The terrain that Opportunity is crossing has been steadily getting more wavy. After a long drive southward from “Voyager” crater, Opportunity’s right-front steering motor stalled out on sol 433 during an end-of-drive turn. While performing tests to help the team diagnose the condition of that motor, the rover also continued to make remote-sensing observations. Testing in sol 435 did show motion in the steering motor, but analysis is still underway. The rover resumed normal science and driving operations on sol 436, but with restrictions on use of the right-front steering motor. It drove 30 meters on sol 437. Opportunity and Spirit are capable of driving with one or more steering motors disabled, though turns would be less precise. The latest revision in flight software on both rovers, uploaded in February, gives them improved capabilities for dealing with exactly this type of condition. It gives them upgraded ability to repeatedly evaluate how well they are following the intended course during a drive, and to adjust the steering autonomously if appropriate.
Original Source: NASA/JPL News Release