Mars Lander Engine Likely Cut Off Early
March 28 -- Inadequate software probably led to the descent engines of the Mars Polar Lander shutting off early, sending the ill-fated NASA spacecraft smashing into the planet’s surface last December, two review boards reported today.
But the underlying problem, the panels said, was trying to do too much with too little, resulting in missions that had little chance of success.
NASA today also canceled its next Mars lander, which had been scheduled for launch next year. That spacecraft shared a design very similar to the Mars Polar Lander’s. A companion orbiting spacecraft will be launched as planned.
Landing at 130 Feet UpThe Mars Program Independent Assessment Team, headed by Tom Young, a retired Lockheed Martin executive vice president and former director of NASA’s Goddard Space Flight Center, found that the process of unfolding the landing legs during descent could have inadvertently triggered sensors telling the onboard computer it was already on the ground.
“This resulted in a premature shutdown of the engines,” Young said at a news conference at NASA’s Washington, D.C. headquarters this afternoon. Shutting down the engines would have sent the lander into a free fall for the final 130 feet, accelerating it to 50 mph. The computer could have easily been programmed to ignore the spurious signals, he said.
A review board at NASA’s Jet Propulsion Laboratory, whose report was also released today, came to the same conclusions.
Four full-scale tests of the landing sequence after the mishap by Lockheed Martin, the builder of the spacecraft, all resulted in early engine cutoffs. “In all four, the lander would have failed,” Young said. “So I think it almost certain if the lander got to this particular part of the mission, this is the cause of the lander failure.”
Before launch, engineers performed the same test with the Mars Polar Lander, but a wiring mistake cut off all signals from the sensors, and the test was never repeated.
Popular Reads
ABC News Live