Three months after a U.S. team announced that they had found hints of ancient life on Mars, a group of British scientists has seconded the claim. The original hints consisted of carbon compounds, minerals, and tiny fossil-like structures in a meteorite that came from the Red Planet. At a news conference today in London, Colin Pillinger, an astronomer at Britain's Open University, and colleagues Ian Wright and Monica Grady announced they have found new kinds of evidence, in both the original Martian meteorite and in a new one.
The scientists found that the second meteorite, EETA79001, contains unusually high amounts of organic carbon--compounds that are a signature of biological processes, though they can also form from other chemical reactions. Pillinger and his colleagues also analyzed the ratio of heavy to light carbon isotopes in both EETA79001 and the first meteorite, ALH84001. The ratios, argue the British scientists, imply that the carbon may have originated as methane given off by microbes.
Everett Gibson, one of the authors of the research article in Science that made headlines in August, said he was "very pleased to see confirmation [of his team's findings] from a well-respected team that does excellent work." He is also excited by a key difference between the two meteorites. The minerals in the one his team studied were dated at more than 3 billion years, but EETA79001 is just 600,000 years old. "If it contains biogenic processes," he says, "that means they were active late into the history of the planet. Does that mean that there is life there now? It increases the possibility."
But Jeffrey Bada of the Scripps Institute, who studies the origin of life on Earth, says even if the carbon signatures on the meteorite are consistent with life, they're a long way from proving it. "It's so difficult to eliminate terrestrial contamination," he says, "especially when you get things that look just like Earth."