15 April 2007 USA

Human error blamed in failure of NASA Mars craft

WASHINGTON (Reuters) – Human error caused NASA's Mars Global Surveyor to fail in November after the spacecraft spent nearly a decade mapping the Martian surface from orbit, the US space agency said on Friday.

Faulty changes made last June to its computer memory and a November 2 command helped cause battery failure in the craft, which had far exceeded its original two-year mission, an internal NASA review board said in a preliminary report.

"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," Dolly Perkins of NASA Goddard Space Flight Center in Greenbelt, Maryland, said in a statement.

November 2 was the last date when the Mars Global Surveyor communicated with Earth, NASA said. Within 11 hours, depleted batteries probably rendered it unable to control its orientation in orbit.

On that day, ground personnel had ordered the craft to carry out a routine adjustment of its solar panels. The review board said the craft repositioned itself in a way that exposed one of its two batteries to direct sunlight, causing that battery to overheat and leading both batteries to deplete.

The team responsible for the spacecraft followed procedures, the report found, but these were not sufficient to detect errors that had taken place.

The Mars Global Surveyor, launched in 1996, orbited Mars for nine years and 52 days, longer than any other spacecraft to Mars and long enough to complete three extensions of its original two-year mission, NASA said.

Among its achievements were images showing changes in the walls of two craters in the southern hemisphere that suggested the presence of liquid water on the Martian surface.

Scientists eager to learn whether Mars has ever harbored life are very interested in evidence of liquid water, considered a requirement for supporting life.

Source: Reuters

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