Simulation Study on Heat Generation by Water-Ice Penetration Impact in Lunar Soil based on the Discrete Element Method

The CE-7 mission plans to adopt a drilling and sampling scheme to obtain in-situ lunar soil water ice samples with layering information. In the vacuum and low-temperature environment of the lunar polar regions, the cemented lunar soil water ice material is highly temperature-sensitive and prone to phase change and escape, leading to loss of layering information and reduced scientific value, posing a significant challenge to sampling technology. Based on the discrete element method, this paper conducts a heat generation simulation study on the temperature field of simulated lunar soil water ice with varying water contents and initial temperatures, subjected to penetration and impact by an ultrasonic drill under vacuum and low-temperature conditions. A theoretical temperature field calculation model is established, and a contact model program is developed via secondary development through the EDEM software API interface. Using the latest thermophysical parameters of lunar soil water ice, the temperature field variations during ultrasonic drilling in lunar soil water ice under vacuum and cryogenic environments are simulated and analyzed. The research methods and experimental and simulation results provide a reference for studying temperature field variations during ultrasonic impact drilling of lunar soil water ice in vacuum and low-temperature environments.