A team of biologists from the US, Canada, UK, and France have developed a scenario for life on Titan, Saturn’s biggest moon.
Rendering of the artist on the surface of Titan, the biggest moon of Saturn. Image credits: Benjamin de Bivort, debivort.org/cc by-sa 3.0.
“Our research focuses on what makes Titan unique when compared to other ice moons and its rich organic content,” said Dr. Antonin Affelder, a researcher at the University of Arizona.
Using bioenergy modeling, Dr. Affholder and colleagues discovered that Titan’s underground ocean, estimated at around 483 km (300 miles), could support life forms that consume organic materials.
“There’s been a lot of speculation about scenarios that could create organisms on Titan based on lunar organic chemistry, but previous estimates suffer from an overly simplified approach,” Dr. Affholder said.
“Because Titan has such abundant organic matter, there was a sense that there was no shortage of food sources that could sustain life.”
“Not all of these organic molecules constitute a food source, and the ocean is really big; there is a limited exchange between the ocean and the surface, and all of those organic matter; so I argue for a more subtle approach.”
At the heart of the study is a fundamental approach that sought to come up with a plausible scenario for Titan’s life, which envisioned one of the simplest and most prominent fermentations of all biological metabolic processes.
Fermentation familiar to earthlings, used in breadmaking, beer brewing, and less desirable – sourdough fermentation, accustomed to its use in the spoilage of forgotten leftovers, requires only organic molecules but no oxidants like oxygen.
“Fermentation probably evolved early in the history of Earth’s life, and there’s no need to open the door to unknown or speculative mechanisms that may or may not have happened on Titan,” Dr. Affholder said.
“Life on Earth may have first appeared to eat organic molecules left behind from the formation of the Earth.”
“I asked if there could be similar microorganisms on Titan. If so, could Titan’s underground seas supply the biosphere from a seemingly vast inventory of abiotic organic molecules synthesized in Titan’s atmosphere, accumulate on its surface, and be present in its core?”
The researchers have focused specifically on glycine, the simplest organic molecule of all known amino acids.
“We know that glycine was relatively abundant in all kinds of primitive matter in the solar system,” Dr. Affholder said.
“When you look at clouds of particles and gases where stars and planets form, like asteroids, comets, our solar system, we find glycine or its precursors in almost every place.”
However, computer simulations reveal that only a small portion of Titan’s organic materials may be suitable for microbial consumption.
The microorganisms consumed by Titan’s ocean glycine rely on a stable supply of amino acids from the surface through thick, ice-like shells.
Previous work by the same team showed that meteors that shock Titan’s ice could leave behind a “melt pool” of liquid water.
“Our new research shows that this supply may be sufficient to maintain very few microorganisms, which are up to a few kilograms of physical fitness.”
“A small biosphere like this is an average of less than one cell per liter in Titan’s vast oceans.”
For your future mission to Titan, the possibility of finding life might be like searching for needles in a haystack if it’s actually there.
“We conclude that Titan’s unique, rich organic inventory may actually not be available to play a role in lunar habitat at an intuitive level of thinking,” Dr. Affholder said.
paper It was published in Journal of Planetary Science.
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Antonin abholder et al. 2025. Survival rate of glycine fermentation in the underground oceans of Titan. planet. SCI. j 6, 86; doi:10.3847/psj/adbc66
Source: www.sci.news
