space Administration must make a decision later this month: If engineers cannot come up with a reliable alternative way to control the atmospheric re-entry without one or both of the remaining gyroscopes, the otherwise fully operational Compton observatory will be commanded to make a suicidal plunge back to Earth in late March or April.

Seeking to save the spacecraft, flight controllers and engineers at the Goddard Space Flight Center in Greenbelt, Maryland, are studying two methods for orienting the spacecraft in the event of further gyroscope failures. One is to stabilize the spacecraft by sending it into a slow spin before a re-entry maneuver. Another is to rely on sun sensors and magnetometers, instead of gyroscopes, in orienting the spacecraft for re-entry.

Dr. Donald Kniffen, the deputy program scientist for the Compton project, called both options "realistic ideas," but said engineers might be hard pressed to develop and test the procedures for such maneuvers before time ran out.

"We are not going to take any risk on safety," Kniffen said in an interview. "If Goddard can't have tested procedures in place by April, then the Compton will have to be brought down."