Radar survey aims to solve mystery of Mars's water

A European spacecraft bound for Mars in June will "feel" miles below the surface of the red planet for ice and water.

It will also launch a little British lander, roughly the size of a backyard barbecue, which will bounce down just north of the equator and burrow into the Martian topsoil in search of chemical evidence of life.

Mars Express and Beagle 2 - the orbiter and the lander - will arrive with a package of sophisticated instruments at the end of 2003, roughly at the same time as a Nasa probe which will drop two robot rovers on to the surface.

Augustin Chicarro, of the European Space Agency, is relying on ground-penetrating radar, which will be blinded by the Martian atmosphere during the day, but pierce up to five kilometres (three miles) into the soil each night.

Like seismic instruments which sense for oil, it should be able to detect moisture-bearing strata. In the course of a year, it should have probed every inch of the planet.

"We knew that Mars was a totally different place a long, long time ago," Mr Chicarro said. "When life started on Earth 3.8bn years ago, the two planets had water, a thick atmosphere and warmer climate. Suddenly, Mars changed and became a cold, hostile place.

"We don't know why it happened, but there are traces of all that water on the surface of Mars. We would like to know if it escaped into space or [if] its remains are buried.

"These are the two main thrusts of the mission: to make an inventory of water with the orbiter instruments, but also to shed light on the possibility of life having formed on Mars." The orbiter will be the relay station for data sent from the probe on the ground.

Beagle 2 was proposed by Colin Pillinger of the Open University six years ago, after a Nasa team claimed that a meteorite known to have come from Mars contained what might be fossil bacteria.