Mars Rover Fighting For Survival

Dec. 11, 2007 -- After making what may be its key scientific contribution since arriving on Mars nearly four years ago, the rover Spirit is battling time to get itself in position to survive the Martian winter.

Spirit has about two weeks left to reach a sun-facing slope on the northern edge of a plateau known as Home Plate in Gusev Crater. So much dust blankets its solar panels however, that the rover needs to spend a day charging its batteries just to crawl for an hour, project manager John Callas said during a briefing at the American Geophysical Union conference in San Francisco this week.

"We don't have that much time to drive every day," Callas said.

Global dust storms swept over the planet for two months earlier this year, blotting out 99.5 percent of the direct sunlight. The rovers survived the storms, but Spirit is so coated with debris that its solar power panels are operating at 42 percent of their original capacity.

"It's almost camouflaged. There's so much dust on the arrays," Callas said.

Even if Spirit reaches its winter resting spot, surviving its third Martian winter will be tough, Callas said. Engineers estimate Spirit's power levels will be reduced to 30 percent -- about what is needed just to keep its equipment from freezing.

Spirit had 50 percent power during the last winter and 70 percent during its first winter on Mars.