IOS PLASMA ENVIRONMENT DURING THE GALILEO FLYBY - GLOBAL 3-DIMENSIONAL MHD MODELING WITH ADAPTIVE MESH REFINEMENT

The first results for applying a three-dimensional multiscale ideal MH D model for the mass-loaded flow of Jupiter's corotating magnetospheri c plasma past Io are presented. The model is able to consider simultan eously physically realistic conditions for ion mass loading, ion-neutr al drag, and intrinsic magnetic field in a full global calculation wit hout imposing artificial dissipation. Io is modeled with an extended n eutral atmosphere which loads the corotating plasma torus flow with ma ss, momentum, and energy. The governing equations are solved using ada ptive mesh refinement on an unstructured Cartesian grid using an upwin d scheme for MHD. For the work described in this paper we explored a r ange of models without an intrinsic magnetic field for Io. We compare our results with particle and field measurements made during the Decem ber 7, 1995, flyby of Io, as published by the Galileo Orbiter experime nt teams. For two extreme cases of lower boundary conditions at Io, ou r model can quantitatively explain the variation of density along the spacecraft trajectory and can reproduce the general appearance of the variations of magnetic field and ion pressure and temperature. The net fresh ion mass-loading rates are in the range of similar to 300-650 k g s(-1), and equivalent charge exchange mass-loading rates are in the range similar to 540-1150 kg s(-1) in the vicinity of Io.