Mars rover back at work after diagnosis of electrical glitch

NASA says its Mars rover Curiosity has resumed full science operations after a successful diagnosis of the likely cause of a change in voltage on the vehicle. The decision to resume science activities during the weekend came after the efforts to trace the source of the voltage change that occurred on Nov. 17, NASA's Jet Propulsion Laboratory in Pasadena, Calif., reported Monday. "We made a list of potential causes, and then determined which we could cross off the list, one by one," rover electrical engineer Rob Zimmerman at JPL said. The voltage change did not affect the rover safety or health because its electrical system has a "floating bus" design feature to tolerate a range of voltage differences between the vehicle's chassis and the 32-volt power lines that deliver electricity throughout the rover, the scientists said. They reported the likely cause is an internal short in Curiosity's power source, the Multi-Mission Radioisotope Thermoelectric Generator. Due to resiliency in design, they said, such a short does not affect operation of the power source or the rover, and testing of another example of the generator for many years found no loss of capability in the presence of these types of internal shorts.