NASA’s Opportunity Mars rover, which landed on the Red Planet in 2004, now holds the off-Earth roving distance record after accruing 25 miles (40 kilometers) of driving, and is not far from completing the first extraterrestrial marathon. The previous record was held by the Soviet Union’s Lunokhod 2 rover. “Opportunity has driven farther than any other wheeled vehicle on another world,” said Mars Exploration Rover Project Manager John Callas, of NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California. “This is so remarkable considering Opportunity was intended to drive about one kilometer and was never designed for distance.”
http://science.nasa.gov/science-news/science-at-nasa/2014/28jul_oppy/