CPSH Seminar Series: Marc Hesse, The University of Texas at Austin

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April 25, 2022 at 1:00pm CT

Marc Hesse

Speaker: Marc A. Hesse, Associate Professor, Department of Geological Sciences, Jackson School of Geosciences, The University of Texas at Austin

Host: David Goldstein

Title: Downward oxidant transport through Europa’s ice shell by density-driven brine percolation

Abstract: Jupiter’s moon Europa is thought to have an ocean beneath its ice shell and the habitability of the internal ocean depends on the availability of redox gradients. Downward transport of radiolytic materials produced at the surface through the ice shell sets the flux of oxidants into the ocean. Here, we propose that oxidants are transported through the ice shell by the drainage of near-surface brines formed concurrently with chaotic terrains. We estimate that Europa’s porous regolith contains 3.7 × 1014 to 5.6 × 1018 moles (1.2 × 1013 − 1.8 × 1017 kg) of trapped O2. Simulations of coupled melt-migration and eutectic phase behavior show that brines drain before they refreeze, delivering ∼85% of the surface oxidants to the ocean on timescales of 2×104 years. From the distribution of chaotic terrains and from Europa’s surface age we estimate that brine drainage could deliver O2 to the ocean at rates of 2.0 × 106 to 1.3 × 1010 mol/yr.

Collaborators: Jakob Jordan (Rice), Apurva Oza and Steve Vance (JPL)

Hesse figure