Novel and High-Throughput Spectroscopic Technique for Lunar Dust Surface Quantification

Due to the preciousness of real lunar dust, the lunar dust simulant is usually employed to replace the real one in the large numbers of experimental investigations about its mechanical property and engineering property. Therefore, the investigation on mechanical property of lunar dust simulant is also extremely significant. This research has put forward several methods for measuring mechanical property, which are used to measure the parameters including particle size distribution, particle proportion, relative density, void ratio, cohesion, internal friction angle, etc. of lunar dust simulant. The lunar dust simulant is determined to be suitable for application in the moon exploration project experiment after comparing these parameters with relevant typical mechanical parameters of foreign lunar dust simulant.

Unlike the Earth, the Moon lacks is not protected from the atmosphere and global magnetic field, and will be directly exposed to complex radiation environments such as high-energy cosmic rays, solar wind, and the Earth’s magnetotail plasma. The surface of the Moon is covered with a thick layer of lunar soil, and the particles in the soil with a diameter between 30 nm–20 μm are called lunar dust. In the complex environments such as solar wind or magnetotail plasma, lunar dust carries an electric charge and becomes charged lunar dust. Charged lunar dust is prone to migration under the action of the electric field on the lunar surface. Charged migrated lunar dust is easy to adhere to the surface of instruments and equipment, resulting in visual impairment, astronauts’ movement disorders, equipment mechanical blockage, sealing failure, and material wear, which affects the lunar exploration mission. As an important lunar exploration landing site, the lunar south pole receives special solar radiation and produces a special dust plasma environment due to its special location. In order to provide an environmental reference for lunar south pole exploration, it is necessary to explore the characteristics of the dust plasma environment in the lunar south pole and its impact. In view of the lunar south pole environment, The Spacecraft Plasma Interactions Software (SPIS) software developed by the European Space Agency is used to carry out modelling and simulation in this work. Through the simulation, the logarithmic distribution of the lunar dust space density in a range of 0–200 m at the lunar south pole, the potential distribution near the lunar surface, and the spatial distribution characteristics of plasma electrons and ions are obtained. The obtained lunar dust space density and lunar surface potential are similar to the previous theoretical derivation and field detection data, so the simulation results have high reliability. The spatial potential distribution and the spatial density distribution of electrons and ions in the lunar environment with and without lunar dust are compared. Finally, the conclusions can be drawn as follows. The space potential increases with altitude increasing. The potential at 0–10 m near the lunar south pole is about –40 V, and the space potential at 100 m is about –20 V. The density of lunar dust in an altitude range below 10 m is 10<sup>7.22</sup> m<sup>–3</sup>–10<sup>4.66</sup> m<sup>–3</sup>. The electron density in the dust plasma near the lunar surface is 10<sup>5.47</sup> m<sup>–3</sup>, and the ion density is 10<sup>6.07</sup> m<sup>–3</sup>, and both increase with altitude increasing. Charged lunar dust affects the spatial distribution of lunar dust, mainly through affecting the distribution of the space electric field, which leads to difference in electron distribution, but has little effect on ions.

The feasibility of extended exploration and human presence on the Moon and Mars depends critically on dealing with various environmental factors, and especially on the effects of dust. One of the most restricting facets of lunar surface exploration, as experienced by the prior Apollo landed missions, is the fine lunar dust, its high adherence, and its restrictive friction-like action. Moreover, the lunar dust particle size distribution extends generally into the submicron range, where it could potentially have toxic effects on exposed astronauts through their respiratory system. MoonDust is a project being performed in collaboration with the Canadian Space Agency to study the effects of lunar dust on optics and mechanical elements, and to develop innovative nano-filtration solutions to extend their operational lifetime within a lunar and/or Mars environment. To assist this work, a small lunar environment simulation vacuum chamber is being developed at MPBC, to enable the study of lunar dust effects on optics elements and rotary mechanisms, at pressures brought down below 10 -5 Torr. The developed simulator includes an injection system for lunar dust simulants, an excimer UV laser-light source for vacuum UV (VUV), and various diagnostic ports for relevant optical and electrical measurements. The MoonDust innovative dust mitigation solution exploits key characteristics of the lunar dust while incorporating nano-filtration technologies based on carbon nanotubes (CNT) materials. The aim is to minimize the required consumables while providing high capacity and high efficiencies for the more dangerous submicron particles. This paper reports on the development of the lunar environmental chamber and the associated lunar dust simulator. Some of the preliminary trial experimental results for filters based on CNTs for optical devices and rotary mechanical joint protection are also presented.

Korea Pathfinder Lunar Orbiter (KPLO), launched in August 2022, is successfully carrying out its mission. Korea's lunar lander and rover programs are expected to proceed in the future. To successfully carry out the mission after the lunar lander has landed on the surface, the performance of the equipment to be mounted should be checked in a laboratory environment similar to the Moon. Scientists and engineers of several countries, including the United States and China, use lunar soil simulant which is developed to resemble lunar soil for simulating the surface of the lunar landing site. Several lunar probe landing sites are being discussed in Korea, and lunar soil simulants such as Korea Hanyang Lunar Simulant-1 (KOHLS-1), Korea Aerospace University Mechanical Lunar Simulants (KAUMLS), and Korea Lunar Simulant-1 (KLS-1), which are similar to the characteristics of lunar mare soil, have been developed. However, those simulants are not useful if the landing site is chosen as a highland area. In this study, we introduce the process of developing KIGAM-L1, a lunar highland soil simulant similar to the chemical composition of the Apollo 16 lunar soil sample and the particle size distribution of lunar soil sample 60500-1, in case the lunar lander lands at highland area.

Water ice has been found in the permanently shadowed regions of impact craters around the lunar South Pole, which makes them ideal areas for in situ exploration missions. However, near the rim of impact craters, construction and exploration activities may cause slope instability. As a result, a better understanding of the shear strength of lunar soil under higher stress conditions is required. This paper mainly uses the finite element method to analyze slope stability to determine the position and shape of the slip surface and assess the safety factor. The height and gradient of the slope, the shear strength of lunar soil, and the lunar surface mission all influence the stability of the slope. We also analyze the soil mechanical properties of a soil slope adjacent to the traverse path of the Chang’E-4 Yutu-2 rover. Determining the stability of the slope at the lunar South Pole impact crater under various loading conditions will enhance the implementation of the lunar surface construction program. In this respect, this paper simulates a lunar mission landing at the Shackleton and Shoemaker craters and indicates that areas with higher cohesion lunar soil may be more stable for exploration in the more complex terrain of the South Pole.

<div class="htmlview paragraph">ORBITEC is currently developing simulant materials that mimic many of the unique properties of lunar dust. First, a proprietary process creates simulated agglutinates and glass spherules that contain metallic iron globules (including nanophase Fe<sup>0</sup>). The processed material is then ground down to create the lunar dust simulant. This paper will discuss the characteristics of lunar dust, provide an overview of the process used to create several prototype lunar dust simulants, and summarize the NASA characterization of the prototype lunar dust simulants.</div>

On December 2, 2020, a 2-m class robotic drill onboard the Chinese Chang’E 5 lunar lander successfully penetrated 1 m into the lunar regolith and collected 259.72 g of samples. This paper presents the design and development, terrestrial tests, and lunar sampling results of the robotic drill. First, the system design of the robotic drill, including its engineering objectives, drill configuration, drilling and coring methods, and rotational speed determination, was studied. Subsequently, a control strategy was proposed to address the geological uncertainty and complexity of the lunar surface. Terrestrial tests were conducted to assess the sampling performance of the robotic drill under both atmospheric and vacuum conditions. Finally, the results of drilling on the lunar surface were obtained, and the complex geological conditions encountered were analyzed. The success of the Chinese Chang’E 5 lunar sample-return mission demonstrates the feasibility of the proposed robotic drill. This study can serve as an important reference for future extraterrestrial robotic regolith-sampling missions.

Profiling lunar dust dissolution in aqueous environments: The design concept

Since the moon has an extremely rarefied atmosphere, the full spectrum of the electromagnetic radiation of the sun reaches the surface, charging the surface dust and affecting its current charge state. Lunar surface dust thus remains electrostatically charged at all times. Charged lunar dust will adversely affect the operations of most mechanical systems required by manned and unmanned exploration missions. Charged dust will also stubbornly adhere to solar panels and thermal radiators, thus reducing their efficiencies. Researches on the charged lunar dust can help to investigate lunar dusty environment as well as to solve those particle-induced problems by both simulation and experiment in laboratory. In this work, two different charging processes of charged lunar dust in the environment of electron beam and the radiation of ultraviolet source are considered. The computer numerical simulation method is used to analyze these two different charging processes of lunar dust, to explore the charging mechanisms of lunar dusts, and to choose an appropriate way of charging for the lunar environment simulation device in laboratory. On the basis of the classic dust charging equation, the charging equation of a dust in pure electron environment is given for the first time in this work. Meanwhile, the charging process under ultraviolet radiation is discussed and combined with the specific application of charging dusts. A solver of fourth-order Runge-Kutta algorithm is made to solve differential equations under two different irradiation sources. The main simulation results show that:1) in electron environment, the surface dust charge number increases as the particle size and the current intensity of electron guns increase, while the charge number increases as the beam spot radius of electron guns decreases; 2) under ultraviolet radiation, the dust charge number increases with the particle size and irradiance increasing, but charging efficiency is slow. A great dust charge number needs a long time radiation from sun (equivalent to 74 deuterium lamps), which means that more ultraviolet radiation sources are essential to speeding up the experiment in laboratory. Although the calculated efficiency of ultraviolet radiation is lower than electron irradiation, the secondary-electron emission, the scattering and the transmission process of electron irradiation are ignored, which can greatly reduce the efficiency of charging by energetic electron guns in the actual experiment. Therefore, comparing these two charging mechanisms and considering the actual design requirements for the space environment simulation device, charging by lots of ultraviolet radiation is an appropriate scheme for electrification of lunar dusts.

The interest in Moon exploration has substantially grown in the last years, making the Moon an attractive testbed to develop the required technologies and capabilities for human Deep Space exploration. In the past decades, lunar missions have almost entirely relied on Direct-to-Earth (DTE) communications, whilst using ranging radiometric measurements from Earth for navigation. The growing trend in the number of missions to the Moon is creating demand for the deployment of a dedicated lunar communication and navigation infrastructure to support the international community. The European Space Agency’s vision, represented by the Moonlight initiative, is to stimulate the creation and development of lunar communication and navigation services that will support the next generation of institutional and private Lunar Exploration Missions, including enhancing the performance of those missions currently under definition. Within this initiative, ESA has defined a lunar navigation roadmap in 3 phases: firstly, making use of terrestrial GNSS signals (Phase 1), then adding in some limited (initial) lunar infrastructure (Phase 2) before transitioning to full lunar service capabilities (Phase 3). This contribution presents both ongoing and planned activities related with phase 1 and 2 of the roadmap. Regarding phase 1, the GNSS experiment planned with Lunar Pathfinder is described and the expected performance levels are presented: the experiment aims to demonstrate, for the first time in a lunar orbit, the use of a GNSS receiver to compute the satellite orbit on-board in real time. Regarding phase 2 of the roadmap, aiming to provide a dedicated navigation service in cis-lunar space as part of the Moonlight initiative, this contribution describes the Moonlight navigation service and analyses the potential user performance levels that can be achieved when landing on the lunar surface.

Lunar soil simulants play a crucial role in scientific research, payload tests and in-situ resource utilization (ISRU) experiments. However, the currently available lunar soil simulants are either low in TiO2 content (≤3 wt%) or high in TiO2 content (≥6.7 wt%), despite orbital observations indicating lunar soils with moderate TiO2 content being widely distributed on the lunar surface. In December 2020, China's Chang'e−5 (CE-5) mission successfully returned a new mare soil sample characterized by high FeO content (22.5 wt%) and moderate TiO2 content (5.5 wt%), providing an opportunity to develop moderate-TiO2 lunar soil simulants. This study presents a newly developed simulant of the CE-5 lunar soil named IGG-01, which closely replicates the major physical and chemical properties of the CE-5 lunar soil. The median particle size of IGG-01 is 68.69 ± 4.44 μm, and its estimated specific surface area is 0.34 m2/g. It contains 17.6 wt% FeO and 4.8 wt% TiO2. It consists of pyroxene (49.3 wt%), plagioclase (40.9 wt%), ilmenite (6.1 wt%), and olivine (3.7 wt%), with specific gravity and bulk density are 3.33 g/cm³ and 1.86 g/cm³, respectively. The friction angle is 41.8°, and the cohesion is 19.2 kPa. It exhibits strong and weak reflectance absorption features in the 1 and 2 μm band centers. The physical properties of IGG-01 are also comparable to those of Apollo samples and typical lunar mare soil simulants. The unique chemical composition of IGG-01 makes it suitable for various scientific and engineering experiments, including but not limited to the study of dusty plasma migration, water formation via solar wind injection, oxygen preparation via hydrogen reduction, and tests involving the movement of rovers and excavation equipment.

Lunar magnetic field investigation connects the interior, the surface, and the space environment of the Moon. Measuring and understanding the lunar magnetic field at different length-scales and time-scales is of critical importance to understand the bulk water content and temperature profile in the lunar mantle, the existence and properties of a partial melt layer above the lunar core, the size of the lunar core, the origin of volatiles on the lunar surface, and the origin and properties of the past lunar dynamo, all of which are intimately connected to the origin of the Earth-Moon system and the subsequent thermal-chemical-environmental evolution of the Moon. The surface of the Moon, however, is a challenging environment, including contrasting temperatures between lunar day and lunar night, dust, and surface charging. Here we report our progress in the designing, building, and testing of a temperature-stabilized fluxgate magnetometer (FGM) system for long-term operations on the surface of the Moon. We refer to this FGM system configuration as L-MAG. The sensor design draws heritage from those onboard the NASA Magnetospheric Multiscale (MMS) mission, InSight Mars Lander, the Europa Clipper mission, and most recently the TRACERS mission. One of the key improvements is a magnetically clean AC heater that directly surrounds the FGM sensor, improving power efficiency and responsiveness compared to Europa Clipper Magnetometer’s distant heater pod. Thermal losses are reduced with a low-emissivity enclosure and lightweight Kapton flex harness. The heater system is designed to yield a temperature stability of ± 0.1 degrees °C around two set-point temperatures (day and night) to further reduce long-term drift, allowing the inference of lunar induction responses at periods of 105 seconds and longer, necessary to probe the lower lunar mantle and core. This power efficient FGM design will be compatible with installation onto a lunar lander or placed on the surface of the moon by an astronaut. Our L-MAG system will significantly improve measurement capabilities for upcoming lunar science missions including those via the Commercial Lunar Payload Services (CLPS) and via Artemis astronaut deployments.

Simulating lunar highlands regolith profiles on Earth to inform infrastructure development and ISRU activities on the Moon

Understanding the mechanical behavior of lunar regolith is of great importance for future missions to the Moon and other similar extraterrestrial environments. However, due to the scarcity of lunar regolith a number of simulants have been developed to facilitate experimental testing. This paper presents the geotechnical properties of an inexpensive lunar regolith simulant named Black Point 1 (BP-1). An experimental program including particle-size distribution, microscopy observations using scanning electron microscope (SEM) images, density measurements, compressibility, and shear strength was performed. Additionally, BP-1 was compared with regolith recovered from lunar missions and a number of its simulants. The physical properties of BP-1 were found to be similar to other existing simulants and to the natural lunar regolith.

Geology dominated the science of the six successful Apollo lunar sampling expeditions. About 380 kg of rocks and soils were collected in 2400 samples, along with many thousands of documenting photos. Lunar dust shrouding Moonscapes, obscuring and coating rock samples, was a nuisance for geologist-advisers and plagued each astronaut with its inescapable presence, sticking to every surface. Lunar dust was judged by Apollo 17 geologist-astronaut Harrison Schmitt as ‘No. 1 environmental problem on the Moon.’ As fine as talcum powder but more abrasive than sandpaper, dust jeopardised vacuum sealing of sample containers to preserve rocks free from terrestrial contamination, just as later at Houston it jeopardised long-term archives of lunar samples. Yet the only one type of Apollo experiment to measure dust and its movements in situ was a matchbox-sized Dust Detector Experiment (DDE) weighing 270 g deployed on Apollo 11, 12, 14 and 15 Apollo Lunar Surface Experiment Packages (ALSEPs), which transmitted DDE data to Earth every 54 s between 21 July 1969 and 30 September 1977. This report by the Australian inventor and Principal Investigator of the minimalist DDE, designed to hitch-hike, outlines its discoveries of basic characteristics of movements and stickiness of lunar dust. Unexpected realities include effects of (1) an out-gassing aura metres in extent surrounding an astronaut and (2) contamination and heating effects of ‘collateral dust,’ lunar surface dust kicked up and splashed by astronauts on experiments and rock samples. Some interpretations of DDE data presented in Apollo-era literature are challenged and alternative interpretations are presented, with two Apollo-era dust discoveries not referenced for 40 years. Little-known potential contamination of Apollo experiments, Moon rock samples and photographic validity is discussed, together with ongoing discoveries of the basics of dust such as dynamic behaviour and long-term accretion.