NASA Twin Mars Rovers Marks 8 Pioneering Years on Mars

Two NASA robots a world away are marking eight years on the surface of Mars. The golf-cart-size Spirit rover landed on the Red Planet eight years ago on January 3. Its twin, Opportunity, touched down three weeks later, on January 25, 2004. The two robots were originally supposed to spend 90 days searching for signs of past water activity on Mars. They found plenty of such evidence, dramatically reshaping scientists’ understanding of the Red Planet and its history. And the rovers just kept chugging along, continuing to make observations years after their warranties expired. NASA declared Spirit dead just last year, and Opportunity is still going strong. Between them, the twin  robots  have  covered  26.15  miles (42.08 kilometers) on the  Martian  surface to date, with Opportunity racking up the lion’s share (21.35 miles, or 34.36 km). 

After a three-year trek, Opportunity made it to the 14-mile-wide (22-km) Endeavour Crater in August 2011. The robot has spent the last few months poking around Endeavour‘s rim, where it recently uncovered what researchers say is the best evidence yet for liquid water on ancient Mars. Over the next few months, the rover team also plans to track radio signals from Opportunity, using the robot’s movement as a proxy for the rotation of Mars. Scientists can thus get very precise measurements of the planet’s spin, which could reveal information about Mars’ interior structure. According to researchers Opportunity should be ready to rove again by June or Jul. While the robot is showing some signs of its advanced age, such as an arthritic shoulder joint in its robotic arm, there’s no reason to think it won’t hit the ground running.
source:www.space.com