94-20705 Smyth The Principal Investigator will conduct a theoretical study of the dynamics, structure, and escape of Io's atmosphere. The objective is two-fold: To understand (1) the vertical transport dynamics and gross structure of the satellite's atmosphere and (2) the escape rate and velocity distribution of neutral gases at the satellite's exobase. The long-term goal is detailed aeronomy studies that include multi-species chemistry. The work will couple 1-dimensional (1-D) hydrodynamic models of the lower atmosphere with kinetic models of the middle and upper atmospheric regions. A 2-D description will be developed for the mid-levels to determine the interactions of the co-rotating heavy-ion plasma flow with the neutral lower atmosphere. The chemistry of such chemical species as sodium, potassium, sulfur, and sulfur oxides will be considered. This project will further our understanding of Io's atmosphere, the interactions of the atmosphere with the magnetospheric plasma, the nature and composition of the heavy ion sources for Jupiter's plasma torus, and the effect of these gases on the satellite's magnetosphere. **
