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C. C. Porco (Space Science Inst.), L. Dones (SWRI), J.N. Spitale, E. Baker (Space Science Inst.), C.D. Murray (Queen Mary U. London, UK), A. Brahic (CEA Saclay), J.A. Burns (Cornell), Cassini Imaging Team
A striking set of images was collected immediately after Cassini was placed in orbit around Saturn, as the spacecraft flew across the unilluminated side of the rings, from the outer C ring to the F ring, and then again, after it crossed the ring plane onto the illuminated side. This collection, totalling 43 narrow angle images and 18 wide angle images, has revealed a varied array of features -- some previously known but seen now in greater two-dimensional detail, and some brand new -- all created by the perturbations of moons, both external and internal to the rings. Density waves created at second-order inner eccentric resonances (IER) by moons such as Janus are easily seen, as well as waves created by first-order IER's by the small moons Atlas (which orbits just outside the A ring) and Pan (which orbits within the Encke gap). These waves are linear and are expected to yield reliable measures of ring viscosity and masses for the perturbing bodies. Previously unseen structures found on the outer edges of both the Encke and Keeler gaps in the outer A ring suggest the action of Pan in the first case, and a new, presently unseen moon in the Keeler gap. Study of these features will allow independent measures of satellite mass. Future imaging sequences will scour the major gaps in Saturn's rings, including the Keeler Gap, for such embedded satellites. These new results and their implications will be discussed. The authors acknowledge the suppport of the Cassini Project, JPL/NASA.
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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.