Numerical simulation of temperature rise and sublimation of water-ice during drilling in lunar polar ice-soils

The lunar polar regions are rich in resources, particularly the water resources that are urgently needed for the establishment of a lunar research station. One of the Chang'e 7 missions is utilize a drilling sampling method to collect in-situ ice-soil samples, the heat generated during drilling can cause the water-ice in the ice-soil to sublimate, seriously affecting the in-situ nature of the drilling and sampling. Therefore, this paper considers the lunar soil as a continuous ice-covered ice-soil mixture structure, provides a numerical calculation methods for water-ice sublimation and heat absorption, simulates the drilling sampling process by the discrete element method, and obtains the water-ice volatilization and the drilling temperature rise information during the sampling process, and to establish a discrete element simulation system for the ice-soil drilling. The reliability of simulation model is verified by comparing the experimental and simulation results of ice soil drilling. The drilling simulation of ice-soil particles with 5% moisture content is carried out in article, and the results of temperature rise and moisture content of ice-soil drilling under the consideration of water-ice sublimation are investigated. The results of the study indicate that, in the drilling time of 120s, the temperature rise of ice-soil samples with the consideration of water-ice sublimation is lower than that of ice-soil samples without the consideration of water-ice sublimation by 4°C, and the moisture content is reduced to 4.873%, and the rate of water loss is about 2.54%, and the moon soil drilling and mining information is more accurate and has theoretical guidance for drilling high-fidelity samples.