NASA said May 24 that it is ending attempts to regain contact with the Spirit Mars Exploration Rover, which fell silent in March 2010.

A transmission that ended May 25 was the last in a series of attempts NASA has made to communicate with the rover during the last 10 months. NASA officials had been holding out hope that Spirit would reawaken as the sunlight reaching its solar arrays increased after an especially stressful martian winter without much sunlight. Without enough energy to run its on-board heaters, NASA said, the rover likely experienced colder internal temperatures last year than in any of its six prior years on the planet.

NASA said that recent assessments have shown a very low probability of regaining contact with Spirit. Communications assets that NASA has used in its attempts to raise Spirit, including the agency’s Deep Space Network of antennas and two NASA Mars Orbiters that can relay communications, are needed to prepare for the Mars Science Laboratory mission launching late this year.

“We’re now transitioning to support the November launch of our next generation Mars rover, Curiosity,” Dave Lavery, NASA program executive for solar system exploration, said in a statement. “However, while we no longer believe there is a realistic probability of hearing from Spirit, the Deep Space Network may occasionally listen for any faint signals when the schedule permits.”

Spirit landed on Mars in January 2004 for a mission designed to last three months. For the next five years, Spirit drove across the martian surface examining rocks and surface features before becoming mired in soft sand in May 2009.