Enceladus' Icy Plume - The E-Ring Cradle

点击翻译按钮获取中文摘要

During three flybys of Enceladus in 2005 the Cassini-spacecraft spotted a gigantic gas-dust plume emanating from a geologically young, scarred and remarkably warm region at the south pole. This unique detection made clear that the Saturn's E ring is seeded in the geo-physically active south pole of the small icy world Enceladus.In this project we plan to develop a model of the origin of the E ring particles with the goal to derive the velocity and the size distribution of the icy grains. The basic ideas include nucleation, growth and acceleration of icy motes in the water vapor in underground channels or cracks perforating the south-polar ice-shell of Enceladus. The studies will incorporate the thermo - and hydrodynamics/kinetics of the channel-flow of the supersaturated gas from where solid ice particles steadily emerge. In order to reproduce the properties of the observed dust plume, the model must include processes which allow for a deceleration of the plume-grains like collisions with the channel walls. The resulting distributions of velocities and sizes of the launched particles will determine the properties of Enceladus' plume and eventually the subsequent dynamics and appearance of the E ring of Saturn.With an iterative approach between modeling and analysis of the Cassini-date of the dust plume and the E ring we try to gain new insights in the underground channel-geology and flow dynamics which otherwise remained hidden by the south-polar ice. Furthermore, we expect that predictions of our modeling will be of vital interest for the planning of the upcoming close flybys of the Cassini spacecraft of Enceladus in 2008 and later.