The Subsurface Saline Ocean and Fractured Ice Shell of Dione
Orbiting deep within the dense radiation belts of the Kronian system, the icy moon Dione presents one of the most structurally complex geological profiles among the mid-sized satellites of the outer Solar System. With a mean diameter of approximately 1,122 kilometers, Dione is the fourth-largest moon of Saturn , maintaining a tidally locked orbit locked into a precise 2:1 mean-motion orbital resonance with Enceladus . Long observed as a heavily cratered and enigmatic icy sphere marked by bright, filamentary surface markings, precision data collected across dozens of close flybys by the Cassini-Huygens spacecraft has established that Dione is a dynamic ocean world, housing a deep, global reservoir of liquid water buried beneath a rigid, tectonically scarred outer shell of water ice. The interior architecture of Dione is governed by a differentiated structural profile consisting of a dense, silicate-rich rocky core surrounded by a hydrosphere comprising both liquid water and high-st...