British scientists yesterday told a meeting in London that they had found new evidence, in a Martian meteorite discovered in 1979, of past life on Mars. But whereas the United States space agency's meteorite left Mars 15 million years ago, the newest findings relate to one which was blasted off its home planet just 600,000 years ago, when man had already descended from the trees.
Geologically, that could mean that any life which existed then is likely to still exist on the planet. But the new findings also strengthen the expectation that life on Mars probably consists exclusively of microscopic transparent bacteria, rather than little green men.
The latest evidence consists of "significant amounts" of organic material, according to scientists from the Open University, who examined the composition and concentrations of carbon-based molecules in EETA 79001, a 1.3 billion- year-old piece of rock.
Within it, the scientists found evidence of complex hydrocarbons - the sort of "organic soup" that can be produced when living material is subjected to high pressures and temperatures.
"We looked at individual grains in the rock, and analysed the carbon molecules," Dr Ian Wright, of the Open University's geology department, said. "We found concentrations of those molecules which can only have been produced by microbial activity."
The findings have yet to be formally published but are sure to be taken up eagerly by Nasa, which has been trying to add to the air of excitement around the launch on 6 November of a spacecraft which will arrive at Mars next year. Another Nasa spacecraft, to be launched in December, will land on the planet near one of the poles and could search for signs of life, though it does not have the range of on-board experiments that scientists would wish for.
However, the Nasa findings have already been called into question by scientists who say that the "microfossils" observed in that meteorite could have occurred through inorganic processes. The team at the Open University had previously examined the Nasa meteorite - known as ALH 84001 - without concluding that it contained signs of life. The question of whether the original announcement was correct is still unclear.
The latest news emerged at a meeting of scientists to discuss the possibility of extraterrestrial life, hosted by Science Minister Ian Taylor. They also heard what was described as further evidence of life from ALH 84001. Tiny amounts of carbonate from the rock were said to contain a component whose composition suggested it was formed from methane produced by micro- organisms. The composition also matched values measured for organic matter in rocks where Earth's oldest fossils - 3.87 billion years old - have been found.Reuse content