Perturbations of JUICE/JDC Ion Measurements Caused by Spacecraft Charging in the Jovian Magnetosphere and the Ionosphere of Ganymede

Abstract

AbstractSpacecraft charging is a well‐known effect that occurs when a spacecraft is located in a charged environment such as plasma. In this process, the surface of the spacecraft acquires an electrostatic potential through the accumulation and emission of positive and negative charges. In addition to causing severe electrostatic discharges, it also significantly affects low‐energy particle measurements performed by instruments onboard the spacecraft as it causes a change in energy and a distortion of the Field Of View (FOV) of the instrument by modifying the trajectory of measured particles. Spacecraft charging is therefore an important aspect to consider for Jovian plasma Dynamics and Composition analyzer (JDC), an instrument which aims to perform cold plasma measurements around the Galilean moons onboard JUpiter ICy moons Explorer (JUICE). In this study we use SPIS to perform simulations to study the FOV distortion of JDC for positive ions caused by spacecraft charging in two environments of the JUICE mission: the ionosphere of Ganymede and the Jovian magnetosphere. We show that the resulting distortion of the instrument FOV is highly space dependent and varies in shape and intensity from a pixel to another. However, we show that in both environments the complexity of the interactions between measured positive ions and the spacecraft can be decomposed and described as a superposition of a finite number of elementary interactions (i.e., modes). We show that each mode is caused by a specific element of the spacecraft and leads to a characteristic distortion of the instrument FOV. This study constitutes a first step toward necessary spacecraft potential corrections of the measurements performed by JDC.