Observation of high energy particles in Jupiter’s magnethospere within the Io region

Since 2016, the Juno spacecraft has been orbiting Jupiter. Recently unique insights in the regions within Io’s orbit has been accessible by the evolution of Juno's orbit. The Advanced Star Compass (ASC) primarily serves to determine the orientation of the magnetometer. However, the ASC detector is also sensitive to high-energy particles, enabling it to measure the Jovian radiation environment. Specifically, the ASC can detect electrons with energies greater than 15 MeV and protons with energies exceeding 120 MeV.

Juno has performed 80 orbits since its arrival at Jupiter system, traverses longitudinal regions of the Jovian system and it scans effectively the entire Jovian radiation belts with its orbit evolution drift of the line of apsides south. The ASC has consistently recorded variations in radiation levels when Juno crosses magnetic field regions. In the region within the Io orbit, the shape of the radiation belts is confirmed where particles are trapped in the magnetic field and they bounce between the mirror points. Closer to the planet particles are lost due to the extremely inhomogeneity structure of the Jovian magnetic field in these regions, where there is not a minimum of the magnetic field and thus a particle consequently are lost when reaching the planet’ atmosphere. This extremely dynamic region offers insight into both charged particle transport and energization of these, hitherto unexplored.

We present the observations and a possible transport mechanism for these particles in this region, which will allow us to estimate the particle flux and their energy levels