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)'s Jet Propulsion Laboratory, Tuesday, Jan. 27, 2004, in Pasadena, Calif. Behind them is a high-resolution image of an intriguing slab of layered Martian bedrock located just yards from the Opportunity rover. (AP Photo/Ric Francis)

PHOTO: Members of the Mars Exploration rovers team, Steve Squyres, left; Andrew Knoll, second from left; Jim Erickson, third from left and Jennifer Trosper discuss the status of rovers Spirit and Opportunity during a news briefing at NASA (news - web sites)'s Jet Propulsion Laboratory, Tuesday, Jan. 27, 2004, in Pasadena, Calif. Behind them is a high-resolution image of an intriguing slab of layered Martian bedrock located just yards from the Opportunity rover. (AP Photo/Ric Francis)


By ANDREW BRIDGES, AP Science Writer
PASADENA, Calif. - NASA (news - web sites) scientists on Tuesday unveiled a high-resolution photograph of an intriguing slab of martian bedrock near the Opportunity rover, while they studied a thermostat problem and worked to avoid the computer troubles that crippled its twin, Spirit.

The sharp image could provide new details on what scientists call the first bedrock ever seen on the surface of Mars. Pictures of the rock that the rover beamed back earlier were less clear.

The stone forms a portion of the rim of the shallow crater into which Opportunity bounced to a stop after landing during the weekend.

Scientists want to know if it was formed volcanically or is sedimentary rock, which can be formed by water or through wind action.

"Opportunity has now sent us the most striking image yet," said Steve Squyres of Cornell University, the mission's main scientist.

The rock intrigues scientists because it could contain evidence that Opportunity's landing site once was a strikingly different place, perhaps wet enough to support life. NASA expects it will be one of Opportunity's first targets, once it rolls off its lander sometime in the next two weeks.

To keep Opportunity on track, engineers have begun actively managing the files stored in its flash memory, said Jim Erickson, a mission manager.

Spirit, which landed on the opposite side of Mars, was crippled because its random-access memory proved inadequate to manage its flash memory, which had become packed with unnecessary files that piled up since the spacecraft's launch.

Together, the two 384-pound rovers make up a single $820 million mission to prospect for geologic evidence that Mars was once a wetter world capable of supporting life. NASA launched Spirit on June 10 and it landed Jan. 3. Opportunity was launched July 7 and landed Saturday.

Scientists did report one problem aboard Opportunity: a drain on power believed to be caused by a heater that was operating without being turned on by mission controllers. A sensor was automatically turning on the heater when the martian temperature fell, and engineers are unable to control it, said Jim Erickson, a mission manager.
Whether or not the power drain would become serious remained under evaluation, he said.
"We don't normally want it on. Right now we believe it's going to be continuously on whenever it's cold enough," Erickson said.
The prognosis for Spirit, 6,600 miles and halfway around the planet from Opportunity, remained iffy.
"We do not yet know if Spirit will be perfect again," mission manager Jennifer Trosper said.
Spirit began acting up last week, when it stopped sending data and began rebooting its computer, eventually resetting it roughly 130 times. At one point, the rover thought it was the year 2053, Trosper said.
To tame Spirit's computer, engineers temporarily disabled its flash memory. Engineers believe they gave Spirit too little random-access memory, or RAM, to adequately manage its file-packed flash memory, which is similar to the memory used by digital cameras to store photographs.
Cutting off the flash memory eased the burden on Spirit's RAM and ended the rebooting loop, Trosper said.
Engineers planned to begin deleting this week hundreds of unneeded files, stored in the months since launch, to make the memory more manageable for the rover's RAM, Trosper added.

"It's kind of like we have a patient in rehab and we are nursing her back to health," Trosper said.

Spirit could resume normal science operations in two to three weeks, NASA said.

Opportunity could move off its lander in 10 to 14 days, after fully unfolding from the cramped position it held during its seven-month trip from Earth.
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On the Net:
marsrovers.jpl.nasa.gov

PHOTO: Members of the Mars Exploration rovers team, Steve Squyres, left; Andrew Knoll, second from left; Jim Erickson, third from left and Jennifer Trosper discuss the status of rovers Spirit and Opportunity during a news briefing at NASA (news - web sites)'s Jet Propulsion Laboratory, Tuesday, Jan. 27, 2004, in Pasadena, Calif. Behind them is a high-resolution image of an intriguing slab of layered Martian bedrock located just yards from the Opportunity rover. (AP Photo/Ric Francis)