06 November 2012 – Seminar

When: 4pm on Tuesday, 06 November 2012
Where: DIAS, Geophysics Section, 5 Merrion Square, Dublin 2, (library)

Speaker: Dr. Ondrej Soucek (Charles University in Prague, Mathematical Institute, Czech Republic)
Title: Melting of ice and liquid water transport in the ice shell of Europa

Abstract:

Europa, the smallest of the Galilean satellites of Jupiter, is very likely differentiated into a metallic core surrounded by a rock mantle and an icy outer layer. Its outermost part might contain liquid water, possibly decoupling the ice shell from the silicate mantle. Presence of liquid water at shallow depth is often used to explain formation of the so-called ‘chaos’ terrain, and may be also related with other tectonic features on Europa’s strikingly young surface, such as fractures, ridges, etc. Despite the fact that the presence of liquid water and its transport within the ice may dramatically affect the state and properties of the ice layer, the problem of ice melting and water percolation in the outer shell of Europa has not yet been treated thoroughly. We attempt to overcome this deficiency by treating the system as a two-phase incompressible mixture of water ice and liquid water and by developing numerical model of a partially molten ice layer which captures both the water/heat transport and ice melting. Several scenarios of possible generation and evolution of a partially molten region are investigated. Locally, under certain conditions, relatively large melt fractions or even liquid water layers up to few kilometers thick may be obtained. Even though both the formation and time evolution of the molten water reservoir are quite sensitive to the particular physical setup (water-ice permeability, initial temperature profile, heating scenario, etc.), our preliminary results indicate that most of the water produced at shallow depths by tidal/shear heating is transported downwards on timescales of few tens of kyrs. This implies that substantial water accumulation at shallow depths within the ice shell is possible but the duration of such event is relatively short (~10¹ kyrs).