Proving to be a real Mars hotrod, the Spirit rover has become the most traveled vehicle on the Red Planet, surpassing the distance accumulated by the Pathfinder rover nearly seven years ago.

"We certainly knew that was likely to occur, but it is good to see that it did after about 45 days on the surface," Richard Cook, the newly named Mars Exploration Rover project manager, said Tuesday.

Pete Theisinger, project chief for the past few years, has been selected to manage NASA's nuclear-powered Mars Science Laboratory mission scheduled for launch in 2009.

Spirit looking behind as its empty lander base and the tracks across the Martian surface. Credit: NASA/JPL Download a larger version of image here

Spirit drove 21.6 meters (70.9 feet) to the north-northeast on Monday night (U.S. time), pushing its odometer to 108 meters (354 feet). The tiny Sojourner rover racked up 102 meters during its mission in 1997.

Spirit is heading to the impact crater nicknamed by scientists as Bonneville. Along the way, the rover is stopping to collect science data on rocks, tiny dunes and soil samples across the wind-swept Martian surface.

"We are doing robotic field geology," says Ray Arvidson, deputy principal investigator. "We are in the middle of a long set of drives with traverse science where we have started at the landing site and we are moving up to the rim of Bonneville Crater."

Mission officials elected to dispatch Spirit to the crater with the goal of studying rock layers and obtaining information about the planet's history, including the potential of a watery past.

"The idea is the impact crater would have overturned the stratigraphy and exposed it for our viewing pleasure," Arvidson said.

This mosaic image from Spirit's panoramic camera shows a forward-looking view. Credit: NASA/JPL/Cornell Download a larger version of image here

Spirit is expected to reach Bonneville in a couple of weeks, but the exact timeline depends on the amount of science activities performed en route.

"It depends on what we find between where we are now and where we are going. We are looking for new materials to stop and to make detailed measurements of," Arvidson said.

"The focus is on the traverse science and getting to the rim of Bonneville over the next dozen or so sols (Martian days). We should get there expeditiously. The rate at which we get there depends on what we discover in terms of new materials. Then once we are on the rim and finish making measurements, then the issue becomes can we get into the crater? What are the slopes of the walls? Or should we head for the Southeast Hills?"

Video coverage for subscribers only:
   VIDEO: SPIRIT'S FORWARD-LOOKING PANORAMA W/NARRATION QT
   VIDEO: SPIRIT PAN LOOKING BACK AT LANDER W/NARRATION QT
   VIDEO: TODAY'S MARS ROVER STATUS AND SCIENCE BRIEFING QT

   MORE: PREVIOUS MISSION COVERAGE!
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