When Laboratory Studies of Plumes Shed the Veil of the Enceladus' Interior

Abstract

Since the discovery by Cassini of plumes of water vapor and icy particles erupting from the South Polar Terrain (SPT) of Enceladus, numerous numerical models have been proposed to explain the mechanism driving these plumes, and how they relate to the thermodynamic conditions inside the underlying crevasses. In this study, we present a series of analog experiments designed to reproduce plume activity under controlled laboratory conditions. Water vapor is generated from a reservoir and forced through channels maintained between 230 and 260 K under low‐pressure. These experiments highlight the competing roles of convective cooling and exothermic phase change associated with ice accretion and deposition inside the fractures, where colder walls produce higher velocity jets. We develop a theoretical framework treating the plume system as a single‐stream heat exchanger to link observable vent conditions to internal flow properties, including kinetic acceleration and heat exchange with the crevasse walls. Extrapolating to Enceladean conditions, we sweep across Cassini‐observed plume parameters. The resulting analysis maps the heterogeneous nature of the crevasse system of Enceladus. Narrow supersonic jets characterized by higher solid fractions and larger mass‐flow rates can co‐exist alongside wider and less‐dense sonic flows for global ice‐shell thicknesses on the order of 1–2 km beneath the SPT. These preliminary results demonstrate how laboratory‐scale analog experiments can provide additional constraints on the internal structure and activity of icy moons from plume observations alone, particularly relevant in the context of future exploration missions to icy moons.