Fig. 7: Heat flow required for basal melting on super-Earths as a function of the ice sheet thickness.
From: Liquid water on cold exo-Earths via basal melting of ice sheets
a Temperature distribution as a function of depth and time on LHS 1140 b for a 70 km thick ice sheet, Ts of 235 K, and heat flow of 30 mW m−2. b Ice phase evolution as a function of depth and time on LHS 1140 b over a 10-million-year time period. The melt water underneath the high-pressure ice phases quickly migrates to shallower depths; however, the migration of buoyant liquid water is not modeled here. c Temperature distribution as a function of depth and time on LHS 1140 b for a 70 km thick ice sheet, Ts of 265 K, and heat flow of 5 mW m−2. d Ice phase evolution as a function of depth and time on LHS 1140 b over a 10-million-year time frame. e The black and blue lines show the average geothermal heat flow (y-axis) required for an ice sheet of certain thickness (x-axis) to undergo basal melting on LHS 1140 b assuming a surface temperature of 265 and 235 K. The black horizontal lines show the average heat flow observed on planets in the solar system. The presence of pressurized ice phase Ih with reduced melting point at 10–40 km depth enables basal melting with relatively low geothermal heat. Higher geothermal heating is required to melt thicker ice sheets as the melting temperature increases with ice thickness (see Fig. 2).
