Quantitative measurement of changes in mechanical properties of lunar soil simulant caused by drilling disturbances

Deep samples obtained from drilling are indispensable for lunar exploration missions. However, the unique properties of lunar soil make it highly susceptible to disturbance; ignoring this will lead to drilling accidents or even mission failure. To achieve an accurate prediction of lunar soil properties, this article proposed a method to quantitatively measure the lunar soil disturbance caused by the drilling process. By measuring the penetration resistance of the needle at the same position before and after drilling, the change of density and internal friction angle can be obtained from the theoretical derivation based on soil mechanics, where the derivation has been proved to be of sufficient accuracy. A series of experiments was conducted to investigate the effects of various parameters (drilling depth, diameter, rotational speed, spiral thickness, and pitch). Through data analysis, this study elucidates the coupled interaction between drilling processes and lunar soil properties, providing critical insights for lunar exploration missions.