JOVIAN SYSTEM DATA ANALYSIS PROGRAM PROPOSAL SUMMARY

The Galileo Solid State Imaging (SSI) experiment has produced images of the moving clouds, images of the aurora and satellite flux tubes, and images of lightning and thunderstorms. Several papers, in which the PI is either the first author or a co-author, have come out of this effort, but much remains to be done. Belton et al. (1996) presented data from orbit 1, and reported on rapidly-varying, small-scale structures resembling terrestrial thunderstorms and other wave-like features around the Great Red Spot (GRS). Vasavada et al. (1998) presented data from orbits 1 through 6, and presented wind fields derived from cloud tracking. The areas covered include the GRS, an equatorial belt-zone boundary, two of the classic white ovals, and a 5-micron hotspot. Ingersoll et al. (1998) presented data from orbits 3 and 7 that show the jovian aurora and Io flux tube footprints on the night side of the planet. Banfield et al. (1998) analyzed multi-spectral data from orbits 1 through 6 to infer vertical structure of the jovian clouds. We propose to analyze data from orbits 7 through 11, the end of the nominal mission. The first task is to derive wind fields, estimate vorticity and divergence, and use the results to test numerical models. Deriving wind fields is a time-consuming task, since Galileo does not have a wide-angle camera. Most of the effort goes into the determination of camera pointing. So far, the Caltech group (Vasavada and Ingersoll) are the only ones who have got the method to work. We are also the only group to use TRACKER3, a program that automatically connects features in one image to features in other images taken at different times. The second task is to derive the height of the aurora above the 1 bar level, the location of the auroral oval relative to the magnetic field lines, and the longitude of the Io flux tube footprint relative to the ?zero-current? model. The results from orbits 3 and 7 point to significant day-night changes. The night side aurora is lower in altitude than expected and is associated with smaller L-shells than expected. Also, the Io flux tube is more variable than expected. Camera pointing is crucial to these measurements as well, and we are the only group that is doing this analysis. The third task is to locate lightning flashes relative to the belts and zones and measure the intensity of the flashes and the size of the storms. We hope to match the lightning to bright storms seen in HST images. Again, knowledge of camera pointing is crucial. Belton et al. (1996) Science 274, 377-388; Banfield et al. (1998) Icarus, in press; Ingersoll et al. (1998) Icarus, in press; Vasavada et al. (1998) Icarus, in press.