Could there be simple life floating within the freezing lakes of methane on Titan? A new study presents one of the first experimental tests of the azotosome hypothesis, which proposes that molecules on Titan could form stable closed membranes similar to cells. The findings contradict the hypothesis, showing that the ingredients of Titan’s lakes are more likely to form crystal-like structures instead of membrane-like compartments. Titan is Saturn’s largest moon and has long piqued the interest of astronomers due to its many similarities with Earth. The moon boasts a dense atmosphere and is one of the few places in the Solar System that possesses large bodies of surface liquid. Unlike on Earth, Titan’s seas and lakes are made of liquid methane and ethane, which are extremely cold. Nevertheless, Titan is a prime candidate in the search for extraterrestrial life, with some scientists theorizing that exotic life could form within the moon’s standing methane lakes. One hypothesis posits that compounds named acrylonitriles could assemble into self-enclosed structures called azotosomes capable of housing biochemical reactions. However, models have yielded conflicting results about whether and how azotosomes could form. Here, Tuan Vu and Robert Hodyss performed some of the first experimental tests of the azotosome hypothesis. Using microscopy and calorimetry, they interrogated the chemical behavior and thermodynamic properties of acrylonitrile-methane and acrylonitrile-ethane in liquid methane and ethane, under conditions that simulated Titan’s lakes. These studies revealed that acrylonitriles tended to crystallize within liquid methane and ethane, and didn’t form any structures resembling an azotosome. “This finding further reduces the prospect for vesicles on Titan from a thermodynamic standpoint, but it does not rule out the possibility that they might exist temporarily or be transiently stable,” Vu and Hodyss write. “Titan’s surface habitability thus remains an intriguing notion, whether by way of vesicles or other means.”