Water is synonymous with life on Earth and that is the reason why astrobiologists look for traces of water whenever they hunt for life on other planets and satellites. However, there could be other forms of life which do not depend on water. A team of researchers has modeled a life form which depends on methane, instead of oxygen, for its survival and can metabolize as well as reproduce like the life forms on Earth. The study indicates that such type of life could exist in the methane lakes of Titan, Saturn’s moon. The study has been published in the journal Science Advances.
According to the theory of the team, its cell membrane is composed of organic nitrogen compounds and can function in liquid methane with -300 degrees Fahrenheit temperature. Jonathan Lunine, the co-author of the paper collaborated with Paulette Clany, a chemical molecular dynamics expert and James Stevenson and James Stevenson, a graduate student in chemical engineering for the study. Clancy stated “We’re not biologists, and we’re not astronomers, but we had the right tools. 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.’”
Phospholipid bilayer membrane forms the basis of life on Earth which is a strong, permeable, water based vesicle, holding the organic matter of cell. Researchers searching for life beyond Earth look for conditions which support the creation of this membrane. The researchers stated that they “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 – a colorless, poisonous, liquid organic compound used in the manufacture of acrylic fibers, resins and thermoplastics – is present in Titan’s atmosphere.”
Researchers are now trying to demonstrate the behavior of these cells in cold, liquid and methane-rich environment. Lunine is hoping to test the theory of the team on Titan itself by “someday sending a probe to float on the seas of this amazing moon and directly sampling the organics.” This plan could achieve success as earlier this month NASA Innovative Advanced Concepts program described a theoretical design demonstrating a robotic submarine which could be used for exploring the lakes of Titan.