Researchers from Chalmers University of Technology in Sweden and NASA have made a surprising discovery that challenges a fundamental rule of chemistry and sheds new light on Saturn’s largest moon, Titan. In Titan’s extremely cold environment, substances that normally do not mix – polar and nonpolar molecules – can combine. This finding expands our understanding of chemistry under prebiotic conditions, offering clues about how life’s building blocks might have formed.

Titan’s thick atmosphere of nitrogen and methane resembles that of early Earth, making it an ideal place to study chemical processes that may have preceded life. The research, published in PNAS, shows that hydrogen cyanide (a highly polar molecule) can form stable crystals with nonpolar molecules like methane and ethane. Such interactions are unexpected, since these substances typically separate, like oil and water.

The study began with NASA’s Jet Propulsion Laboratory experiments that mixed hydrogen cyanide with methane and ethane at extremely low temperatures (around 90 Kelvin, or -180°C). Using laser spectroscopy, scientists observed interactions that traditional chemistry could not explain. Collaborating with Chalmers researchers, they used large-scale computer simulations to reveal that hydrocarbons had penetrated hydrogen cyanide crystals, forming stable “co-crystals.” These structures could exist naturally on Titan’s surface, explaining the behavior of hydrogen cyanide there.

According to Associate Professor Martin Rahm, this finding challenges the long-standing principle “like dissolves like,” though it doesn’t overturn chemistry itself – it simply reveals new possibilities under extreme conditions. The results may influence our understanding of Titan’s unique geology, including its lakes and dunes, and provide insight into how essential biomolecules might form in cold, extraterrestrial environments.

NASA’s Dragonfly mission, arriving on Titan in 2034, will further investigate these phenomena. The ongoing collaboration between Chalmers and NASA continues to explore hydrogen cyanide’s role in space chemistry and the origins of life.

For more details, read the full article by Chalmers University of Technology.