Pioneer 11 Observations of Energetic Particles in the Jovian Magnetosphere

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Science  02 May 1975:
Vol. 188, Issue 4187, pp. 459-462
DOI: 10.1126/science.188.4187.459


Knowledge of the positional distributions, absolute intensities, energy spectra, and angular distributions of energetic electrons and protons in the Jovian magnetosphere has been considerably advanced by the planetary flyby of Pioneer 11 in November-December 1974 along a quite different trajectory from that of Pioneer 10 a year earlier. (i) The previously reported magnetodisc is shown to be blunted and much more extended in latitude on the sunward side than on the dawn side. (ii) Rigid corotation of the population of protons Ep ≈ 1 million electron volts in the magnetodisc is confirmed. (iii) Angular distributions of energetic electrons Ee > 21 million electron volts in the inner magnetosphere are shown to be compatible with the Kennel-Petschek whistler-mode instability. (iv) A diverse body of magnetospheric effects by the Jovian satellites is found. (v) Observations of energetic electrons in to a radial distance of 1.59 Jovian radii provide a fresh basis for the interpretation of decimetric radio noise emission.