On time. On Budget. On Mars. <- Pick Two.
NASA report: Software, tight budget doomed Mars lander
By Richard Stenger
CNN Interactive Staff Writer
March 28, 2000
Web posted at: 5:42 p.m. EST (2242 GMT)
WASHINGTON -- A software flaw probably caused the Mars Polar Lander to shut off its descent engines prematurely, sending it on a fatal plunge into the red planet, 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 a NASA blue ribbon report on the fate of the $165 million spacecraft.
"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 at 22 meters per second, or 50 miles per hour," he said.
If the lander had come that close to the red planet, "undoubtedly" this malfunction caused its destruction, Young told reporters. But no one could know for certain. The design of the lander prevented any communications as the spacecraft attempted to land.
Software fix was easy, cheap
Regardless of the cause, Young suggested, similar NASA missions should 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 touchdown sensors were incorrectly wired, Young said. After the wiring was corrected, the test was not repeated.
Had the defect been known, a software correction would have been simple and inexpensive, he said...
...He said the mission failures were regrettable, but not entirely unexpected, after NASA, faced with shrinking budgets, adopted a policy of "faster, better, cheaper," almost a decade ago.
"We said up front that this will be painful. We will be taking risks. We will be pushing the limits. We may lose two out of every 10 missions," he said.
But Weiler defended NASA's Mars missions, saying most have been successful and that ones in recent decades have gone aloft at a fraction of the cost of their predecessors...
(From:
http://www.cnn.com/2000/TECH/space/03/28/lander.report.03/)