Science and Technology Wimax

Nasa's Mars Odyssey orbiter is set to listen for possible radio transmissions from the Phoenix Mars lander, to check if it has survived the Martian winter.

The agency said that communication from the lander was "extremely unlikely".

Phoenix's last communication was on 2 November 2008, after it completed its study of an arctic Martian site.

Since then, this landing site has gone through autumn, winter and part of spring, and Phoenix was not designed to survive such temperature extremes.

Its electronics are likely to have broken up as temperatures plummeted.

But, just in case, Odyssey will pass over the Phoenix landing site approximately 10 times each day during three consecutive days of listening, beginning on 18 January.

It will undertake two longer "listening campaigns" in February and March.

Chad Edwards, chief telecommunications engineer for the Mars Exploration Programme at Nasa's Jet Propulsion Laboratory in Pasadena, US, said: "If Phoenix is transmitting, Odyssey will hear it.

"We will perform a sufficient number of contact attempts that if we don't detect a transmission from Phoenix, we can have a high degree of confidence that the lander is not active."

Dr Tom Pike from the UK's Imperial College, in London, led the development of Phoenix's microscopy station, one of the only instruments that will still be functional if the lander comes back to life.

He told BBC News that the major concern was that the batteries would "not have held out through the winter".

Dr Pike explained that temperatures had plummeted as low as minus 120C during the winter - cold enough to form a carbon dioxide snow.

"The batteries were not designed to withstand those temperatures," he said. "I think it's highly unlikely they have survived, and I think that's going to be the break point.

"If it does come back up, I will be very surprised - very pleasantly surprised. I think we will beg, steal or borrow the money to get back out to Arizona, into mission control and back into our old seats to get the show on the road again."

The solar-powered Phoenix landed in May 2008, in the middle of the Martian summer, when the Sun never set at its polar landing site.

During its ground operations, the robot dug up and tested the Martian soil to see whether it had ever been capable of supporting life.

Probably its biggest achievement was in becoming the first Mars mission to "touch water" in the form of the ice it found just below the topsoil.