Dwayne Brown
Headquarters, Washington
202-358-1726
Guy Webster
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6278
RELEASE: 07-88
REPORT REVEALS LIKELY CAUSES OF MARS SPACECRAFT LOSS
WASHINGTON - After studying Mars four times as long as originally
planned, NASA's Mars Global Surveyor orbiter appears to have
succumbed to battery failure caused by a complex sequence of events
involving the onboard computer memory and ground commands.
The causes were released today in a preliminary report by an internal
review board. The board was formed to look more in-depth into why
NASA's Mars Global Surveyor went silent in November 2006 and
recommend any processes or procedures that could increase safety for
other spacecraft.
Mars Global Surveyor last communicated with Earth on Nov. 2, 2006.
Within 11 hours, depleted batteries likely left the spacecraft unable
to control its orientation.
"The loss of the spacecraft was the result of a series of events
linked to a computer error made five months before the likely battery
failure," said board Chairperson Dolly Perkins, deputy
director-technical of NASA Goddard Space Flight Center, Greenbelt,
Md.
On Nov. 2, after the spacecraft was ordered to perform a routine
adjustment of its solar panels, the spacecraft reported a series of
alarms, but indicated that it had stabilized. That was its final
transmission. Subsequently, the spacecraft reoriented to an angle
that exposed one of two batteries carried on the spacecraft to direct
sunlight. This caused the battery to overheat and ultimately led to
the depletion of both batteries. Incorrect antenna pointing prevented
the orbiter from telling controllers its status, and its programmed
safety response did not include making sure the spacecraft
orientation was thermally safe.
The board also concluded that the Mars Global Surveyor team followed
existing procedures, but that procedures were insufficient to catch
the errors that occurred. The board is finalizing recommendations to
apply to other missions, such as conducting more thorough reviews of
all non-routine changes to stored data before they are uploaded and
to evaluate spacecraft contingency modes for risks of overheating.
"We are making an end-to-end review of all our missions to be sure
that we apply the lessons learned from Mars Global Surveyor to all
our ongoing missions," said Fuk Li, Mars Exploration Program manager
at NASA's Jet Propulsion Laboratory, Pasadena, Calif.
Mars Global Surveyor, launched in 1996, operated longer at Mars than
any other spacecraft in history, and for more than four times as long
as the prime mission originally planned. The spacecraft returned
detailed information that has overhauled understanding about Mars.
Major findings include dramatic evidence that water still flows in
short bursts down hillside gullies, and identification of deposits of
water-related minerals leading to selection of a Mars rover landing
site.
The Jet Propulsion Laboratory, Pasadena, Calif., manages Mars Global
Surveyor for NASA's Science Mission Directorate, Washington. Lockheed
Martin Space Systems, Denver, developed and operates the spacecraft.
Information about the Mars Global Surveyor mission, including the
preliminary report from the process review board and a list of some
important discoveries by the mission, is available on the Internet
at:
http://www.nasa.gov/mission_pages/mgs
EDITORS NOTE:
NASA will hold a media teleconference today at 3 p.m. EDT, to discuss
the report.
Reporters should call 1-888-398-6118 and use the pass code "Mars" to
participate in the teleconference. International media should call
1-773-681-5826. Replays of the teleconference will be available by
calling 866-369-3645. International media may call: 203-369-0243.
Audio of the teleconference will stream live at:
-end-
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