The total distance driven on Mars by NASA's Mars Exploration Rover, 21.35 miles by early December 2011, is approaching the record total for off-Earth driving, held by the robotic Lunokhod 2 rover operated on Earth's moon by the Soviet Union in 1973. Lunokhod 2 drove 23 miles. NASA's astronaut-driven Apollo 17 Lunar Roving Vehicle drove 22.30 miles during the Apollo 17 mission to the moon in 1972.
The chart also indicates driving distances for two earlier Apollo lunar rovers, one earlier Lunokhod, NASA's Mars Exploration Rover Spirit (Opportunity's twin) and the first rover on Mars, NASA's Sojourner.
NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover project for the NASA Science Mission Directorate, Washington.