Research On The Measurement Method For Characteristics Of Thermal Conduction For In-situ Penetration Of Icy Lunar Regolith

The characteristics of thermal conduction of icy lunar regolith contains a wealth of information,accurate measurement of its thermal conductivity may provide a feasible method for determining whether it contains ice and judging the ice content.Sample return may change the natural state of the sample,and in-situ penetration probing has low cost and low sample perturbation,the future development prospects are very broad.This subject is based on icy lunar regolith detection missions in the permanent shadow area of the lunar south pole in future deep space exploration.Facing the demand for in-situ penetration of icy lunar regolith,a method for measuring characteristics of thermal conductivity is presented.The measurement method uses multiple cone-shaped probes as a thermal sensor carrier,thermal conductivity,volumetric heat capacity and thermal diffusivity of water ice in lunar soil were measured by active heating and dynamic heating.Firstly,in this paper,the thermal conductivity of lunar regolith and its main influencing factors are analyzed,the range of thermal conductivity of icy lunar regolith is predicted.The equivalent simulant of the thermal conductivity of icy lunar regolith is determined according to the needs of the validation experiments of the thermal conductivity measurement method.Combined with the characteristics of the measurement object and the specificity of unmanned autonomous penetration probing of planet,the effect of each structural parameter of the thermal probe on the measurement of thermal conductivity is analyzed by means of COMSOL simulation,an in-situ penetration probing solution for the characteristics of thermal conduction of icy lunar regolith based on the thermal probe method was designed.Secondly,the physical model of heat transfer for the thermal penetration probing icy lunar regolith was constructed,the main sources of interference in the process of measuring characteristics of thermal conduction of icy lunar regolith by thermal probes were analyzed by means of building the thermal resistance and heat capacit y network.Based on COMSOL simulation software,the heat flow pathways during thermal measurements are analyzed,the differences between the conical configuration probe and the instantaneous line heat source model-based probe method for measuring thermal properties are discussed.The inversion method for measuring the characteristics of thermal conduction of icy lunar regolith with a cone probe was studied and designed,and its accuracy was verified by simulation.The inversion method for the characteristics of thermal conduction of icy lunar regolith by conical configuration probes is studied and designed,and its accuracy is verified by means of simulations.Finally,the prototype of the in-situ penetration thermal probe for icy lunar regolith was developed and calibrated,its ability to measurement the characteristics of thermal conduction of icy lunar regolith was verified through the functional verification experiment of the thermal probe.