The rover's arm suddenly stopped working on Feb. 27 as it was in the middle of transferring rock powder from the drill on its arm to instruments inside its body that were designed to analyze the powder, NASA reported this week.
The shutdown was caused by fault-protection mechanisms that kicked in as a response to a "transient" short circuit, communications from the rover showed.
The rover's explorations have been put on hold and its arm remains immobilized while NASA runs tests to figure out where the short is and how serious it is.
In some cases, it might have "little effect." In others, the rover team may have to "restrict use of a mechanism," NASA says, suggesting that the rover might have to scale back some of its activities.
The U.S. space agency noted that the same activity that the rover was doing at the time of the short circuit had been completed smoothly five times in the past two years.
Curiosity is on a mission to figure out if Mars ever had the conditions to support microbial life. So far, its findings suggest that the answer is yes, based on evidence of water on the surface of Mars in the past, such as a large freshwater lake and a fast-flowing stream. The rover's recent findings suggest that a warm, wet period on Mars occurred more recently and that its lakes could have lasted longer than previously suspected.