Enceladus Ice-Shell Thickness from the South Polar Heat Flow: A Conductive Inversion with Temperature-Dependent Conductivity

The south polar terrain of Enceladus radiates about 15.8 gigawatts of endogenic power, and that single measured quantity, combined with the temperature dependence of ice conductivity, fixes the conductive thickness of the ice shell beneath the pole. This study inverts the heat flow directly: for a polar cap covering 12 percent of the surface the mean flux is 164.9 milliwatts per square metre, and a shell conducting with conductivity 651 divided by temperature gives a polar thickness of 5.102 kilometres, against 2.642 kilometres for a constant-conductivity estimate. Spread globally, powers of 25 to 40 gigawatts imply mean shell thicknesses of 26.87 to 16.79 kilometres. The polar shell is therefore thin enough for fractures to reach the ocean, while the global shell remains thick enough to insulate it. All values are computed from stated assumptions, not measured.