Dusty-Gas Simulations of Io's plumes

<p>Io is the innermost Galilean satellite of Jupiter and is the most volcanically active body</p><p>in our solar system. Its largest volcanic plumes can rise up to several hundred kilometers</p><p>above the surface. These volcanic plumes are one known source of Io's SO₂ atmosphere,</p><p>but additionally the surface of the moon is covered with surface frost which sublimates in</p><p>sunlight and condenses during the night and when Io enters eclipse behind Jupiter. There-</p><p>fore, Io's atmosphere is a result of the combination of volcanism and sublimation, but it is</p><p>unknown exactly how these processes work together to create the observed atmosphere. We</p><p>are investigating the flow of SO₂ gas from the source of a plume, into the umbrella-shaped</p><p>canopy, and eventually back onto the surface. Additionally, we also study the interaction of</p><p>the plumes with an ambient sublimation atmosphere. Both, the gas flow of the plume and</p><p>the sublimation atmosphere, are modelled using the Direct Simulation Monte Carlo (DSMC)</p><p>method first utilised by G.A.Bird. The DSMC method is the most suitable for this case</p><p>because the gas dynamics can be modeled over a great range of gas densities which is es-</p><p>pecially important for rarefied gas flows at high altitudes and on the night side of Io. Our</p><p>DSMC code is multi-species and also allows the simulation of gas emission from lava lakes</p><p>that may also contribution to the atmosphere. Finally, we are also able to implement dust</p><p>particles in the plume and analyse the effect for different dust sizes. Our goal is to gain a</p><p>better understanding of the plume structure, the interaction with the ambient atmosphere</p><p>and the overall contribution of different processes to Io's atmosphere in preparation for future</p><p>missions such as JUICE, Europa Clipper and a possible future Io Volcano Observer.</p>