MER Rover Artist Concept

NASA's twin robot geologists, the Mars Exploration Rovers, will launch toward Mars in 2003 in search of answers about the history of water on Mars. The rovers will be targeted to sites that appear to have been affected by liquid water in the past. They will drive to various locations to perform on-site scientific investigations over the course of their 90-day missions. This mission is part of NASA's long-term effort of robotic exploration of the red planet.