Investigating water ice content at different locations on the Moon is crucial for crewed space missions and serves as a foundation for establishing lunar bases, which necessitates lunar soil sampling to gather information. Aiming to minimize the water ice loss caused by heat generation during drilling, this paper proposes a water ice highconservation sampling system based on frozen CO2 spray cooling. The thermodynamic and hydrodynamic models of the frozen CO2 generation subsystem and heat exchange subsystem are established. The impact of design parameters, flow and thermal conditions, and operation modes on water content has been analyzed. The spray cooling method indirectly affects the lunar soil temperature by reducing the drill bit temperature to increase the water conservation ratio (WCR) during drilling. The method combines frozen CO2 sublimation heat flow and jet cooling flow. Jet cooling is closely associated with the temperature difference between the fluid and the drill bit, as well as the flow velocity. Meanwhile, sublimation heat flow depends on the temperature difference between the drill bit and the saturation temperature of frozen CO2, along with the content of frozen CO2. Jet cooling is predominant at lower mass flow rates, while sublimation cooling prevails at higher rates. In addition, the time the lunar soil is at low-sublimation temperature is an important factor in WCR. Thus, to increase WCR, one can enhance flow velocity by reducing the nozzle diameter, raise sublimation heat flow by increasing mass flow and lowering the initial temperature, and maintain lunar soil at low-sublimation temperatures by increasing cooling time, duty ratio and decreasing the cooling period. Among others, increasing the cooling time has the most significant effect. The increasing slopes of WCR with cooling durations are about 20 %/100 s (at 0.4 g/s, liquid CO2) and 10 %/100 s (at 0.1 g/s, liquid CO2). However, the cooling time should not exceed the drilling time. This study provides an effective water ice conservation system that is useful for other planetary sampling missions.

Knowledge regarding the abundance and distribution of solar wind (SW)-sourced water (OH/H2O) on the Moon in the shallow subsurface remains limited. Here, we report the NanoSIMS measurements of H abundances and D/H ratios on soil grains from three deepest sections of the Chang'E-5 drill core sampled at depths of 0.45-0.8 m. High water contents of 0.13-1.3 wt.% are present on approximately half of the grain surfaces (topmost similar to 100 nm), comparable to the values of Chang'E-5 scooped soils. The extremely low delta D values (as low as -995 parts per thousand) and negative correlations between delta D and water contents indicate that SW implantation is an important source of water beneath the lunar surface. The results are indicative of homogeneous distribution of SW-derived water in the vertical direction, providing compelling evidence for the well-mixed nature of the lunar regolith. Moreover, the findings demonstrate that the shallow subsurface regolith of the Moon contains a considerable amount of water.

PROSPECT is a comprehensive payload package developed by the European Space Agency which will support the extraction and analysis of lunar surface and subsurface samples as well as the acquisition of data from additional environmental sensors. The key elements of PROSPECT are the ProSEED drill and the ProSPA analytical laboratory. ProSEED will support the acquisition of cryogenic samples from depths up to 1 m and deliver them to the ProSPA instrument. ProSPA will receive and seal samples in miniaturized ovens, heat them, physically and chemically process the released volatiles, and analyze the obtained constituents via mass spectrometry using two types of spectrometers. Contextual information will be provided by cameras which will generate multi-spectral images of the drill working area and of acquired samples, and via temperature sensors and a permittivity sensor that are integrated in the drill rod. The package is designed for minimizing volatile loss from the sample between acquisition and analysis. Initially developed for a flight on the Russian Luna-27 mission, the payload package design was adapted for a more generic lander accommodation and will be flown on a lunar polar lander mission developed within the NASA Commercial Lunar Payload Services (CLPS) program. PROSPECT targets science and exploration in lunar areas that might harbor deposits of volatiles, and also supports the demonstration of In-Situ Resource Utilization (ISRU) techniques in the lunar environment. PROSPECT operations are designed to be automated to a significant degree but rely on operator monitoring during critical phases. Here, we report the PROSPECT flight design that will be built, tested, and qualified according to European space technology engineering standards before delivery to the lander provider for spacecraft integration. The package is currently in the hardware manufacturing and integration phase with a target delivery to the NASA-selected CLPS lander provider in 2025.

Currently, sampling and water detection of lunar regolith in the permanently shadowed regions (PSRs) of lunar polar regions is a hotspot in lunar exploration. Using deep fluted augers (DFAs) for lunar regolith sampling was proposed long ago. However, a comprehensive study on how to effectively capture regolith using a DFA has not been reported so far. In this study, based on the principles of regolith capturing with a DFA (RCDFA), we analyzed the factors possibly affecting the mass of the captured sample in terms of lunar soil conditions, drilling operating parameters, and structural design. Using the CUG-1A lunar regolith simulant (LRS), an experimental study was conducted on the influence of drilling operating parameters and the structure of the auger flutes on the mass of the captured sample during sampling operation. The experimental results revealed that the regolith sample might not be captured at all with unreasonable operating parameters; however, when using operating parameters within the feasible range, the mass of the captured sample was positively correlated with the cut per revolution (CPR) at the sampling and retracting stages and with the length and depth at the sampling stage. Among all factors, the CPR at the sampling stage had the most significant impact on the mass of the captured sample. Moreover, the width-to-depth ratio (WDR) of the auger flutes should be neither too small nor too large to obtain a good trade-off between the mass of the captured sample and the stability of the brushing efficiency. This study lays the foundation for further research on the mechanism of how DFAs capture lunar regolith and the optimal design of drilling tools. (c) 2023 COSPAR. Published by Elsevier B.V. All rights reserved.