Mars rover surpasses Viking 1's longevity record

[May 20, 2010]  LOS ANGELES (AP) -- Pop quiz: What spacecraft holds the record for longest-surviving mission on the bitterly cold and dusty surface of Mars?

As of Thursday, there's a new -- but possibly temporary -- champion.

For decades, the NASA Viking 1 lander held the title after toiling away six years and 116 days on the red planet. But Opportunity, one of the twin rovers that landed in 2004, has surpassed that record and shows no signs of stopping.

Unlike Viking 1, which conducted science experiments in one spot, the six-wheel, solar-powered Opportunity has been on the go, driving into craters and peering at rocks along the way.

Designed to last three months, the golf cart-size rover has logged more than 12 miles on its odometer and is inching toward the largest impact crater yet -- a journey that is expected to take several years.

With winter under way in the southern hemisphere, Opportunity has had to alternate between driving and resting to recharge its battery and stay warm.

"The expectation is that Opportunity will keep on going and going and going," said project manager John Callas of NASA's Jet Propulsion Laboratory.

Since parachuting to the surface, Opportunity has survived dust storms and bone-chilling winters.

Washington University researcher Ray Arvidson, who worked on the Viking and twin-rover missions, is in awe of Opportunity's feat.

"I didn't think I'd see this in my lifetime," Arvidson said.

Opportunity's record might be contested come Martian spring. Spirit, its twin, landed 21 days before Opportunity and may have eclipsed Viking 1's record on April 29. But NASA doesn't know if the silent, sand-trapped rover is still alive.

Spirit last communicated with Earth in late March and is presumed to be in a hibernation state because the sun is too low in the winter sky for the rover's solar panels to gather energy. Scientists have to wait until spring to see if Spirit sends back a signal, indicating it didn't freeze to death.

"I'm confident that Spirit is alive and well, but I think that verification that she holds the record will have to wait," said rover chief scientist Steve Squyres of Cornell University.

The record is measured in Earth time. A Martian year is equivalent to 687 Earth days, or nearly two Earth years. A Martian day lasts 24 hours and 39 1/2 minutes.

The twin Viking spacecraft landed on Mars in 1976, but both rovers passed Viking 2's mark long ago. Viking 2 operated on the surface for 3 years and 221 days. It was turned off in 1980 after its batteries died.

What finally did Viking 1 in? Alas, human error. The lander was accidentally shut down in 1982 and never regained contact.

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On the Net:

Mars Exploration Rover Mission:
http://marsrovers.jpl.nasa.gov/home/index.html

[Associated Press; By ALICIA CHANG]

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