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Saturn's rings and associated ring plasma cavity: Evidence for slow ring erosion
Journal article   Open access   Peer reviewed

Saturn's rings and associated ring plasma cavity: Evidence for slow ring erosion

W. M. Farrell, W. S. Kurth, D. A. Gurnett, A. M. Persoon and R. J. MacDowall
Icarus (New York, N.Y. 1962), Vol.292, pp.48-53
08/01/2017
DOI: 10.1016/j.icarus.2017.03.022
url
https://doi.org/10.1016/j.icarus.2017.03.022View
Published (Version of record) Open Access

Abstract

We re-examine the radio and plasma wave observations obtained during the Cassini Saturn orbit insertion period, as the spacecraft flew over the northern ring surface into a radial distance of 1.3 R-s (over the C-ring). Voyager era studies suggest the rings are a source of micro-meteoroid generated plasma and dust, with theorized peak impact-created plasma outflows over the densest portion of the rings (central B-ring). In sharp contrast, the Cassini Radio and Plasma Wave System (RPWS) observations identify the presence of a ring-plasma cavity located in the central portion of the B-ring, with little evidence of impact-related plasma. While previous Voyager era studies have predicted unstable ion orbits over the C-ring, leading to field-aligned plasma transport to Saturn's ionosphere, the Cassini RPWS observations do not reveal evidence for such instability-created plasma 'fountains'. Given the passive ring loss processes observed by Cassini, we find that the ring lifetimes should extend >10(9) years, and that there is limited evidence for prompt destruction (loss in <100 Myrs). Published by Elsevier Inc.
 Astronomy & Astrophysics Physical Sciences Science & Technology

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