Chemical engineers from the US have theorised that a life form subsisting on methane and not on oxygen can thrive on the largest moon of Saturn, Titan. They made a model of the membrane of such an organism based on knowledge of the chemicals and compounds that could possibly reassemble to form a cell membrane.
Planet Saturn in the background with its moon, Titan
The scientists have constructed a model of a methane-based life form that would flourish on the icy moon of Saturn, Titan. Titan’s atmosphere is known to consist of pressurised nitrogen and methane. Furthermore, it is the only heavenly body in our solar system (apart from our own planet) to have liquid occurring naturally on its surface: three methane seas have been spotted in its North Pole after observations made by the unmanned spacecraft of the NASA named Cassini were evaluated by scientists.
How Saturn would possibly look from the surface of Titan
Researchers have formulated the hypothesis that the icy moon can hold life in its midst – one that is different from those generally found on Earth. It is believed that the extremely cold seas on Titan might be having organisms out there.
Titan in natural colour as the human eye would see it. Image taken by Cassini.
Titan’s hydrocarbon seas in false colour. Photo credits: NASA/ JPL-Caltech/ University of Arizona/ University of Idaho
The model built by the group of researchers has a cell membrane, called an azotosome, that is in no need of oxygen to function. They have described it as the “first concrete blueprint of life not as we know it“. The azotosome (a nitrogen body) has many small organic nitrogen compounds, unlike cells found on Earth which have a phospholipid bilayer membrane. It can be kept alive at liquid methane temperatures like – 292˚C.
“We’re not biologists, and we’re not astronomers, but we had the right tools,” admitted molecular chemist Paulette Clancy.
“Perhaps it helped, because we didn’t come in with any preconceptions about what should be in a membrane and what shouldn’t. We just worked with the compounds that we knew were there and asked, ‘If this was your palette, what can you make out of that?’”
The team made use of knowledge pertaining to the substances found in the methane atmosphere and seas of Titan. They worked out the potential molecules that might rearrange together and assemble into a membrane. The one put forward by the scientists proved to be stable and flexible, two characteristics that are also reflected by cells on Earth. One of the compounds making up the membrane is acrylonitrile which is a colourless and poisonous liquid used in the making of acrylic fibers.
A representation of an azotosome, open showing its interior. Photo credits: James Stevenson.
It is to be noted that the findings do not imply that life does exist on Titan. Rather, the scientists have just constructed a model of what a possible life form on the moon might be.