Infrared Spectroscopic Study of the Moon Based on Apollo and Chang’E-5 Samples

With the advancement of remote sensing technology and the rapid development of deep space exploration, thermal infrared hyperspectral remote sensing has become a frontier hotspot in planetary remote sensing. Infrared spectra contain rich information about the material composition, temperature, and surface physical properties of celestial bodies. Current research on the infrared spectra of the Moon is mainly based on the ancient Apollo samples, lacking studies on younger lunar soil samples. China's Chang'E-5 (CE-5) mission has for the first time collected young lunar soil, providing new samples for a deeper understanding of the thermal infrared spectral characteristics of the Moon. By comprehensively utilizing the spectral data of the ancient Apollo samples and the young CE-5 samples, the infrared spectral characteristics of the moon were analyzed to reveal the influence of different terrains and maturity on the infrared spectra of the moon. The results show that the overall shapes of the infrared spectra of different lunar terrains are similar, with the emissivity reaching its minimum around 4 μm and then sharply increasing to reach the maximum around 8 μm. There are differences in spectral characteristics among different terrains; the CF (Christiansen Frequency) value of the CE-5 samples is greater than that of most Apollo samples and is similar to that of Apollo 11, reflecting its mafic-rich mineral composition characteristics. The plagioclase emission peak at 5.45 μm is more pronounced in the CE-5 samples compared to Apollo 16 samples. The pyroxene emission valley at 11.4 μm is deeper in the CE-5 samples. Space weathering affects the infrared spectra of lunar soil, mainly manifested as an increase in the emissivity of RB (Reststrahlen Bands) and a decrease in spectral contrast. The CF characteristics of lunar soil are related to the SCFM (Si, Ca, Fe, Mg) index and are not affected by maturity. The research results provide support for the thermal infrared hyperspectral remote sensing studies of the moon and other celestial bodies.