The magnetosphere of Jupiter harbors the most extreme fluxes of MeV electrons in the solar system and therefore provides a testbed of choice to understand the origin, transport, acceleration, and loss of energetic electrons in planetary magnetospheres. Along this objective, the Pitch Angle Distribution (PAD) of energetic electrons may reveal signatures of the dominant physical processes. Furthermore, studying the anisotropy of energetic electrons at Jupiter is important for (1) surface weathering of the icy moons, and (2) radiation hazard for artificial satellites.

Here, we analyze for the first time the PAD of MeV electrons observed by the Galileo-Energetic Particle Detector (EPD) experiment in orbit around Jupiter from 1995 to 2003. Galileo-EPD reveals persistent pancake distributions at the M-shell of M = 9 (where Europa orbits). Outward of this distance, at M = 15 (Ganymede) and M = 20–60 (Callisto), MeV electron distributions have pancake, isotropic, and scattered beam field-aligned distributions. The scattered beam distributions indicate that high-latitude auroral acceleration may be a dominant source of trapped electrons for the Jovian radiation belts.

The impact of these results on JUICE science and radiation hazard will be presented.