Anybody home? NASA/JPL/University of Arizona/University of Idaho

Conditions on Titan are looking more and more promising for life. For the first time, the building blocks of cell membranes have been detected in the moon’s atmosphere.

On Earth, each cell is a packet of mostly water surrounded by a thin membrane made of lipids. Neither of these components would fare very well on Saturn’s largest moon. Titan is far too cold for liquid water, with average surface temperatures of -149°C. Instead, its seas are made of liquid methane, in which the lipid membranes necessary for life on Earth would be unable to develop.

But maybe life on Titan could be made of different stuff. Maureen Palmer at NASA’s Goddard Space Flight Center in Maryland and her colleagues have detected traces of vinyl cyanide in the moon’s nitrogen atmosphere. According to a 2015 study, vinyl cyanide is particularly good at forming the stable, flexible structures necessary to build a cell membrane.


Palmer says there is enough vinyl cyanide on Titan to form up to 30 million cell membranes per cubic centimetre of liquid in one of the hazy moon’s largest seas. That much potential membrane material means a higher likelihood that membranes could grow large enough to support more complicated structures, like cell innards.

Building block

“It’s like the advice they give to people who are stranded on a desert island: the first thing you have to do is find shelter,” says Paulette Clancy at Cornell University in New York, an author of the 2015 study identifying vinyl cyanide as potential cell material. “In a way it’s the same as what cells have to do – they have to find some way to protect themselves from the ravages of the outside world in order to get things started.”

Membranes alone wouldn’t be enough, though. “Membranes are necessary for life, we think, but you also need some sort of genetic material and some sort of metabolism,” says Palmer.

Evidence for the chemistry that could help these processes along comes from the Cassini spacecraft, which is in the last phase of its mission to explore Saturn and its moons. High in Titan’s atmosphere, it has detected a molecule called a carbon chain anion that might help life along. Ravi Desai at University College London and his colleagues think that these anions may form the seeds for larger, more complex molecules closer to the surface.

Learn more at New Scientist Live in London: Discover Cassini’s grand finale

“If they can survive long enough to reach the sea, perhaps they can play a role in any chemical reactions that take place there, maybe even the ones within the shelter of the vinyl cyanide membrane that could lead to a metabolic process,” says Clancy.

Titan’s thick nitrogen atmosphere and methane seas provide the best laboratory in our solar system for examining the possible evolution of lifeforms that are truly alien from anything that we see on Earth. “Titan is definitely a tantalising target in looking for this super weird biochemistry, and seeing where the boundaries of biochemistry are,” says Palmer.

Journal references: Palmer’s study: Science Advances, DOI: 10.1126/sciadv1700022; Desai’s study: Astrophysical Journal Letters, DOI: 10.3847/2041-8213/aa7851

Read more: How Saturn’s moon Titan could spark chemistry of life