Eruptive Volcanism on Saturn’s Icy Moon Dione

Introduction: Although Enceladus has garnered the greatest attention, Saturn’s other icy moons also betray a diverse range of phenomenon (e.g., Rhea‘s ring, Iapetus‘ ridge, Tethys’ fracture). Even in Voyager’s limited global mapping, some cryptic evidence of resurfacing was evident [e.g., 1, 2]. Global mapping by Cassini reveals that a large resurfaced terrain covers much of the leading hemisphere of Dione. In addition, Cassini magnetic field observations [3] indicate that Dione is losing mass to space at a rate greater than can be explained by sputtering, although only a fraction of the rate observed at Enceladus’ plumes. It is not clear whether Dione’s excess plasma material emanates from a discrete internal source or from the global surface via sputtering or bombardment. We focus our attention here on Dione’s geologic history in an effort to determine the degree and style of resurfacing.