PASADENA, Calif. - NASA engineers say a balky arm on one of the Mars rovers has worsened recently.
Last week, a tiny motor in Opportunity's arm that controls the sideways motion of the shoulder joint stopped working while the robot was exploring an inner crater slope. The failure meant that the rover could not extend its arm.
The shoulder motor, one of five in the robotic arm, has stalled several times since 2005 and usually starts up again by applying voltage.
Engineers are studying whether the motor is still usable. Project manager John Callas of NASA's Jet Propulsion Laboratory said Wednesday the rover would still be able to do science without the motor.
Opportunity and its twin Spirit have been exploring Mars since landing in 2004.
