Close Cassini flybys of Saturn’s ring moons Pan, Daphnis, Atlas, Pandora, and Epimetheus

Abstract

Saturn’s main ring system is associated with a set of small moons that either are embedded within it or interact with the rings to alter their shape and composition. Five close flybys of the moons Pan, Daphnis, Atlas, Pandora, and Epimetheus were performed between December 2016 and April 2017 during the ring-grazing orbits of the Cassini mission. Data on the moons’ morphology, structure, particle environment, and composition were returned, along with images in the ultraviolet and thermal infrared. We find that the optical properties of the moons’ surfaces are determined by two competing processes: contamination by a red material formed in Saturn’s main ring system and accretion of bright icy particles or water vapor from volcanic plumes originating on the moon Enceladus.

Sources, Sinks, and Transport of Energetic Electrons Near Saturn's Main Rings

“…During Cassini's proximal orbits (days 113-258/2017) the L shells of the F ring and the A ring edge were crossed 45 times, providing a unique opportunity to study those rings' interactions with the electron belts in a systematic way. An initial, brief description of these observations is provided in Buratti et al (2019). Besides identifying several ring-and moon-driven losses of energetic protons and electrons, those authors reported the detection of a series of unexpected, localized enhancements of energetic electron intensities in the vicinity of the A and F rings, which here we refer to as microbelts.…”

“…In the present study we expand on the initial observations by Buratti et al (2019) and touch upon several of the open questions summarized above, the answers to which we believe are interlinked: (a) Is the transport of energetic electrons on the rings diffusive or convective? (b) Is the F ring an important sink of energetic electrons?…”

“…An initial, brief description of these observations is provided in Buratti et al (2019). An initial, brief description of these observations is provided in Buratti et al (2019).…”

Cassini's Final Year at Saturn: Science Highlights and Discoveries

“…In November 2016, Cassini's trajectory transitioned to a set of nearly identical Ring Grazing orbits with the closest approach distances just outside Saturn's F ring (Figure , gray orbits). These 20 orbits offered the closest‐ever flybys of tiny ring moons such as Pan and Daphnis, which orbit inside two ring gaps, as well as the tiny moons Atlas and Prometheus just outside the main rings (Buratti et al, ). High‐resolution panoramas of Saturn's A and F rings (Tiscareno et al, ) and in situ plasma and dust composition measurements were also conducted during this period.…”

Visualizing texts: a tool for generating thematic-progression diagrams

“…Topical Themes are in bold typeface. Text examples in this report are taken from the extended abstract of a research article on Saturn's moons (Buratti et al 2019); the article was published in 2019 in the journal Science, and was the most recent article at the time of preparing this report. The extended abstract is reproduced in full in the Appendix.…”