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
Mars sample-return mission basis for a Mars sample-return mission. In September 2012, NASA announced its intention to further study several strategies of bringing a sample of Mars to Earth – including a multiple launch scenario, a single-launch scenario and a multiple-rover scenario – for a mission beginning as early as 2018. Dozens of samples would be collected and cached by the Mars 2020 rover, and would be left on the surface of Mars for possible later retrieval. A "fetch rover" would retrieve the sample caches and deliver them to a Mars ascent vehicle (MAV). In July 2018 NASA contracted Airbus to produce a