Sampling of lunar regolith with a deep fluted auger: Experimental study on sampling performance

Abstract

Currently, sampling and water detection of lunar regolith in the permanently shadowed regions (PSRs) of lunar polar regions is a hotspot in lunar exploration. Using deep fluted augers (DFAs) for lunar regolith sampling was proposed long ago. However, a comprehensive study on how to effectively capture regolith using a DFA has not been reported so far. In this study, based on the principles of regolith capturing with a DFA (RCDFA), we analyzed the factors possibly affecting the mass of the captured sample in terms of lunar soil conditions, drilling operating parameters, and structural design. Using the CUG-1A lunar regolith simulant (LRS), an experimental study was conducted on the influence of drilling operating parameters and the structure of the auger flutes on the mass of the captured sample during sampling operation. The experimental results revealed that the regolith sample might not be captured at all with unreasonable operating parameters; however, when using operating parameters within the feasible range, the mass of the captured sample was positively correlated with the cut per revolution (CPR) at the sampling and retracting stages and with the length and depth at the sampling stage. Among all factors, the CPR at the sampling stage had the most significant impact on the mass of the captured sample. Moreover, the width-to-depth ratio (WDR) of the auger flutes should be neither too small nor too large to obtain a good trade-off between the mass of the captured sample and the stability of the brushing efficiency. This study lays the foundation for further research on the mechanism of how DFAs capture lunar regolith and the optimal design of drilling tools.