Possible existence of microbes on Mars

"A very large amount"

Michael Mumma of NASA's Goddard Space Flight Center in Greenbelt, Maryland, said there were three regions slowly releasing "a very large amount" of methane. The regions all showed evidence of ancient ground ice or flowing water.

There was no sign of gases expected if methane was produced by volcanoes, particularly sulfur dioxide, Mumma said.

In mid-summer, methane is being released there at a rate similar to that of a massive hydrocarbon seep at Coal Oil Point in Santa Barbara, California, Mumma said.

Living organisms release much of Earth's methane as they digest nutrients, but strictly geological processes such as oxidation of iron also yield the gas.

Michael Meyer, lead scientist for NASA's Mars program, said the methane indicates "that Mars is active. Now, whether or not it's because of geology or biology or both, we don't know."

Methane is composed of four atoms of hydrogen bound to a carbon atom, and is the main component of natural gas.

On Earth, methane is known as swamp gas and made by decaying plants or found in the burps, belches and other emissions of animals from termites to cattle and people.

Editor:Zhang Pengfei