Limited direct fluid exchange between the deep subsurface ocean and the shallow subsurface environment of Europa

This study challenges the assumption that liquid water from Europa’s deep subsurface ocean can readily rise through fractures in the ice shell to form shallow subsurface reservoirs. Using numerical simulations of turbulent water flow through cracks, we find that rapid cooling drives frazil ice formation, which clogs these pathways within hours and suppresses direct exchange between the ocean and the shallow subsurface. This suggests that shallow water pockets detected on Europa are more likely produced by localized melting within the ice shell itself, rather than by direct communication with the deep ocean, and that Europa’s ice shell may be a stronger barrier between the ocean and surface than previously assumed.