NASA ends effort to free rover from Martian sand

[January 27, 2010]  LOS ANGELES (AP) -- The Mars rover Spirit has logged nearly five miles during six years of rolling around the red planet. It has driven forward, backward and uphill over plains, plateaus, and even a mountain as tall as the Statue of Liberty.

No more.

NASA on Tuesday declared an end to Spirit's roving career after repeated attempts to free it from a sand pit where it's been stuck for nine months. With Martian winter approaching, the focus instead will turn to improving Spirit's tilt so its solar panels can receive maximum sunlight.

"Spirit has encountered a golfer's worst nightmare: the sand trap that no matter how many strokes you take you can't get out of it," said Doug McCuistion, who heads the Mars exploration program at NASA headquarters.

Trying to look on the bright side, NASA said Spirit can still do research while stuck in place, provided it survives the winter. Scientists wasted no time drawing up new research priorities for the former rover, including studying the planet's core, tracking the weather and examining the soil in detail.

Spirit and its twin, Opportunity, parachuted to opposite ends of the Martian equator in 2004. By poking into craters, drilling into rocks and driving across the bumpy surface, they discovered geological evidence that water flowed on the Martian surface eons ago.

Designed to last three months, both have dazzled scientists and the public by working past their warranty, and they're closing in on the record for the longest-running Mars surface mission. That achievement is held by the Viking 1 lander, which lasted on the red planet for six years and 116 days.

"We're not giving up on Spirit. Since the start of this mission, we've really done everything that we can to try to squeeze every last little bit of science out of these rovers. We're going to keep doing exactly that," said chief scientist Steve Squyres of Cornell University.

Spirit's troubles began last April, when driving backward because of a gimpy wheel, it broke through the crusty surface and became mired in soft sand.

After spending half a year testing escape routes on Earth, NASA decided to drive Spirit out the way it came in. Despite several attempts, the rover's operators made little progress, and slippage caused the wheels to sink deeper. Hopes for a great escape dimmed further when another wheel stopped turning, leaving four of its six wheels working.

Spirit started making small progress in the last two weeks by driving backward. But NASA conceded that was not enough to get it unstuck before winter.

With attention switched to winter survival, engineers are hurrying to get Spirit in position before the seasons change. Over the next few weeks, driving commands will be sent to Spirit to try to lift its rear wheels up so that it's facing north.

If the solar-powered robot geologist cannot significantly improve its angle, it will likely hibernate and have limited contact with Earth for months until it reactivates, project manager John Callas said.

Spirit is no stranger to hardship. It had a rocky start on Mars, going into critical condition and sending nonsense back to Earth weeks after landing. Engineers eventually fixed the computer problem. Unlike its twin, Spirit landed in a Connecticut-sized crater named Gusev that contained limited evidence of past water and had to head for the hills to make discoveries.

There were moments of glory. Spirit climbed a mountain in 2005. It also became the first to record dust devils as they were forming, which NASA made into movie clips.

During its mobile career, Spirit struggled with a balky wheel that forced it to drive backward.

Though Spirit can no longer trek to new destinations, Opportunity continues to hum along. It recently wrapped up its study of a rock and is headed toward a crater. It has recorded nearly 12 miles on its odometer.

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On the Net:

NASA Mars page:
http://marsrovers.jpl.nasa.gov/home/index.html

[Associated Press; By ALICIA CHANG]

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