Thermal Modeling of the Lunar Regolith at the Chang'E-4 Landing Site

Accurate assessments of surface temperatures on the Moon are important for understanding the physical properties of the lunar surface regolith and thermal effects on the reflectance spectra beyond 2 mu m. The local time resolved spectral measurements of the same region were used to estimate the surface temperature at the Chang'E-4 landing site. The results show that the surface temperatures at the landing site at lunar local time 14:28-14:41 are 346 +/- 8 K. The spectral absorptions at similar to 2 mu m of the lunar surface are overestimated without sufficient thermal removal, and consequently may have resulted in overestimation of pyroxene and/or glasses at the landing site. The results play a foundation for correcting thermal effects of reflectance data that will be acquired by Chang'E-5 and -6 and possible other future Chang'E missions. Plain Language Summary Surface temperature is an important physical parameter of the lunar surface and it reflects the thermal state of the lunar regolith. Though some orbital observations have been conducted to measure the surface temperature, the in situ detections are very limited. We derived the surface temperature at the Chang'E-4 landing site using the in situ spectral measurements acquired at different local time. In addition, we found that the thermal contributions on reflectance would induce significant errors on estimating pyroxene and/or glass abundances. The thermal correction model is critical for removing thermal contributions from reflectance data that will be acquired by Chang'E-5 and -6.

Automated summary

Accurate assessment of surface temperatures on the Moon is crucial for understanding physical properties of the lunar surface regolith and thermal effects on reflectance spectra. Spectral measurements at the Chang'E-4 landing site revealed surface temperatures of 346 ± 8 K. Thermal contributions to reflectance data may lead to overestimation of pyroxene and/or glasses, highlighting the importance of thermal correction models for future missions like Chang'E-5 and -6.