Of Titan and Methane

A new study seeks to list out the circumstances under which biological sources of methane should be considered when it comes to rocky worlds.

IMAGE: Methane in a planet’s atmosphere may be a sign of life if nonbiological sources can be ruled out. This illustration summarizes the known abiotic sources of methane on Earth, including outgassing from volcanoes, reactions in settings such as mid-ocean ridges, hydrothermal vents, and subduction zones, and impacts from asteroids and comets. CREDIT: 2022 Elena Hartley

There is a place where planetary science and astrobiology start to cross over, and that is generally where we start questioning just how to go about finding life on other worlds. So far, we haven’t found anything anywhere, which is a huge disappointment to pretty much everyone. Right now, all we have are hypotheses about where life could exist, and we continue to expand on that list sort of as a thread of optimism that we’re not alone. Frankly, I’d be happy if we found some microbes somewhere that isn’t Earth, and we’ve definitely been adding to the possibilities the more extremophiles we find.

But how do we go about detecting said life if it’s there? And where should we look? Sure, we’ve found life here in sulfur pools and at the bottom of the ocean, under the ice caps, at the tops of mountains living in the snow. I mean, the planet is teeming with life. What’s next?

A new study published this week in Proceedings of the National Academy of Science focuses on one particular potential sign of life: methane. In particular, this study seeks to list out the circumstances under which biological sources of methane should be…