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NASA: Software Problems May Explain Crippled Communications With <i>Spirit</i> - 2004-01-23

The U.S. Mars rover has sent back engineering data to Earth for the first time since Wednesday. But mission officials do not expect it return to service anytime soon as they analyze what is causing its erratic communications.

After two days of receiving only beeps and garbled data from the Spirit rover, engineers at the Jet Propulsion Laboratory received what they call a limited data stream.

The rover transmitted two feeds one hour apart lasting a total of 30 minutes Friday morning in response to a command they had sent asking it to send diagnostic data on its condition.

Engineers are scanning it for clues about what is causing the communications trouble, but project manager Peter Theisinger says the vehicle's computer software is still not functioning normally and he calls its condition critical.

"We do not know to what extent we can restore functionality to the system because we don't know what's broken," he said. "We don't know what started this chain of events and I think personally that it's a sequence of things and we don't know therefore the consequences of that."

Mr. Theisinger says he suspects a hardware malfunction might be affecting the software's ability to communicate. Since hardware is unlikely to be fixed remotely, he suggests that engineers might have to devise a method to work around the problem. Whatever the trouble, the NASA official says the rover's computer senses a problem and is resetting itself many times a day.

Mr. Theisinger says if Spirit can be made to work again, it might take several days or weeks under the best of circumstances.

"I expect that we will get functionality back out of this rover," he said. "The chances that it will be perfect again I would think are not good. The chances that it will not work at all I think are also low. I think we're somewhere in that broad middle and we need to understand the problem to find out exactly where we are."

The six-wheeled rover arrived on Mars three weeks ago to search for signs that water once flowed on the planet and made it habitable for some microbial forms of life. Its landing and subsequent operations were almost flawless until this trouble developed.

While engineers struggle to diagnose the problem, another Jet Propulsion Laboratory team is guiding an identical U.S. rover to a Sunday landing on the opposite side of Mars.

Mission officials say their objectives are not lost if Spirit fails because their minimum standard for success is to have one of the two rovers operating on Mars for 90 days. NASA's lead scientist for Mars exploration, James Garvin, says the space agency purposely designed somewhat redundant missions because of the strong possibility one might fail.

"A choice was made at NASA to fly two Mars exploration rovers not just for science but to be able to handle what Mars can throw at us," he said. "Together, they are part of a program. So we're aware of the stress and the risks and the challenges and that's a choice we actually made when we started."

NASA says the second rover, named Opportunity, is on a perfect course for Sunday's touchdown.