Simulating water vapor plumes on Europa

A computational investigation of water vapor plumes on the Jovian moon Europa was performed with a focus on characteristics relevant to observation and spacecraft mission operations. The Direct Simulation Monte Carlo (DSMC) method was implemented to model the plume expansion. The structure of the plume, including the number density, temperature, and velocity fields was determined. Integrated line of sight column densities of ~1018 H2O molecules/m2 were calculated and compared to observations. The possibility of grain condensation above the vent was considered, but determined to be negligible for the postulated vent size. However, preexisting grains of three diameters (0.1, 1, 50 μm) were included in the simulation and their trajectories examined. A preliminary study of photodissociation of H2O into OH was performed to demonstrate the behavior of daughter species. Different vent parameters were evaluated to determine their effects on the plume, including vent Mach number (Mach 2, 3, 5) and a reduced temperature “Cold” case that was a proxy for energy loss to the region surrounding the vent. Future research pathways are discussed, including higher mass flow cases, unsteady plumes, and accurate modeling of internal energy modes in photodissociation products.