Lecturer: Elias Roussos (Max Planck) Date: 2016-05-30 10:00 Place: Aniara
Saturn's proton radiation belts: a unique magnetospheric structure
Max Planck Institute for Solar System Research
Saturn's radiation belts have been continuously monitored since the arrival of Cassini spacecraft at the planet in 2004. The measurements by Cassini's MIMI/LEMMS detector between 2004 and today reveal that the proton component of the radiation belts is very stable in intensity and structure, unlike any other magnetospheric structure known in our solar system. More specifically, the permanent proton belt fluxes above about 1 MeV vary less than a factor of 2 over both short and long time scales, modulated primarily by the phase of the solar cycle. Furthermore, the belts have an outer boundary that continuously coincides with the L-shell of Saturn's moon Tethys and comprise different sectors, each separated from the other mapping magnetically to the orbits of the icy moons of Saturn. Extensions of the proton belts beyond the orbit of Tethys, that may last up to several months, can occur after the interaction of Saturn's magnetosphere with a Solar Energetic Particle event (SEP). Still, these transient extensions have no impact on the structure of the inner stable belts. It is clear that the stable belts are populated solely by secondaries that originate from nuclear collisions between Galactic Cosmic Rays and the planet's main rings and atmosphere. As a consequence, Saturn's proton radiation belts provide a unique laboratory set-up for high precision measurements of magnetospheric processes, such as the the Cosmic Ray Albedo Neutron Decay (CRAND) or charged particle diffusion, as well as for geophysical studies (e.g. probing the properties of Saturn's rings and atmosphere).
Created 2016-04-20 11:18:05 by Mats HolmstrÃ¶m Last changed 2016-05-23 18:26:35 by Mats HolmstrÃ¶m