The first attempts to listen for beeps of life from NASA's long-frozen Phoenix Mars Lander have found only silence, though scientists aren't holding their breath.
NASA's Mars Odyssey spacecraft flew over Phoenix's landing site in the Martian arctic 30 times this week on the off chance that the spacecraft was able to send a signal back to Earth. So far, Phoenix remains silent.
At NASA's Jet Propulsion Laboratory in Pasadena, Calif., spokesman Guy Webster said that Mars Odyssey did not hear a single peep. "It's not a 'Hey, are you there?'" Webster told Space.com of the effort. "It's just listening."
Phoenix has been dormant since November 2008, when it completed a nearly five-month mission to dig for buried water ice near the Martian north pole. The harsh cold of winter on Mars, as well as the season's dwindling levels of sunlight, sent Phoenix into a deep freeze.
It is extremely unlikely that Phoenix's systems survived the cold, long Martian winter, but engineers equipped the probe to try to call Earth just in case it wakes up. Phoenix is programmed with a so-called "Lazarus mode" that would reboot the spacecraft once its power-generating solar arrays have collected enough sunlight.
With winter now turning to spring on Mars, NASA is waiting to see if enough of Phoenix's systems survived to allow it to phone home. The $475 million lander's systems were not designed to withstand the severe cold of Martian winter.
Recent images of the lander taken by NASA's Mars Reconnaissance Orbiter have shown the probe blanketed in frost on an arctic plain dotted with patches of carbon dioxide ice and bare ground.
Webster told Space.com that this week's campaign won't be the last of NASA's efforts to revive Phoenix.
Longer listening campaigns are planned in February and March, when the sun will have climbed higher in the Martian sky above Phoenix's landing site. For those efforts, Odyssey will actually transmit radio signals that could be picked up by Phoenix if it has revived.
Phoenix landed on Mars on May 25, 2008, and began what was planned as a three-month mission to search for buried Martian water ice and study the planet's surface and polar weather. The probe confirmed the presence of water ice just beneath the surface and lasted two months longer than expected.
NASA cannot listen for the probe indefinitely. Scientists have had to trade away observation time on Odyssey in order to dedicate the orbiter to scan for Phoenix signals.
"It's not a freebie," Webster said. "There is some science that's not being performed."
This report was updated by msnbc.com.