Can hydrothermal plumes melt through Europa’s ice shell?

Introduction: The formation mechanism for regions of chaotic terrain on Europa is the subject of much debate. Several models have been proposed to account for these disrupted areas of Europa's surface including melting through the ice shell by a concentrated heat source in the underlying ocean [1,2], coalescence of solid-state diapirs [3], extrusion of warm ice onto the surface [4], and melting within the ice shell [5]. While the melt-through hypothesis is attractive from the standpoint of explaining why chaos areas look, at first glance, like disrupted sea ice, it is more difficult in this model to explain the origin of the concentrated heat source beneath the floating ice shell. O'Brien et al. [6] developed a numerical model of the melt-through process in order to explore the range of energies and timescales necessary to melt through the ice shell. Assuming a 6 km thick conductive ice shell with heat sources of 50500 GW spread out over a 20-200 km wide area at the base of the shell, O'Brien et al. find that melt-through is possible over timescales on the order of 10 to 10 years, depending on the chosen heat flux. We have investigated these results using a different numerical scheme, and find that total melt-through will not occur under these conditions.