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Edwin Kite Colloquium Abstract (February 17, 2016)

Powering Cryo-Volcanoes on Icy Moons

Spacecraft observations suggest that the plumes of Saturn's moon Enceladus draw water from a subsurface ocean. However, the sustainability of conduits linking ocean and surface is not understood. Observations show sustained (though tidally modulated) fissure eruptions throughout each orbit, and since the 2005 discovery of the plumes. I will show that a model of the tiger stripes as tidally-flexed slots that puncture the ice shell can simultaneously explain the persistence of the eruptions through the tidal cycle, the phase lag, and the total power output of the tiger stripe terrain, while suggesting that the eruptions are maintained over geological timescales by a novel tectonic feedback. This "turbulent dissipation" model makes testable predictions for the final flybys of Enceladus by the Cassini spacecraft. The turbulent dissipation mechanism shows how open connections to an ocean can be reconciled with, and sustain, long-lived eruptions. Turbulent dissipation in long-lived slots helps maintain the ocean against freezing, is plausibly the major energy source for tiger stripe activity, and maintains access to ocean materials for future Enceladus missions.