Titan, Saturn’s largest moon, has long fascinated scientists.
With rivers and lakes of liquid methane, icy boulders, and dark sandy dunes, it looks like something out of science fiction. Underneath its thick, hazy atmosphere, some have wondered if life might exist.
A new study suggests that while life on Titan is possible, it would likely be extremely rare.
An international team of researchers, led by Antonin Affholder from the University of Arizona and Peter Higgins from Harvard University, set out to answer some big questions: If life exists on Titan, what might it look like?
Where would it be? And how much of it could there be?
Titan is special because of its rich supply of organic materials, which are the building blocks of life. Beneath its surface, scientists believe there is a deep ocean, about 300 miles down.
The team used bioenergetic modeling to see if simple life, like tiny microbes, could survive by eating these organic materials.
Their results, published in The Planetary Science Journal, show that Titan could, in theory, support life, but only in tiny amounts.
The researchers estimate that all the living organisms in Titan’s ocean combined would weigh just a few kilograms — about as much as a small dog.
Earlier guesses about life on Titan were more optimistic, based on the idea that there was plenty of “food” available. But Affholder’s team pointed out that not all organic molecules can actually be used as food. Plus, most of these materials are stuck on the surface, and there’s very little exchange between the surface and the hidden ocean below.
Instead of imagining complex alien life, the team focused on something very simple: fermentation. This process, familiar on Earth from things like breadmaking and brewing beer, doesn’t require oxygen and could have been one of the first types of metabolism on Earth. They asked if simple microbes on Titan could survive by fermenting glycine, a basic amino acid found all over the solar system.
Their computer models showed that only a small trickle of glycine would make it into Titan’s ocean, probably through rare events like meteorite impacts. This means only a tiny biosphere could exist, averaging less than one cell per liter of water across the entire ocean.
For future missions like NASA’s Dragonfly, finding life on Titan could be incredibly difficult — like searching for a needle in a haystack. Despite Titan’s rich surface chemistry, its potential for life may be far more limited than scientists once hoped.
Source: University of Arizona.
