Publication Date:
2011-08-17
Description:
Observations of the magnetosphere of Saturn made by the cosmic-ray experiment on board Pioneer 11 are summarized. Detailed energy spectra and angular distributions of protons from 0.2 to 22 MeV and electrons from 0.1 to 2 MeV were obtained, together with measurements of helium nuclei between 0.65 and 22 MeV/n. The time histories of proton and electron data suggest a division of the Saturn magnetosphere into three regions: (1) an outer magnetosphere between 17 and 7.5 Saturn radii, which is characterized by monotonically increasing fluxes and spectral hardening inward from the magnetosphere, with large changes in low-energy electron angular distributions; (2) a slot region between 7.5 and 4 Saturn radii where marked decreases in proton and low-energy electron fluxes are observed, apparently due to the presence of Dione, Tethys and Enceladus; and (3) an inner region between 4 Saturn radii and the ring edge, which exhibits sharp increases in proton fluxes with energies up to 20 MeV, which are broken near the orbits of Mimas, Janus and possibly S 11. A sharp cutoff of proton and electron fluxes is observed just beyond the nominal edge of the A ring.
Keywords:
LUNAR AND PLANETARY EXPLORATION
Type:
Science; 207; Jan. 25
Format:
text
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