Mothership gives Beagle probe one last push for Mars

The Beagle 2 space probe has been given a final rocket thrust to send it straight to Mars in its quest to find the first definitive signs of extraterrestrial life. Scientists confirmed yesterday that the Beagle 2's mother ship,Mars Express, received the final commands that have propelled it on a collision course with the Red Planet.

Mars Express, which was launched on 2 June, was, until this week, aimed slightly away from Mars to avoid crashing into the planet and contaminating its surface if anything went wrong. Now the spacecraft and the Beagle 2 are due to arrive at Mars on Christmas Eve but, whereas Mars Express will go into orbit, Beagle 2 is programmed to land on the planet's surface, where it will search for the chemical signature of life.

Mars Express is taking nearly seven months to travel the 70 million kilometres (43.5 million miles) to the Red Planet. It still has about 20 million kilometres to go to its final destination. A key moment for the mission is scheduled for 19 December, when the Beagle 2 is gently jettisoned fromMars Express by a "spin and eject" mechanism similar to the spin used to stabilise a rugby ball in flight.

John Reddy, the principal electrical systems engineer for Mars Express, said that, if Beagle 2 failed to separate, the rest of the mission would be jeopardised. "We don't think it can go wrong. All the mechanisms have been thoroughly tested and we are convinced that we've done everything we can to maximise the possibility of ejecting the Beagle."

Beagle 2, which is about the size of a large garden barbecue, is packed with instruments powered by solar arrays that are designed to open up like a pocket watch within moments of arriving on Mars.

It is due to land in an impact crater called Isidis Planitia in the northern hemisphere of Mars, where the Martian spring is beginning to turn into summer, helping to ensure a plentiful supply of solar energy for the scientific tests.

A second key moment will be on Christmas morning when scientists at the National Space Centre in Leicester will try to detect the first radio call sent from Beagle 2 via a second spacecraft orbiting Mars. Once contact has been established, scientists, led by Professor Colin Pillinger of the Open University, can begin the battery of experiments intended to detect the chemistry of life, such as the presence of methane in the Martian atmosphere or of minerals called carbonates in the pores of rocks. He said: "We are dealing with the magnetic question of, 'Is there life on the second planet of the solar system'. We're talking about the possibility of not being alone in the universe."

The mission is meant to last about 180 days. Scientists are unlikely to make any discoveries until Beagle 2's instruments begin to take measurements up to four days after the landing.