Saturnian trapped radiation and its absorption by satellites and rings: the first results from Pioneer 11
Electrons and protons accelerated and trapped in a Saturnian magnetic field were found by the University of Chicago experiments on Pioneer 11 within 20 Saturn radii (R/sub S/) of the planet. In the innermost regions, strong absorption effects due to satellites and ring material were observed, and from approx.4 R/sub S/ inwards to the outer edge of the A ring at 2.30 R/sub S/ (where the radiation is absorbed), the intensity distributions of protons (greater than or equal to 0.5 million electron volts) and electrons (2 to 20 million electron volts) were axially symmetric, consistent with a centered dipole aligned with the planetary rotation axis. The maximum fluxes observed for protons (> 35 million electron volts and for electrons > 3.4 million electron volts) were 3 x 10/sup 4/ and 3 x 10/sup 6/ per square centimeter per second, respectively. Absorption of radiation by Mimas provides a means of estimating the radial diffusion coefficient for charged particle transport. However, the rapid flux increases observed between absorption features raise new questions concerning the physics of charged-particle transport and acceleration. An absorption feature 2.5 R/sub S/ has led to the discovery of a previously unknown satellite with a diameter of greater than or equal to 200 kilometers, semimajor axis of 2.51 R/sub S/, and eccentricity of 0.013. Radiation absorption features that suggest a nonuniform distribution of matter around Saturn have also been found from 2.34 to 2.36 R/sub S/, near the position of the F ring discovered by the Pioneer imaging experiment. Beneath the A, B, and C rings a low flux of high-energy electrons was observed. It is concluded that the inner Saturn magnetosphere, because of its near-axial symmetry and the many discrete radiation absorption regions, offers a unique opportunity to study the acceleration and transport of charged particles in a planetary magnetic field. 5 figures, 2 tables
- Research Organization:
- Univ. of Chicago, IL
- OSTI ID:
- 5150171
- Journal Information:
- Science; (United States), Vol. 207
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
SATURN PLANET
RADIATION BELTS
SATELLITES
CHARGED-PARTICLE TRANSPORT
ELECTRON DENSITY
MEV RANGE
PIONEER SPACE PROBES
PLANETARY MAGNETOSPHERES
PROTON DENSITY
RADIATION FLUX
TRAPPED ELECTRONS
TRAPPED PROTONS
ATMOSPHERES
BARYONS
ELECTRONS
ELEMENTARY PARTICLES
ENERGY RANGE
FERMIONS
HADRONS
LEPTONS
NUCLEONS
PLANETARY ATMOSPHERES
PLANETS
PROTONS
RADIATION TRANSPORT
SPACE VEHICLES
640107* - Astrophysics & Cosmology- Planetary Phenomena