Posted by tourdemars to Mars Exploration Rovers at June 15, 2004 11:23 PM

NASA's Mars rovers are delighting scientists with their extra credit assignments. Both rovers successfully completed their primary three-month missions in April. The Spirit rover is exploring a range of martian hills that took two months to reach. It is finding curiously eroded rocks that may be new pieces to the puzzle of the region's past. Spirit's twin, Opportunity, is also negotiating sloped ground. It is examining exposed rock layers inside a crater informally named "Endurance."