资源环境科技发展态势分析平台

We report the first in situ observations of electron measurements at a Europa footprint tail (FPT) crossing in the auroral region. During its 12^th science perijove pass, Juno crossed magnetic field lines connected to Europa’s footprint tail. We find that electrons in the range ~0.4 to ~25 keV, with a characteristic energy of 3.6 ± 0.5 keV, precipitate into Jupiter’s atmosphere to create the footprint aurora. The energy flux peaks at ~36 mW/m², while the peak ultraviolet (UV) brightness is estimated at 37 kR. We estimate the peak electron density and temperature to be 17.3 cm⁻³ and 1.8 ± 0.1 keV, respectively. Using magnetic flux shell mapping, we estimate that the radial width of the interaction at Europa’s orbit spans roughly 3.6 ± 1.0 Europa radii. In contrast to typical Io FPT crossings, the instrument background caused by penetrating energetic radiation (>~5‐10 MeV electrons) increased during the Europa FPT crossing.