Study On The Characteristics And Adaptability Of Lunar Regolith Rotary Cutting Micro-Quantitative Sampling

Whether the moon has water,the source of water and its occurrence in the lunar soil have always been a research hotspot in the field of deep space exploration at home and abroad.This topic comes from the sub-system of the scientific payload detector of the fourth phase of the lunar exploration project "Chang’e-7"-the micro-sampling unit of the volatile matter measuring instrument.The load adopts the method of in-situ detection and verification,by heating and quantifying lunar soil samples,and using mass spectrometry to determine the volatiles,moisture and their contents.In order to ensure the measurement accuracy of volatile matter and moisture in the polar lunar soil,it is necessary to research and develop a sampling method that can realize micro-quantitative collection of lunar soil samples.Ice resource exploration missions are critical.Since this mission will be carried out in extreme environments such as the lunar south pole,and the in-situ detection of lunar soil is the first in the world.Therefore,there is an urgent need to study the sampling characteristics of this type of sampler for lunar soil in polar regions and to verify its environmental adaptability in future on-orbit missions.Due to the particularity of the polar lunar soil,it is very important to carry out the preparation and mechanical properties of the polar lunar soil simulant samples on the ground.In this paper,through the investigation of relevant materials at home and abroad,the physical parameters of the polar lunar soil are explored.On the basis of this,several preparation methods of the polar lunar soil simulants are studied and compared,and the "water-soil mixing" method is finally selected.Prepare the simulated lunar soil;after the preparation of the lunar soil,a mechanical property test was carried out using the lunar soil water ice simulant as the base material,and the influence of different moisture content,temperature,and relative density on the compressive strength was analyzed,which provided a basis for subsequent verification.The preparation of simulated lunar soil samples and the study of sampling characteristics in the experiment provided basic support.Aiming at the goal of quantitative sampling of lunar soil in polar regions,a new sampler scheme is proposed.Based on rock and soil mechanics and simulated lunar soil physical properties tests,the Rankine passive earth pressure theory was applied to analyze the breaking principle of lunar soil during the sampling process,and a mechanical model of the interaction between the sampler and lunar soil was obtained.Based on the basic hypothesis of Janssen powder stress,the filling process of lunar soil samples in the cavity was analyzed,and the variation curve of the confining pressure in the cavity was obtained.Referring to the ground spiral transport theory,the migration process of lunar soil after being damaged by cutting is analyzed,and a lunar soil migration model is established,which is used to guide the design of the sampling operation procedure of the sampler.Based on the discrete element theory of soft spherical particles,the accumulation angle simulation test model was built in the EDEM simulation system,and the simulation parameters of the simulated lunar soil were obtained.The discrete element simulation method is used to optimize the sampling procedure under typical lunar soil conditions,laying the foundation for the ground test verification of the sampler.Finally,the sampling characteristics of the sampler under different lunar soil conditions were verified by building a simulated environment test bench.Through the study of the sampling characteristics of the polar lunar soil rotary-cut sampler in this paper,the sampling procedures for the sampler under typical working conditions are determined,and the sampling tests under different working conditions of the lunar soil are simulated on the ground.The sampler can adapt to most working conditions in the polar regions of the moon,and still has a certain sampling capability under extreme working conditions.The research results of this paper provide technical support for the lunar soil sampling of my country’s future "Chang’e-7" volatile content measuring instrument.