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The article presents the results of the analysis of data from the Russian neutron spectrometer LEND (Lunar Exploration Neutron Detector), installed aboard NASA's lunar orbiter LRO (Lunar Reconnaissance Orbiter). An estimate of the content of subsurface water ice in the permanently shadowed region Cabeus-1, located inside the large Cabeus crater in the vicinity of the lunar south pole, has been obtained. The analysis used observations made with the LEND instrument from 2009 to 2023. It is shown that the surface neutron albedo in the vicinity and inside of Cabeus-1 correlates with the relief height and the distribution of average annual temperatures. The average subsurface water ice content over the entire Cabeus-1 region was estimated to be 0.49 ± 0.05% by mass fraction. The maximum value of about 0.7% is observed at the very bottom of the crater on the surface area where the minimum average annual temperature was recorded. This site coincides with the site of the LCROSS (Lunar Crater Observation and Sensing Satellite) impact experiment, which confirmed a significant amount of water ice in the near-surface material of the Moon. [ABSTRACT FROM AUTHOR]

The paper presents new detailed radar maps and polarimetric data covering the southern polar region of the near side of the Moon measuring 400 × 800 km with a spatial resolution of about 75 m. The data were obtained using the 64-meter antenna (TNA-1500) of the Satellite Communications Center Bear Lakes of the Special Design Bureau of the Moscow Power Engineering Institute and the 13.2-meter radio telescope (RT-13) of the Svetloe Observatory of the Institute of Applied Astronomy, Russian Academy of Sciences, at a wavelength of 4.2 cm. At this wavelength, radar signals penetrate the lunar regolith to depths of up to 1 m and are sensitive to surface and suspended rocks larger than 1 cm. The maps show 39% of the area of permanently shadowed regions not observable by optical Earth-based instruments, which may hide water ice deposits. Analysis of radar maps did not reveal any relationship between the polarization properties of the surface in these regions and the presence of solar illumination. The data obtained as a result of this work can be used to study the surface and subsurface regolith features of the lunar south polar region, including searching for ice deposits in permanently shadowed regions, as well as for planning future lunar missions. [ABSTRACT FROM AUTHOR]

The article provides a description of the crater in the marginal zone of the southern polar region of the Moon with the coordinates of the center 126.59° W, 64.32° S The diameter of the crater is 34 km. It has a fractured bottom, which is considered a sign of magma intrusion into the subcrater space. The absolute age of formation of the crater under study was estimated to be ~3.85 billion years based on the spatial density of small craters superimposed on its rim. In the vicinity of the studied crater, low-iron anorthosite material is predominant. It can be argued that the basin of the crater under study is very dry compared to its surroundings. A significant loss of hydrogen/water and its redistribution from the bottom of the crater to the area around the crater could be caused by reworking of the surface due to the intrusion of magma under the crater, traces of which can be traced by the presence of cracks on the bottom of the crater. [ABSTRACT FROM AUTHOR]

The paper considers the results of a study of the geological structure of the floor of the crater Boguslawsky selected as a primary target for the Luna-Glob mission. The deplanate floor of the crater is covered by the material ejected from remote craters and the crater Boguslawsky-D on the eastern inner slope of the crater Boguslawsky. It is highly probable that the sampling of the crater Boguslawsky-D ejecta will provide the unique possibility to detect and analyze the material that predates the formation of the largest and most ancient currently known basin on the Moon-the South Pole-Aitken basin. The rockiness degree of the Boguslawsky crater floor has been estimated from the radar data and the manual boulder counts in the superresolution images (0.5 m/pixel obtained with the Narrow Angle Camera from the Lunar Reconnaissance Orbiter). Comparison of the radar data to the results of the photo-geological analysis shows that the main contributor to the radar signal is the rock debris located in the subsurface layer sounded by radar (1-1.5 m), while there are practically no boulders on the surface. The two most rocky regions on the crater Boguslawsky floor are associated with the relatively fresh impact craters 300-400 m in diameter. The spatial density of boulders near the craters suggests that one of them is 30-50 Myr older than the other. For both of these craters, the spatial density of boulders drops with the distance from their rims. The rate of the decrease in the boulder spatial density is the same for both craters, which points to the constant-in-time intensity of the fragmentation of boulders. The size distribution of boulders versus the distance from a rim of the older crater is approximated by the curve with a slope of-0.02, while the curve slope for the younger crater is-0.05. The gentler curve slope for the older crater is obviously connected with the equalization of sizes of the rock debris with time. The size-frequency distribution of all rock fragments for the both craters, regardless of the distance from the rim, shows that mainly large boulders first crumble away as the surface age increases. Some large boulders near the young crater demonstrate the traces of rolling, while such traces are absent for the boulders near the older crater. This allows us to estimate the intensity of the reworking of a thin surface layer at 0.01 m/Myr. [ABSTRACT FROM AUTHOR]

The hypsometric map and the basin height profiles, for the first time relying upon a spherical daturence surface, have been constructed based on the generalization of the heights measured within the hemisphere including the ring structure of the South Pole-Aitken basin. The distribution of the major chemical elements (Fe and Th), depending upon the structure height levels, has been obtained. The relationship between these lunar rock indicators and the height levels of the rock preferential distribution has been revealed. The outer basin ring has been distinguished and the ring structure of the central basin depression has been revealed against a combined hypsometric and geochemical background. A total basin diameter of about 3500 km has been reliably determined for the first time. A unique feature of the basin structure consists in that the arrangement of the basin inner rings does not show a central circular symmetry, which can indicate that a hypothetical impactor moved along the trajectory (or orbit) oriented almost normally to the ecliptic plane. In combination with the revealed very small depth-diameter ratio in the initial basin structure, this circumstance makes it possible to put forward the hypothesis that a comet impact produced the South Pole-Aitken basin. [ABSTRACT FROM AUTHOR]