The role of cryo-minerals in ice shell processes at the Solar System’s icy worlds – Seminar by Mark Fox-Powell (Open University)

Several icy worlds in the outer Solar System harbour salty oceans beneath their icy surfaces, which may contain the requisite conditions for life. Although the subsurface oceans of worlds such as Enceladus and Europa are hidden under kilometres of solid ice, salts have been detected on their surfaces, indicating that some ocean-surface communication takes place. Interpreting the archive of ocean chemistry recorded at icy world surfaces requires a new ‘cryo-geology’ that accounts for how ocean materials evolve within the dynamic ice shells of these worlds. In this talk, I will present results from experimental work aimed at understanding the evolution and fate of ocean-derived brines within the ice shells of icy worlds. I will highlight the possible distribution and composition of ocean-derived brines at within icy world ice shells, and outline how the presence of salts can influence long-term evolution of icy world surface features. Then, I will describe our recent discovery of a new hydrate of sodium chloride that is stable at icy world conditions, and show how it provides an archive of fluid freezing rate that could be used by upcoming missions, such as NASA’s Europa Clipper and ESA’s JUICE, to identify regions of recent fluid delivery to the surfaces of Jupiter’s icy moons.