^1,7,8Wen Yu et al. (>10)
Earth and Planetary Science Letters 655, 119263 Link to Article [https://doi.org/10.1016/j.epsl.2025.119263]
¹Center for Lunar and Planetary Sciences, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
⁷CAS center for Excellence in Comparative Planetology, Hefei 230026, China
⁸Key Laboratory of Space Manufacturing Technology, Chinese Academy of Sciences, Beijing, 100094, China
Copyright Elsevier

The image of a bone-dry surface in the Moon’s non-polar regions impinged by the Apollo missions was changed by the detection of widespread absorption near 3 µm in 2009, interpreted as a signature of hydration. However, debates persist on the relative contribution of molecular water (H2O) and other hydroxyl (OH) compounds to this hydration feature, as well as the cause of the potential temperature-dependence of the OH/H2O abundance. Resolving these debates will help to estimate the inventory of water on the Moon, a crucial resource for future space explorations. In this study, we measured the abundance and isotope composition of hydrogen within the outermost micron of Chang’e-5 soil grains, collected from the lunar surface and from a depth of 1 m. These measurements, combined with our laboratory simulation experiments, demonstrate that solar-wind-induced OH can be thermally retained in lunar regolith, with an abundance of approximately 48–95 ppm H2O equivalent. This abundance exhibits small latitude dependence and no diurnal variation. By integrating our results with published remote sensing data, we propose that a high amount of molecular water (∼360 ± 200 ppm H2O) exists in the subsurface layer of the Moon’s non-polar regions. The migration of this H2O accounts for the observed latitude and diurnal variations in 3 µm band intensity. The inventory of OH and H2O proposed in this study reconciles the seemingly conflicting observations from various instruments, including infrared/ultraviolet spectroscopies and the Neutral Mass Spectrometer (NMS). Our interpretation of the distribution and dynamics of lunar hydration offers new insights for future lunar research and space

¹ Tiwari,¹Gaurav Joshi,¹Pradyut Phukon,¹Amar Agarwal,²Mamilla Venkateshwarlu
Meteoritics & Planetary Science (in Press) Link to Article [https://doi.org/10.1111/maps.14323]
¹Applied Structural Geology Lab, Department of Earth Sciences, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh, India
²CSIR-National Geophysical Research Institute, Hyderabad, Telangana, India
Published by arrangement with John Wiley & Sons

At the Dhala impact structure, the monomict breccia and the impact melt rock outcrops are present in proximity. Generally, these impactite lithologies are formed by different mechanisms and in different parts of the crater. The emplacement setting of impact melt rocks at Dhala has been well studied. Therefore, we studied the emplacement of monomict breccia using field, microscopic, and magnetic fabric investigations. Our results show that the intensities of the rock magnetic parameters in monomict breccia are comparable with the unshocked target granitoid at Dhala. Thus, the magnetic fabrics developed during pre-impact processes and were not altered due to impact. The absence of the reorientation of magnetic fabrics indicates that the peak shock pressures were below 0.5 GPa. Such shock pressures typically exist near the crater wall/floor or outside the crater. Moreover, there is no local variation in the orientations of magnetic fabrics at different locations in the same outcrop. Thus, the monomict breccia was not displaced from their pre-impact position. Based on the shock barometry and absence of displacement, we propose that the present-day annular outcrops of monomict breccia are located just outside the final crater. Furthermore, the monomict breccia annular outcrop ring has an internal diameter of ~4.5 km and is juxtaposed with impact melt rocks, which formed within the crater (previous studies). We, thus, suggest that the present-day crater diameter is ~4.5 km.