Life as we know it requires water, but could an environment without H2O give rise to life as we don't know it? Scientists say it's theoretically possible, in a place that's as close as Titan, a smog-shrouded moon of Saturn that has seas containing hydrocarbons instead of water. Cornell University researchers say Titan's nitrogen-based chemistry could give rise to types of membranes as suitable for cellular life as Earth's lipid-based membranes.
In Friday's issue of the open-access journal Science Advances, Cornell's James Stevenson, Paulette Clancy and Jonathan Lunine lay out the case for the theoretical existence of "azotosomes," cell membranes that could be made from nitrogen, carbon and hydrogen. The most promising constituent is acrylonitrile, a liquid organic compound that's been detected in Titan's nitrogen-methane atmosphere. (On Earth, the stuff is poisonous.)
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Although it's conceivable that azotosomes could be produced amid Titan's cryogenic conditions, the real point of the research is to suggest that planets beyond our solar system need not have water to have life.
So far, the Cornell researchers have merely shown that azotosomes could exist based on molecular simulations. The next step would be to demonstrate in the laboratory how such cell membranes could function in a methane environment. In a news release, Lunine said he'd like to see the concept put to a real-world test on Titan by "sending a probe to float on the seas of this amazing moon and directly sampling the organics."
— Alan Boyle