Energetic Neutral and Charged Particle Measurements in the Inner Saturnian Magnetosphere During the Grand Finale Orbits of Cassini 2016/2017

Abstract

AbstractWe give an overview of the charged and neutral particle measurements during the Grand Finale of Cassini performed by the Magnetosphere Imaging Instrument, MIMI, on board. The first in situ measurements of MeV particles between the D‐ring and the atmosphere of the planet showed protons with energies above 300 MeV with higher count rates when magnetically connected to the D‐ring which was less dense than expected, while more material was present at the inner edge. The variability in the count rates was a combination of sensor look direction, pitch angle coverage, changes in the L‐range, and latitude. Enhanced emissions of energetic neutral atoms during ring current activity was detected and confirmed the existence of a low‐energy ion radiation belt discovered by Cassini in 2004. No detection of low‐energy ions was indicative of a source population from a region closer than 1,800 km above the 1 bar cloud level.