Among other achievements, Spirit (illustrated here) provided evidence that Mars was geological active, and had once hosted water hospitable to life. Credit: NASA/JPL-Caltech
Following in the wheelmarks of Sojourner (NASA’s first Mars rover, which landed on Mars in 1997), Spirit launched for Mars on June 10, 2003, and Opportunity launched less than a month later, on July 7. Both would land in January 2004 and begin observations that would stretch far beyond the planned 90-day mission: Spirit was active until 2011, and Opportunity finally closed its eyes in 2018. Over the course of the 28 miles (45 kilometers) of martian terrain that Opportunity covered, the rover provided clear geological and mineral evidence of Mars’ past status as a water world.
