Thermal-vacuum regolith environment simulator for drilling tests in lunar polar regions

Water ice, extensively detected in the lunar south polar region, represents a valuable resource for future lunar base construction and energy utilization. To gain a comprehensive understanding of the origin, distribution, and properties of water ice in the lunar polar regions, on-site measurement is essential. In alignment with this goal, China’s Chang’E 7 mission, scheduled for launch in 2026, aims to explore water ice within permanently shadowed regions of the lunar south pole through drilling and in-situ measurement of water content. This work presents the design and development of a thermal-vacuum regolith environment simulator, specifically created to test the performance of a robotic drill under conditions simulating the icy lunar regolith of the lunar polar environment. The simulator comprises a vacuum acquisition system, a cryogenic cooling system, and a preparation system for icy lunar regolith simulant. Additionally, the simulator can effectively adjust the position of the lunar regolith container and visually monitor it. The vacuum acquisition system provides a low-pressure environment suitable for drilling tests with icy lunar regolith simulant, while the cryogenic cooling system refrigerates the simulant to a temperature as low as 95 K (−178 °C). The regolith preparation system, moreover, enables controlled mixing and compaction of regolith simulant to specific bulk densities and water contents. To enhance testing efficiency in simulated thermal-vacuum environments, the simulator includes a rotation mechanism that allows multiple drilling tests within a single environmental setup by adjusting the position of the regolith container. Experimental validation confirms the capacity of the simulator to replicate conditions similar to those in lunar polar regions. Specifically, the vacuum acquisition system can pump the chamber to a pressure in the order of 10−1 Pa when loaded with icy lunar regolith simulant, and the cryogenic cooling system can refrigerate the regolith simulant with water contents of 0.5 wt% and 4 wt% to 95 K. This work can provide essential ground-testing support and technical validation for the upcoming drilling and sampling tasks of the Chinese Chang’E 7 mission.