With an average temperature of -290 F, Titan has plenty of water ice but hardly any water vapor, due to water’s very low vapor pressure. That means any life that might exist would have to be non-water based — that is, unlike any life on Earth.
Still, Earth and Titan have important traits in common. “Titan is the only other place in the solar system, aside from Earth — with the possible exception of Mars — where there are flowing liquids on the surface,” Martin Rahm, research associate at Cornell University and lead author of the study, tells Digital Trends. These liquids fall as rain and affect geology through erosion. Rahm adds: “There are sources of energy — sunlight, cosmic rays — and organic molecules, hence Titan is of keen interest for studying prebiotic processes.”
Titan’s flowing liquids are composed of such things as methane and ethane, rather than water, and its atmosphere is full of hydrogen cyanide (HCN), which the researchers recognize as a molecule believed to be key in prebiotic — existing or occurring before the emergence of life — reactions that eventually led to life on Earth.
Though HCN is plentiful in the atmosphere, it seems to convert to a different compound on the moon’s surface. “Such transformative chemistry is proceeding despite the fact that it is extremely cold on Titan, which is maybe the most profound difference compared to Earth,” Rahm says. “If life could exist there, it would need to function very differently from ‘life as we know it,’ and offer clues to the limitations of life in the universe.”
Along with Jonathan I. Lunine, director of the Cornell Center for Astrophysics and Planetary Science, Rahm and the team ran data collected by the Cassini-Huygens mission through density functional theory — a quantum mechanical modeling method — to predict various compounds that could be made from HCN, and to calculate some of these compounds’ properties. In the end, the calculations suggested that the prebiotic reactions were possible and the resulting chemical structures were capable of functions like light absorption.
“We should stress that this paper does not predict life on the surface of Titan,” Rahm says. “Rather, we provide data in support of an environment that might support prebiotic chemistry, to some extent.
“Finding the limits and possible origins of life is a fundamental challenge, and there are many paths to explore,” Rahm continues. “It has proven very difficult to synthesize well-characterized materials from HCN on Earth, needed to study this chemistry.”
Moving forward, the Cornell team hope to run simulations of these systems evolving over time, while investigating their reactions at various temperatures and expanding their study to examine even more complicated chemistries. In the end, they hope to conduct experiments on Earth that are modeled off of Titan’s chemistry to give an even more detailed description of the moon’s potential for life.
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