Mars rover to regain contact. Mars 2, Mars 3 were physically tethered probes; "Sojourner" was dependent on the Mars Pathfinder base station for communication with Earth; MER-A & B and "Curiosity" were on their own. Of these "Curiosity" is still active, and "Spirit", "Opportunity" and "Sojourner" completed their missions before losing contact. Seven rovers have been dispatched to Mars: "Examples Landed instrumentation" (Rovers) Mars rovers in development include: One experimental design, not proposed for any actual mission, is: NASA distinguishes between "mission" objectives and "science" objectives. Mission objectives are related to progress in space technology and development processes. Science objectives are met
Spirit (rover) to attempt to regain contact until May 24, 2011, when NASA announced that efforts to communicate with the unresponsive rover had ended, calling the mission complete. A formal farewell took place at NASA headquarters after the 2011 Memorial Day holiday and was televised on NASA TV. The Jet Propulsion Laboratory (JPL), a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover project for NASA's Office of Space Science, Washington. The primary surface mission for "Spirit" was planned to last at least 90 sols. The mission received several extensions and lasted about 2,208 sols. On August