Comparative Earth and Jupiter's radiation belts

Abstract:

Since the 1990s ONERA has developed physical models of the Earth radiation belts, called the Salammbô models. During the early 2000s, these models have been adapted to Jupiter case, and then to Saturn since 2009. Salammbô models include the main physical processes that govern the dynamics of the particles of the radiation belts and are based on solving the Fokker Planck equation. These models have been successfully compared to measurements and, for the Jovian case, to radio astronomy images. From lessons learned over the last 3 decades, we aim here to discuss our main achievements, still unresolved challenges and typical caveats encountered for which multi-planet and multi-species modelling is an incredible benefit.
We will first detail the Salammbô modelling similarities between planets and particle type, as well as their related specificities. In particular, in the Earth case, the lower magnetic field intensity leads to strong dynamics while in the Jupiter and Saturn cases, there is a strong influence of dust particles and moons. Then, we will focus on how studying several species (electrons, protons and helium) allows us to validate physical processes modelling (radial diffusion, drop-out) and to better understand measurements (like EPI on Galileo for example). We would finally conclude on the ongoing efforts conducted at ONERA and our next decade prime challenges first guess to tackle.