Surface Of Moon Research Articles

Surface Variability Mapping and Roughness Analysis of the Moon Using a Coarse‐Graining Decomposition

AbstractThe lunar surface contains a wide variety of topographic shapes and features, each with different distributions and scales, and any analysis technique to objectively measure roughness must respect these qualities. Coarse‐graining is a naturally scale‐dependent filtering technique that preserves scale‐dependent symmetries and produces coarse elevation maps that gradually erase the smaller features from the original topography. In this study of the lunar surface, we present two surface variability metrics obtained from coarse‐graining lunar topography: fine elevation and coarse curvature. Both metrics are isotropic, deterministic, slope‐independent, and coordinate‐agnostic. Fine (detrended) elevation is acquired by subtracting the coarse elevation from the original topography and contains features that are smaller than the coarse‐graining length‐scale. Coarse curvature is the Laplacian of coarsened topography, and naturally quantifies the curvature at any scale and indicates whether a location is elevated or depressed relative to its neighborhood at that scale. We find that highlands and maria have distinct roughness characteristics at all length‐scales. Our topographic spectra reveal four scale‐breaks that mark characteristic shifts in surface roughness: 100, 300, 1,000, and 4,000 km. Comparing fine elevation distributions between maria and highlands, we show that maria fine elevation is biased toward smaller‐magnitude elevations and that the maria–highland discrepancies are more pronounced at larger length‐scales. We also provide local examples of selected regions to demonstrate that these metrics can successfully distinguish geological features of different length‐scales.

Summer Antarctic expeditions in seasonal stations as analogs for long-duration space exploration missions: A critical review

This critical review aims to compare the conditions of summer Antarctic expeditions in seasonal stations with key characteristics of long-duration space exploration missions (LDSEM). Utilizing NASA's Analog Assessment Tool and data from the COMNAP Antarctic Station Catalogue, along with scientific literature, the review identifies significant parallels for LDSEM analog research. We assess how seasonal and year-round stations differ and highlight aspects of where seasonal stations serve as a better or worse analog for LDSEM. Key findings include that while summer expeditions allow for more feasible evacuations than winter-overs, their access to medical care is more limited. Crowdedness in summer stations with shared rooms better represents LDSEM conditions than the lower density of winter-over settings. Varying daylight hours in summer stations provide a closer parallel to Mars or Moon surface missions than the continuous darkness of winter-over conditions. Additionally, constant hazards, risk management strategies, isolation, sensory deprivation, workload, leadership structures, autonomy, and communication challenges in summer stations align well with LDSEM scenarios. Conclusively, we propose a shift in perceptions, recognizing seasonal Antarctic expeditions as a valuable analog of planetary LDSEM with several advantages over traditionally accepted winter-over settings. Further comparative and longitudinal studies between seasonal and year-round Antarctic stations should be pursued to enhance LDSEM analog research and support interdisciplinary collaboration. This approach will not only advance progress in space exploration research but also improve the quality of life and safety in remote and extreme environments.

High-Efficiency Forward Modeling of Gravitational Fields in Spherical Harmonic Domain with Application to Lunar Topography Correction

Gravity forward modeling as a basic tool has been widely used for topography correction and 3D density inversion. The source region is usually discretized into tesseroids (i.e., spherical prisms) to consider the influence of the curvature of planets in global or large-scale problems. Traditional gravity forward modeling methods in spherical coordinates, including the Taylor expansion and Gaussian–Legendre quadrature, are all based on spatial domains, which mostly have low computational efficiency. This study proposes a high-efficiency forward modeling method of gravitational fields in the spherical harmonic domain, in which the gravity anomalies and gradient tensors can be expressed as spherical harmonic synthesis forms of spherical harmonic coefficients of 3D density distribution. A homogeneous spherical shell model is used to test its effectiveness compared with traditional spatial domain methods. It demonstrates that the computational efficiency of the proposed spherical harmonic domain method is improved by four orders of magnitude with a similar level of computational accuracy compared with the optimized 3D GLQ method. The test also shows that the computational time of the proposed method is not affected by the observation height. Finally, the proposed forward method is applied to the topography correction of the Moon. The results show that the gravity response of the topography obtained with our method is close to that of the optimized 3D GLQ method and is also consistent with previous results.

Thermal modeling of the lunar South Pole: Application to the PROSPECT landing site

Water ice is distributed on the surface and in the subsurface of the Moon, as confirmed by observational data, and predicted by several numerical models. In this respect, the direct search for lunar water is the main objective of the ESA’s PROSPECT package, that aims to analyze a region of interest at the lunar South Pole. PROSPECT, originally on the Russian Luna 27, is now on the CLPS (Commercial Lunar Provider Service) “CP” 22 mission. In this work, we applied our 3-D FEM thermophysical model to investigate the landing site selected for the CP 22 mission, which is centred at −84.496°S, 31.588°E, and located on the Leibnitz Plateau and within an area of high elevation. The purpose of our model is to investigate regions of interest (ROI) on the lunar surface by working with the real topography at the scale of 5 m, by using the DEM (Digital Elevation Model) of the region. Since the lunar surface is characterized by topographic variations such as craters or boulders, a 3-D model is preferable over a 1-D numerical model. We produced temperature maps of the surface and 1-D temperature vs depth, as well as we produced illumination maps, computing also the indirect contribution. These simulations will provide a complete thermophysical vision of the landing site, offering a theoretical support to the researchers and engineers of the CP 22 mission, and of future lunar missions. In addition, this model can be applied to every site of the Moon surface and subsurface and, in general, to any airless body of the Solar System.

Characterization of carbon dioxide on Ganymede and Europa supported by experiments: Effects of temperature, porosity, and mixing with water

Context. The surfaces of icy moons are primarily composed of water ice that can be mixed with other compounds, such as carbon dioxide. The carbon dioxide (CO2) stretching fundamental band observed on Europa and Ganymede appears to be a combination of several bands that are shifting location from one moon to another. Aims. We investigate the cause of the observed shift in the CO2 stretching absorption band experimentally. We also explore the spectral behaviour of CO2 ice by varying the temperature and concentration. Methods. We analyzed pure CO2 ice and ice mixtures deposited at 10 K under ultra-high vacuum conditions using Fourier-transform infrared (FTIR) spectroscopy and temperature programmed desorption (TPD) experiments. Laboratory ice spectra were compared to JWST observation of Europa’s and Ganymede’s leading hemispheres. The simulated IR spectra were calculated using density functional theory (DFT) methods, exploring the effect of porosity in CO2 ice. Results. Pure CO2 and CO2-water ice show distinct spectral changes and desorption behaviours at different temperatures, revealing intricate CO2 and H2O interactions. The number of discernible peaks increases from two in pure CO2 to three in CO2-water mixtures. Conclusions. The different CO2 bands were assigned to ν̃3,1 (2351 cm−1, 4.25 μm) caused by CO2 dangling bonds (CO2 found in pores or cracks) and ν̃3,2 (2345 cm−1, 4.26 μm) due to CO2 segregated in water ice, whereas ν̃3,3 (2341 cm−1, 4.27 μm) is due to CO2 molecules embedded in water ice. The JWST NIRSpec CO2 spectra for Ganymede and for Europa can be fitted with two Gaussians attributed to ν̃3,1 and ν̃3,3. For Europa, ν̃3,1 is located at lower wavelengths due to a lower temperature. The Ganymede data reveal latitudinal variations in CO2 bands, with ν̃3,3 dominating in the pole and ν̃3,1 prevalent in other regions. This shows that CO2 is embedded in water ice at the poles and it is present in pores or cracks in other regions. Ganymede longitudinal spectra reveal an increase of the CO2 ν̃3,1 band throughout the day, possibly due to ice cracks or pores caused by large temperature fluctuations.

Optimizing translucent multilayer membrane for lunar habitats: A design study

In the recently boosted scenario, the eventual settlement in extreme extra-terrestrial environments, notably the Moon and Mars, stands as critical objective driving the forefront of space exploration endeavours: the possibility of realizing a lunar settlement is currently under study by NASA Artemis Program and others active subjects in the aerospace sector (Schrunk et al., 2008) [1]. As mission duration tends to increase, the wellness of crew members emerges as a stronger concern, affecting the habitat features and driving the design towards solutions that still must face environmental constraints. A wide exploration in the aerospace field has been conducted, starting from the experience accumulated in more than 50 years of experimentation and activity on board of the active and decommissioned space stations.In recent years, several pioneering concepts for human living structures on our satellite have been proposed, with an extensive adoption of transparent inflatable or deployable shells. Even if these proposals can lead the way for optimized solution identification, the technical characterization of these shells has not been extensively explored yet, and it represents a mandatory step in the path for achieving the best possible prototype to be built on the Moon surface. Our research aims to assess the viability of employing transparent or translucent inflatable-type envelopes within the harsh conditions of extra-terrestrial environments.The research background has been extensively investigated in order to identify best practices and promising solutions, which have been proposed here. Where no previous tests were conducted, traditional Earth-related engineering tools where utilized. The result of this work is a multilayer membrane to be deployed through internal air pressurization, with the correct size of each of the composing layers calculated by employing multi-physics simulations employing multi-physics simulations and computational.The outcome of this work represents not a definitive design, but an introductive experience with the aim to launch wider investigations to reach higher TRLs. Finally, we aimed to identify the limits of this research that need to be addressed in order to make an inflatable multilayer membrane feasible to be adopted for long permanent human missions on the Moon.

Simulations on Levitation and Spatial Distribution of Charged Dust on the Moon Surface

The levitation of charged dust, which may cause serious hazards to astronauts and lunar rovers, has been one of the most significant challenges in lunar exploration. Here we simulate lunar sheath potentials in different solar wind conditions and solar zenith angles (SZAs) on the lunar surface by the particle-in-cell method. The simulated potentials exhibit two types of distributions as a function of height, depending on the SZAs. For SZA ∼ 0°–70°, the nonmonotonic distribution with positive surface potential dominates in the photoelectron sheath. For SZA >∼81°, the monotonic distribution with negative surface potential is observed in the plasma sheath. With the calculated potentials and the assumption that the dust radius distribution exponentially decreases, we further investigate spatial distributions of the dust levitated above the surface. It is found that number density of the levitating lunar dust is enhanced at the terminator (SZA ∼ 81°) in the plasma sheath. In the photoelectron sheath it gradually decreases as the SZA increases from 0° to 70°. Further calculations of the potential and the derived electrostatic field suggest that the dust spatial distributions can be influenced by the bulk velocity, number density, and temperature of the solar wind. Those findings deepen our understanding of lunar surface charging and the mechanism of lunar dust levitation, which can provide technical support for lunar explorations.

Lunar Lithium-7 Sensing (δ7Li): Spectral Patterns and Artificial Intelligence Techniques.

Lithium, a critical natural resource integral to modern technology, has influenced diverse industries since its discovery in the 1950s. Of particular interest is lithium-7, the most prevalent lithium isotope on Earth, playing a vital role in applications such as batteries, metal alloys, medicine, and nuclear research. However, its extraction presents significant environmental and logistical challenges. This article explores the potential for lithium exploration on the Moon, driven by its value as a resource and the prospect of cost reduction due to the Moon's lower gravity, which holds promise for future space exploration endeavors. Additionally, the presence of lithium in the solar wind and its implications for material transport across celestial bodies are subjects of intrigue. Drawing from a limited dataset collected during the Apollo missions (Apollo 12, 15, 16, and 17) and leveraging artificial intelligence techniques and sample expansion through bootstrapping, this study develops predictive models for lithium-7 concentration based on spectral patterns. The study areas encompass the Aitken crater, Hadley Rima, and the Taurus-Littrow Valley, where higher lithium concentrations are observed in basaltic lunar regions. This research bridges lunar geology and the formation of the solar system, providing valuable insights into celestial resources and enhancing our understanding of space. The data used in this study were obtained from the imaging sensors (infrared, visible, and ultraviolet) of the Clementine satellite, which significantly contributed to the success of our research. Furthermore, the study addresses various aspects related to statistical analysis, sample quality validation, resampling, and bootstrapping. Supervised machine learning model training and validation, as well as data import and export, were explored. The analysis of data generated by the Clementine probe in the near-infrared (NIR) and ultraviolet-visible (UVVIS) spectra revealed evidence of the presence of lithium-7 (Li-7) on the lunar surface. The distribution of Li-7 on the lunar surface is non-uniform, with varying concentrations in different regions of the Moon identified, supporting the initial hypothesis associating surface Li-7 concentration with exposure to solar wind. While a direct numerical relationship between lunar topography and Li-7 concentration has not been established due to morphological diversity and methodological limitations, preliminary results suggest significant economic and technological potential in lunar lithium exploration and extraction.

Design and Development of an Autonomous Rover Application using A Rocker-Bogie Mechanism In Agriculture

The crucial topic of upgrading the rover over its earlier designs is covered in the project work "STUDY ON ROCKER ROVER AND ITS IMPLEMENTATION IN THE FIELD OF AGRICULTURE." The ROCKER rover was intended for use on similar excursions that require it to function in challenging conditions, such as the Moon's surface. However, the use of the rocker rover can be expanded even further in fields of employment where the land has to be used for operations, such as agricultural farming. Our research focuses on how the rocker rover can be modified for use in farming, greatly increasing the automation of the agricultural sector. The rover's body is entirely composed of PVC to boost. With the introduction of cutting-edge technologies, agricultural practices are changing with the goal of enhancing sustainability, accuracy, and efficiency. The design and construction of an autonomous rover with a rocker-bogie suspension system specifically intended for agricultural applications is the main goal of this study. When doing in-situ scientific investigation of goals that are separated by several metres to tens of km, rocker bogie are crucial. The complicated mobility designs of today use numerous wheels or legs. They are vulnerable to mechanical failure brought on by Mars' hostile atmosphere. a four-wheeled rover with a high degree of mobility suspension system that is effective in navigating uneven terrain. The main mechanical characteristic of the rocker bogie design is how simple its drive train is—it only requires two motors to move. Because both motors are housed inside the body, where heat variance is minimised, dependability and efficiency are raised. Because there aren't many barriers on natural terrain that call for the rover to use all of its front wheels, four wheels are used

Erosion rate of lunar soil under a landing rocket, part 1: Identifying the rate-limiting physics

Multiple nations are planning activity on the Moon's surface, and to deconflict lunar operations we must understand the sandblasting damage from rocket exhaust blowing soil. Prior research disagreed over the scaling of the erosion rate, which determines the magnitude of the damage. Reduced gravity experiments and two other lines of evidence now indicate that the erosion rate scales with the kinetic energy flux at the bottom of the laminar sublayer of the gas. Because the rocket exhaust is so fast, eroded particles lifted higher in the boundary layer do not impact the surface for kilometers (if at all; some leave the Moon entirely), so there is no saltation in the vicinity of the gas. As a result, there is little transport of gas kinetic energy from higher in the boundary layer down to the surface, so the emission of soil into the gas is a surprisingly low energy process. In low lunar gravity, a dominant source of resistance to this small energy flux turns out to be the cohesive energy density of the lunar soil, which arises primarily from particles in the 0.3 to 3 μm size range. These particles constitute only a tiny fraction of the mass of lunar soil and have been largely ignored in most studies, so they are poorly characterized.

Metal impact and vaporization on the Moon's surface: Nano‐geochemical insights into the source of lunar metals

AbstractMillimeter‐to‐nanometer‐sized iron‐ and nickel‐rich metals are ubiquitous on the lunar surface. The proposed origin of these metals falls into two broad classes which should have distinct geochemical signatures—(1) the reduction of iron‐bearing minerals or (2) the addition of metals from meteoritic sources. The metals measured here from the Apollo 16 regolith possess low Ni (2–6 wt%) and elevated Ge (80–350 ppm) suggesting a meteoritic origin. However, the measured Ni is lower, and the Ge higher than currently known iron meteorites. In comparison to the low Ni iron meteorites, the even lower Ni and higher Ge contents exhibited by these lunar metals are best explained by impact‐driven volatilization and condensation of Ni‐poor meteoritic metal during their impact and addition to the lunar surface. The presence of similar, low Ni‐bearing metals in Apollo return samples from geographically distant sites suggests that this geochemical signature might not be restricted to just the Apollo 16 locality and that volatility‐driven modification of meteoritic metals are a common feature of lunar regolith formation. The possibility of a significant low Ni/high Ge meteoritic component in the lunar regolith, and the observation of chemical fractionation during emplacement, has implications for the interpretation of both lunar remote‐sensing data and bulk geochemical data derived from sample return material. Additionally, our observation of predominantly meteoritic sourced metals has implications for the prevalence of meteoritic addition on airless planetary bodies.

Assessing the survival of carbonaceous chondrites impacting the lunar surface as a potential resource

The Moon offers a wide range of potential resources that may help sustain a future human presence, but it lacks indigenous carbon (C) and nitrogen (N). Fortunately, these elements will have been delivered to the Moon's surface by carbonaceous chondrite (CC) asteroid impactors. Here, we employ numerical modelling to assess the extent to which these materials may have sufficiently survived impact with the lunar surface to be viable sources of raw materials for future exploration. We modelled the impact of a 1 km diameter CC-like asteroid, considering impact velocities between 5 and 15 km s−1, and impact angles between 15 and 60° to the horizontal. The most favourable conditions for the survival of C-rich, and especially N-rich materials, are those with the lowest impact velocities (≤10 km s−1) and impact angles (≤15°). Impacts with velocities >10 km s−1 and angles >30° were found not to yield any significant amount of surviving solid material, where bulk survival is defined as material experiencing temperatures less than the impactor material's estimated melting temperature (∼2100 K, based on a commonly adopted Equation of State for serpentine). Importantly, oblique and low velocity impacts result in concentrations of unmelted projectile material down-range from the impact site. For the canonical 1 km-diameter CC impactor considered here, with an impact angle ≤15° and velocity ≤10 km s−1, this results in ∼109–1010 kg of C and ∼108–109 kg of N being deposited a few tens of km down-range from the impact crater, where it might be accessible as a potential resource. Such low-velocity and oblique impacts have a low probability - we estimate that only ∼5 such impacts may have occurred on the Moon in the last 3 billion years (the number of impacts of smaller impactors will have been higher, but they will concentrate lower masses of potential resources). As the estimated C and N concentrations from such impacts greatly exceed those expected for ices within individual permanently shadowed polar craters, searching for these rare impact sites may be worthwhile from a resource perspective. We briefly discuss how this might be achieved by means of orbital infra-red remote-sensing measurements.

Shape-from-shading Refinement of LOLA and LROC NAC Digital Elevation Models: Applications to Upcoming Human and Robotic Exploration of the Moon

The Lunar Reconnaissance Orbiter (LRO) has returned a wealth of remotely sensed data of the Moon over the past 15 years. As preparations are under way to return humans to the lunar surface with the Artemis campaign, LRO data have become a cornerstone for the characterization of potential sites of scientific and exploration interest on the Moon's surface. One critical aspect of landing site selection is knowledge of topography, slope, and surface hazards. Digital elevation models derived from the Lunar Orbiter Laser Altimeter (LOLA) and Lunar Reconnaissance Orbiter Camera (LROC) instruments can provide this information at scales of meters to decameters. Shape-from-shading (SfS), or photoclinometry, is a technique for independently deriving surface height information by correlating surface reflectance with incidence angle and can theoretically approach an effective resolution equivalent to the input images themselves, typically better than 1 m per pixel with the LROC Narrow Angle Camera (NAC). We present a high-level, semiautomated pipeline that utilizes preexisting Ames Stereo Pipeline tools along with image alignment and parallel processing routines to generate SfS-refined digital elevation models using LRO data. In addition to the present focus on the lunar south pole with Artemis, we also demonstrate the usefulness of SfS for characterizing meter-scale lunar topography at lower equatorial latitudes.

Temporal and Spatial Variability of the Electron Environment at the Orbit of Ganymede as Observed by Juno

AbstractThe thermal and energetic electrons along Ganymede's orbit not only weather the surface of the icy moon, but also represent a major threat to spacecraft. In this article, we rely on Juno plasma measurements to characterize the temporal and spatial variability of the electron environment upstream of Ganymede. In particular, we find that electron spectra observed by Juno have fluxes larger by a factor of 2–9 at energies above 10 keV than what was measured two decades earlier by Galileo. This result will advance our understanding of the surface weathering and may be a concern for the radiation safety of the JUICE mission. Furthermore, the June 2021 close fly‐by of Ganymede through the moon's wake reveals that the open field line regions of its magnetosphere attenuate electron fluxes at all energies by a factor of 1.6–5, thereby offering a natural shelter to visiting spacecraft crossing this region.

The Deep Space Radiation Probe: Development of a first lunar science payload for space environment studies and capacity building

Regions outside of Low Earth Orbit (LEO, altitudes above approximately 1000 km) are classified as “deep space”, including Medium Earth Orbit (MEO), geostationary orbit (GEO), as well as cislunar and lunar space. The deep space environment poses many challenges for human and robotic exploration, including stronger ionizing radiation fluxes, more extreme temperature variations, as well as limited data downlink volume. With the growth of the rideshare and hosted payload model aboard government and commercial lunar missions, developing the capacity to design and implement payloads and other space avionics for this environment is of increased importance this decade. Utilizing one of the growing number of rideshare opportunities offered by commercial lunar mission providers, National Central University (NCU) has been working on the rapid development of Taiwan’s first scientific payload for lunar lander use, with launch aboard the HAKUTO-R Mission 2 (M2) lander from ispace, inc. scheduled not earlier than Q4 2024. This Deep Space Radiation Probe (DSRP) will provide measurements of radiation dose, dose rate, and single event upset (SEU) rate during the Earth-Moon transit, in lunar orbit, as well as on the lunar surface. DSRP utilizes elements of the on-board computer (OBC) developed and flight qualified aboard the NCU-developed IDEASSat 3U CubeSat mission in 2021, and was developed by a student team, in consultation with experienced engineers from the lunar lander team. In this paper, we will report on the objectives, concept of operation, design, and implementation of the DSRP project. We will also describe the steps taken to facilitate parallel development of the DSRP payload and the HAKUTO-R M2 lander, as well as lessons learned during the design, implementation, and qualification process. The radiation data provided by DSRP will be beneficial for the development of future deep space spacecraft avionics, as well as crewed missions, and will also serve to build the capacity for deep space spacecraft and payload development at NCU.

Numerical study on modeling the soil footpad interaction of lunar soft landers at touchdown

Soft landers are a common systems for planetary exploration and have been successfully landed on Moon, Mars and the comet Churyumov–Gerasimenko. In this study numerical simulations of the touchdown process of soft landers on the moon surface are presented. The focus is on the soil footpad interaction and the resulting loading on the primary strut of the landing gear. Main influence parameters like slope inclination, touchdown velocities and soil properties are varied to show each individual influence on the structural loading of the landing gear. The numerical simulations are done using the CEL-Method allowing for significant soil deformation at touchdown.

Optimized manufacturing process of homogeneous microwave-sintered blocks of KLS-1 lunar regolith simulant

The use of materials from the Moon's surface based on In-Situ Resource Utilization (ISRU) is gaining considerable attention as a means of constructing infrastructure to sustain a human presence there. In particular, the sintering of lunar regolith appears a promising way to fabricate infrastructure on the lunar surface. This study presents a method to manufacture homogeneous blocks using a lunar regolith simulant. The tested simulant, KLS-1, was sintered under diverse conditions in a multi-mode microwave sintering furnace. Successful sintering requires the sample to be heated throughout, without generating a temperature gradient. This was achieved by testing various heating rates and sample sizes. X-ray computed tomography was used to assess the pore structure of sintered samples. While the optimized sintering conditions resulted in the formation of internal cracks by outgassing, preheating the KLS-1 in a vacuum oven at 250 °C effectively prevented the formation of internal cracks. The homogeneity of the blocks was confirmed by coring and measurements of true density, bulk density, porosity, and unconfined compressive strength. The robust reproducibility and similarity in physical and mechanical properties validate the viability of microwave sintering in manufacturing large and uniform blocks suitable for application as construction materials on the Moon.

High-energy particle observations from the Moon.

The Moon is a unique natural laboratory for the study of the deep space plasma and energetic particles environment. During more than 3/4 of its orbit around the Earth it is exposed to the solar wind. Being an unmagnetized body and lacking a substantial atmosphere, solar wind and solar energetic particles bombardthe Moon's surface, interacting with the lunar regolith and the tenuous lunar exosphere. Energetic particles arriving at the Moon's surface can be absorbed, or scattered, or can remove another particle from the lunar regolith by sputtering or desorption. A similar phenomenon occurs also with the galactic cosmic rays, which have fluxes and energy spectra representative of interplanetary space. During the remaining part of its orbit the Moon crosses the tail of the terrestrial magnetosphere. It then provides the opportunity to study in-situ the terrestrial magnetotail plasma environment as well as atmospheric escape from the Earth's ionosphere, in the form of heavy ions accelerated and streaming downtail. The lunar environment is thus a unique natural laboratory for analysing the interaction of the solar wind, the cosmic rays and the Earth's magnetosphere with the surface, the immediate subsurface, and the surface-bounded exosphere of an unmagnetized planetary body. This article is part of a discussion meeting issue 'Astronomy from the Moon: the next decades (part 2)'.

Advanced microstructural and compositional analysis of a lunar agglutinate from the Apollo 11 mission

AbstractThe microstructural characterization of lunar agglutinate samples serves many essential purposes in lunar science and cosmochemistry, from understanding the formation process of lunar regolith to preparing for human activity on the Moon. In this study, an advanced correlative characterization methodology was employed to examine the microstructure of a lunar agglutinate particle retrieved from the Apollo 11 mission. The multimodal characterization efforts were centered around 3‐D x‐ray computed tomography (XCT) and were complemented by 2‐D techniques, including scanning electron microscopy and energy‐dispersive x‐ray spectroscopy. The nondestructive nature of the XCT allowed us to preserve the lunar dust particles, while its 3‐D nature allowed us to extract meaningful microstructural information inaccessible via traditional 2‐D characterization techniques. The multimodal correlative analysis further allowed us to identify the compositional and microstructural features of the agglutinate. These observations were linked to the formation process of the agglutinate to inform a hypothesis on the dynamic formation sequence of lunar regolith.

Numerical investigations of translocation characteristics of nano-silica lunar dust across pulmonary surfactant monolayer

The interactions between nano-silica lunar dust (NSLD) on the moon surface and pulmonary surfactant (PS) monolayer will pose risks to astronaut health in future manned lunar exploration missions, but the specifics of these interactions are unknown. This study investigates them using the coarse-grained molecular dynamics method considering different sizes (5, 10, and 15 nm) and shapes (sphere, ellipsoid, and cube), with special focus on the unique morphology of NSLDs with bugles. The key findings are as follows: (1) The 10 nm and 15 nm NSLDs embed in the PS monolayer through the major sphere of spherical-type, major ellipsoid of ellipsoidal-type, or one edge of cubic-type NSLDs upon contact the PS monolayer. (2) Adsorbed NSLDs cause a higher Sz value (ASz > 0.84), while embedded NSLDs cause a lower Sz value (0.47 < ASz < 0.83) that decreases with an increase in the number of bulges. (3) The embedding process absorbs 50–342 dipalmitoylphosphatidylcholine (DPPC) molecules, reducing the PS monolayer area by 0.21%–6.05%. NSLDs with bulges absorb approximately 9–126 additional DPPC molecules and cause a 0.05%–3.22% reduction in the PS monolayer area compared to NSLDs without bulges. (4) NSLDs move obliquely or vertically within the PS monolayer, displaying two distinct stages with varying velocities. Their movement direction and speed are influenced by the increasing complexity of NSLD with more bulges on them. In general, larger NSLDs with sharper shapes and increasing complex morphology of more bulges cause more significant damages to the PS monolayer. These findings have implications for safeguarding astronaut health in future manned lunar exploration missions.