Spirit, also known as MER-A (Mars Exploration Rover-A) or MER-2, was a Mars rover that operated from 2004 to 2010. Spirit spent 2208 Martian days, or 3.3 Martian years (2249 days; 6 years and 77 days), on Mars. It was one of two rovers in NASA's Mars Exploration Rover mission, managed by the Jet Propulsion Laboratory. At 04:35 on January 4, 2004, Spirit successfully landed in Gusev Crater, three weeks earlier than its twin, the Opportunity rover (MER-B). Its name was chosen through a NASA-sponsored student essay competition. In late 2009, the rover became trapped in a crater, its angle hindering the charging of its solar panels. Its last communication with Earth was on March 22, 2010.
The rover completed its planned mission of 90 Martian days (slightly fewer than 92.5 Earth days). With the help of clean-up activities, the solar panels generated more electricity. Spirit operated for more than 20 times longer than NASA mission planners anticipated, and it also recorded a distance of 7.73 kilometers (4.8 miles) instead of the planned 600 meters (0.4 miles), allowing for a more extensive geological analysis of Martian rocks and surface features. Preliminary findings from the first phase of the mission (the 90-Martian-day primary mission) were published in a special issue of the journal *Science*.
On May 1, 2009 (5 years, 3 months, and 27 Earth days after landing, 21 times the planned mission duration), Spirit became stuck in soft sand. This was not the first "stuck event" encountered on the mission. Over the next eight months, NASA carefully analyzed the situation, conducted theoretical and practical simulations on Earth, and finally programmed the rover to attempt to drive itself out of the predicament. These efforts continued until January 26, 2010, when NASA officials announced that the rover might be stuck in soft sand, but it could still continue its exploration activities in place.
The rover continued to serve as a stationary exploration platform until communication ceased on March 22, 2010 (the 2208th Martian day). The Jet Propulsion Laboratory continued to attempt to restore communication, but on May 24, 2011, NASA announced that it would no longer contact the unresponsive rover and declared the mission over. Shortly thereafter, NASA held a formal farewell ceremony at its headquarters.
