The prospects for the Beagle 2 lander on Mars look increasingly gloomy after a radio sweep of the planet failed to detect any sign of the UK-built probe.
Jodrell Bank can scan a large area of the Martian surface
The Jodrell Bank telescope in Cheshire scanned Mars for two hours late on Thursday, but no signal was picked up indicating the lander was alive.
Scientists remain optimistic despite the silence and further efforts will be made to contact Beagle on Friday.
The big fear is the probe could have crashed into the Martian surface.
"Jodrell Bank listened out for Beagle 2 tonight, but did not detect a transmission," said team spokesman Peter Barratt.
Nasa's Mars Odyssey craft will pass over the landing zone at 1815 GMT on Boxing Day.
The US space agency orbiter has already tried once to hear a transmission from Beagle - and failed. Researchers must hope it has better luck on the second fly-over.
WHY MIGHT BEAGLE NOT CALL?
A computer glitch has delayed the transmission
Perhaps the probe has a misaligned antenna
There was some catastrophic failure during landing
Beagle made it down but fell into a crevasse
The Beagle 2 lander was supposed to have dived into the Martian atmosphere at 0245 GMT on Christmas Day and reached the surface about seven minutes later; its impact softened by parachutes and gas-filled bags.
The scientific team are expecting a pre-planned signal from the disc-shaped robotic probe, informing Earth it survived the fiery entry.
A picture of itself and the surrounding terrain should also be among the early data returns.
Even if Mars Odyssey fails on Friday to capture and relay the Beagle transmission, the search for the British lander will go on.
Both Jodrell and Odyssey will have other opportunities in the coming days to sweep the Martian surface for signs of the 70-kg robotic probe.
In addition, the Beagle team have been offered the services of another large radio telescope at Stanford in California to assist the search.
COST OF BEAGLE 2
Total cost: Between £35m and £40m
Numerous private companies have invested in the project
Underwritten by European Space Agency and UK's Department of Trade and Industry
And Mars Express (Beagle's mothership) should also be in position soon to try to make contact with its "baby".
The success of Mars Express in obtaining an orbit around the Red Planet has certainly cheered European scientists as they endure the agony of waiting for word on Beagle.
Controllers at the European Space Agency's (Esa) operations centre at Darmstadt, Germany, clapped and hugged each other when a big screen showed blips indicating they had regained the orbiter's data feed after it emerged from behind Mars following its first circle.
"At least the initial checks show that the spacecraft is in very good condition," said flight director Michael McKay.
The orbit of Mars Express must now be refined so it can take up its science mission - and make contact with Beagle if it truly is operational on the surface.
"The arrival of Mars Express is a great success for Europe and for the international science community. Now, we are just waiting for a signal from Beagle 2 to make this Christmas the best we could hope for," said David Southwood, head of Esa's science directorate.
Mars Express is the major part of the European mission - Beagle was a late add-on - and will search for water, ice and key chemicals buried under the Martian surface.
It has a powerful stereo camera system which could in early January, if all else fails, search the planet for signs of Beagle's parachutes and airbags.
Beagle scientists will update the media on their search for the lander on Friday morning, London time.