SM052-0008
Ion radiation belts outside of the main rings of Jupiter and Saturn
Wednesday, 16 December 2020
Poster
Peter Kollmann1, George B Clark2, Barry Mauk3, Chris Paranicas1, John F Cooper4, Quentin Nenon5, Elias Roussos6, Anna Kotova7, Angelica Sicard8, Dennis K Haggerty9 and Abigail M Rymer2, (1)Johns Hopkins University Applied Physics Laboratory, Laurel, MD, United States, (2)Applied Physics Laboratory Johns Hopkins, Laurel, MD, United States, (3)The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, United States, (4)NASA Goddard Space Flight Center, Heliospheric Physics Laboratory, Greenbelt, MD, United States, (5)Space Sciences Laboratory, University of California at Berkeley, Berkeley, United States, (6)Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany, (7)IRAP, Toulouse, France, (8)ONERA, DPHY - Department PHYsics, instrumentation, environment, space, Toulouse, France, (9)Johns Hopkins Univ, Laurel, MD, United States
Abstract:
The ion radiation belts outside of the main rings of Jupiter (at radial distances of about 2-6 Jupiter radii to the planet) and Saturn (distances of 2-5 Saturn radii) show some of the highest intensities of the most energetic particles found in the solar system. The question of what produces ions of such high energies is still open. Theories exist but we cannot test them as long as the ion distributions in these regions are not known with certainty. Unfortunately, many instruments designed to measure radiation do not perform properly in such harsh radiation environments and sophisticated data processing is needed in order to back out reliable measurements of differential intensity.
In the case of Saturn, published differential proton intensities based on the Cassini/MIMI/LEMMS show a peak around 10MeV. This shape is inconsistent with state of the art predictions of the CRAND source that is thought to provide protons from cosmic rays hitting the rings. Here we reconstruct intensities based on new instrument response functions that account for penetrating radiation. First results suggest that the spectrum in this energy is a power law, consistent with the CRAND theory. Pitch angle distributions become steeper closer to the planet, consistent with growing loss into the atmospheric loss cone.
For Jupiter, reliable ion measurements in this region have been limited to the hundreds on MeV energy range. The Juno/JEDI instrument is able to resolve two populations in this region: 1) We identify and calibrate >60MeV protons penetrating through the Juno/JEDI instrument. 2) After cleaning and validating the remaining data, we find significant intensities of protons, oxygen, and sulfur ions in the hundreds of keV energy range. Such measurements at relatively low energies are critical in order to understand what accelerates these ions and to test if these energies can result from adiabatically heating material released from Jupiter’s moons.
