Under lunar polar cold traps, volatile molecules within porous regolith may experience temperature and depth dependent slow mobility. Many degraded lunar craters exhibit thick regolith fill based on models of topographic diffusion and observations of fresh and degraded craters. Regolith has a low thermal conductivity relative to megaregolith and may act as a blanket for internal lunar heat flow, leading to increased temperatures at depth. We develop 2D thermal models of fresh and regolith-filled lunar craters over depths of meters to hundreds of meters below the surface. We find that the base of the stability and slow mobility zones migrate upward with regolith fill, which leads to temperatures that may increase the sublimation rate of volatiles at depth. For a notional cold trap crater 1.6 km in diameter and 3.6 billion years old, topographic diffusion fills it with approximately 90 m of regolith, and the regolith fill's blanketing effect causes the 110 K isotherm to shift about 180 m upward. This places it approximately 25 m below the current cold trap surface and well above the initial crater floor. The slow water ice mobility zone below the 110 K isotherms also shifts upward with regolith fill, potentially increasing volatile concentrations at shallower depths. These secondary volatile concentrations may be targets for sampling and testing hypotheses of volatile system processes. In addition, remobilized volatile concentrations may be a resource for future In -Situ Resource Utilization (ISRU) applications. The thick regolith fill in degraded craters and volatile remobilization potential in lunar subsurface cold traps have implications for future exploration instruments, sampling, and ISRU architectures.

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.

The scavenging of atmospheric trace gases has been recognized as one of the lifestyle-defining capabilities of microorganisms in terrestrial polar ecosystems. Several metagenome-assembled genomes of as-yet-uncultivated methanotrophic bacteria, which consume atmospheric CH4 in these ecosystems, have been retrieved in cultivation-independent studies. In this study, we isolated and characterized a representative of these methanotrophs, strain D3K7, from a subarctic soil of northern Russia. Strain D3K7 grows on methane and methanol in a wide range of temperatures, between 5 and 30 degrees C. Weak growth was also observed on acetate. The presence of acetate in the culture medium stimulated growth at low CH4 concentrations (similar to 100 p.p.m.v.). The finished genome sequence of strain D3K7 is 4.15 Mb in size and contains about 3700 protein-encoding genes. According to the result of phylogenomic analysis, this bacterium forms a common clade with metagenome-assembled genomes obtained from the active layer of a permafrost thaw gradient in Stordalen Mire, Abisco, Sweden, and the mineral cryosol at Axel Heiberg Island in the Canadian High Arctic. This clade occupies a phylogenetic position in between characterized Methylocapsa methanotrophs and representatives of the as-yet-uncultivated upland soil cluster alpha (USC alpha). As shown by the global distribution analysis, D3K7-like methanotrophs are not restricted to polar habitats but inhabit peatlands and soils of various climatic zones.

Volatiles including water on the Moon has been one of the most interesting scientific objects for decades. In this study, we systematically introduced a concept for China's Chang'E- 7 (CE-7) lunar polar exploration mission which consists of five elements, the orbiter, lander, rover, and leaper, and one relay satellite. The orbiter will provide a high-resolution image preparing for landing site selection. We also proposed three phases for in-situ investigation after landing. (1) The rover and leaper will jointly investigate the sunlit area; (2) the leaper will explore cold traps; and (3) the leaper will fly back to the sunlit area and continue an extended exploration mission. An experimental penetrator launched by the lander will penetrate permanently shadowed crater walls for water ice detection. Data will be transmitted to Earth through the relay satellite due to the limited Earth visibility. We also calculated the illumination rate within a 15 x 15 km area that partially covers the Shackleton crater at a high spatial resolution of 20 m/pixel during lunar southern summer. Specifically, we compared two potential landing sites with accumulated illumination at different altitude levels, slopes, and distances to the target. We found that one part of the Shackleton crater rim can be a primary landing site for CE-7's both sunlit areas and cold trap explorations.

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.

Understanding how spacecraft alter planetary environments can offer important insights into key physical processes, as well as being critical to planning mission operations and observations. In this context, it is important to recognize that almost any powered lunar landing will be an active volatile release experiment, due to the release of exhaust gases during descent. This presents both an opportunity to study the interaction of volatiles with the lunar surface and a need to predict how nonindigenous gases are dispersed, and how long they persist in the lunar environment. This work investigates these questions through numerical simulations of the transport of water vapor during a nominal lunar landing and for two lunar days afterward. Simulation results indicate that the water vapor component of spacecraft exhaust is globally redistributed, with a significant amount reaching permanently shadowed regions (cold traps) near the closest pole, where temperatures are sufficiently low that volatiles may remain stable over geological timescales. Exospheric evolution and surface deposition patterns are highly sensitive to desorption activation energy, providing a means to constrain this critical parameter through landed or orbital measurements during future missions. Contamination of cold traps by exhaust gases is likely to scale with exhaust mass and proximity of the landing site to the poles. Exhaust propagation is perhaps the most widespread and long-lived impact of spacecraft operations on a nominally airless solar system body and should be a key consideration in mission planning and in interpreting measurements made by landed lunar missions, particularly at near-polar regions.

The Polar Regions (PRs) are characterized by ice sheets, sea ice, glaciers, tundra, and other cryospheric landscapes and associated aboriginal cultural features. This primitive polar landscape is a huge contrast to the current human living environment and is a strong tourist attraction. Rapid environmental changes and the emergence of conflicts between tourism development and ecological protection, have affected sustainable development of polar tourism (PT). Polar high-latitude characteristics determine the vulnerability of their environment and the higher sensitivity of PT to climate change. This study comprehensively analyzed the status quo of PT development, systematically revealed mutual influence between environmental changes and tourism development, and proposed some adaptive measures to coordinate environment protection and tourism development.

Potential water ice concentrated within the permanently shadowed regions (PSRs) near lunar poles is both scientifically significant and of value for future explorations. However, after decades of observations, the existence and characteristics of PSR water ice remain controversial. The 1,064-nm laser reflectance measurements collected by the Lunar Orbiter Laser Altimeter (LOLA) onboard the Lunar Reconnaissance Orbiter (LRO) provide a unique opportunity to detect and characterize PSR water ice. In this work, we focus on all major PSRs on the flat floors of lunar polar craters and analyze their detailed LOLA 1,064-nm albedo and then compare this with the adjacent flat non-PSRs. We find that the LOLA albedo of the majority of these PSRs is systematically higher than their adjacent non-PSRs. Potential contributions of various factors to the observed LOLA albedo are individually quantitatively evaluated; we show that each of them is unable to account for the observed LOLA albedo anomalies and that the presence of surface water ice is the most likely explanation. Combined characterization of LOLA albedo and substrate impact cratering records (crater populations and depths) reveals that the inferred PSR water ices are in very small quantity (probably in the form of a surface frost layer or admixture with regolith) and are laterally heterogeneous in model ice concentration, ranging from negligible to similar to 6%. We recommend that these PSRs as priority targets for future surface in situ exploration endeavors, and a case assessment of Amundsen crater is presented.

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.

The permafrost regions currently occupy about one quarter of the Earth's land area. Climate-change scenarios indicate that global warming will be amplified in the polar regions, and could lead to a large reduction in the geographic extent of permafrost. Development of natural resources, transportation networks, and human infrastructure in the high northern latitudes has been extensive during the second half of the twentieth century. In areas underlain by ice-rich permafrost, infrastructure could be damaged severely by thaw-induced settlement of the ground surface accompanying climate change. Permafrost near the current southern margin of its extent is degrading, and this process may involve a northward shift in the southern boundary of permafrost by hundreds of kilometers throughout much of northern North America and Eurasia. A long-term increase in summer temperatures in the high northern latitudes could also result in significant increases in the thickness of the seasonally thawed layer above permafrost, with negative impacts on human infrastructure located on ice-rich terrain. Experiments involving general circulation model scenarios of global climate change, a mathematical solution for the thickness of the active layer, and digital representations of permafrost distribution and ice content indicates potential for severe disruption of human infrastructure in the permafrost regions in response to anthropogenic climate change. A series of hazard zonation maps depicts generalized patterns of susceptibility to thaw subsidence. Areas of greatest hazard potential include coastlines on the Arctic Ocean and parts of Alaska, Canada, and Siberia in which substantial development has occurred in recent decades.