Moon rock, the only planetary material to have been brought back to earth by humans, could soon be outdone by Mars rock, if a plan by Nasa comes to fruition.
The United States space agency has decided that technology has become sufficiently cheap to justify landing on Mars, scooping up some of its geology and whizzing it back to earth for analysis. The trip could be done in 2005 and cost around $400 million. It would be a boon for the search for extraterrestrial life.
Nasa already has a series of trips to Mars, the Mars Global Surveyor Programme, beginning this November. But these journeys will either orbit Mars or land never to return.
The new plans were discussed at a meeting of the international Committee on Space Research, held at Birmingham University this week.
Donald De Vicenzi, chief of the life sciences division at Nasa, said: "This would be the highest priority science mission for Mars. Viking [the 1970s mission to detect life on Mars] showed us how limited we are in our capability to do research on Mars. We can't send our instrumentation up there."
John Rummel, former head of the planetary protection programme at Nasa, said: "We have to hold out the possibility that there is life on Mars. There are environments identified as probably existing on Mars where earth organisms could exist, for example organisms thousands of metres below the surface."
One drawback to the plan is that the price of protecting earth from Martian life returning with the spacecraft could be astronomical, the meeting heard.
A spacecraft landing on Mars would end up coated with Martian soil which could contain "hitch-hiker organisms" that would reach earth on the sides of the craft.
One solution would be to send up another craft that would receive the sample container, wrapping it in a "surgical gown".
Or the craft's surface could be coated with a substance that would burn up on its return.