compton_stay_000216 WASHINGTON -- NASAs Compton Gamma Ray Observatory may get a stay of execution.
Speaking before a solar system exploration advisory group February 15, Edward Weiler, NASA's associate administrator for space science, said planners are studying options to keep the
observatory in orbit a while longer.However Weiler said the safety of the public is paramount and would take precedence over any extra science that the observatory might do.
The observatory was deployed from Space Shuttle Atlantis in April 1991. Since that time, the 17-ton (15,422-kilogram) spacecraft has been eyeing the universe, relaying data on such mysterious phenomena as black holes, quasars and gamma-ray bursts.
While it has used up its two-year design life, the space observatory is still cranking out loads of solid scientific data.
But the observatory, scientists said, just isnt what she used to be.
A recent loss of one of its gyroscopes poses the threat of a potentially uncontrolled reentry --
a scenario that NASA wants to avoid.Planners are scrambling to come up with a way to bring the observatory down safely through the atmosphere as NASA policy requires.
The observatory carries its own fuel reserve on board, enabling controllers to accurately propel it into the atmosphere where it would burn up. A working set of gyros assures that the observatory can be targeted for its destructive plunge at an unpopulated area like the ocean.
Gamma rays: The highest energy portion of the electromagnetic spectrum.
Because there could be a slight chance of human injury during the observatory's fall from grace, NASA may well decide to bring it out of orbit before another one of its gyroscopes fails, just to make sure it is able to send it nosediving into the Pacific Ocean this April.
Donald Kniffen, NASA deputy program scientist for the observatory, said that around-the-clock work by engineers at the Goddard Space Flight Center in Greenbelt, Maryland, have given planners new hope that they might be able to keep the satellite up and operating for years to come.
"But weve got a fairly short fuse on this," Kniffen told SPACE.com.
Kniffen said Goddard engineers have come up with a plan using a set of small thrusters on the observatory that could work in unison with larger thrusters to precisely steer the craft into Earth's atmosphere at a specific point.
Also under review is a plan to use other gear on the satellite -- a magnetometer and a sun sensor -- to keep the craft on a steady-as-she-goes path circling Earth, even without any gyroscopes, Kniffen said.
Techniques like that could keep the observatory orbiting Earth for up to 11 more years. By that time, it is possible that a space shuttle retrieval might be an option, Kniffen said, although that would be an expensive choice.
If the observatory can be nudged into a controlled reentry, there still is a chance that several hundred pounds of debris would likely survive the fiery fall.
Kniffen said the chance of any debris hitting Earth and causing damage or injuries is small. But it doesnt matter how small it is, you cant take any risk," Kniffen said.
If the observatory is brought down, the debris "footprint" on Earth would stretch out some 1,000 miles (1,609 kilometers), Weiler said.
NASA will make a public announcement regarding the observatory's fate in March, he told the advisory group.
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