From LiveScience.com: Mars Methane: Geology or Biology?

Plumes of methane gas detected over certain locations on Mars in 2003 could point to active geological processes on the red planet, or perhaps even to methane-burping microbes deep below the Martian surface, a new study reports.

There is no firm evidence for life on the red planet, however, despite news reports early today suggesting as much. Rather, scientists are puzzled by the new findings.

The methane gas is concentrated in small areas of the northern hemisphere of Mars, suggesting it is released from deep fractures or from only limited areas of soil; and that it breaks down over time in the atmosphere. Additionally, these releases of gas occur only in the summer.

It is best to have multiple working hypotheses in a situation like this. Here are some possibilites:

• Shallow geochemical processes in the soil.
• Deeper geochemical processes or reservoirs of methane, with release occurring when ice in the subsurface melts.
• Magma in the subsurface (though this is unlikely as other volcanic gases have not been observed in these plumes).
• Biological activity. On Earth, bacteria in the subsurface rely on chemosynthesis, which is like photosynthesis, except that the energy source is oxidation of inorganic molecules rather than sunlight.

Discovery of bacteria on Mars, of course, would be a major discovery. The next question would be, how did it get there?

A perspective from Reasons to Believe can be found here: Bacteria or Boulders? Methane and Life on Mars. I have two disagreements with Fazale Rana’s RTB article:

• He seems to jump to the conclusion that the geological answer is the correct one. It may be, but this seems a bit premature.
• He states: “Rather than life-confirming methanogens, it seems that boring rocks may be responsible for Martian methane.” I object. Rocks aren’t boring!!!

Grace and Peace