Project Galileo represents the work of thousands of people. They all deserve acknowledgement for the many accomplishments of Galileo to date and for the tremendous promise it holds at Jupiter. Thanks go to Tiffany Chiu, Maynard Hine, and Bill Hoffman for illustrations, editing, and production of this paper. The research described in this paper was carried out by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not constitute or imply its endorsement by the United States Government or the Jet Propulsion Laboratory, California Institute of Technology.