Juno flybys and reanalyzed Galileo magnetometer data have reignited a fundamental disagreement about Europa's ice shell thermal regime.

The convective model predicts a thin (~5 km) brittle lid over a ~20 km warm convecting layer, explaining chaos terrain formation and surface renewal. The conductive model argues for a thick (~30 km) rigid shell where tidal dissipation concentrates at the base, with surface features driven by tidal flexure rather than endogenic overturn.

The stakes are direct: convection implies material exchange between ocean and surface, making biosignature detection feasible from landers. A purely conductive shell means ocean-derived material never reaches the surface.

The critical test: Europa Clipper's ice-penetrating radar (REASON) will measure shell thickness to ±2 km accuracy. A shell thinner than 15 km effectively rules out the conductive-only model. What thickness would settle this debate?