London, Oct 22 : A scientist has claimed to have found concrete evidence that confirms the detection of methane gas on Mars and also identifies key sources of the gas.

The scientist in question is Michael Mumma, of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, US.

While on Earth, methane is mostly biological in origin, on Mars, it could signal microbes living deep underground.

According to a report in Nature News, the latest work suggests that Martian methane is concentrated in both space and time.

At a handful of hotspots hundreds of kilometers across, plumes of methane bloom and dissipate in less than a year.

News of the detection is rippling through the Mars community just months before a destination is picked for the Mars Science Laboratory (MSL), the 2-billion dollars rover that is due to launch in 
2009.

It will carry an instrument that could both detect trace amounts of methane and help discern whether it is of biological or geological origin.

Mumma has been arguing for methane on Mars since 2003, when other startling findings began to emerge.

Mumma, a spectroscopy expert, obtained data from telescopes in Hawaii and Chile that supported the notion of methane hotspots.

Having obtained four more years of data, Mumma has confirmed the presence of methane by matching four lines in his infrared spectra of the planet’s atmosphere to the characteristic signature of methane.

This is a more definite determination than previous analyses, and has made Mumma find more evidence that the methane is localized in discrete hotspots, which peak at levels of 60 parts per billion.

“Whether the methane plumes are biological or geological in origin is impossible to know at the moment,” said Sushil Atreya of the University of Michigan in Ann Arbor.

For example, microbes could be living in deep groundwater below a perma­frost zone, and their waste methane could percolate up and leak out.

The methane could also come from chemical reactions in which buried volcanic rocks rich in the mineral olivine interact with water.

A third possibility is that the methane is escaping from buried clathrates, deposits of methane ice formed long ago by one of the other two mechanisms.

NASA’s next Mars rover will be able to analyze, at levels of parts per trillion, the fractional concentrations of the carbon isotopes in each methane molecule. (ANI)