NASA is stepping up efforts to regain communications with the Mars rover Spirit before spring ends on southern Mars in mid-March, the Jet Propulsion Loboratory (JPL) said on Tuesday, Xinhua reported.
NASA lost communications with Spirit after it sent back last signals nine months ago.
"The amount of solar energy available for Spirit is still increasing every day for the next few months," said Mars Exploration Rover Project Manager John Callas of JPL, Los Angeles. "As long as that's the case, we will do all we can to increase the chances of hearing from the rover again."
But after mid-March, prospects for reviving Spirit would begin to drop, according to JPL. Southern-Mars spring began in November 2010.
Communication strategies would change based on reasoning that Spirit's silence is due to factors beyond just a low-power condition, JPL said, adding that mission-ending damage from the cold experienced by Spirit in the past Martian winter is a real possibility.
Spirit landed on Mars Jan. 4, 2004 for a mission designed to last for three months. After accomplishing its prime-mission goals, Spirit worked for more than five years in bonus-time extended missions.
The rover's motors worked far beyond their design life, but eventually, Spirit lost use of drive motors on two of its six wheels, leaving it unable to obtain a favorable tilt for solar energy during the rover's fourth Martian winter, which began last May, JPL said.
The rover team had anticipated that Spirit would enter a low- power fault mode with minimal activity except charging and heating the batteries and keeping its clock running.
With most heaters shut off, Spirit's internal temperatures dipped lower than ever before on Mars. That stress could have caused damage, such as impaired electrical connections, that would prevent reawakening or, even if Spirit returns to operation, would reduce its capabilities, according to JPL.
Spirit and its twin, Opportunity, which landed three weeks after Spirit and is still active, both have made important discoveries about wet environments on ancient Mars that may have been favorable for supporting microbial life.