SPACE.com -- NASA's Mars Rovers Get Green Light for Longer Mission

Opportunity's panoramic view of a region dubbed Anatolia, which features a trough and rock outcrop similar to the one studied in Eagle Crater. CREDIT: NASA/JPL/CORNELL. Click to enlarge.

The light-toned rocks seen here by Spirit's panoramic camera are strewn across the rover's path leading to the Columbia Hills. Scientists believe the light color may be due to a coating of material possibly formed in a past, wetter environment on Mars. CREDIT: NASA/JPL/CORNELL. Click to enlarge.

After leaving Bonneville crater, Spirit will make its way east to the Columbia Hills, making stops along the way for science studies. CREDIT: NASA/JPL. Click to enlarge.

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	NASA's Mars Rovers Get Green Light for Longer Mission By Tariq Malik Staff Writer posted: 04:15 pm ET 08 April 2004

NASA has given its Mars rovers Spirit and Opportunity the green light for an extended mission that stretches into mid-September now that one of the hardy robots has completed its primary goals

NASA has cleared the Mars rovers Spirit and Opportunity for an extended mission that stretches well into September now that one of the hardy robots has completed its primary goals.

This week, the Spirit rover surpassed not only its primary 90-day Mars mission, but has driven farther and visited more locations than mission planners had planned to see in its Gusev Crater landing site. Meanwhile, Opportunity is closing in on Spirit's mission success and set a new drive-distance record Monday, roving 328 feet (100 meters) in a single jaunt.

Both rovers are currently going through a four-day software upload that will enhance their autonomous driving abilities, help conserve energy and allow some on-site computer problem-solving should Spirit suffer a similar glitch to one that stalled it for more than two weeks earlier in its mission.

"The extended mission has been approved for another five months into mid-September, taking it to about sol 250 relative to Spirit's landing," said Firouz Naderi, Mars program manager at NASA's Jet Propulsion Laboratory (JPL), during a mission briefing Thursday. "It's approximately tripling the mission lifetime."

The mission timelines of Spirit and Opportunity are measured in Martian days, or sols.

Naderi said the equipment aboard both Spirit and Opportunity has been tested to withstand the day-night temperature variations on mars for at least 270 sols. The drop in power production due to dust accumulation and the oncoming Martian winter is expected to level off as well, he added.

Spirit of success

Jennifer Trosper, Spirit's mission manager, said the rover holds the bulk of mission success milestones set for the two-robot Mars Exploration Rover (MER) program.

JPL scientists hoped that at least one rover would drive1,968 feet (600 meters) on Mars. Spirit has reached 2,004 feet (611 meters) and is preparing for a 1.5-mile (2.5-kilometer) trek to the Columbia Hills, a month's journey at least.

Mission planners also hoped their two rovers would visit a total of eight locations combined. Spirit alone has stopped at 11, with more expected to follow.

"So the warranty is kind of up, and we'll see what happens next," Trosper said.

The increased autonomous navigation abilities included in Spirit's software upgrade should afford the rover an easier time traversing the rock-strewn terrain on the path to Columbia Hills. When complete, the robot should be able to boost its single-drive distance up to 246 feet (75 meters) a day, a step up from its longest drive to date of 164 feet (50 meters).

Researchers are also interested in using Spirit to peer at a number of light-colored rocks sitting on the road to the Columbia Hills.

"Light-toned rocks, many of us feel, speaks to water because of the coating process," said Ray Arvidson, deputy principal investigator for the rover missions.

Arvidson said there is some speculation that the coating could be residual salt or iron oxide possibly leftover from ice or snow that deposited on the rocks, then melted as seasons changed.

Opportunity's record

Currently in the 74^thday on Mars, Opportunity is the red planet's reigning champion of robot day-trip driving.

It's 100-meter drive this week took the rover away from "Bounce Rock," one of the few geological interruptions in the sandy desolation of its Meridiani Planum landing site. Awaiting the completion of its own software upgrade, part of which is designed to shut down a faulty heater at night to save power, Opportunity has reached a rock outcropping very similar to the one that dominated its attention in Eagle Crater.

"We hope to spend a few sols hereand we're poised for this extended mission," Arvidson said.

Opportunity's extended mission will hopefully carry it another 2,427 feet (740 meters) toward a crater dubbed "Endurance" where mission scientists hope to find more science targets that will put the wealth data collected at Eagle Crater, and more recently on the surrounding plains, into perspective.

Arvidson said the plains of Meridiani Planum are sparse with rock targets because the region sits atop 984 feet (300 meters) of fine grain material deposited over long periods of time. Unlike the impacts in of Spirit's Gusev Crater, which showered the area with rocky ejecta, Meridiani Planum craters don't appear to be deep enough to have punctured through the fine grain layer, he added.

In addition to setting individual extended mission goals for both Spirit and Opportunity, MER planners hope the rovers' combined atmospheric studies will lead to a better picture of seasonal changes on Mars.

In addition to the scheduled end of the extended mission in mid-September, Mars will be in solar conjunction around September 13, a period when the sun lies between Earth and the red planet. That positioning will block communications with both rovers for at least a week to 10 days, mission scientists said.