Here we go again - Britain leads charge to Mars

British scientists will take part in an ambitious European project to dig for life under the surface of Mars using a laboratory on wheels.

The European Space Agency has earmarked about €600m (£410m) to build the ExoMars spacecraft and its six-wheeled roving robot and a further €175m to launch it in 2011.

A unique feature of the robotic laboratory is a probe that will enable it to drill up to 6ft under the Martian ground to test for signs of life with a device that has been likened to a pregnancy-testing kit.

The device - called a life marker chip - will contain biological molecules that can readily bind to other organic molecules once they come into contact.

Mark Sims, a principal investigator on the ExoMars mission at the University of Leicester, said: "Essentially, we are using biological molecules - proteins - and biological principles to look for biology.

"It will provide not only an instrument for space research but will, we hope, have many terrestrial applications," Dr Sims added.

Like pregnancy-testing kits, the device will exploit the property of some biological molecules, such as antibodies, which can selectively bind to other organic substances much like a key can turn a particular lock.

David Cullen of Cranfield University, said: "In essence, we are proposing to send hi-tech pregnancy-test type devices to Mars."

"In other words, molecular receptor-based devices that can look for multiple pieces of molecular evidence of life but the intention and expectation is not to find pregnant Martians," Dr Cullen added.

The ExoMars mission is scheduled for launch in 2011 but it will take at least two years for it to arrive at its final destination. The European Space Agency has yet to decide on the mission's final configuration, for instance whether it will have an additional orbiting spacecraft as well as the one that lands on the surface.

Nasa has two Mars missions planned during the same period. One will be launched in 2007 and the other in 2011 but neither will be able to drill more than 50cm (20 ins) below the Martian surface.

Few scientists believe life could exist on the highly irradiated surface of Mars but there is a possibility that traces of living organisms - organic biomolecules- may be preserved several feet below the surface.

Dr Sims said that if life had once evolved on Mars there is a good chance the robot laboratory of ExoMars would be able to detect signs of it with the help of its drill.

"The whole basis of ExoMars is to look for biomarkers and the signs of life. It has this drill that can go for two metres and we will be able to get at any organics that would have been degraded at the surface," Dr Sims said.

Britain's Particle Physics and Astronomy Research Council announced yesterday it is spending £1.7m on the initial research to develop the instruments and the rover for the mission.

Britain is expected to be one of the biggest funders of the mission, contributing about 17 per cent of the total cost, and British scientists are keen to take a key role in building the rover and its scientific instruments.

Professor Keith Mason, chief executive of the research council, said the UK expertise developed during the development of the highly successful Mars Express mission - despite the failure of its Beagle 2 rover - would be invaluable for ExoMars.

"Mars Express has, and still is, delivering outstanding science from orbit around the Red Planet," Professor Mason said.

"It has revealed some amazing facts about Mars and even more amazing images but we have unfinished business on the surface. To really understand the mysteries of Mars we need 'ground-truth' data and ExoMars will deliver it with the rover and base station."

Life on Mars: four scenarios

* NO LIFE

There is no life on Mars and never has been. Any attempt at searching for it will fail to find evidence of life that had evolved there, though it may find evidence of life that has arrived on Mars through other means (see below).

* A COMMON ANCESTOR

Life evolved just once in the solar system and spread from one planet or moon to another with a suitable habitat through the exchange of material ejected from bombardments by meteorites and asteroids. This would mean life on Mars and Earth had a common ancestor. The biomarkers used to detect living organisms on Earth would then be ideal for the search for life on Mars.

* INDEPENDENT DEVELOPMENT

Life on Mars evolved independently of life on Earth meaning the two lifeforms could share little, though most biologists believe all forms of life have similar needs, such as liquid water. Certain biomolecules, such as sugars or amino acids, may also therefore be common to both lifeforms.

* HUMAN CONTAMINATION

Human exploration of Mars has contaminated the planet with material that could be confused for evidence of Martian life. So the issue of life on Mars can only be resolved with a more detailed investigation, possibly a manned mission that brings samples of Martian rock back.