HR: 0800h
AN: P21B-0542    [Abstracts]
TI: Hot Spot of Enceladus: Role of Thermal Convection and Tidal Internal Heating in the Ice Shell
AU: * Mitri, G
EM: Giuseppe.Mitri@jpl.nasa.gov
AF: Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109,
AU: Showman, A P
EM: showman@lpl.arizona.edu
AF: Lunar and Planetary Lab., University of Arizona, 1629 E. University Blvd., Tucson, AZ 85721,
AB: The south pole of Enceladus is geologically active at the present time, with elevated surface temperatures, fractures, and jets of water and fine grained particles. We explore whether thermal convection can occur in Enceladus' ice shell and the spatial localization of tidal heating within convective plumes. To determine whether concentrated dissipation can occur in convective plumes, we develop a two-dimensional model to compute the volumetric dissipation rate for an idealized, vertically oriented, isolated convective plume obeying a Maxwellian viscoelastic compressible rheology. We apply the model to the Enceladus ice shell, and we investigate the consequences for partial melting and resurfacing processes. Calculations by us and others have demonstrated that thermal convection can occur in the ice shell of Enceladus under a range of conditions. Here, we show that tidal heating is strongly temperature dependent in a convective ice plume and could produce elevated temperatures and local partial melting in the ice shell of Enceladus. Our calculation provides the first quantitative verification of the hypothesis by Sotin et al. (2002) and others that the tidal dissipation rate is a strong function of temperature inside a convective plume. Localized tidal heating in a thermal plume could explain the concentrated activity at the south pole and its associated heat transport (2-7 GW).
DE: 5430 Interiors (8147)
DE: 6020 Ices
DE: 6280 Saturnian satellites
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting