An anomaly of an unknown nature has disrupted communications with the Spirit rover on Mars for more than 24 hours, mission managers said Thursday.
Since Wednesday morning, NASA has received only intermittent blips, all hinting at a problem affecting the golfcart-sized spacecraft's computerized brain, the managers told reporters at NASA's Jet Propulsion Laboratory in Pasadena, Calif. But they said they could not yet pinpoint the cause of the problem.
The news came a day after the managers said they were experiencing communication problems with the rover because of bad weather at a radar transmission site in Australia. On Thursday, project manager Peter Theisinger amended that view: The loss of data was no longer linked to the weather, but to a "very serious anomaly on the vehicle."
He said several attempts to contact the rover, using direct Earth links as well as satellite relays on NASA's Mars Odyssey and Mars Global Surveyor, were unsuccessful.
"There is no one single fault that explains all the observables," Theisinger said. Among the possibilities could be a software glitch that caused the rover to reset itself, or a power surge, or a temperature-related hardware failure, or perhaps even a cosmic-ray hit, he said.
Theisinger said Mars Global Surveyor did make contact with the Spirit rover's radio transmitter during one pass, but the telemetry contained no meaningful data.
"It was only sending ... a random pattern of zeroes and ones," deputy project manager Richard Cook said. "Effectively, what it means is that the radio was on but the computer wasn’t sending information over to it."
Toward the end of Thursday's news briefing, Theisinger passed along word that managers had sent a series of specially coded signals to the rover in the morning, and received confirmation back from Spirit that the signals were received. That would mean the rover had detected a software fault and was trying to protect itself, he said.
"That would be more information, good news — but we need to confirm that," Theisinger said.
If the problem was confined to the rover's onboard software, mission controllers could go through a process to reset the software and gradually return Spirit to normal operations. Such system resets occurred several times during the 1997 Mars Pathfinder mission.
In a midafternoon status report, the Jet Propulsion Laboratory said engineers would try to follow up on Thursday morning's hopeful blip during satellite relay sessions scheduled for 7:10 and 10:35 p.m. PT Thursday. The solar-powered Spirit was scheduled to "wake up" at about 3 a.m. PT (6 a.m. ET) Friday, after Martian sunrise.
Spirit landed on Mars Jan. 3 as part of a two-pronged, $820 million mission to find out whether the now-dry planet was wetter and warmer long enough for life to develop in ancient times.
The rover rolled off its lander only a week ago and was just getting ready to use a grinding tool on its robotic arm to drill into a rock nicknamed Adirondack.
Spirit’s twin, Opportunity, is scheduled to land on Mars on Saturday. Spirit had been scheduled to reduce its operations in the run-up to Saturday, but Theisinger and Cook said the engineers assigned to the two missions might have to be shifted somewhat to cope with Spirit's problems as well as Opportunity's landing.