Description: Standing proudly is the Mars Exploration Rover on the surface of Mars. Two rovers, Spirit and Opportunity, will reach Mars in January 2004. Each has the mobility and toolkit to function as a robotic geologist. NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Mars Exploration Rover Project for the NASA Office of Space Science, Washington, D.C. Credit NASA, JPL, Cornell University Maas Digital