Astrobiological aspects of Titan and Enceladus: from Cassini-Huygens to TSSM
- Paper number
IAC-08.A1.6.2
- Author
Prof. François Raulin, Université de Paris XII et Paris VII, France
- Coauthor
Dr. Athena COUSTENIS, LESIA, France
- Coauthor
Dr. Jean-Pierre LEBRETON, European Space Agency (ESA), The Netherlands
- Coauthor
Dr. Mai-Julie NGUYEN, LISA, France
- Coauthor
Dr. Patrice COLL, LISA, France
- Coauthor
Dr. Eric HEBRARD, LISA, France
- Coauthor
Dr. Yves BENILAN, LISA, France
- Year
2008
- Abstract
After four years of close observation by remote sensing and in situ instrumentations from the Cassini-Huygens mission, Titan does not look anymore like a frozen primitive Earth, but it looks like an evolving planet, geologically active, with cryo-volcanism, eolian erosion, clouds and precipitations, and a methane cycle very similar to the water cycle on Earth. But the new data also show that a complex organic chemistry is taking place in the very high atmospheric zones of the satellite, with the formation in the ionosphere of high molecular weight (up to several 1000 Daltons) ions. Are these ions abundant enough in the lower zones to act as organic monomers which will grow by aggregation, sedimentation and condensation down to the surface? This is one of the key questions that photochemical models have now to answer. The coupling between ionospheric and atmospheric chemical models is also of high priority. In addition those models will have to take into account the uncertainties on the input data, which so far are so high that the models are usually not constrained enough by the observational data. In spite of the low surface temperature, the organics reaching the surface are probably evolving once in contact with water ice and may form organic molecules of biological interest. However, only few data are so far available on the possible molecular composition of Titan’s surface. Another discovery of tremendous importance for astrobiology by the Cassini-Huygens mission are the large plumes ejected from Enceladus, mainly made of water vapour and ice and which include organic compounds. This strongly suggests the potential presence of a complex organic chemistry going in the interior of this small satellite, in the presence of liquid water. What is the level of complexity which has been reached by the organic chemistry in Titan and Enceladus environments ? What are the habitability potentialities of these two planetary objects? A new mission TSSM (Titan/Saturn System Mission), currently under study as a joint ESA-NASA large mission, could answer these questions. These astrobiological aspects of Titan and Enceladus will be presented and discussed as well as the current working TSSM concept.
- Abstract document
- Manuscript document
IAC-08.A1.6.2.pdf (🔒 authorized access only).
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