[meteorite-list] Report Reveals Likely Causes of Mars Global Surveyor Loss

[Ron Baalke]

April 13, 2007

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: 

http://www.nasa.gov/newsaudio

	
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