Findings on rings and inner satellites of Saturn by Pioneer 11

The introductory part of this paper gives a short account of the theory of absorption by planetary rings and satellites of energetic charged particles that are trapped in a planet's magnetic field and describes the observable consequences of such absorption processes. The University of Iowa observations of absorption features during Pioneer 11's passage through Saturn's inner radiation belt on 1 September 1979 are critically reanalyzed and related to other evidence on rings and inner satellites, especially that from Voyagers 1 and 2. It is found: (1) that satellites 1979 S1, 1979 S2, and 1980 S3 are almost certainly identical; (2) that 1979 S4 appears to be the shadow of an otherwise unreported satellite of radius or approx = 25 km at an orbital radius of 151,300 + or - 80 km and at a longitude between 195 deg and 208 deg at JED 244 4118.25654; (3) that 1979 S5 and two other nearby absorption features and 1979 S6 and one other nearby absorption features are probably caused by longitudinal and radial structure of Ring F; and (4) that absorption feature 1979 S3 at 169,300 + or - 600 km is identified with Ring G.