A spacecraft is being designed which will travel to the planet to analyse the surface for signs of life. The "Beagle 2" project will cost millions of pounds, but scientists hope the lure of advertising from Mars will encourage companies to pay for the scheme.

Science Correspondent James Wilkinson reports on Beagle 2

The European Space Agency (ESA) hopes the Beagle 2 probe, which has been designed by scientists in the UK, will unlock the mystery of life on Mars.

The ESA says the cost of the project could be £25m but it is hoping to raise £45m through commercial sponsorship.

The probe, manufactured by Matra Marconi, will take soil samples from Mars

One idea is for the two giant balloons which are needed to parachute the probe onto the planet to be covered with advertising slogans.

It would be the first time adverts have been displayed on another planet and market experts estimate firms would pay between £40m and £50m.

For years scientists have argued about whether Mars could have once had an atmosphere and climate suitable for plant or even animal life.

Enigmatic planet

Last year Nasa sent the Pathfinder probe to the Red Planet. But many questions remain unanswered.

Giant balloons will parachute down and then roll across the planet

Beagle 2 is set to take off in 2003 aboard the ESA's Mars Express rocket, which will map Mars' landscape, mineral deposits and weather systems.

Beagle 2, which is being developed by Matra Marconi of Bristol in partnership with the Space Research Centre in Leciester, will be parachuted onto the surface of the planet.

Its petal-like solar panels will power an electronic mole which will push itself into the surface to take earth samples.

This would be analysed by instruments, such as a mass spectrometer, inside the tiny, unmanned probe. A robot arm will be able to pick up larger rocks.

The tiny Beagle probe will cost £25m to launch

Roger Bonnet, of the European Space Agency, said: "This lander, with its capacity to analyse in situ the possible existence of life on the Red Planet, either active life or past life, is an extraordinary element in the success of this project."

Project leader Professor Colin Pillinger, of the UK's Open University, is convinced the conditions on Mars are "appropriate for life".

But he added: "It does not mean that life is there or that it was there."

Professor Pillinger believes Beagle 2 is extremely important for the ESA but also for the UK's scientific community.

He says: "If Britain could be the first nation, other than a super-power, to land on a planetary surface and demonstrate it has the scientific and technological capacity to look for things like the evidence of past life then that ultimately could stimulate a great number of people to follow scientific careers."