A Reduced Chi Squared Analysis of Pickup Ions in the Plasma Field about Europa

Abstract

Jupiter’s magnetosphere hosts large plasma fields that weather the surface of Europa during its transit, freeing neutral molecules into the atmosphere. As these molecules travel into the ionosphere, they are ionized by the plasma field and picked up by streamlines dictated by the magnetic field about Europa. On 29 September 2022, the Juno mission transited Europa’s wake and measured these pickup ions. Through a χ2 analysis of pickup ion and plasma speeds, we constrained the interaction strength α to 0.45 ±0.07 and the ionospheric height HI to 15.2+15.0km, giving new insights into the composition of and dynamics about Europa.