Faulty software was responsible for the loss of the Mars Global Surveyor (MGS) late last year, a NASA review board announced today.
Confirming previous speculations, the board said the MGS loss was likely due to faulty computer code uploaded five months before that ultimately caused one of the spacecraft's battery to overheat.
"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 in Maryland.
The board was formed earlier this year to investigate the probe's sudden disappearance in November 2006 and to make recommendations to prevent the loss of other spacecraft.
Ground controllers last heard from the MGS on Nov. 2, 2006 after being ordered to perform a routine adjustment of its solar panels. The spacecraft reported a series of alarms but, in a final transmission, indicated it had stabilized.
Subsequently, the spacecraft reoriented to an angle that exposed one of its two batteries to direct sunlight. The battery overheated and, over the course of 11 hours, depleted the other battery as well. An incorrectly oriented antenna prevented the spacecraft from communicating its status to controllers.
A later attempt to use NASA's Mars Reconnaissance Orbiter (MRO) to spot the silent MGS yielded no sightings.
The board concluded that the MGS team followed existing protocols correctly, but that the procedures were insufficient to spot the errors that occurred. It has recommended other missions review all non-routine instructions uploaded to spacecraft and to evaluate 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.
Launched in 1996, MGS operated four times longer than the original mission plan, and was operational and conducting science on a routine and normal basis longer than any spacecraft in history. Among its many achievements, the spacecraft tracked the evolution of dust storms on the planet, found compelling evidence of gullies carved apparently by flowing water, and exposed the infamous "face on Mars" to be a natural phenomenon.
NASA will hold a media teleconference to discuss the board's findings at 3 pm EDT today. Audio of the teleconference will stream live at: http://www.nasa.gov/newsaudio.