Scientists studying the Red Planet have developed a few possible explanations for the presence of methane in Mars' atmosphere. Methane on Mars is being constantly depleted by a chemical reaction triggered by sunlight, meaning that the methane is also replenished at a significant rate. One theory, that methane was being carried into the atmosphere by extramartian bodies such as meteorites, has been taken off the table thanks to a new study by researchers at Imperial College London. The study found that the volume of methane released by meteorites upon entering the atmosphere is far too low to supply Mars' current methane levels. Other studies have ruled out another possibility, that volcanic activity has been producing the methane.

This leaves two frontrunner solutions to Mars' methane mystery. One possibility is that the methane is produced as a byproduct of a chemical reaction between volcanic rock and water. The other is that microorganisms are living on the planet's surface and that their metabolic process produces methane.

It's far, far away from indicating life on Mars, but it does narrow down the hunt for the methane's source. A joint NASA/ESA mission is scheduled to head to Mars in 2018 to look for the source of the methane.

Life on Mars theory boosted by new methane study [PhysOrg]

The scientists published their findings in Science. One of the co-authors, planetary scientists Michael Mumma, said:

The fact that we have found three discrete regions where Mars is releasing methane at this time means we have a window into processes occurring under the surface of the planet. The production (of methane) is likely due to only one of two possibilities. The first is geochemistry, the second is biology. That raises much interest on which one is the dominant production mechanism. [If it's geochemical in origin] we might expect the methane to be released only under regions that are volcanic districts. On the other hand, there could be biology that's going on either very near the surface or deep below the permafrost layer.

And with that simple phrase "there could be biology that's going on," we have our first admission - based on hard evidence - that there's a strong likelihood that life exists on Mars.

Most methane on Earth is released from biological organisms, which is why scientists speculate that the same might be true on Mars. But don't start getting excited about Martian cows. If there is life creating this methane on Mars, it's probably microbial life beneath the planet's surface, where liquid water exists.

One thing is for certain: This methane is coming from a source that renews it continuously. Researchers have been monitoring methane plumes on the planet's surface via satellite for five years. That means that it's either caused by seasonal volcanic activity, or the seasons in the lives of a creature or creatures.

Researchers not involved in NASA's study have confirmed that these findings are quite plausible, and nobody has yet ruled out the idea that the methane might be signs of life under the Martian permafrost.

SOURCES:

Science Journal

BBC News