MARS PROBE: Anxious scientists now believe that their best chance of getting in touch with Beagle 2 - the spacecraft so far stubbornly silent on the surface of Mars - is on January 4th, when its mothership passes overhead.
Right now, the European Space Agency's Mars Express is in a huge elliptical orbit around the red planet. Its engines will fire for three minutes tomorrow and the craft should slip into a polar orbit, passing regularly over Beagle.
"We haven't yet played all our cards," said Mr David Southwood, the space agency's director of science. "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."
Beagle, the lander designed to search for signs of life on Mars, reached the planet on Christmas Day after a 250-million-mile journey, equipped with a transmitter about as powerful as a mobile phone.
Since then - and assuming it landed in one piece - it may have been fitfully trying to relay a message back to Earth via a Nasa spacecraft, Mars Odyssey, perhaps mis-timing its call on each overhead pass.
Beagle was meant to be a pioneer and a scene stealer, but from Sunday it will have to share the limelight. January 4th is the day the full-scale assault on Mars begins. Mars Express itself carries a camera which will photograph the Martian landscape to a resolution of two metres - small enough to spot Beagle's discarded parachute or the airbags that should have cushioned its fall - and radar that can penetrate up to three miles below the Martian surface, to detect underground rivers, aquifers and permafrost.