British scientists say they have found the strongest evidence yet that there was once life on Mars - a second meteorite carrying organic material.
The Britons say they found organic matter in two meteorites - one retested after NASA first reported finding traces of life in it, and another, newly tested meteorite, billions of years younger than the first."This is a smoking gun for life on Mars," said chemist Ian Wright, one of the trio of scientists in the new study. "I believe we will be in a position soon to study Martian metabolism."
"I believe I can say life existed - and may still - exist on Mars," Wright said.
In August, scientists at NASA said they had found microscopic and chemical evidence of life on Mars in meteorite ALH 84001, which dates back about 3.6 billion years.
Wright and Colin Pillinger of Britain's The Open University and Monica Grady of London's Natural History Museum studied pieces of that meteorite, and of another, EETA 79001, which was formed 180 million years ago and blown into space about 600,000 years ago.
The meteorites were found in Antarctica in 1979 and 1984. The British scientists' findings on the rocks have not yet been reviewed by their peers.
News of their research was certainly exciting, said Doug Blanchard, head of a research group at the National Aeronautics and Space Administration in Houston.
The fact that the meteorite examined by the London group is much younger than the one NASA scientists looked at suggests that life could have continued on Mars for much longer than previously thought - and perhaps could still be there, Blanchard agreed.
"It would be incredibly egotistical to believe we are the only planet with life on it," astronomer Colin Pillinger said at a news conference Thursday announcing his group's findings. "To think we are the only place uniquely selected for life would be incredible."
Pillinger said he first presented chemical evidence from meteorite 79001 in 1989 in the magazine Nature to suggest that life existed on Mars.