Calibration Methods and Error Analysis of the Mid- to Long Wave Bands of the Chang’E-7 Wide-band InfraRed Imaging Spectrometer

The Chang’E-7 orbiter is expected to carry the Wide-band InfraRed Imaging Spectrometer (WIRIS), which will acquire high spectral resolution images and thermal emission data of the lunar surface across a broad spectral range from the visible to longwave infrared (0.45～10 µm). These data will support scientific investigations into lunar surface mineral composition, thermal environment, and water/hydroxyl detection. Compared to previous lunar orbital hyperspectral instruments, WIRIS enhances quantitative retrieval capabilities for key spectral features such as the Christiansen Feature of silicate minerals and molecular water. Building upon the design of the Tianwen-1 Mars Mineralogical Spectrometer, WIRIS extends its spectral coverage into the mid- to long-wave infrared range (3.3～10 μm), and incorporates simultaneous temperature measurements to reduce thermal correction uncertainties in the 3 μm water/hydroxyl absorption region. This study addresses the quantitative calibration requirements of the newly extended spectral range by proposing spectral, radiometric, and geometric calibration methods tailored for the mid- to long-wave infrared bands. Based on calibration experiments, the sources of error and associated uncertainties are analyzed. The results provide essential methodological and technical support for accurate physical parameter retrieval and scientific application of WIRIS mid- to long-wave infrared data.