Enceladus' Icy Plume - The E-Ring Cradle

土卫二的冰羽 - E 环摇篮

• 批准号: 50029128
• 负责人: Professor Dr. Frank Spahn, Ph.D.
• 金额: --
• 依托单位: Institut für Physik und Astronomie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2008
• 资助国家: 德国
• 起止时间: 2007-12-31 至 2010-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/50029128?language=en
• 关键词: Enceladus; Icy; Plume; Ring; Cradle

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.

在2005年三次飞越土卫二期间，卡西尼号航天器发现了一个巨大的气尘羽流，它来自南极一个地质上年轻、伤痕累累、非常温暖的地区。这一独特的探测清楚地表明，土星的E环是在地球物理活动的小冰行星土卫二的南极播撒的。在这个项目中，我们计划建立一个E环粒子起源的模型，目标是推导出冰粒的速度和大小分布。其基本思想包括在土卫二南极冰壳穿孔的地下通道或裂缝中的水蒸气中冰粒的成核、生长和加速。这些研究将结合过饱和气体通道流动的热力学和流体力学/动力学，固体冰粒从这里稳定地出现。为了重现观测到的尘埃羽流的性质，模型必须包括允许羽流颗粒减速的过程--类似于与通道壁的碰撞。由此产生的发射粒子的速度和大小分布将决定土卫二羽流的性质，最终决定土星E环的后续动力学和出现。通过对尘埃羽流和E环的卡西尼数据的模拟和分析之间的迭代方法，我们试图获得关于地下通道的新见解-地质和流动动力学，否则将被南极冰所隐藏。此外，我们预计，对我们建模的预测将对计划2008年及以后的土卫二卡西尼号航天器的近距离飞行具有至关重要的意义。