Dissolution processes at the poles of Titan: from observations to models
Séminaires Planétologie et Sciences Spatiales
Salle 727 - Lamarck A -
ESA - ESAC
Saturn's moon Titan possesses a thick and opaque atmosphere, composed in majority of nitrogen and methane. Both compounds are subject to photodissociation processes producing a plethora of byproducts, of which ethane and solid organics. Under surface conditions, methane and ethane are liquid at the surface. Since the arrival of the Cassini mission at Saturn in 2004, lakes and seas, probably composed of these two liquids, have been discovered in the polar regions. The morphology of the lakes and empty depressions is strongly different from that of the large seas, which suggest that the geological formation mechanism are also probably different. In this seminar, I'll focus on the in-depth geomorphological analysis of Ontario Lacus, the largest lacustrine depression of the southern hemisphere of Titan. The geological settings of the area, as well as the analogy with terrestrial landforms, suggest that the depression developed thanks to the episodic dissolution of a surface soluble layer on Titan. The dissolution processes are then tested quantitatively thanks to a thermodynamic-climatic model designed to estimate the theoretical dissolution rate of Titan's surface. This model shows that dissolution could be a major geological process that shapes Titan's surface through time.