Mars Exploration Rover
Objectives
On May 1, 2009, during its fifth mission extension, Spirit became stuck in soft soil on Mars. After nearly nine months of attempts to get the rover back on track, including using test rovers on Earth, NASA announced on January 26, 2010 that Spirit was being retasked as a stationary science platform. This mode would enable Spirit to assist scientists in ways that a mobile platform could not, such as detecting "wobbles" in the planet's rotation that would indicate a liquid core. Jet Propulsion Laboratory (JPL) lost contact with Spirit after last hearing from the rover on March 22, 2010 and continued attempts to regain communications lasted until May 25, 2011, bringing the elapsed mission time to 6 years 2 months 19 days, or over 25 times the original planned mission duration.
Mars Exploration Rover-5