Martian mystery: Large plumes of methane have been discovered on Mars, but the source is as yet a mystery.

Credit: NASA

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WASHINGTON DC: Plumes of methane gas detected on Mars could be a sign of geological or biological activity – and possibly the latest indication that life can be sustained on the Red Planet.

The presence of methane implies active processes on Mars, and the amount of methane observed is comparable to some active sites on Earth, a new study published today in the U.S. journal Science has found.

Increased prospects for life

"We believe this definitely increases the prospects for finding life on Mars," principal researcher Michael Mumma of NASA's Goddard Space Flight Centre in Maryland, U.S., told The Washington Post newspaper. "No other discovery has done as much to increase the chances of finding life."

Researchers noted that living systems produce more than 90 per cent of Earth's methane, with the other 10 per cent being geochemical in origin.

The authors behind the discovery said that one primary plume of Martian methane contained an estimated 19,000 metric tons of the gas – about as much as is produced at a massive hydrocarbon seep at Coal Oil Point in Santa Barbara, California.

"Methane is quickly destroyed in the Martian atmosphere in a variety of ways, so our discovery of substantial plumes of methane in the northern hemisphere of Mars in 2003 indicates some ongoing process is releasing the gas," said Mumma.

Uncertain source

The scientists said they have detected seasonal variations of methane emissions over some locations on Mars, but remain uncertain about the source of the gas.

"The methane we detected is of unknown age. Its origin could be ancient or perhaps recent," wrote Mumma and his co-authors. "Both geochemical and biological origins have been explored, but no consensus has emerged."

Mumma and a team of researchers used high-dispersion infrared spectrometers to monitor about 90 per cent of the planet's surface for three Martian years (the equivalent of seven Earth years) for their study.