Rover's Robotic Arm ailing

A small motor in the robotic arm of NASA's Mars Exploration Rover Opportunity that began stalling occasionally more than two years ago has become more troublesome recently. Rover engineers at NASA's Jet Propulsion Laboratory, Pasadena, Calif., are diagnosing why the motor, one of five in the robotic arm, stalled on April 14 after much less motion than in the case of several earlier stalls. They are also examining whether the motor can be used and assessing the impact on Opportunity's work if the motor were no longer usable. The motor controls sideways motion at the shoulder joint of the rover robotic arm. Other motors provide up-and-down motion at the shoulder and maneuverability at the elbow and wrist. Controllers said even under the worst-case scenario for this motor, Opportunity still has the capability to doing some contact science with the arm. Opportunity and and sister rover Spirit landed on Mars in January 2004 to begin missions originally planned for three months. They have continued operating for more than four years, though each with some signs of aging.