|An artist's impression of the only spacecraft, Huygens to land on Titan.|
This new study by the researchers from the Cornell University, challenges current theories which state that we should only look for alien life within the habitable zone of a remote star, rather than on icy space objects such as Titan.
According to the astronomers, the habitable zone of a star, also known as the Goldilocks zone, is an area within a solar system where planets can have liquid water on its surface, i.e. the zone is neither too hot nor too cold for water to evaporate, or, in the latter case, freeze.
However, the researchers who have an expertise in chemical engineering and astronomy speculate that primitive cells that are permeable to liquid methane and do not necessarily require oxygen to survive may dwell on Titan. They modeled a `different` type of life form – which is oxygen-free and methane-based – that can metabolize and reproduce similar to life on earth.
Paulette Clancy, professor of Chemical and Biomolecular Engineering, and the lead author of the study, said, “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 researchers theorized cell membrane which is composed of small organic nitrogen compounds and capable of functioning in liquid methane temperatures of 292 degrees below zero. This is different to the life based on Earth, which based on the phospholipid bilayer membrane, the strong, permeable, water-based vesicle that houses the organic matter of every cell.
The cell membrane theorized by the researchers, weren’t based on water, but on methane, which has a much lower freezing point. They called it ‘azotosome’— ‘azote’ being the French word for nitrogen. The researchers employed a molecular dynamics method that screened for candidate compounds from methane for self-assembly into membrane-like structures.
The most promising compound they found is an acrylonitrile azotosome, which showed good stability, a strong barrier to decomposition, and a flexibility similar to that of phospholipid membranes on Earth. Acrylonitrile is a colorless, poisonous, liquid organic compound used in the manufacture of acrylic fibers, resins and thermoplastics – is present in Titan`s atmosphere.
The researchers added that the next step is to try and demonstrate how these cells would behave in the methane environment – what might be the analogue to reproduction and metabolism in oxygen-free, methane-based cells.