On Earth, life is based on water. Where we find life, we always find water nearby. Because of this, most astronomers search for extraterrestrial life in the habitable zone around stars - the narrow band around a star where liquid water can exist. (Some astronomers call planets within the habitable zone "Goldilocks Planets").
Similarly, many scientists also believe that a vast ocean of different types of liquid would also satisfy the base requirement for life - although life that thrives in different liquids may look very alien to us. Saturn's moon, Titan, has abundant sources of liquid. But instead of liquid water, Titan holds oceans of liquid methane.
One problem with super-chilled liquid methane being the candidate life-supporting liquid is that even at the surface of the methane it is too cold for cell membranes to form or persist. For life on Earth, cell membranes are a requirement to form an environment where life can thrive - the membranes form a barrier between living components in a cell and harsh external environments.
A team of researchers at Cornell University have put together a plausible theory that would explain how life could thrive in the harsh environment on Titan. These researchers have discovered a candidate chemical that could shield living cells from the frigid environment. This compound - known to exist in Titan's atmosphere - can organize itself into a structure that can encircle cells and form environments where the cells can grow and thrive in the frigid temperatures that exist on Titan. This finding, computational in nature, would provide a basis for life to exist in the supercool liquid methane lakes on Titan's surface.
You can think of the compound as having the potential to form a protective covering over living cells and cell components, which would allow living cells to survive in the extreme environment on Titan.
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The photo above shows the sun reflecting off of Saturn's moon, Titan. It's the only other body in the solar system that has lakes on its surface, however instead of water lakes like those that we find on Earth, Titan has lakes of insanely cold, liquid methane.
This new finding from the team at Cornell leads to an important scientific theory that explains how life could exist and even thrive at and below the surface of Titan's lakes. The study demonstrates that "at least in a computer simulation, one can build structures of a size and geometry [roughly] equivalent to the containers that were on Earth when life began," says Jonathan Lunine, one of the study co-authors.
Like Earth, Titan has a dense and complex atmosphere with clouds, mountains, riverbeds, and liquid seas at the surface. Because of the liquid methane at it's surface, and the sheer variability of different types of environments on the planet, many scientists agree that Titan would be the best place to search for extraterrestrial life in the solar system.
There has been much anticipation in the scientific community over new designs for submarines or probes that could explore Titan's seas, but those missions are likely several decades away. Until then, the scientific community will continue to focus on computational and laboratory-based experimental methods to form and test theories about life on Titan and beyond.
You can read the full press report from the study
here.
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