Are signs of life on Mars floating in the atmosphere? Scientists have been searching for the source of methane on Mars, and their search has put them on the hunt for methane-producing microorganisms.
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.