Europa is Embedded in Non-Maxwellian, Anisotropic Electron Distributions

In September 2022, the Juno spacecraft flew by Europa, providing new insight into the electron pitch angle and energy distributions via the Jovian Auroral Distributions Experiment electron analyzers (JADE-E). We fit these observations with two anisotropic kappa distributions (cold and hot), accounting for spacecraft potential, which we find to be between −10 V and −18 V, indicating that dust grains near Europa's orbit are similarly charged. We find these distributions to be non-Maxwellian and often anisotropic, exhibiting substructure with ∼20 km spatial resolution, providing a database of reaction rates near Europa. We further provide constraints on the emission of UV photons from electrons impacts, finding near constant 1,356 (Formula presented.) /1,304 (Formula presented.) line ratios from (Formula presented.), (Formula presented.) and (Formula presented.). The electron beams, wake, and upstream/downstream regions all exhibit distinct characteristics across density, temperature, anisotropy, and thermodynamic (Formula presented.), illuminating the complexity of Europa's magnetospheric interaction.