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
Scientific information from the Mars Exploration Rover mission made during a press conference, where mission scientists listed a number of observations that strongly support this view: Detailed analysis of environmental, chemical, and mineralogical data taken from the Opportunity rover led to the elimination of the competing hypotheses, and the confirmation of the conclusion that the spherules were formed in place as post-depositional sedimentary concretions from an aqueous source On March 23, 2004, NASA announced that they believe that "Opportunity" had not landed in a location merely "drenched in water", but on what was once a coastal area. "We think "Opportunity" is parked on what was once the shoreline