Saturnian trapped radiation and its absorption by satellites and rings: the first results from Pioneer 11

Journal Article · Fri Jan 25 04:00:00 EST 1980 · Science; (United States)

DOI:https://doi.org/10.1126/science.207.4429.411· OSTI ID:5150171

Simpson, J A; Bastian, T S; Chenette, D L; Lentz, G A; McKibben, R B; Pyle, K R; Tuzzolino, A J

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), Journal Name: Science; (United States) Vol. 207; ISSN SCIEA
• Country of Publication: United States
• Language: English

Related Subjects

640107* -- Astrophysics & Cosmology-- Planetary Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
BARYONS
CHARGED-PARTICLE TRANSPORT
ELECTRON DENSITY
ELECTRONS
ELEMENTARY PARTICLES
ENERGY RANGE
FERMIONS
HADRONS
LEPTONS
MEV RANGE
NUCLEONS
PIONEER SPACE PROBES
PLANETARY ATMOSPHERES
PLANETARY MAGNETOSPHERES
PLANETS
PROTON DENSITY
PROTONS
RADIATION BELTS
RADIATION FLUX
RADIATION TRANSPORT
SATELLITES
SATURN PLANET
SPACE VEHICLES
TRAPPED ELECTRONS
TRAPPED PROTONS