photographist

“Titan is the largest satellite of Saturn. It is around the same size as Mars, and has high atmospheric pressure on its surface. This dense atmosphere, mainly composed of nitrogen and methane, is subject to the action of solar radiation, which results in the transformation of matter. In Titan’s atmosphere, the chemical processes initiated by the solar protons trigger the formation of new molecules. Titan is the only body in the solar system that is known to have this type of mechanism, which leads to the formation of extremely large molecules made up of as many as several hundred atoms; these are equivalent to materials comprising carbon, nitrogen and hydrogen at the same time. This triggers chemical functions that are very interesting in terms of everything to do with the structure of so-called prebiotic materials – the chemistry of the formation of complex materials – as these perform functions that are favourable to the emergence, creation and evolution of life.

The Cassini Huygens mission, which was sent to Titan in 1997, arrived at the end of 2004. The Cassini orbiter went into orbit around Saturn, leaving the Huygens probe high above Titan’s atmosphere. We have measurements of Huygens’ journey through the atmosphere until it reached the ground, as it was crammed full of infrared and mass spectrometry instruments. Scientists are processing this data, while others are modelling the chemical reactions that take place in Titan’s atmosphere. We are already able to encode thousands of reactions, but this is woefully inadequate. Around Titan we can observe a fog of small solid grains in suspension; these are organic components that have resulted from these reactions in the atmosphere, but the composition of them remains unknown. We are using an experimental approach in the laboratory to explore this chemistry. As an exo-biologist, I work with reactors in which we are going to create experimental simulations of atmospheric systems.”

Nathalie Carrasco
Assistant Professor, University of Versailles Saint-Quentin

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