Influence of Ice Distribution on Thermal Mining Performance and Strategies to Counter Sublimation Lag

The unclear nature of ice deposits within the lunar permanently shadowed regions poses many challenges to prospecting and utilisation of those resources. Recent recalculations of LCROSS data suggest that ice concentration is more likely depth-dependent, which may also be similar to Martian ice tables. Heterogeneous deposits have to be analysed in the frame of thermal mining architecture to inform us about the expected performance and drawbacks of the technology, which currently is the most promising method of ice extraction beyond Earth, able to produce multiple tons of water per extraction. In this paper, a reworked combined heat and mass transfer model is utilized to provide further insights into phase change dynamics, when beamed energy is applied to a heterogeneous instead of a homogeneous deposit. New strategies are shown to counter performance loss due to sublimation lag build-up and bulk thermal conductivity decrease. Strategies include continuous thermal mining and fracking-thermal mining methods. The first method is analysed with a combined heat and mass transfer model and compared to the expected outcomes in the original thermal mining method. Bulk granular ice is also introduced in the modelling to show thermal mining performance in a more likely scenario of porous ice deposit.