Crater Relaxation and Stereo Imaging of the Icy Satellites of Jupiter and Saturn
Understanding the evolution of Solar System diversity is a top-level question identified by the 2006 NASA Solar System Exploration Roadmap. The satellite systems of Jupiter and Saturn provide opportunities to compare the very different evolutions of satellites which likely had similar starting points. These satellite systems range from currently active (Io and Enceladus) to geologically dead (Callisto and Mimas). Different satellites have evidently experienced radically different thermal histories, but as yet few quantitative constraints on these histories have been published.
Our proposal consists of two main components. 1) First, we will quantify one aspect of icy satellite diversity, by using Galileo Solid State Imager (SSI) and Cassini Imaging Science Subsystem (ISS) images to construct stereo topography of large impact features and determine their degree of relaxation. Crater counts will be used to determine likely relative ages. 2) Second, we will combine our observations with numerical models of crater relaxation to infer how the heat flux on the different bodies has evolved as a function of time. In doing so, we will provide constraints on the thermal and orbital evolution of these bodies that will allow us to compare and contrast the history both within and between satellite systems.