By Tom Beal

Tucson, Arizona | Published: 01.11.2010

The return of sunshine to Mars' north pole brings with it a long-shot hope for resurrection of the Phoenix Mars Lander, which is presumed to have fatally frozen after being encased in dry ice during the long Martian winter.

Scientists at the Jet Propulsion Laboratory have scheduled a series of overflights this month by NASA's Odyssey orbiter, which will listen for telltale transmissions from an awakening Phoenix.

Phoenix already is a success story, NASA's Chad Edwards said. University of Arizona scientists used a suite of scientific instruments to reach out, touch and analyze "water ice" and other elements collected from the Martian surface during a five-month mission that ended in November 2008.

Nobody expects the lander to come back to life, but hey — it is called Phoenix.

"We owe it to the lander, for all the good science it did, to give it a shot," Edwards said.

Phoenix landed duringthe Martian summer, when the sun was above the horizon in the north pole for the entire day.

It continued two months past its scheduled 90 days as hours of sunlight shortened and temperatures dropped.

Now, Edwards said, the lander has been sitting in frigid temperatures and probably is encased in frozen carbon dioxide (dry ice) through a long winter. The 687-Earth-day orbit of Mars makes for much longer seasons.

No part of the lander was built to survive Mars' winter temperatures, which dip to 300 degrees below zero Fahrenheit.

But the lander is programmed to signal its survival, should it prove hardier than expected considering its engineering. As the sun begins to shine, if its solar panels are intact and capable of generating electricity and if its redundant radios and antennas haven't succumbed to the cold, it will broadcast a signal every 21 hours for a two-hour span.

It won't know the time, so it's impossible to synchronize a fly-by of the Odyssey.

NASA will send the orbiter over the landing site 30 times during a three-day period, next Monday to Jan. 21, trying to detect radiation and listening for a radio signal.

It will do the same thing, twice more, in subsequent months.

"Again, our expectation is not that the lander will be alive," Edwards said. "We want to be able to say confidently that, if it had been alive, we'd have heard it."

If Odyssey gets a signal, NASA will have to decide what to do. A signal would be no guarantee that the lander is capable of doing anything scientifically valuable, Edwards said.

"There are currently no plans to continue the mission," he said.