NASA's Mars Exploration Rover (MER) scientists gather to pay tribute to the Mars rover Spirit Tuesday, July 19, 2011, at NASA's Jet Propulsion Laboratory in Pasadena, Calif. From left are project ... more 
NASA's Mars Exploration Rover (MER) scientists gather to pay tribute to the Mars rover Spirit Tuesday, July 19, 2011, at NASA's Jet Propulsion Laboratory in Pasadena, Calif. From left are project manager and space craft mission director Pete Theisinger, staff mechanical engineer Kobie Boykins, and flight system engineer Daniel Limonadi. NASA's Mars rover Spirit operated on the surface for six years. In May, NASA declared Spirit dead after it had not responded to commands for more than a year. (AP Photo /Damian Dovarganes) less 
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Associated Press
Tue, Jul 19, 2011 10:20 PM EDT