High-fidelity in-situ spectroscopy under thermal extremes enables cross-scale validation of the Chang’e-6 landing area

Abstract In-situ spectroscopy serves as a critical bridge between laboratory analysis of returned samples and orbital remote sensing of planetary surfaces. During China's Chang'e-6 (CE-6) mission, the first mission to return samples from the lunar farside, the Lunar Mineral Spectrometer (LMS) experienced internal temperatures exceeding 74 °C, threatening the fidelity of spectral measurements and undermining cross-scale comparisons. Here, we develop a Temperature-Compensated Radiometric Calibration (TCRC) framework to correct thermally induced measurement deviations. The framework improves the consistency of repeated observations acquired at different instrument temperatures by approximately 65%, while maintaining a signal-to-noise ratio above 40 dB under peak-temperature conditions. The corrected dataset enables cross-scale validation of surface properties at the lunar farside landing area. FeO abundance retrieved from LMS (15.36 – 19.54 wt%) agrees with both orbital Kaguya MI data (17.42 wt%) and returned sample analyses (~17.2 wt%). Centimeter-scale mapping on the Chang’e-6 landing area further reveals spatial heterogeneity in optical maturity and water content associated with lander plume disturbance. These results demonstrate that the TCRC framework supports reliable in-situ spectral acquisition under thermal extremes lunar surface conditions. Furthermore, the corrected spectra enable cross-scale validation and provide a practical reference for future planetary spectroscopic payloads operating under thermally challenging environments.