Saturn's moon Titan could harbor life – but only extremely little
Besides Earth, Titan is seen as one of the most life-friendly places in the solar system. But it could only carry a few kilograms of cells - in total.
Artistic representation of the methane lakes on Titan
(Image: NASA/JPL-Caltech)
The ocean beneath the surface of Saturn's moon Titan could be home to life forms that live on organic material – but only a few kilograms of it in total. This is the result of a recently presented analysis that differs from overly simplistic earlier studies, writes the University of Arizona. Instead, the team led by biologist Antonin Affholder used bioenergetic models to find out how possible life forms in the ocean could use the abundant organic material on the surface. The most plausible scenario does not see many possibilities. If there really is life, you would have to be very lucky to find it.
Too little food for possible microbes
Because there are comparatively many organic compounds – i.e., carbon-based compounds – on Titan, it has often been assumed that there is at least enough food for possible life forms, explains Affholder. However, his group has now come to the conclusion that none of these compounds are suitable as food, the ocean beneath the surface is really large and the exchange between it and the surface is only minimal. None of this should be ignored when making assumptions about possible life forms. That is why they have now turned their attention to one of the simplest metabolic processes and examined whether so-called fermentation on Titan could make life possible.
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The conversion of organic substances through fermentation does not require oxygen, which is why the process is considered to be one of the oldest on Earth. It is assumed that the first life forms here fed on substances created by fermentation, explains Affholder. His team has determined that glycine could have been formed on Titan in this way. This in turn would have to come through holes in the ocean that meteorites punch into the ice sheet, separating it from the surface. The supply delivered in this way could actually keep a small population of microbes alive, but only less than one cell per liter of water. In total, that would be a few kilograms on the entire moon.
The work now presented in the Planetary Science Journal therefore significantly dampens expectations for more precise exploration of Titan. It is still considered one of the most life-friendly environments in the solar system. Different research teams have come to very different conclusions about what exactly this means. In 2021, for example, it was said that “almost optimal” habitable ecosystems could be created on Saturn's moon. Affholder now believes that the search for possible life could be like looking for the proverbial needle in a haystack. NASA plans to send a mission there in 2028, during which a drone is to pick up precisely this needle.
(mho)
