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Investigation of the Saturn dust environment from the analysis of energetic charged particle measurementsIn order to assist the Cassini project in evaluating risks of collisions with particulate matter in the rotational equatorial plane, available Pioneer 11 and Voyager energetic charged particle data were reinvestigated to constrain the column mass density of absorbing material within several radial ranges. Within the orbit of Mimas, CRAND proton phase space densities maximize near 2.67 R sub s and exhibit secondary maximum at 2.43 R sub s. From the condition that sources must exceed losses near these maxima and using available theoretical models for CRAND proton production rates, upper bounds on the column mass density at these two radial locations are calculated. Detailed fits of radial diffusion models to the observed flux maxima yield somewhat more restrictive upper limits. The upper limits compare to a lower limit on the column mass density, estimated from previous model calculations by Van Allen. Aside from continuous rings, longitudinally limited, low optical depth clouds of particulates may exist in orbit with several of the inner satellites including Mimas and Enceladus. A brief review of Voyager energetic particle microsignatures that suggest the presence of material co-orbiting with these two satellites is presented. Finally, Pioneer 11 and Voyager measurements of low energy electron fluxes exhibit minima near the location of the tenuous E Ring centered on approx. 4 R sub s. Pioneer 11 pitch angle distributions appear to support the possibility that direct absorption by Ring E particulates produced the observed flux decreases.
Document ID
19900017468
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Hood, L. L. (Arizona Univ. Tucson, AZ, United States)
Date Acquired
September 6, 2013
Publication Date
January 1, 1989
Subject Category
Lunar And Planetary Exploration
Report/Patent Number
NAS 1.26:186727
NASA-CR-186727
Accession Number
90N26784
Funding Number(s)
CONTRACT_GRANT: NAG2-576
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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