Mass transport through Europa’s ice shell and the habitability of Europa’s internal ocean

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• Professor Marc Hesse, University of Texas
• Tuesday 27 September 2022, 12:00-13:00
• Open Plan Area, BP Institute, Madingley Rise CB3 0EZ.

If you have a question about this talk, please contact Catherine Pearson.

Jupiter’s moon Europa is thought to have an ocean beneath its ice shell and the habitability of this internal ocean may depend on the availability of redox gradients. Downward transport of radiolytic materials produced at the surface through the ice shell likely sets the flux of oxidants into the ocean. Astronomical observations suggest that Europa’s near surface regolith contains 1014 to 1018 mol of O2 and likely other oxidants. Today I will discuss recent work in my group on three different potential transport mechanism for the oxidants through the ice shell: Convective overturn, brine percolation and impacts. Due to the strong temperature dependence of the thermal conductivity the ice-shell has very thick conductive lid that prevents the transport of oxidants through the ice by convective overturn. A second process is the drainage of large volumes of near-surface brines beneath chaos terrains. I argue that these brines percolate readily and can potentially transport surface-oxidants into the ocean at a rate of 106 to 1010 mol/yr. Finally, I discuss the effect of impacts on mass transport through the ice. We have shown that impacts do not need to penetrate the ice shell to generate vertical mass transport. The foundering of impact generated brines though the ice provides a potential mechanism to bring oxidants into the ocean at a rate of 101 to 105 kg/yr. Assuming sufficient production of reductants due to weathering of Europa’s seafloor, our estimated oxidant fluxes are deemed sufficient to sustain primitive life in Europa’s internal ocean. Our simulations also imply that large volumes of near surface brine are not be stable in long timescales, a hypothesis that is testable by NASA ’s Europa Clipper mission.

This talk is part of the Institute for Energy and Environmental Flows (IEEF) series.

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