WASHINGTON -- NASAs Compton Gamma Ray Observatory successfully fired its thrusters Tuesday night to lower its orbit around Earth, putting it on track for a planned crash-landing in a remote part of the eastern Pacific Ocean on June 4.
Controllers at the Goddard Space Flight Center in Greenbelt, Maryland, sent commands at 9:51 p.m. Eastern Daylight Time (Wednesday, 01:51 GMT) for the 17-ton, bus-sized spacecraft to fire its maneuvering rockets for 23 minutes.
"Everything went just great. Everything went as expected," Nancy Neal, a Goddard spokeswoman told SPACE.com. "Were all just thrilled about it."
That rocket burn will shave nearly 100 miles from Comptons altitude above Earth, lowering it from 316 miles (510 kilometers) to 217 miles (350 kilometers) by Wednesday morning.
Three additional thruster firings are on tap to bring the $670 million spacecraft out of orbit and to a fiery destruction in Earths atmosphere. Each of those burns is expected to last between 23 and 30 minutes.
The next firing comes Wednesday night, when Comptons orbit will drop to 155 miles (250 kilometers). The final two thruster firings are scheduled for June 4, pushing the satellite so low to Earth that most of Compton will break up due to atmospheric friction.
Some pieces ranging from ounce- (gram-) size fragments to chunks weighing several hundred pounds (kilograms) are expected to fall in an uninhabited part of the Pacific Ocean, about 2,500 miles (4,025 kilometers) southeast of Hawaii. As much as 6 tons of metal debris could survive the plunge to Earth.
Launched from the space shuttle Atlantis in 1991, the Compton has been a scientific workhorse -- charting hundreds of new gamma-ray bursts from distant objects in the universe.
NASA decided to bring it out of orbit when one of its three stabilizing gyroscopes failed. Managers feared another failure would prevent them from having any control over Comptons eventual reentry into Earths atmosphere.
Compton is the first science satellite NASA has tried to bring to Earth in a controlled reentry. It also is the heaviest spacecraft to fall from orbit since the nearly 100-ton Skylab fell over the Indian Ocean and parts of western Australia in 1979.
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