Twoyears after setting out for a big Martian crater that could hold clues aboutthe Red Planet's potential to support life, NASA's rover Opportunity has hit amilestone: It's more than halfway there.
Opportunityturned its wheels toward the Endeavour crater in August 2008, after exploringanother crater, Victoria, for about two years. But Endeavour is a differentbeast; at 14 miles (22 km) wide, it will be the biggest crater a NASA rover hasever seen up close.
Thetrip from Victoria to Endeavour is about 12 miles (19 km) long. The Opportunityrover has covered about 6 miles (10 km) of that distance at this point,NASA officials confirmed Wednesday. [Latestphotos from Opportunity rover.]
"Weare actually beyond halfway," said Matt Golombek,chairman of the Mars rover science operations working group at NASA's JetPropulsion Laboratory.
Getto the clay
Opportunitylanded on Mars with its twin rover, Spirit, in January 2004. Their missionswere supposed to last only about three months, but both far surpassed thatlifetime. Spirit got bogged down in soft sand in 2009 and stoppedcommunicating with Earth in spring of this year. Opportunity, though, isstill going strong.
NASAscientists are keen for the rover to reach Endeavour. Last year, the agency'sMars Reconnaissance Orbiter spacecraft detected clay deposits on the crater'srim. Clay-bearing rocks are a strong indication of the past presenceof water, which is necessary for life as we know it.
"They'rea kind of mineralogical marker bed for places with biological potential," Golombek told SPACE.com. "So that's our ultimate goal,to get to them."
Infact, NASA's next Mars rover, the car-sized Curiosity, will prioritize lookingat clays. The rover is scheduled to launch in November 2011 and land on Mars inAugust 2012. All of its potential landing sites sport clays similar to thosefound on Endeavour's rim, Golombek said.
Anotherintriguing aspect of Endeavour's clay is its age. The terrain surroundingEndeavour dates to about four billion years ago, Golombeksaid ? around the time when life likely started on Earth. Mars may have beenmore conducive to life back then, and such old rocks could tell us more.
Scientistsalso have a general interest in Martiancraters, clay-bearing or not. Big holes in the ground allow researchers topeer beneath the top layers of dirt ? much deeper thanrovers' robotic arms can dig.
"Youcan use craters as a poor-man's probe into the subsurface," Golombek said. "You can often see actual strata oroutcrop on their upper rims."
It'staken Opportunity about two years to go 6 miles (10 km), so the rover won't bereaching Endeavour for a while. Its travels are of the slow-but-steady variety.
"Ona really good day, we can go about 100 meters [330 feet]," Golombek said. "A short day is maybe half ofthat."
Still,there's no reason to think Opportunity won't make it, he said. The rover is inpretty good shape, besides a broken right front wheel that doesn't turn. Forthat reason, engineers are driving it backward, but that shouldn't pose aproblem.
"We'renot seeing anything that's going to stop us," Golombeksaid.
IfOpportunity doesn't reach to Endeavour, it should still gather some useful dataalong the way.
"Evenif we don't make it, we're going through some tremendously interestinglandscapes," Golombek said.
- Gallery: Latest Mars Photos From Spirit and Opportunity
- Most Amazing Mars Rover Discoveries
- Video Show: Rover Tracks on Mars