Mars Exploration Program (MEP) is a long-term effort to explore the planet Mars, funded and led by NASA. Formed in 1993, MEP has made use of orbital spacecraft, landers, and Mars rovers to explore the possibilities of life on Mars, as well as the planet's climate and natural resources. The program is managed by NASA's Science Mission Directorate by Doug McCuistion of the Planetary Science Division. As a result of 40% cuts to NASA's budget for fiscal year 2013, the Mars Program Planning Group (MPPG) was formed to help reformulate the MEP, bringing together leaders of NASA's technology, science, human operations, and science missions.

The Mars Surveyor 2001 project was a multi-part Mars exploration mission intended as a follow-up to Mars Surveyor '98. After the two probes of the 1998 project, Mars Climate Orbiter and Mars Polar Lander, were both lost, NASA's "better, faster, cheaper" exploration philosophy was re-evaluated, with a particular eye on the two 2001 project probes. As a result, the mission, along with the launch of its lander and rover, were canceled in May 2000, but the decision was made to continue development with its orbiter counterpart. The orbiter launched as 2001 Mars Odyssey in April 2001, in a mission independent of the Mars Surveyor project, and reached Mars in October 2001. After being placed in a cleanroom in 2001 and stored since, the nearly-completed lander component was eventually reused to fly the Phoenix mission, which launched in August 2007 and landed successfully on Mars in May 2008.