Los Angeles: The prospect of ever hearing from the stuck Mars rover Spirit is fading after it failed to respond to repeated calls from Earth.
Despite the dismal outlook, Nasa will make a last-ditch effort to communicate with Spirit, which fell silent a little over a year ago. If there's still no contact in the next month or so, the space agency will scale back its listening campaign for Spirit and focus on its healthy twin, Opportunity.
That Spirit has not called home suggests that something is more seriously wrong than just a power issue, said programme manager John Callas at the Nasa Jet Propulsion Laboratory in Pasadena, California.
The solar-powered rover became bogged in a sand trap in April 2009 during a routine drive. Despite efforts to wiggle free, it remained stuck and could not tilt itself toward the sun as the Martian winter approached. Without an adequate amount of energy reaching its solar panels, it went into hibernation last March. Engineers had expected Spirit to wake up once there was maximum sunlight where it's trapped. But summer solstice in southern Mars came and went earlier this month with no response.
Ray Arvidson, of Washington University in St Louis, said odds were less than 50-50. Still, he stood by attempts to call it.
"I would be surprised if we re-establish communication, happy but surprised," said Arvidson, a mission deputy principal investigator.
Backup transmitter
Ground controllers are paging Spirit over a range of frequencies and at various times in case its internal clock stopped working and it lost track of time. They're also commanding the rover to turn on its backup radio transmitter in case the main one died.
Nasa will have to declare Spirit lost if there's no word. When that happens, efforts will be reduced to sporadic listening, Callas said.
Spirit and Opportunity parachuted to opposite sides of Mars in 2004. Both have worked beyond their original, three-month mission during which they discovered geologic evidence of water on the red planet.