A software glitch that likely doomed the Mars Polar Lander might have done the same to NASAs next spacecraft to alight on the Red Planet had the problem not been uncovered by accident, a Lockheed Martin Astronautics official said Wednesday.
NASA announced this week that the $165 million Polar Lander likely made a deadly 132-foot (40-meter) free fall to the martian surface after faulty software incorrectly signaled that the spacecraft had already safely landed.
That signal prompted the Polar Lander to prematurely shut down its descent engines that were to have slowed the spacecraft to land at 5 m.p.h. (8 kilometers per hour). Instead, it hit while traveling 10 times as fast.
The problem came to light at spacecraft-builder Lockheed Martin in early February, well after the Polar Landers failed attempt to reach Mars on December 3, 1999.
But it was discovered by mistake, during testing of a lander initially set for launch in 2001. (NASA has delayed launch of that spacecraft to 2003 at the earliest.)
"It was by luck, quite frankly, that we found this error," said Edward Euler, Lockheeds program director for the Mars 98 missions.
Euler said Lockheed alerted a NASA team investigating the loss of the mission, which has since determined it to be the most plausible among seven potential failure scenarios.
The software problem was a simple matter of one line of code that could have been corrected while Polar Lander was still winging its way to Mars. It had been previously unknown, despite testing at Lockheed.
"There was a full scale test doneprior to the flight, but when this test was done, the touchdown sensors were improperly wired due to a design problem," said Thomas Young who authored a report, released Tuesday, that examined NASAs Mars program. "After the wiring was corrected, the test was not repeated and therefore the system test did not demonstrate this particular problem."
The glitch later escaped notice during intensive reviews of the Polar Lander undertaken in the two months immediately following the loss of the Mars Climate Orbiter in September.
Euler said Lockheed was unaware the problem lurked in the software that it intended to use aboard the 2001 lander as well -- until its accidental discovery.
"It perhaps would have showed up a little later," Euler said of the glitch.
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