Credit: NASA-JPL

After studying Mars four times as long as originally planned, NASA's Mars Global Surveyor (MGS) orbiter appears to have succumbed to battery failure due to a complex sequence of events involving the onboard computer memory and ground commands.

The reasons were released on Friday, 15 April 2007, in a preliminary report by an internal review board. The board was formed to peer into why MGS fell silent in November 2006 and recommend any processes or procedures that could increase safety for other spacecrafts.

MGS last communicated with Earth on 2 November 2006. Within 11 hours, depleted batteries probably left the spacecraft's attitude control disabled.

"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's Goddard Space Flight Center.

On 2 November 2006, after the spacecraft was commanded to perform a routine adjustment of its solar panels, the spacecraft signaled 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 onboard batteries to direct sunlight. This overheated the battery, and led to the depletion of both batteries. Incorrect antenna pointing prevented the orbiter from informing controllers its status, and its programmed safety response did not feature assuring the thermal safety of the spacecraft orientation.

MGS, launched in 1996, operated longer at Mars than any other spacecraft in history, and for more than four times as long as its expected mission. The spacecraft produced a wealth of data that has revolutionized understanding about Mars. Startling discoveries include dramatic evidence that water still flows in short bursts down hillside gullies, and deposits of water-related minerals leading to selection of a Mars rover landing site.

Further Reading

MGS

http://mars.jpl.nasa.gov/mgs/overview/

Aymen Mohamed Ibrahem

Senior Astronomy Specialist