Voyager UVS observations of Saturn's rings and the ring atmosphere
During the Voyager 1 and 2 Saturn encounters the Voyager ultraviolet spectrometers (UVS) made numerous observations of Saturn's rings in the extreme and far ultraviolet. HI Lyman a (1216 Å) observations of the rings from a number of different aspects are used to define the extent and density of the neutral hydrogen “atmosphere” associated with the rings. Voyager 2 observations of the 520 to 1700 Å spectrum of the rings (~20 Å resolution) are used to derive the albedo of particles in the B ring at these wavelengths. These albedo measurements are compared with the laboratory reflectance spectrum of water ice longward of 1200 Å. The significance of the lack of ring reflectance in the Voyager 1 UVS data is also discussed. Finally, UVS spectra of the rings obtained in Saturn's shadow are used to establish upper limits on the presence of any emission from the neutral and ionic states of oxygen possibly associated with the Saturn electrostatic discharges (SED) discovered by the Voyager Planetary Radio Astronomy experiment.