Further opportunities to scan for a signal from Beagle 2 will be undertaken over the coming days. Tonight the radio telescopes at Jodrell Bank and Stanford University in California will again listen for the carrier signal from Beagle 2, while the next Mars Odyssey pass will take place tomorrow evening at 18.57 GMT.

Meanwhile, scientists are eagerly awaiting the arrival of the European Space Agency's Mars Express spacecraft in its operational polar orbit on 4 January. Mars Express was always intended to be the prime communication relay for Beagle 2, and the lander team is hopeful that a link can be established at that time if it has not already been achieved with Mars Odyssey.

"We need to get Beagle 2 into a period when it can broadcast for a much longer period," said Professor Colin Pillinger, Beagle 2 lead scientist. "This will happen around the 4th January after the spacecraft has experienced a sufficient number of communication failures to switch to automatic transmission mode."

Both Professor Pillinger and Professor David Southwood, ESA director of science, agreed that the best chance to establish communication with Beagle 2 would now seem to be through Mars Express.

At present, Mars Express is far from the planet and preparing to fire its engines for a major trajectory change that will move it into a polar orbit around the planet. "We haven't yet played all our cards," said Professor Southwood. "With Mars Express we will be using a system that we have fully tested and understand."

"At the moment, I am frustrated rather than concerned," he added.

One possible cause of the communication failure is that the clock on Beagle 2 may have been reset as the result of a computer glitch. An attempt was made to reset the clock during this morning's Odyssey pass, the first to take place during daylight hours at the Beagle 2 landing site. The outcome of this "blind command" is still awaited.

Meanwhile, specialists at the Lander Operations Control Centre continue to investigate other potential reasons for the failure of Beagle 2 to call home, including a possible landing off course, a tilting of the spacecraft and a problem in fully opening the solar arrays which could result in a blockage of the weak signal from Beagle's antenna.

Future opportunities to communicate with Beagle 2 are listed on the Beagle 2 Web site. The results of these sessions will be announced on the Beagle 2 and PPARC Web sites as soon as they are available.

The next press briefing will be held in the Beagle 2 Media Centre at 08.30 GMT on Monday, 29 December, when Lord Sainsbury, Minister for Science and Innovation, will be a principal speaker.