MHD simulations of Europa’s interaction with the jovian magnetosphere: insights from the Juno flyby

Europa, the smallest of the Galilean moons, is embedded within Jupiter’s magnetosphere where a rapidly flowing plasma interacts electromagnetically with the moon’s atmosphere and its surface. The magnetic field in the plasma is also affected by Europa’s induced magnetic field in a subsurface conducting layer. On September 29^th, 2022 the Juno spacecraft flew by the vicinity of Europa at a distance of ~350 km, and it provided the first in-situ observations since Galileo’s last pass on January 3^rd, 2000.

In this work, we model the large scale interaction of Jupiter’s magnetospheric plasma with Europa and its atmosphere for the conditions of the Juno flyby. We apply the single fluid MHD PLUTO code based on Mignone et al., [2007], and also employed by Duling et al. [2022] to describe Ganymede’s plasma interaction. Our model accounts for ion-neutral collisions, electron impact ionization, dissociative recombination, and electromagnetic induction in a subsurface water ocean. In particular, we prescribe Europa’s O₂ atmosphere with a number of analytical models in which we consider several degrees of asymmetry. Furthermore, we include a tracer description in the model and solve advection equations for the production of the water-group pickup ions H⁺ and H₂⁺. The simulation results are compared with in-situ measurements provided by the magnetometer and the JADE instrument onboard the Juno spacecraft. Our study is used to further constrain properties of the moon’s atmosphere and to quantify the effects of their variability on the plasma interaction.