Event DetailsEvent Dates: Wednesday, April 13, 2016 - 4:00pmSeminar Location: Duane Physics Room G1B20Speaker Name(s): Sascha KempfSpeaker Affiliation(s): University of Colorado Boulder, LASP Seminar Type/SubjectScientific Seminar Type: Physics Department ColloquiumEvent Details & Abstract: Even 450 years after Galileo Galilei’s discovery of Saturn’s rings, their origin and evolution is still not known. The rings are the brightest of the four ring systems in the solar system and have at least the mass of the moon Mimas. Interactions with Saturn’s moons and viscous spreading of the ring material seem to imply a ring age of about a tenth of the age of the Saturnian system. A young ring age is problematic because the disruption of a Mimas-sized body or a comet in the Roche zone of Saturn would result in a ring with a much larger rock content than observed today. The unique ring color resulting mainly from the pollution of the ring material with interplanetary meteoroids provides a key for constraining the ring age. Direct measurements of the meteoroid flux into the Saturnian system by Cassini’s Cosmic Dust Analyzer (CDA) allowed us for the first time to constrain the ring age. The discovery that Saturn’s small ice moon Enceladus maintains an active ice volcano is surely one of the most exiting findings by the Cassini mission and data obtained by the Cosmic Dust Analyzer contributed significantly to our understanding of this phenomenon. In fact, knowledge of the dynamics and composition of the ice particles forming the plume allow us to obtain information about the moon’s interior and in particular provide evidence for a subsurface ocean. In October 2015 Cassini performed its last close flyby at Enceladus. Data obtained during this flyby together with numerical simulations allow us to constrain the Enceladus dust source rate and to draw conclusions about the emission of plume particles along the fractures in the south polar terrain.