The Moon, as the celestial body closest to Earth, is a prime target for human deep space exploration. China's Lunar Exploration Project IV aims to explore and sample the lunar polar region's water-containing regolith. To effectively simulate the characteristics of this watery lunar regolith, this paper proposes a deep low-temperature preparation system. The feasibility of the system design is validated through theoretical and methodological analysis, including cold source selection, heat dissipation analysis, and energy consumption calculations. Subsequently, a deep low-temperature aqueous lunar regolith preparation system was developed, and tests were conducted to verify its performance. The results confirm that the system can generate water-containing lunar regolith at -238 degrees C and maintain its temperature during drilling. This capability is significant for subsequent research on the drilling performance of deep low-temperature watery lunar regolith.

The lunar poles are thought to contain vast ice deposits that could be beneficial to future space exploration efforts. However, it is not well characterized how water ice content affects regolith and dust physical properties. In order to develop suitable technologies that can operate safely in the cryogenic regolith, testing should be conducted in simulated regolith. We present a new production method for lunar permanently shadowed regions (PSRs) icy regolith simulant. We build on an existing lunar highlands simulant, by adapting it for lunar poles, where water ice might be present in PSRs. We have demonstrated a production concept using controllable simulant and water flow rates to make granular icy simulant with variable water ice content. We found that with this production method, icy simulant has a porosity of 0.6 to 0.7, that persists even after dehydration. (c) 2024 COSPAR. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Ever since the Lunar Crater Observation and Sensing Satellite (LCROSS) data helped confirm the presence of water in the permanently shadowed regions (PSRs) of the lunar polar area, interest in developing systems for the production of water on the Moon has peaked. Considering the extremely cold environment on the lunar surface, geotechnical properties of icy lunar regolith could have notable variance depending on water content and cryogenic environment. It is essential to have an in-depth understanding of the geotechnical properties of icy lunar regolith under varying conditions such as different water contents and cryogenic temperatures. Previous studies have shown that icy regolith behaves similarly to rock, depending on the water content and degree of compaction. Characterizing icy regolith is critical for any drilling and excavation operations for the development of the bases or for mining activities. This study estimated geotechnical behaviors of icy lunar regolith in cryogenic environments. Geotechnical tests such as unconfined compressive strength (UCS), Brazilian tensile strength (BTS), and punch penetration tests were conducted in simulated lunar cryogenic environments on samples of basaltic lunar simulant with changing water content. The results indicate that geotechnical properties of icy lunar regolith vary substantially in simulated moon environments. Icy lunar regolith tends to behave like rock with soft to medium strengths but has nonbrittle (or ductile) properties. Correlations between strength properties and water content as well as between strength properties and cryogenic temperature are offered. The results of this paper could provide valuable suggestions for future mining and civil activities and other exploration purposes on the moon. The results of mechanical characterization of icy regolith provided in this paper, such as UCS, BTS, and punch penetration tests to determine ductility and brittleness, are among the novel aspect of the study to offer better understanding of the behavior of such materials in future mining and construction activities on the moon.

Lunar water ice can be broadly categorized as belonging to one of two populations: deep, ancient, stable deposits, and shallow, transient, recent deposits. However, a third state for lunar ice is also possible. Temporary sequestration occurs when ice is deposited into a transiently shadowed region at the lunar poles. These temporarily sequestered ice deposits are unstable over geologic time scales, but in the short term, are capable of a wide range of migration, sublimation, and retention patterns due to their thermally dependent sublimation and migration rates. We developed a model to characterize the range of possible migration and retention behaviors for temporarily sequestered ice deposits within locations with dynamic illumination conditions. We found that water ice migration, sublimation, and retention varies across the lunar polar environment, with neighboring locations experiencing different illumination and thermal conditions. We found that the residence times of temporarily sequestered ice deposits in some high latitude, non-shadowed regions can be similar to or greater than the length of time spent above the long term stability temperature of ice during lunar winter months, leading to incomplete removal of surface or near surface ice during the day. We also found that shallowly buried, unstable ice deposits take longer to sublimate than surface deposits, leading to a temporal lag in escaping ice. This work suggests that temporary sequestration can lead to complex ice migration and retention patterns at high latitudes, with ice sublimation efficiency varying across the lunar polar environment due to local, small scale differences in illumination conditions.

Water ice may be allowed to accumulate in permanently shaded regions on airless bodies in the inner solar system such as Mercury, the Moon, and Ceres [Watson K, et al. (1961) J Geophys Res 66: 3033-3045]. Unlike Mercury and Ceres, direct evidence for water ice exposed at the lunar surface has remained elusive. We utilize indirect lighting in regions of permanent shadow to report the detection of diagnostic near-infrared absorption features of water ice in reflectance spectra acquired by the Moon Mineralogy Mapper [M (3)] instrument. Several thousand M (3) pixels (similar to 280 x 280 m) with signatures of water ice at the optical surface (depth of less than a few millimeters) are identified within 20 degrees latitude of both poles, including locations where independent measurements have suggested that water ice may be present. Most ice locations detected in M (3) data also exhibit lunar orbiter laser altimeter reflectance values and Lyman Alpha Mapping Project instrument UV ratio values consistent with the presence of water ice and also exhibit annual maximum temperatures below 110 K. However, only similar to 3.5% of cold traps exhibit ice exposures. Spectral modeling shows that some ice-bearing pixels may contain similar to 30 wt % ice that is intimately mixed with dry regolith. The patchy distribution and low abundance of lunar surface-exposed water ice might be associated with the true polar wander and impact gardening. The observation of spectral features of H2O confirms that water ice is trapped and accumulates in permanently shadowed regions of the Moon, and in some locations, it is exposed at the modern optical surface.