Mars Rover Heads to a New Crater

After two years exploring a half-mile-wide crater, NASA’s Mars rover Opportunity is heading for an even wider destination: a crater 13.7 miles wide. (Manhattan, at 13.4 miles long, would fit inside.)
Within the larger crater, named Endeavour, scientists expect that Opportunity would see deeper layers of rock, which would provide more information on the geological past of Mars. But to get there, the rover needs to drive about seven miles southeast. That would match its total driving distance since it landed in January 2004, and NASA warns that Opportunity might not make it.
“It’s a long shot,” said Steven W. Squyres, the principal investigator for Opportunity and its sister rover, Spirit, on the other side on Mars. “We’ve got 12 kilometers on the odometer and another 12 to go to get to this thing.”
At a pace of about 110 yards a day, and allowing time for obstacles, glitches and sightseeing, the trip could take two years. Opportunity has already far outlived its original mission target of three months.
But the journey itself has its own scientific rewards, Dr. Squyres said. In the geology of the region, plains known as Meridiani Planum, the top layers of exposed bedrock, are younger to the south, so the rover will get to see rocks it has not seen before. Also, the plains are strewn with potato-size rocks; examinations of a handful of these show them to be very different from the rocks of Meridiani Planum.
“We think they are pieces of ejecta, things that have been thrown from very distant craters,” Dr. Squyres said. The biggest craters in the area lie to the south. “Those are the most likely source of the cobbles,” Dr. Squyres said.
In its four and a half years on Mars, Opportunity has already explored three craters. By chance, it landed in a small crater. Then it headed to the stadium-size Endurance Crater, followed by the half-mile-wide Victoria Crater. It left Victoria Crater this month.
Meanwhile, the Spirit rover is still sitting still in Gusev Crater on the other side of Mars, conserving energy through the Martian winter. With the lengthening days of spring, Spirit is likely to resume its driving and exploration in a couple of months, Dr. Squyres said.

source: The New York Times