PARTICLE ENTRAINMENT AND ROTATING CONVECTION IN ENCELADUS' OCEAN

Tidal heating of Enceladus is the favored mechanism to form and maintain a global liquid ocean in Enceladus’ interior. Deformation and friction within a porous silicate core likely generates hot upwelling zones at the core-ocean boundary; diffusive heat fluxes at the base of the ocean may drive convection and mixing in the ocean. Thus, we assume that thermal convection drives flow in Enceladus’ ocean and that convective entrainment causes the upward transport of hydrothermal products, such as silica particles, from the ocean floor to the surface to be ejected at the south polar plumes. We apply a particle entrainment model and use scaling relations to characterize ocean convection to zeroth order, using a parameter space constrained from the results of the particle entrainment model. We find that convective transport in the ocean of Enceladus can explain Cassini’s observation of nanometer-sized silica grains in Saturn’s E-ring. Furthermore, the heat fluxes out of the core we predict to be necessary to entrain particles of this size, as well as the transport times associated with these heat fluxes, are consistent with observations and predictions from pre-existing models. Constraining the ocean dynamics of Enceladus, and by extension other icy worlds in the outer solar system, will lead to a better understanding of heat transport throughout the ocean, its influence on ice shell geology, and its role in promoting habitable environments.