Compton Gamma Ray Observatory Re-entry Activities

Dolores Beasley

Headquarters, Washington, DC

May 26, 2000
(Phone: 202/358-1753)

Nancy Neal

Goddard Space Flight Center, Greenbelt, MD

(Phone: 301/286-0039)

NOTE TO EDITORS: n00-24

On Sunday, June 4, the successful nine-year mission of the
Compton Gamma Ray Observatory (CGRO) will end when NASA redirects
the spacecraft into Earth’s atmosphere. Debris from the
controlled re-entry is expected to fall in a remote area of the
Pacific Ocean, approximately 2,500 miles southeast of Hawaii.

NASA controllers will fire CGRO’s thrusters four times to
lower the observatory’s orbit. After each burn, mission trackers
at Goddard Space Flight Center, Greenbelt, MD, will determine the
observatory’s exact position and, if necessary, adjust the
descent. The engine burns will occur at:

Re-entry Burn #1: 9:54 p.m. EDT, Tuesday, May 30

Re-entry Burn #2: 10:41 p.m. EDT, Wednesday, May 31

Re-entry Burn #3: 1:37 a.m. EDT Sunday, June 4

Re-entry Burn #4: 3:05 a.m. EDT, Sunday, June 4

Recorded status reports will be available after each burn on
the Goddard Audio News Service (301/286-NEWS). Status reports will
be posted the following morning to:

http://www.nasa.gov/hqpao/status_index.html

For news media interested in covering the final descent from
Goddard, the newsroom in Goddard’s Central Flight Control Building
(Building 3) will open at 12:30 a.m. June 4. At 6 a.m. EDT, team
members will hold a final news briefing in the Building 3
auditorium. The newsroom phone numbers, which will only be
operational June 4, are 301/286-4127 or 301/286-4734.

Scientists and members from the Compton re-entry team will
periodically stop by the newsroom to speak with reporters
throughout the deorbit activities. News media interested in
coming to Goddard on June 4 should contact Nancy Neal at 301/286-
0039 by noon EDT Friday, June 2.

Live coverage on NASA Television of the deorbit activities
will begin at 1 a.m. EDT June 4 and conclude at the close of the 6
a.m. briefing.

NASA Television coverage will include science highlights, re-
entry animation and commentary on the re-entry activities by Dr.
Neil Gehrels, CGRO project scientist. A NASA fact sheet on the
re-entry can be found at:

http://pao.gsfc.nasa.gov

Unlike most satellites, Compton is too large to burn up
entirely in the atmosphere during re-entry. More than 6 tons
(12,400 pounds) of metal debris is expected to fall to the Earth’s
surface. The debris fragments will range in size from the size of
a small stone to several hundred pounds or kilograms.

To ensure the safety of aircraft and surface vessels in or
near the target impact area, Debris Hazard Warning Areas were
established well away from land. Shipping and air traffic in the
area have been notified to ensure that craft will not be in the
vicinity of the impact area.

NASA decided before Compton was launched that, due to the
observatory’s size, it would be returned to Earth by controlled
re-entry when the mission was over. Extensive research showed
that it was significantly safer to perform a controlled re-entry
than any other method of dealing with the satellite.

NASA Television is broadcast on GE-2, transponder 9C located
at 85 degrees West longitude, with vertical polarization.
Frequency is on 3880.0 MHz, with audio on 6.8 MHz.

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