How thick is Europa's ice shell and does it exchange material?
In plain words
Europa, a moon of Jupiter, has an ocean under a shell of ice whose thickness estimates range from a few to tens of kilometers. Whether surface material can reach the ocean, carrying chemical energy sources for possible life, depends on that thickness and on how the ice moves.
Precise statement
Determine the total thickness of Europa's ice shell and the thickness of its conductive lid versus convecting layer, and whether material is transported between surface and ocean by convection, subduction-like processes or melt-through, on timescales below the surface age of about 60 Myr. An answer is a thickness with uncertainty and a demonstrated exchange pathway and rate.
What would settle it
Ice-penetrating radar, gravity and magnetic induction data from Europa Clipper combined with geodynamic models constrained by surface geology.
Status in the literature
Unverified note
Juno microwave radiometer data (Levin et al. 2025, Nature Astronomy) indicate a thermally conductive outer shell of 29 +/- 10 km, with near-surface cracks too shallow to carry nutrients to the ocean.