Close to the planet, Saturn’s rings act as an effective shield or absorber of charged particles. The rings themselves are apparently substantially affected in this process, however, as evidenced by their “spokes” of fine particles and the lightning-like electrical discharges attributed to the rings. Scientific Investigations INVESTIGATION SATURN ENCOUNTER OBJECTIVES Imaging science Planetary meteorology; satellite geology; ring structure and dynamics Infrared Atmospheric composition, thermal structure interferometry and dynamics; satellite surface composition and thermal properties; ring composition Radio science Atmospheric and ionospheric structure, constituents, and dynamics at Saturn and Titan; ring particle size Ultraviolet Upper atmospheric composition and structure; spectroscopy auroral processes; distribution of ions and neutral atoms in the Saturn system Magnetic fields Planetary magnetic field; magnetospheric structure Plasma particles Magnetospheric ion and electron distribution; solar wind interaction with Saturn; ions from satellites Plasma waves Plasma electron densities; wave-particle interactions; low-frequency wave emissions Planetary radio Polarization and spectra of radio-frequency astronomy emissions; plasma densities Low-energy charged Distribution, composition, and flow of particles energetic ions and electrons; satellite-energetic particle interactions Cosmic ray particles Distribution, composition, and flow of high-energy trapped nuclei; energetic electron spectra “_Notre voyageur connaissait merveilleusement les lois de la gravitation, et toutes les forces attractives et répulsives. Il s’en servait si à propos, que tantôt à l’aide d’un rayon de soleil, tantôt par la commodité d’une comète, il allait de globe en globe, lui et les siens, comme un oiseau voltige de branche en branche._” “_Our voyager knew marvelously the laws of gravitation, and all attractive and repulsive forces. He used them in such a timely way that, once with the help of a ray of sunshine, another time thanks to a cooperative comet, he went from globe to globe, he and his kin, as a bird flutters from branch to branch._” VOLTAIRE—Micromégas, Histoire Philosophique, 1752. [Illustration: NASA] National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Pasadena, California JPL 400-100 12/80 Transcriber’s Notes