After nine years of operation, contact with the Mars Global Surveyor (MGS) orbiter was lost in November 2006. MGS was the first in a series of spacecraft destined for Mars. It was in a near-polar orbit on a mission to globally map the planet, examining the planet's ionosphere, atmosphere, surface, and interior using six science instruments. Designed to study Mars from orbit for two years, it accomplished many important discoveries during nine years in orbit. On Nov. 2, 2006, the spacecraft transmitted information that one of its arrays was not pivoting as commanded. Loss of signal from the orbiter began on the following orbit.
According to a NASA Watch report, in a meeting of the Mars Exploration Program Analysis Group (MEPAG), NASA's John McNamee (Mars Exploration Program) stated "We think that the failure was due to a software load we sent up in June of last year. This software tried to synch up two flight processors. Two addresses were incorrect - two memory addresses were over written. As the geometry evolved, we drove the [solar] arrays against a hard stop and the spacecraft went into safe mode. The radiator for the battery pointed at the sun, the temperature went up, and battery failed. But this should be treated as preliminary."
An internal review board will review the events to determine what caused the MGS failure, and make recommendations for future missions.