A new site being explored by the Mars rover Opportunity has yielded soil samples unlike any examined before on the red planet and that appear more favorable for life, scientists said.
Opportunity, the indefatigable robot that has been exploring Mars for seven and a half years, arrived three weeks ago at the edge of a 22 kilometer (13.6 mile) wide crater named Endeavour and has been sending back images of the surrounding environment.
The first rock it examined is a flat-topped object about the size of a foot stool that apparently was cast up by an impact that left an impression the size of a tennis court on the rim of the crater.
Called Tisdale 2, the rock "is different from any rock we've ever seen on Mars," said Steve Squyres, a Cornell University scientist who is the principal investigator for Opportunity.
"It has a composition similar to some volcanic rocks, but there's much more zinc and bromine than we've typically seen," he said at a news conference.
The observations and measurements taken by the American Martian orbiters leads scientists to believe that the rocks on the rim of the crater contain clay minerals that form in wet conditions and which are less acidic and possibly more favorable for life, they said.
A bench around the edge of the crater resembles sedimentary rock that has been cut and filled with veins of material possibly left there by water, said Ray Arvidson, another member of the team who is from Washington University in St Louis, Missouri.
During the past two weeks, researchers have used an instrument attached to Opportunity's robot arm to identify the elements that make up the rock.