On Jan. 3, NASA’s Mars Exploration Rover Project will deliver the first mobile laboratory to the surface of Mars. The rover will perform robotic geological fieldwork that may reveal a history of water on Mars. Engineers at NASA’s Jet Propulsion Laboratory (JPL), Pasadena, Calif., have navigated the first rover, Spirit, to arrive at Mars at approximately 11:35 p.m. EST Jan. 3. Three weeks later, the second rover, Opportunity, will reach the Meridiani Planum, a region containing exposed deposits of a mineral that usually forms under watery conditions.