Distinguishing the origin of lunar water ice requires in situ isotopic measurements with high sensitivity and robustness under extreme lunar conditions; however, challenges such as uncertain water contents and isotopic fractionation induced by regolith particles restrict isotopic analysis. Herein, we present a miniaturized tunable diode laser absorption spectrometer (TDLAS) developed as the core prototype for the Chang'E-7 Lunar Soil Water Molecule Analyzer (LSWMA). The wavelength range of the instrument is 3659.5-3662.0 cm-1, and the system integrates a Herriott cell for stable multi-isotope (H2 16O, H2 18O, H2 17O, and HD16O) detection and employs regolith samples of known isotopic experiments to quantify adsorption-induced fractionation. Performance evaluations demonstrated a dynamic water detection range of 0.01-2 wt % and isotope precision up to 1.3 parts per thousand for delta D (30.5 s), 0.77 parts per thousand for delta 18O (36 s), and 0.75 parts per thousand for delta 17O (21.5 s) with extended averaging. Repeated injections of three types of standard water revealed a volume-dependent deviation (Delta delta D up to -59.5 parts per thousand) attributed to multilayer adsorption effects, while simulated lunar soil experiments identified additional isotopic fractionation (Delta delta D up to -12.8 parts per thousand) caused by particle binding. These results validate the ability of the spectrometer to resolve subtle isotopic shifts under lunar conditions, providing critical data for distinguishing water origins and advancing future resource utilization strategies.

The presence of water in lunar materials can significantly impact the evolution of lunar geology and environment, as well as provide necessary conditions for the utilization of lunar resources. However, due to the limitations of lunar remote sensing methods, it is challenging to obtain direct evidence of water or determine its form of occurrence. Laser Raman spectroscopy, on the other hand, can provide valuable information on the type, distribution, and content of water in lunar materials without the need for illumination, sample pretreatment, or destructive measures. In this study, we utilized Raman spectroscopy to detect and quantify the water-containing characteristics of typical lunar rocks and minerals, including adsorbed water, ice, crystalline water, and hydroxyl-structured water. First, we used a 532 nm laser micro-Raman spectroscopy to identify and analyze the water-containing signals of various forms of water in lunar soil simulants. We then examined and analyzed the detection limits of adsorbed water, crystalline water, and hydroxyl- structured water in these simulants, as well as the relationship between their content and signal intensity. Finally, we employed linear regression (LR), ridge regression (RR), and partial least squares regression (PLSR) to quantitatively analyze the contents of these three forms of water in the lunar soil simulants. Our results demonstrate that the characteristic spectral peaks of the four forms of water in the lunar soil simulants can be clearly identified, with peak distribution regions located at 100-1 700 cm(-1) and 2 600-3 900 cm(-1) for the lunar soil components and water bodies, respectively. The spectral peaks of water are a combination of broad envelope peaks of hydrogen-bonded OH and sharp peaks of non- hydrogen-bonded OH stretching vibrations in varying proportions. The detection limits for adsorbed water, crystalline water (MgSO47H(2)O), and hydroxyl water (Al2Si2O5(OH)(4)) in the lunar soil simulants are 1.3 wt%, 0. 8 wt%, and 0. 3 wt%, respectively. There is a linear relationship between the intensity of water-containing peaks and the water content in the lunar soil simulants, with root mean square errors of 1. 75 wt%, 1. 16 wt%, and 1. 19 wt% obtained through LR, RR, and PLSR.