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 landing heat flow from the deep interior of Mars, was launched on May 5, 2018. It landed successfully in Mars's Elysium Planitia on November 26, 2018. Additional future missions are the Mars 2020 rover, the Chinese Mars Global Remote Sensing Orbiter and Small Rover, and the Indian Mars Orbiter Mission 2 orbiter. The ESA ExoMars rover, also planned for launch in 2020, should obtain soil samples from up to 2 meters depth and make an extensive search for biosignatures and biomolecules. There is a proposal for a Mars Sample Return Mission by ESA and NASA, but this has been delayed until