NASA: Premature engine shutdown likely doomed Mars lander

Kennedy Space Center technicians lower the Mars Polar Lander onto a workstand in this 1998 file photo

March 28, 2000
Web posted at: 2:35 p.m. EST (1935 GMT)

From staff reports.

WASHINGTON -- The Mars Polar Lander probably shut off its engines prematurely as it prepared to land, sending it hurtling toward the red planet where it crashed and was destroyed, according to a report released Tuesday.

So goes the most likely scenario for the demise of the lander, according to Tom Young, a former Lockheed Martin executive who presented the NASA report on the fate of the $165 million spacecraft.

Young presented several possible ends for the lander, which disappeared December 3. According to the most likely scenario:

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"Spurious signals were generated when the lander legs deployed during descent," Young said. "It gave a false indication that the lander (had) landed."

The malfunction would have happened when the lander was about 40 meters, or slightly more than 100 feet, above the surface. "It would have hit it at 22 meters per second, or 50 miles per hour," he said.

Young said he didn't know if the lander had actually come so close to the red planet. But if it did, undoubtedly this was the cause of its destruction, he told reporters.

Regardless of the cause, he suggested that similar NASA missions would require more funding, better training and more computer program testing.

"There was inadequate software design and testing. The software should have been designed to prevent premature engine shutdown," he said. "In space, one strike and you're out."

There was a full-scale test of the suspect software before flight, but some sensors were incorrectly wired, Young said. After the wiring was corrected, the test was not repeated.

The spacecraft was to have landed near the planet's south pole to search for signs of water. Two small probes that ejected from the craft also disappeared. They were supposed to plunge to the martian surface and analyze subsurface soil samples.

The Lander's companion spacecraft, the Mars Climate Orbiter, was destroyed in September in a mix-up over metric and English measurements. Engineers failed to convert numbers in a navigational program, leading the spacecraft to pass too close to the planet.

Presumably, it burned up in the martian atmosphere. The two spacecraft cost a total of $320 million.

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