Mars scientists puzzle over water vapour-methane source
Data from the European Space Agency (ESA) Mars Express orbiter has shown that concentrations of water vapour and methane in the atmosphere of the Red Planet significantly overlap. The finding has excited some scientists, as it could be an indication of microbial life on Mars. Others believe it more likely that the overlap could be explained by alternative processes. The Planetary Fourier Spectrometer (PFS) instrument, developed by the Italian Space Agency, has observed that, at 10 to 15 kilometres above the surface of Mars, water vapour is well mixed and uniform in the atmosphere. In certain areas, the water vapour is more concentrated, and these locations also correspond with those areas where NASA's Odyssey spacecraft observed a water ice layer below the surface. The PFS data shows that methane is also concentrated in some areas, and in particular in the same places where water vapour and underground water ice have been detected. The correlation implies the existence of a common underground source, according to ESA. One hypothesis for the correlation is that methane molecules are trapped in the water-ice layers beneath the surface. When warmed, both the methane and water would be released together. Geothermal activity from underground heat sources could also cause the release of methane, from the oxidation of iron contained in hot basaltic rocks. But the idea that microbes relying on water are releasing the methane into the atmosphere can also not yet be dismissed.