Investigation of in situ thermal mining of shallow excess ice at Martian northern midlatitudes

Abstract

It is of great significance to investigate the excess ice mining schemes based on water ice sublimation for in situ utilization of water resources on Mars. In this work, we reported an optimization method for a typical in situ thermal mining scheme for Martian shallow excess ice, where the overburden is drilled through and the conducting rods are inserted into the exposed excess ice to heat them into water vapor. A prediction model for the water vapor production was established by combining the thermal model with the water ice sublimation model. The surface temperature evolutions of exposed excess ice during the heating process were analyzed under different conducting-rods configurations, and corresponding average sublimation rates of exposed ice were investigated as well. In addition, the effects of purity of excess ice and packing of conducting rods on ice surface temperature and average sublimation rate were discussed. Our analysis shows that the conducting-rods configurations could be determined in terms of the average sublimation rate and maximum temperature of exposed ice. The configuration with only one central conducting rod is preferred for in situ water mining with relatively low water demand. For higher water demand, the configuration with more than one conducting rod and greater total input power might be required in order to keep the maximum temperature below the melting point. Larger water ice content of excess ice results in the decrease in the mean surface temperature of exposed ice under steady state, thereby reducing the average sublimation rate.