Future human space exploration missions are planned to take humans into permanently shaded regions (PSRs) at the lunar south pole. These areas are among the coldest places in the Solar System and represent a novel operational environment for spacesuits. In addition to this technical challenge, there is scientific interest in volatiles that are cold trapped in PSRs. This paper presents results from several simulations performed to assess the effect of the thermal interactions between the lunar surface and a comparatively warm spacesuit in a permanently shadowed crater on the Moon. After the tools used to perform the simulations and their limitations are discussed, two scenarios are introduced: a crater scenario to investigate the extent and magnitude of the thermal influence of the spacesuit in realistic setting, and a flat plane scenario that is used to analyze the effect of different astronaut translation speeds on the surface temperature changes. While the results show a significant change in lunar surface temperature of up to 60 K within 1.5 m of the astronaut, the effective sink temperature for the spacesuit only changes by a few degrees Kelvin, which is not large enough to have any implications on the design of the spacesuit system. Due to the low thermal conductivity of the lunar regolith and radiation being the dominant mode of heat transfer, the surface temperature increase is only significant for very slow translation rates or periods during which the crewmember remains stationary. The absolute temperature increase can be large enough to release volatiles from their entrapment, which in turn may necessitate a spacesuit design that radiates less heat to protect science objectives. However, further research and experimentation is necessary to determine which species are most susceptible in specific surface compositions and at which temperatures.

Water (ice, liquid, or vapor) is a critical driver of future exploration, and methods of its detection and characterization are a high priority for upcoming lunar missions. Thus, we assess the potential for alteration products resulting from water-ice liberated during various impact events in the lunar polar regions. In this work, we estimate the maximum amount and duration of melted, vaporized, or sublimed water-ice during representative post-impact environments using a model of bulk heat transfer. Our model is sensitive to heat loss by radiation, initial and final near-surface temperatures, and pre-existing water-ice abundance and distribution. Mineral dissolution rates in aqueous solution are used as a metric for potential chemical alteration in the presence of liberated water-ice following an impact. We find that the modeled timescales and potential for water liberation and reactivity are compatible with near-surface chemical alteration in some lunar post-impact environments. While initial surface temperatures less than similar to 110 K are adequate to maintain near-surface ice reservoirs at the lunar poles, when heated, pore pressures below a depth of similar to 35 cm are potentially adequate to sustain liquid water. Mild near-surface environments (e.g., similar to 5 degrees C) lasting a few decades, allow for aqueous alteration of sensitive minerals such as olivine, apatite, and glassy materials. Higher temperatures favor degassing of H2O, but vapor-phase interactions may occur. The limited amounts of available water will likely result in reactions with only the most sensitive minerals such as glasses and Fe-metal. Over time, secondary mineralization would be mixed into the upper few meters of the lunar regolith through subsequent bombardment, assuming it escapes later intense heating events; however, surface exposures would be suttected to space weathering. Nonetheless, based on our modeling, future explorers should consider instrumentation capable of detecting minor to trace amounts of impact-induced chemical alteration in the upper few meters of the lunar surface.

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.