Fig. 1. Overview of Europa fly-by and plasma observations.
a,b, Density of H2+ PUIs directly picked up from Europa’s neutral atmosphere for XEPhiO (a) and ZEPhiO (b). Velocity arrows indicate the plasma velocity vector as determined from proton observations, with the rigid corotation of 104 km s−1. RE ≡ 1,560.8 km is Europa’s radius. Streamlines and associated wake are from an analytic model (Methods). c–e, Fluxes of O2+ and S+ (c), H2+ (d) and H+ (e) from JADE’s TOF product. Horizontal dashed lines indicate the ram energy for O2+ (c) and cutoff energies (c–e) for PUIs assuming rigid corotation (Methods). f, Densities of individual species (orange, black and blue), all ions (dashed black) and electron impact ionization rates (purple, right axis). The altitude is shown underneath c–f. The boundaries of the geometric wake are shown with horizontal grey bars above or below each panel. Juno’s close approach (C/A) was on 2022-272 9:36:29. Each horizontal tick corresponds to 1 min. avg., average; imp., impact.