Titan’s Complex Chemical Makeup Offers Two New Building Blocks for Life

Two new discoveries regarding chemical ingredients that are associated with the formation of life on Titan have been announced. With its dense nitrogen, methane and ethane atmosphere, and liquid hydrocarbon seas, Titan is currently of interest to scientists looking to study an environment resembling Earth’s primordial atmosphere, and also are hopeful that the Saturnian moon’s complex chemical soup will yield evidence of extraterrestrial life.

The first announcement, made on July 26, is of the discovery of carbon chain anions in Titan’s atmosphere. These are negatively-charged particles, and were an unexpected find, as researchers expected the highly-reactive molecules to not last long in Titan’s atmosphere before combining with other molecules. These anions are important, as they can act as building blocks for larger molecules, built out of the abundant nitrogen and methane found in Titian’s atmosphere. This includes the possible the formation of larger and more complex pre-biotic molecules, that can in turn potentially form the basis of life.

The second announcement, made on July 28, is the discovery of a compound called acrylonitrile, also known as vinyl cyanide. This compound, under the right conditions, can coalesce into microscopic spheres that could form cell membranes. While these structures themselves wouldn’t necessarily constitute a lifeform, they could potentially be used by DNA (or whatever the equivalent code might be on Titan) to form single-celled organisms.

"The presence of vinyl cyanide in an environment with liquid methane suggests the intriguing possibility of chemical processes that are analogous to those important for life on Earth," explains Maureen Palmer, with NASA’s Goddard Space Flight Center.

Although biological lifeforms like those found on Earth could not exist on Titan — at -179ºC (-290ºF), Titan is too cold for water-based biology to function — this moon has a hydrological cycle that is an analog of what happens on Earth, with frozen water ice forming its geology, and liquid methane forming rivers and lakes on its surface. This means that if biological life had formed there, it might have been able to take advantage of a chemical processes that we wouldn’t have previously expected.