Mars Methane May Be Geological, Not Biological
Just when the ESA Mars Express spacecraft was collecting data on methane emissions on Mars, leading some to speculate it might be a biomarker, Science Now reported new findings that indicate methane can form naturally in Earth’s mantle by heating water, iron oxide and calcite under pressure (see also Physics Web).
This demonstrates that “hydrocarbons could be produced without the byproducts of life,” and that “The methane recently detected on Mars … may not indicate life, because it could have been produced from simple elements.” It also indicates there could be vast yet currently inaccessible reservoirs of natural gas in Earth’s mantle.
This means also that future missions such as the Space Interferometry Mission and Terrestrial Planet Finder may not be able to assume that the detection of methane is an indicator of the presence of life on a distant planet. Nor could Cassini scientists assume that methane at Titan was a precursor to biology.