On Earth almost all the methane in the air comes from living things, from rotting plants to burping cattle. So when three independent teams found telltale signs of the gas in spectra of the Martian atmosphere last year, people sat up and took notice. Could it really be evidence for living, breathing microbes on the Red Planet today?
Possibly. With the discovery of past water, the conditions needed for life to get started are there. And if life did get started, there is a good chance it would have stayed around in pockets of water kept liquid by geothermal heat. What the spectroscopic measurements show is that the methane possibly exhaled by bacteria turns up in the same spots as water vapour - suggesting these might be promising habitats.
"It's a very exciting detection," says Maria Zuber, a specialist in the geology of Mars at the Massachusetts Institute of Technology. ...
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