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May 23, 2013: Enceladus’ jets and Titan’s organics: latest news from Cassini

Posted on Apr 5, 2013 in Seminars

Christophe Sotin (JPL)

The active cryovolcanism on Enceladus and the formation of heavy organic molecules in Titan’s atmosphere are two major unrelated discoveries of the Cassini mission. These two end-member icy moons of Saturn reveal important processes for our understanding of the evolution of icy moons and their habitability potential. New observations by the Visual and Infrared mapping spectrometer (VIMS) onboard the Cassini spacecraft provide additional constraints on the geological processes responsible for the formation of Enceladus’ jets. The very strong correlation between the brightness of the overall plume and the true anomaly suggests a very strong control by tidal forces as expected by previous models. On Titan, the solar occultation observations provide constraints on the composition of the organic haze by comparing their spectral properties with those of heavy organic molecules synthetized in laboratory experiments simulating Titan’s conditions. These observations also give density profiles from which one can derive the flux of organic particle falling on Titan’s surface. These observations are included in a global model describing the carbon cycle on Titan and the relationships between the different reservoirs including atmospheric methane, organic haze, lakes, seas, dune fields, subsurface clathrate hydrates and a potential deep reservoir.