The Mars Exploration Rover Mission
Spirit and Opportunity are identical twin robotic rovers that have gone far beyond their original scientific
objectives to rewrite our understanding of the early history of Mars. NASA sent these two “robotic geologists”
on a 90-day mission to search for geological clues
regarding environmental conditions on early Mars, and
assess whether those environments were conducive to
life. The mission team chose two landing sites, Gusev
Crater and Meridiani Planum, for the likelihood that
liquid water, a prerequisite for life, was once present
there.
Each rover far outlasted its design lifetime. Spirit
launched June 10, 2003, and landed in Gusev Crater
on January 4, 2004. Opportunity launched July 7,
2003, and landed in Meridiani Planum on January 25,
2004. Opportunity continues to operate in its tenth
year. Spirit’s final communication to Earth occurred on
March 22, 2010, about six years into its mission. The
rover lasted 20 times longer than its original design.
During their journeys of exploration, Spirit and Opportunity outperformed even the most optimistic expectations of their builders. For scientists studying Mars, the
robotic rovers proved to be the next best thing to actually being there with geology tools in hand. The tenyear record of discoveries compiled during the mission
has helped scientists reconstruct a past when Mars
was awash in water, which may have created environments favorable for microbial life.