The Influence of Non‐Thermal Collisions in Europa's Atmosphere

Abstract In this study, we show that non‐thermal collisions can play a significant role in shaping Europa's exospheric structure. Collisions between radiolytically produced and the O produced via electron impact dissociation of affect the exospheric structure and escape rates. Specifically, O + collisions lead to the production of a non‐thermal population, and increase the escape while decreasing the O escape. These collisions are dependent on three specific physical parameters: (a) the density of , (b) the electron impact dissociation rate of , and (c) the O + collision cross section. We demonstrate here that O + collisions affect Europa's atmosphere even in the lowest limits considered. Thus, to more accurately determine the influence O + collisions have on Europa's atmosphere in preparation for the forthcoming spacecraft missions, Europa Clipper and the JUpiter ICy moons Explorer (JUICE), these physical parameters need to be better constrained.