PASADENA, Calif. -- NASA's Spirit rover stopped transmitting data from Mars for more than 24 hours, mission managers said Thursday, calling it an "extremely serious anomaly."
NASA received its last significant data from Spirit early Wednesday, its 19th day on Mars. Since then, it has sent either random, meaningless radio noise or simple beeps acknowledging it has received commands from Earth, said Firouz Naderi, manager of the Mars exploration program at NASA's Jet Propulsion Laboratory. The last such beep was received Thursday morning, Naderi said.
Initially, scientists believed weather problems on Earth caused the glitch. They said they now believe the rover is experiencing hardware or software problems.
"This is a serious problem. This is an extremely serious anomaly," project manager Pete Theisinger said.
Spirit is one half of a $820 million mission. Its twin, Opportunity, is scheduled to land on Mars on Saturday.
NASA last heard from Spirit as it prepared to continue its work examining its first rock, just a few yards from its lander.
Since then, Spirit has transmitted just a few beeps to Earth in response to attempts to communicate with it. It also has skipped several scheduled communications opportunities, either directly with Earth or by way of two NASA satellites in orbit around Mars.
Engineers worked to pinpoint the yet-unknown problem.
"It's not clear there is one cause ... that would explain the observables we're seeing," deputy project manager Richard Cook said.
Preliminary indications from the spacecraft suggest its radio is working and it continues to generate power from the sun with its solar panels, Cook said.
It was unclear if the problem was with the rover's software or hardware, Theisinger said.
NASA can fix software from Earth, beaming fixes across more than 100 million miles of space. If the problem lies with the rover's hardware, the situation would be far more grave, Theisinger said.
The six-wheeled robot had been scheduled Thursday to grind away a tiny area of the weathered face of a sharply angled rock dubbed Adirondack. Examination of the rock beneath could offer clues to Mars' geologic past. Spirit has since remained immobile, Cook said.
On Wednesday, NASA scientists said a thunderstorm near a Deep Space Network radio antenna in Canberra, Australia disrupted controllers' efforts to initiate the drilling. It has since discounted the weather as the source of the communications blackout.
Spirit landed on Mars on Jan. 3 for a three-month mission to search Gusev Crater, a rock-strewn stretch of dusty, streaked soil that scientists believe may be the bed of an ancient lake. If Mars once had surface water, it had the potential to support life.
Until Wednesday, Spirit had functioned nearly flawlessly. It moved out from its lander on Jan. 15 into its surroundings. Since landing it has snapped thousands of pictures of Mars, including microscopic images of the martian soil and Adirondack.
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