Computer programming error causes Mars spacecraft death

Stan Beer
Sunday, 15 April 2007 05:34

Science - Space

Incorrect failsafe programming of the onboard computers of the Mars Global Surveyor orbiter led to its ultimate demise after 10 years of successful operation, according to a NASA report.

Mission control lost contact on November 2, 2006, 10 years after its lauch in 1996. A preliminary report by an internal review board found that computer error eventually led to battery failure causing the Mars Surveyor to go dead.

"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.

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 review board concluded 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 in California.

Despite the eventual computer led shutdown of the Mars orbiter, it operated for 10 years, four times the planned length of the mission and relayed valuable information such as evidence that water still flows on the red planet.