JOVIAN SYSTEM DATA ANALYSIS PROGRAM PROPOSAL SUMMARY

Objectives. Our study will accomplish the first analysis of Galileo's ultraviolet spectrometer (UVS) low/mid-latitude H Lyman-a data which contains dramatic new information about the link between Jupiter's upper atmosphere, the magnetosphere, the dynamic lower atmosphere, and the Sun. The measurements have been made under a variety of geometrical, temporal, and spatial conditions. It is the best dataset compiled to-date for determining the source mechanism of the Lyman-a bulge, the spatial distribution of hydrogen in the thermosphere, the temporal and dynamical variability of that hydrogen, the nature of the extended corona, the magnetosphere/atmosphere coupling, the possible dynamical energy exchange between the lower and upper atmosphere, and the effects of solar Lyman-a irradiances. Our objective is to understand the physical processes producing these observed phenemena. Significance to NASA OSS. The Galileo UVS team seeks to understand the spatial, temporal, and energetic interactions of Jupiter's upper atmosphere with its magnetosphere, the dynamical lower atmosphere, and with the Sun. This knowledge goal complements the primary objective of the NASA OSS Jovian System Data Analysis Program (JSDAP), i.e., to enhance Galileo's scientific return by broadening the participation in the analysis and interpretation of the prime mission Orbiter data. This proposed study between members of the Galileo UVS team and non-Galileo investigators will accomplish these objectives by analyzing, modeling, and understanding the physical processes affecting Jovian upper atmosphere hydrogen. Methods. We plan to use several models with our data analysis. Previous work by Tobiska et al. [1997a] and Pryor et al. [1992, 1996] in solar and interplanetary Lyman-a variability form the basis for characterizing the exogenic radiation field that provides photons to the Jovian upper atmosphere. Gladstone [1988] has developed a radiative transfer model appropriate for Lyman-a radiance and dayglow analysis of Jupiter's thermosphere. Using this model, we will interpret the Galileo measured brightness under different geometrical, spatial, and temporal steady state and perturbed conditions. Performance. In year one we will archive into the PDS atmosphere node the following products: 1) the prime mission 10-volume comprehensive workbook for each orbit's UVS atmospheric observations and 2) the calibrated Lyman-a UVS datasets in longitude, time, view angle, emission angle, and solar phase angle. These data will also be presented at an annual scientific conference. In year two, we will archive the state of our knowledge regarding the physical processes creating and sustaining the: 1) Jovian hydrogen bulge, 2) the Jovian thermospheric low-latitude hydrogen enhancements and depletions, and 3) the Jovian hydrogen corona. Similarly, these results will be presented at annual scientific meetings but will also be published in a peer-review journal. Education and Outreach. Our study will work directly with the Galileo Education and Outreach activities through Leslie L. Lowes, a Collaborator on this proposal for E/PO activities. The Galileo outreach activities for are designed for K-graduate level education and are designed to contribute to NASA's diversity workforce efforts and national education goals. Where possible, we will leverage existing programs outside of Galileo at JPL, ongoing outreach work by FDC, and educational collaborations and activites at SwRI as well as at LASP/University of Colorado.