Despite longshot odds, NASA will begin listening for radio signals from the Phoenix lander on Mars next week as a sheet of dry ice recedes with the onset of Martian spring.

The HiRISE high-resolution camera on NASA's Mars Reconnaissance Orbiter snapped this enhanced color image of the Phoenix landing site on Jan. 6, 2010. Credit: NASA/JPL-Caltech/University of Arizona

Ground teams last heard from Phoenix in November 2008, when the sun began dipping below the horizon at the spacecraft's landing site on Mars' northern polar plains. Phoenix's solar panels could no longer produce enough electricity to power its communications systems.

For the last 14 months, Phoenix has succumbed to a sheet of dry ice, bone-chilling temperatures and months of darkness in the depths of the Martian winter.

If Phoenix survived the extreme conditions, the lander should now be receiving enough sunlight to generate power for limited operations. If that is the case, NASA's Odyssey orbiter should be able to hear Phoenix dutifully attempting to call home.

"During these listening campaigns, we will turn on the Odyssey radio as we overfly the Phoenix site and listen for any signal being transmitted by the Phoenix lander," said Chad Edwards, chief telecommunications engineer for Mars programs at the Jet Propulsion Laboratory in Pasadena, Calif.

NASA says if Phoenix is trying to communicate, Odyssey will hear it.

"If Phoenix were alive and transmitting, we would get a very direct detection, based on the orbiter radio's telemetry, that it's seeing signal power in the UHF band that Phoenix would be transmitting at," Edwards said.

Odyssey will first try to listen for Phoenix for three days beginning Jan. 18. The orbiter will fly over Phoenix 30 times next week, monitoring communications frequencies for signals during each pass.

Two more extensive listening campaigns are planned for the middle of February and late March, according to NASA.

But NASA officials caution the chances are slim that Phoenix is still able to function.

"We think it's very unlikely that we're going to hear from Phoenix. It was certainly not designed to survive the environment that it's experienced over the winter," Edwards said.

"At the same time, we want to have a careful look to see if it survived," Edwards said.

Sunlight is currently reaching Phoenix for 17 hours during each 24.7-hour Martian day, or sol.

Artist's concept of Phoenix. Credit: NASA

"We're coming out of the winter and we're in the spring," Edwards said. "We have roughly the same illumination conditions that we did when we lost the lander. This is the first time that it really made sense to have a look."

Assuming the cold and ice did not damage the lander, Phoenix would automatically wake up when its solar panels generate enough electricity to charge its batteries.

"It would wake up in a mode where it would try to communicate with any assets overhead on a periodic basis," Edwards said.

Phoenix would wake up and transmit for two hours each day with the lander's two radios and two antennas, according to Edwards.

Odyssey flies over Phoenix every two hours and is in range of the lander for about 10 minutes during each pass.

"Assuming that the thing's there and Odyssey is able to lock on to it, we would also recover the telemetry stream that the lander would be communicating, and we would return that information to Earth," Edwards said.

Engineers may be able to determine what capabilities Phoenix still has after its winter slumber.

Phoenix landed on Mars in May 2008, beginning five months of operations that included the confirmation of the existence of water ice just below the surface.

By April, Phoenix will be in constant sunlight as summer begins. Edwards said the spacecraft would "certainly" be energy positive by then, if it is alive.

"We think the odds are very low that Phoenix has survived the winter environment," Edwards said. "But if it has, the available energy to it will be increasing over the next few months."