STATUS REPORT #2:
SECOND DEORBIT BURN FOR OBSERVATORY SUCCESSFUL;
TIME CHANGE FOR LAST TWO BURNS
June 1, 2000
The second of four burns necessary for re-entry of NASA's Compton Gamma Ray Observatory was initiated at 10:36 p.m. EDT May 31. Compton's Attitude Control thrusters and Orbit Adjust thrusters were fired for 26 minutes. The descent burn lowered the spacecraft's orbit's perigee from 226 miles (364 kilometers) to 155 miles (250 kilometers).
Controllers decided late Tuesday to adjust the primary track for re-entry on June 4. This alters the times of burns #3 and #4 by approximately 90 minutes. The new time for burn #3 is midnight EDT. Burn #4 will commence at 1:30 a.m. EDT. Impact is expected at approximately 2:20 a.m. EDT.
"The latest prediction has Compton's orbit tracks moving west. This migration now makes the eastern most track the safest re-entry opportunity. This track is now our primary re-entry track," said Mansoor Ahmed, CGRO mission manager from Goddard.
Because of the change in the burn times, the newsroom in Goddard's Central Flight Control Building (Building 3) will open at 11:30 p.m. June 3. Live coverage on NASA Television will also begin at 11:30 p.m. June 3. The news briefing to announce conclusion of deorbit activities will still be at 6 a.m. June 4 in the Building 3 auditorium.
After nine years in orbit, NASA decided to deorbit CGRO via a controlled re- entry after one of its gyroscopes failed in December. Extensive analysis has shown that it is much safer to bring the satellite back now than to use any other method for dealing with the spacecraft. Compton is scheduled to re-enter the Earth's atmosphere on June 4 in an isolated area of the Pacific Ocean, southeast of Hawaii.
Media contacts:
Dolores Beasley, Headquarters, Washington, DC (202/358-1753)
Nancy Neal , Goddard Space Flight Center, Greenbelt, Md. (301-286-0039)
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