Understanding the global evolution of Saturn's ring current
Krimigis, S. M.; Mitchell, D. G.; Carbary, J. F.; Mauk, B. H.; Brandt, P. C.; Paranicas, C. P.
United States
Abstract
An explanation for the morphology and evolution of the ring current in Saturn's magnetosphere is provided. We use global Energetic Neutral Atom (ENA) images of the 20-140 keV proton distribution obtained by the Ion and Neutral Camera (INCA) on board the Cassini spacecraft. A case where the ring current displays an exceptionally clear spiral shape is analyzed and by using a simple model of rotational velocities and curvature-gradient drifts we reproduce the observed spiral patterns and dispersions. The spiral evolve from an initial large-scale injection around midnight consistent with INCA observations. The drift patterns of the inner magnetosphere have to be relatively undisturbed in order for a clear spiral to evolve. Clear spiral patterns like this do not always occur, which reminds us that the inner magnetosphere of Saturn is indeed very dynamic.