Organic molecules in Titan's atmosphere could rewrite the origins of life on Earth

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Saturn's moon Titan could hold life's building blocks in its hazy atmosphere. New simulations reveal amino acids and nucleotides could be forming there - and that perhaps we should look to the atmosphere for the source of life on Earth.

Researchers at the University of Arizona simulated the chemical processes believed to occur in the ionosphere of Titan, Saturn's largest moon. They were able to observe the synthesis of surprisingly complex molecules, including the five nucleotide bases cytosine, adenine, thymine, guanine and uracil, as well as the simplest amino acids, glycine and alanine. That's not enough to create life, but it's definitely part of what's required.

Titan's atmosphere is interesting because it's constantly showered in intense radiation, which breaks apart even very stable molecules. As the molecules are broken apart, they don't just recombine into simple configurations, according to this simulation, instead form surprisingly complex molecules. This is the first time such a simulation has produced organic molecules without any liquid water, as researcher Sarah Horst explains:

"We can do this entirely in an atmosphere. We don't need liquid water, we don't need a surface. We show that it is possible to make very complex molecules in the outer parts of an atmosphere."


This finding provides a new mechanism for the emergence of life. All previous models had assumed life's building blocks would emerge from a primordial soup, a chemical rich watery body. But now the soup might be replaced with a primordial haze, meaning life on Earth emerged in its most rudimentary form up in the skies. Among other things, a primordial haze might make it easier to explain the role of seemingly space-based chemicals in the formation of life.

Best of all, it's a lot easier to study these process in a moon's atmosphere than in its oceans. A future Titan probe could be able to study these chemical processes in unprecedented detail, giving us new insight into the rise of life on Earth.


[Read more at the Lunar and Planetary Laboratory]