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The azimuthal propagation of solar protons with kinetic energies in the range ∼10 to ∼30 Mev is investigated by using observations made in the period December 1967 through August 1968 with University of Chicago instruments on board the earth satellite Imp 4 and the deep‐space probes Pioneer 6 and Pioneer 7, which were very widely separated from the earth during this period. In the period studied, nine solar‐proton events were observed simultaneously at all three spacecraft. In 6 of the 9 events discussed, the proton fluxes approached uniformity around the sun at the orbit of earth, and in 5 of these 6, the decay was divisible into 2 phases. During phase 1 azimuthal gradients were strong and the decay of the flux was fast, with exponential time‐decay constants in the range ∼10 to 20 hours. During phase 2, azimuthal gradients were weak or nonexistent and decay was slow, with time constants generally in excess of 40 hours. The times required for rise to maximum intensity and approach to uniformity, if interpreted in terms of the 1967 model of L. F. Burlaga, are found consistent with the existence of diffusion coefficients κ∥ > 4.3 × 1020 cm²/sec and κ⊥ ∼ 1020 to 1021 cm²/sec at the orbit of earth. From observations of the energy spectra of the protons in these events, it is concluded that the azimuthal propagation process did not depend strongly on particle energy and that consequently there was no simple general dependence of the spectral form on azimuthal separation from the flare site. Though detailed interpretation and discussion of the theoretical implications of these results are deferred to a later paper, alternative models for the understanding of the observations are mentioned briefly.

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The Pioneer 11 spacecraft encounter with Saturn (closest approach September 1, 1979) has resulted in the discovery of a fully developed magnetosphere with high-energy trapped radiation around Saturn, as reported in Science, 207, 400-453, 1980, by several investigators with charged-particle instruments on the spacecraft. The present paper contains in detail the final energetic charged-particle measurements and new observations obtained from the University of Chicago instrumentation on Pioneer 11, including the overall characteristics of the trapped electron, proton, and helium radiation, which was found to lie inside ~20 Saturn radii (Rs) from the planet, and the regions extending outward to beyond the planetary bow shocks and into the interplanetary medium. For analytical purposes we divided the magnetosphere into an inner magnetosphere (<5 Rs), where the intensity profiles displayed the near-axial symmetry characteristics of the dipole magnetic field alignment with the spin axis, and an outer magnetosphere whose characteristics on the sunward side inbound were significantly different from the dawn side outbound, indicative of a possible magnetotail but with no dramatic evidence in the charged-particle data for an equatorial current sheet, as observed at Jupiter. The intensities and energy ranges of the protons and electrons were intermediate between the levels found previously at Jupiter by Pioneer 10 and 11 and at earth. Energy spectra for protons and electrons and relative abundances of protons and helium nuclei are presented along with the average characteristics of particle anisotropies. At the time of encounter the magnetosphere was immersed in intense fluxes of electrons, protons, and helium nuclei of solar flare origin which are shown to penetrate from I Rs to 10 Rs into the magnetosphere, where they dominated the flux levels in the far outer magnetosphere. A corotation anisotropy has been measured at the proton energy ~ 1 MeV in the rotating magnetosphere after correcting the observed unidirectional anisotropy for the radial gradient of the proton flux. The principal focus of the paper is on the analysis of the trapped radiation in the inner magnetosphere, where the radiation reaches high intensity, and has a high degree of symmetry in the L shells around Saturn. Consequently, the absorption signatures in the radiation intensity profiles produced by tings and moons of Saturn can be analyzed quantitatively. Among other resuits the observation of the charged-particle absorption features have led to the discovery of satellite 1979 S2 at L --2.53, which corresponds with the optically detected 1979 S I, a concentration of matter probably located at a Lagrangian point in the orbital range of Mimas, and the identification of narrow rings of matter and one or more satellites inside the radial range of the F ring discovered by the optical-imaging investigators. It is pointed out that these discoveries will provide important tests for models of accretion of matter, satellite formation and the stability of narrow r...

The Ulysses spacecraft made the first exploration of the region of Jupiter's magnetosphere at high Jovigraphic latitudes ( approximately 37 degrees south) on the dusk side and reached higher magnetic latitudes ( approximately 49 degrees north) on the day side than any previous mission to Jupiter. The cosmic and solar particle investigations (COSPIN) instrumentation achieved a remarkably well integrated set of observations of energetic charged particles in the energy ranges of approximately 1 to 170 megaelectron volts for electrons and 0.3 to 20 megaelectron volts for protons and heavier nuclei. The new findings include (i) an apparent polar cap region in the northern hemisphere in which energetic charged particles following Jovian magnetic field lines may have direct access to the interplanetary medium, (ii) high-energy electron bursts (rise times approximately 17 megaelectron volts) on the dusk side that are apparently associated with field-aligned currents and radio burst emissions, (iii) persistence of the global 10-hour relativistic electron "clock" phenomenon throughout Jupiter's magnetosphere, (iv) on the basis of charged-particle measurements, apparent dragging of magnetic field lines at large radii in the dusk sector toward the tail, and (v) consistent outflow of megaelectron volt electrons and large-scale departures from corotation for nucleons.