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Center for Nonlinear Studies |
Enceladus is a primary target for astrobiology due to the salty plume ejecta measured by Cassini and the inferred subsurface ocean sustained by tidal heating. Sourcing the plumes via a direct connection from the ocean to the surface, requires a fracture through the entire ice shell, which may be difficult due to the small diurnal tidal stresses (~1 bar). Here we explore an alternative: the ocean chemistry is frozen into the shell and shear heating within the tiger stripe fractures produces partial melting in the ice shell, allowing the interstitial fluid to be ejected as geysers. To analyze the possibility of partial melting induced by shear heating, we use the 2D multiphase reactive transport model SOFTBALL to simulate flow through a mushy ice region generated by localized shear heating. From our model, we predict the likely porosity, volume, and salt content of a mushy zone within the ice shell surrounding a fracture. We find that that there is sufficient brine volume within the the mushy zone to sustain the geysers. The shear heating mechanism for geyser formation applies to other icy satellites, altering our understanding of the astrobiological potential of Enceladus and other moons.
Host: Matthew Hoffman