The Mars Polar Lander (MPL) Failure Review Board has identified a fatal design flaw that could be a possible cause of the loss of the spacecraft on 3 December. A simple switch system to turn off the $167 million lander's engine when contact was made with the ground may have malfunctioned, according to the board.
The switch system was a simpler and cheaper method than the radar sensing systems used on Viking landers. The radar system was designed to sense when the first landing leg made hard contact with the planet's surface.
The switch system may have been activated prematurely as the lander's legs deployed and locked into position with a jolt. The engines shut down automatically, resulting in a crash landing from a height of about 30m.
Other possible causes include that the MPL toppled over, the descent thrusters fired unevenly or the radio failed. The cause of the crash may never be known, concedes NASA.
Suggestions that faint radio signals detected by the Stanford University radio telescope might have come from the MPL are considered unlikely. The signals had a terrestrial origin, says NASA.
Following the failure of the MPL mission and the earlier loss of the Mars Climate Orbiter in September, NASA is reviewing its future Mars orbiter and lander plans. The space administration had planned missions to Mars every two years through to 2013.
NASA has lost three spacecraft on Mars missions, placed one in orbit and made one safe landing since 1993.
Source: Flight International
