Selection and thermal physical characteristics analysis of in-situ condition preserved coring lunar rock simulant in extreme environment

With the increasing scarcity of Earth’s resources and the development of space science and technology,the exploration, development, and utilization of deep space-specific material resources(minerals, water ice, volatile compounds, etc.) are not only important to supplement the resources and reserves on Earth but also provide a material foundation for establishing extraterrestrial research bases. To achieve large depth in-situ condition-preserved coring(ICP-Coring) in the extreme lunar environment, first, lunar rock simulant was selected(SZU-1), which has a material composition, element distribution, and physical and mechanical properties that are approximately equivalent to those of lunar mare basalt. Second, the influence of the lunar-based in-situ environment on the phase, microstructure, and thermal physical properties(specific heat capacity, thermal conductivity, thermal diffusivity, and thermal expansion coefficient)of SZU-1 was explored and compared with the measured lunar rock data. It was found that in an air atmosphere, low temperature has a more pronounced effect on the relative content of olivine than other temperatures, while in a vacuum atmosphere, the relative contents of olivine and anorthite are significantly affected only at temperatures of approximately-20 and 200 ℃. When the vacuum level is less than100 Pa, the contribution of air conduction can be almost neglected, whereas it becomes dominant above this threshold. Additionally, as the testing temperature increases, the surface of SZU-1 exhibits increased microcracking, fracture opening, and unevenness, while the specific heat capacity, thermal conductivity,and thermal expansion coefficient show nonlinear increases. Conversely, the thermal diffusivity exhibits a nonlinear decreasing trend. The relationship between thermal conductivity, thermal diffusivity, and temperature can be effectively described by an exponential function(R^(2)>0.98). The research results are consistent with previous studies on real lunar rocks. These research findings are expected to be applied in the development of the test and analysis systems of ICP-Coring in a lunar environment and the exploration of the mechanism of machine-rock interaction in the in-situ drilling and coring process.

Reflectance Spectral Characteristics of Lunar Surface Materials

Based on a comprehensive analysis of the mineral composition of major lunarrocks (highland anorthosite, lunar mare basalt and KREEP rock), we investigate the reflectancespectral characteristics of the lunar rock-forming minerals, including feldspar, pyroxene andolivine. The affecting factors, the variation of the intensity of solar radiation with wavelengthand the reflectance spectra of the lunar rocks are studied. We also calculate the reflectivity oflunar mare basalt and highland anorthosite at 300 nm, 415 nm, 750 nm, 900 nm, 950 nm and 1000 nm. Itis considered that the difference in composition between lunar mare basalt and highland anorthositeis so large that separate analyses are needed in the study of the reflectivity of lunar surfacematerials in the two regions covered by mare basalt and highland anorthosite, and especially in theregion with high Th contents, which may be the KREEP-distributed region.

Laboratory verification of the Active Particle-induced X-ray Spectrometer(APXS) on the Chang'e-3 mission

In the Chang＇e-3 mission, the Active Particle-induced X-ray Spectrometer（APXS） on the Yutu rover is used to analyze the chemical composition of lunar soil and rock samples. APXS data are only valid are only if the sensor head gets close to the target and integration time lasts long enough. Therefore, working distance and integration time are the dominant factors that affect APXS results. This study confirms the ability of APXS to detect elements and investigates the effects of distance and time on the measurements. We make use of a backup APXS instrument to determine the chemical composition of both powder and bulk samples under the conditions of different working distances and integration times. The results indicate that APXS can detect seven major elements, including Mg, Al, Si, K, Ca, Ti and Fe under the condition that the working distance is less than 30 mm and having an integration time of 30 min. The statistical deviation is smaller than 15%. This demonstrates the instrument＇s ability to detect major elements in the sample. Our measurements also indicate the increase of integration time could reduce the measurement error of peak area, which is useful for detecting the elements Mg, Al and Si. However, an increase in working distance can result in larger errors in measurement, which significantly affects the detection of the element Mg.