Scientists have launched a full-scale post-mortem as hopes of finding the lost British Mars probe faded even further today.
As a desperate last resort, an attempt will be made to "reboot" the craft with a command signal transmitted by the American Mars Odyssey orbiter.
But Beagle 2's chief scientist Professor Colin Pillinger admitted that it was a very long shot.
New attempts to hail the lander by its Mars Express mother ship failed over the weekend.
Mars Express made two passes of the probe's landing site but heard nothing. No sign of a transmission from Beagle 2 was detected at the Jodrell Bank radio telescope in Cheshire either.
Earlier, scientists imposed a radio silence to try to force Beagle 2 into an emergency communication mode which would keep its transmitter on most of the time.
Announcing the result of the search today, Prof Pillinger said: "I don't intend to beat about the bush, but simply tell you right from the start that we haven't found Beagle 2 despite three days of intensive searching covering all the angles that we could view the Martian surface, from orbiting round Mars using Mars Express and Odyssey, and all the time that we could believe that Beagle might have been broadcasting from Mars, using the Jodrell Bank telescope.
"None of these techniques actually delivered anything that we could interpret as a signal.
"Under those circumstances I think we have to begin to accept that Beagle 2, if it is on the Martian surface, is not active."
Scientists are now sifting through all the Beagle 2 data obtained since the mission's launch seven months ago in the hope of finding out what went wrong.
The landing site at Isidis Planitia, a low, flat basin that was supposed to be relatively risk-free, is also being reassessed.
Two long lists are being drawn up, one showing what might have gone wrong and the other what could be done differently on a future mission. Prof Pillinger said: "I think we have to look at the future. Let's not grieve.
"It's back to the bottom of the hill and pushing up the boulder again."
PA