Deciphering the innermost radiation belts of Jupiter with pre-Juno observations and the physics-based model Salammbô

Abstract:

Jupiter has the most energetic radiation belts in the solar system, populated by magnetospheric plasma accelerated to relativistic kinetic energies. The radial distance-latitude-energy distribution of radiation belt particles is governed by the balance between various source and loss processes which result from the strong coupling of energetic charged particles with the inner magnetosphere environment: atmosphere of Jupiter, cold plasma, moons, rings, electric and magnetic fields, and electromagnetic waves. Disentangling the different physical mechanisms at work is challenging, but important for space plasma physics and planetary science.

This presentation will give an overview of recent advances enabled by combining the ONERA Salammbô physics-based model (electrons and protons) with radiation belt measurements gathered prior to the Juno mission by Pioneer 10-11, Voyager 1, Galileo Probe, Galileo Orbiter, and remote radio observations of the electron synchrotron radiation.

We will in particular show against electron measurements that whistler-mode hiss and chorus waves located between the orbits of Io and Europa significantly scatter the pitch angle of trapped electrons and precipitate them in the Jovian atmosphere. We will also highlight that the ion cyclotron waves generated by the intense mass loading of the volcanic moon Io is the origin of the strong loss of MeV protons near Io’s orbit. Finally, we will explore with radiation belt modeling and observations the tenuous rings of Jupiter and constrain the density of centimeter grains in the main ring.

Building upon the state of the art, we will highlight overarching scientific questions which remain and will remain open despite the on-going and future exploration of the Jovian system. We will stress the need for a challenging but doable Van Allen Probe type mission dedicated to the radiation belts of Jupiter.