The nitrogen isotopic compositions of lunar soil have important implications for the sources of lunar volatiles and even the evolution of the moon. At present, the research on the lunar nitrogen isotopic compositions is mainly based on the lunar meteorites and the samples brought back by the Apollo and Luna missions. However, volatiles adsorbed on the surface of the lunar soil may be lost due to changes in temperature and pressure, as well as vibration and shock effects when the sample is returned. At the same time, in the case of low N content in the sample, since N is the main component of the earth’s atmosphere, it is easily affected by the atmosphere during the analysis process. Therefore, in situ nitrogen isotopic analysis of lunar soil on orbit is necessary to avoid the problems mentioned above and is one of the primary science goals for the Lunar Soil Volatile Measuring instrument on Chang’e-7 spacecraft. After the nitrogen purification procedure, the volatiles in lunar soil that are released through single-step or stepped heating techniques diffuse to the quadrupole mass spectrometer to obtain the N contents and isotopic compositions of the lunar soil. This paper introduces the ground test for N isotopic analysis of lunar soil in orbit according to the Lunar Soil Volatile Measuring Instrument. After long-term repeated measurements, the background and CO-corrected Air-STD ¹⁴N/¹⁵N ratio is 268.986 ± 4.310 (1SD, n = 35), and the overall reproducibility of measurements is 1.6%. The accuracy of N isotopic compositions is calculated to be better than 5%, which can distinguish different sources of N components in lunar soil.

This study prepared an adsorption-based water-containing lunar regolith simulant under low-temperature conditions to investigate H₂O behavior in simulated lunar environments. Experiments established that water binds to regolith particles via adsorption rather than existing in liquid/solid states, with critical initial pressure thresholds identified at various temperatures to ensure pure adsorption conditions. Crucially, coexisting substances extend H₂O preservation to −100 °C, suggesting substantial water retention in lunar polar regolith even under extreme cold. Sublimation modeling further revealed phase transition boundaries, indicating water ice likely persists in both permanently shadowed regions and illuminated polar areas. These findings provide fundamental insights into: adsorption-driven enrichment/preservation mechanisms of lunar water, thermodynamic stability thresholds at ultralow temperatures, and water ice distribution patterns across lunar polar terrains. The data advance understanding of lunar water’s stability and extractability, offering critical scientific support for future in situ resource utilization and sustained lunar exploration.