The McKay group has promised fresh research in the coming months to bolster their increasingly isolated position. Until they do, the conclusion of many scientists will be that, although they accept the possibility of life on Mars, the ALH84001 meteorite has failed to answer the key question - are we alone in the universe?The Storyof ALH84001THE METEORITE was the first to be found in the Alan Hills area of Antarctica in 1984 - which accounts for its code name. If the public is confused, the news media are more responsible for that confusion than the scientists who are trying to understand this question,'' Professor Zare said.Nevertheless, it is probably fair to say that there are now more sceptics about the ALH80001 question among the scientific community than there were two years ago. In the last few months, the pendulum has swung and the coverage has become overly sceptical. If there has been any public misunderstanding then the news media, rather than the scientists, are to blame.

''At first, the news media were probably too believing in our hypothesis Many ignored the caveats that we voiced repeatedly. ''I feel the sides are moving further apart rather than trying to resolve the issue. They simply have to start considering that their original claims were very inconclusive.''Richard Zare, professor of natural science at Stanford University and a member of the McKay team, said the original arguments for life on Mars were only a hypothesis ''This hypothesis remains unproved and untested,'' he said. The original authors have gone out of their way to criticise their critics instead of producing other new evidence to back up their claims,'' Professor Bada says. Dozens if not hundreds of research papers have been published detailing every turn in the debate with each claim followed by a riposte Yet the Nasa and Stanford scientists have held their ground.

The rock ALH84001, they insist, bears the best evidence to date that there is, or once was, extra-terrestrial life.Debates between the two opposing camps have taken place at several scientific conferences this summer with little or no consensus being reached. ''Unfortunately this has polarised the scientific community and this is not good for the public perception of the life on Mars debate. Other scientists said they were effectively an optical illusion and had nothing to do with biology.The other bits of the jigsaw were also attacked. Ed Scott says the carbonates could only have been formed under very high temperatures - too high to have a biological origin. Jeffrey Bada said the PAHs had resulted from terrestrial contamination rather than coming from Mars, and John Kerridge, a chemist at the University of California, San Diego, dismissed the magnetite evidence because these crystals are so ubiquitous that they were almost certainly not deposited by living organisms.Each line of criticism has itself generated its own criticism with the result that all but a few have been able to follow the arcane nature of the dispute.