New analyses of the Martian atmosphere hints at the possibility of life, deep below the planet's surface, according to the European Space Agency (ESA).
Scientists looking at the distribution of both water vapour and methane in the atmosphere found that concentrations of the two gases overlap, implying a common underground source. The data come from the Italian Space Agency's Planetary Fourier Spectrometer (PFS).
This shows that the two gases are well-mixed in the upper atmosphere. Closer to the ground there are pockets of more concentrated water vapour, in three broad equatorial regions: Arabia Terra, Elysium Planum and Arcadia-Memnonia. These coincide with higher concentrations of methane gas, and are also the regions where NASA's Odyssey space craft detected a layer of water ice less than a metre below the surface.
If even microbial life exists on Mars, it would produce methane, and would need water to survive. So finding the two gases concentrated in the same regions is especially interesting, the scientists explain. But they are equally quick to emphasise that the findings can be explained without invoking little green men.
The methane could be formed by geothermal processes oxidising iron in basaltic rocks, for example. Another explanation could be that there are quantities of methyl hydrate (molecules of methane trapped in an ice lattice) below the Martian ice layer.
Dr Michael Mumma, an atmospheric scientist at the US space agency's Goddard Space Flight Center, told the BBC: "If you happened to warm that beyond the liquidation temperature then you would free both methane and water together."
The ESA says that more observations are needed before anyone can draw any firm conclusions about the cause of the phenomenon. Further studies will "address whether these gases can be linked to water and methane and help answer the unresolved questions. In-situ observations by future lander missions to Mars may provide a more exhaustive solution to the puzzle." ®