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Life from Mars? Or Invaders from Earth?

1 minute read

When NASA claimed in 1995 that it had found evidence of ancient life in the Martian meteorite at left, there were plenty of skeptics. Now comes a paper in Science arguing that organic chemicals in the rock come mostly from contamination on Earth rather than bacteria on Mars. That doesn’t prove Martian microbes didn’t sleep here–but it weakens the case.

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