Spirit is a robotic rover that was active on the planet Mars from 2004 to 2010. Launched on June 10, 2003, Spirit landed on Mars' Meridiani Planum on January 4, 2004, three weeks after its twin Opportunity (MER-B), also part of NASA's Mars Exploration Rover Mission, touched down on the other side of the planet. Spirit became immobile in 2009 and ceased communications in 2010. NASA ended efforts to free the rover and eventually ended the mission on May 25, 2011.[1]