3D Monte-Carlo simulation of Ganymede’s water exosphere

In this paper we present ab initio 3D Monte-Carlo simulations of Ganymede’s surface sputtered and sublimated H 2 O exosphere. As inputs, include water content maps temperature distribution based on Galileo Very Large Telescope (VLT) observations. For plasma precipitation, use hybrid model results for thermal + , energetic S electrons, with unprecedented energy resolution. Our show that up to a solar zenith angle ? 60° 600 km altitude, dominates the atmosphere by four orders magnitudes in number density, while sputtering elsewhere. Sputtering is mainly induced impinging ions, protons (H ) electrons only add about 1% total molecules atmosphere. Electrons are thus not important generation atmosphere, but they spectroscopic observability since main inducer Lyman- ? I emission lines. The extended at altitudes ? 1 Ganymede radius result which ion species substantial fluxes low-energy range (10 eV–10 keV), i.e., efficiently induces nuclear sputtering. Most released return where immediately adsorb, forming thermalized morphology magnetosphere, resulting dichotomies precipitating magnetospheric particles (polar > equatorial leading trailing fluxes), well discernible persisting few thousand kilometers. In-situ measurements, as planned upcoming JUpiter ICy Moons Explorer (JUICE) mission, will probe except encounters near-surface day-side, be probed instead. Finally, compare our first observational evidence Ganymede, find very good agreement. • We simulate initio. dominated ions; ions minor contributors. dominant process deliver high altitudes. Sublimation angles km. useful planning analyzing JUICE measurements.