Research On Key Technology Of Thermal Characteristics Measurement Of Simulated Lunar Soil

To explore and understand the changing process of the thermal environment on the lunar surface,a deep enough understanding of the thermal properties of the lunar soil is required.As the basic parameter of lunar soil thermal characteristics,thermal conductivity is an important condition for studying the lunar thermal evolution process,and it is also an important content of lunar exploration.Accurately measuring the thermal conductivity of the lunar surface and subsurface is extremely important for understanding the internal structure of the moon,analyzing the evolution of the space environment,and establishing the thermal evolution model of the lunar interior.Carrying out in-situ measurement of thermal conductivity parameters of the surface and subsurface layers in different regions of the moon,collecting more and more comprehensive thermal conductivity measured data,and realizing the interpretation of thermal conductivity parameters required for the internal heat flow of the moon.The important basis for the understanding of environmental characteristics is of great significance to the in-depth study of the historical evolution of the moon and other extraterrestrial objects.This topic mainly uses in-situ measurement to measure the thermal conductivity of simulated lunar soil at different depths.A self-propelled penetrator is used as the payload for the simulated lunar soil thermal conductivity measurement.By controlling the penetrator to dive To the target depth,so as to realize the thermal conductivity measurement of simulated lunar soil at different depths,and the following aspects are specifically studied.(1)The selection and analysis of the thermal conductivity measurement method of the simulated lunar soil is carried out,an improved thermal conductivity measurement method of the line heat source is selected,the measurement principle of the method is introduced in detail,and the technical scheme of the whole thermal conductivity measurement system is expounded.(2)The improved line heat source method relies on high temperature measurement accuracy,so the selection and analysis of the temperature sensor simulating the lunar soil is carried out,and finally the NTC(negative temperature coefficient)thermistor is selected as the temperature sensor for simulating the lunar soil temperature measurement,and the constant pressure is selected.The source method is used as a technical method to simulate lunar soil temperature measurement,and the temperature measurement principle is described in detail.(3)The hardware part of the entire simulated lunar soil thermal conductivity measurement system is reasonably selected and designed,and the software part is rigorously constructed and compiled,and the design ideas of the two parts are expounded in detail.(4)In order to achieve high-precision measurement of the thermal conductivity of the simulated lunar soil,it is necessary to improve the temperature measurement accuracy of the simulated lunar soil.Aiming at the nonlinear characteristics of NTC thermistor temperature sensor,a variety of compensation methods are systematically researched and reasonably selected,and a MEA(Mind Evolution Algorithm)optimization BP(Error Back Propagation)algorithm is proposed to measure the temperature of the NTC thermistor.The sensor performs nonlinear compensation to improve the temperature measurement accuracy of the simulated lunar soil.(5)Reasonable selection of the simulated lunar soil analogs is made,and an experimental platform for the simulated lunar soil thermal conductivity measurement system is built.The improved line heat source method is used to measure the thermal conductivity of simulated lunar soil at different depths.The simulated lunar soil thermal conductivity data obtained from the experiment is verified to ensure that the method is reasonable and feasible in actual measurement.