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Global distribution of regolith layer thickness (m) constructed from lunar surface DEM: (a) nearside, (b) farside.
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Helium-3 (3He) implanted by solar wind in the lunar regolith is a valuable resource because of its potential as a fusion fuel. On the
basis of the Apollo regolith samples, a linear relationship between 3He abundance and solar wind flux, optical maturity and TiO2 content has been presented. China successfully launched its first lunar exploration sat...
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... carry out a simulation of brightness temperature observation, we first construct the regolith layer thickness, as a priori knowledge, from DEM (digital elevation mapping) of lunar surface empirically based on correspondence between the lunar regolith layer thickness and the lunar surface altitude. The result is shown as Fig. 9 ( Fa and Jin, 2007). It can be seen that the average difference on the lunar nearside between Fig. 9 and Shkuratov's results (Shkuratov and Bondarenko, 2001) is as small as 1.4 m. However, a flaw in this explicit assumption might be seen from the South PoleAitken Basin, which is an old basin with the lowest elevation, but a thicker ...
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... the regolith layer thickness, as a priori knowledge, from DEM (digital elevation mapping) of lunar surface empirically based on correspondence between the lunar regolith layer thickness and the lunar surface altitude. The result is shown as Fig. 9 ( Fa and Jin, 2007). It can be seen that the average difference on the lunar nearside between Fig. 9 and Shkuratov's results (Shkuratov and Bondarenko, 2001) is as small as 1.4 m. However, a flaw in this explicit assumption might be seen from the South PoleAitken Basin, which is an old basin with the lowest elevation, but a thicker regolith layer. However, this small area does not affect the methodology to initiate our simulation of ...
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... but a thicker regolith layer. However, this small area does not affect the methodology to initiate our simulation of brightness temperature. In fact, as real observations of brightness temperature become available in the future, inversion of the regolith layer thickness is extracted from the observation, Eq. (7), not related to our assumptions in Fig. ...
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... An upper limit of the global inventory of solar wind-implanted volatiles can therefore be estimated if a uniform depth distribution of solar wind volatiles within the regolith is assumed. For example, using the regolith thickness estimated from China's Chang'E-1 microwave radiometer (4.5 m over maria and 7.6 m over nonpolar highlands regions), the global inventory of 3 He was estimated as being 1.70×10 9 kg (8.64×10 8 kg over the nearside, and 8.33×10 8 kg over the farside) for a uniform depth distribution (Fa and Jin 2010b). Total inventories of other solar wind-derived volatiles can be estimated in a similar way, and would be expected to be between two to three orders of magnitude higher. ...
... Scientists believe that there may be areas of higher concentration of Helium-3 on the Moon. The results [25,26] of the Change-1 probe indicate that there may be regions with 3 He concentrations of 80 ppb/m 2 or higher on the Moon most of all in lunar maria. When looking for high concentrations of helium-3, attention should be paid to the presence of titanium and iron, and specifically the mineral ilmenite (FeTiO 3 ). ...
The article uses the Lunar QuickMap tool to analyze and select five highly promising cold microtraps on the Moon in terms of the size of the deposits they contain and their accessibility with the use of rovers and other wheeled vehicles. Since the thickness of the layer containing raw materials is subject to high uncertainty, three arbitrary scenarios for the value of this parameter were assumed: pessimistic (1 cm), nominal (5 cm), and optimistic (1 m). For the analyzed sites, a preliminary market valuation of the raw materials contained therein will be obtained at USD 74 billion; USD 370 billion; USD 7403 billion for the assumed pessimistic, normal, and optimistic scenarios, respectively. The article presents a business and technological perspective on the issue of space mining on the Moon. It is also a selected synthesis of the state of knowledge about space mining on the Moon.
... or the first time, the microwave radiometer (MRM) onboard Chang'e (CE)-1/2 satellites measured the brightness temperature (TB) of the regolith on the Moon in orbit, which provides a fourth new way to assess the surface deposits in addition to the commonly-used optical, thermal infrared (TIR), and radar data. The MRM data have been applied to investigate the various features and parameters of the regolith, including regolith thickness [1], [2], 3 He abundance distributions [1], [2], dielectric properties [2]- [7], geological units [8]- [10], and rock abundances [11]- [13]. These findings hold fundamental importance for enhancing our understanding of the Moon's thermal and basaltic evolutions. ...
... or the first time, the microwave radiometer (MRM) onboard Chang'e (CE)-1/2 satellites measured the brightness temperature (TB) of the regolith on the Moon in orbit, which provides a fourth new way to assess the surface deposits in addition to the commonly-used optical, thermal infrared (TIR), and radar data. The MRM data have been applied to investigate the various features and parameters of the regolith, including regolith thickness [1], [2], 3 He abundance distributions [1], [2], dielectric properties [2]- [7], geological units [8]- [10], and rock abundances [11]- [13]. These findings hold fundamental importance for enhancing our understanding of the Moon's thermal and basaltic evolutions. ...
... Two types of methods have been employed to produce gridded TB maps. The first type is the interpolation-based method, which performs two-dimensional (2D, along longitude and latitude) interpolation using the original MRM data points within a specific local time span that covers the space range [1], [2], [5], [16]- [22]. However, due to the limited amount of dataset, the original MRM data points cannot cover an extensive spatial range within a short time span. ...
The Chang’e-1/2 satellites carried microwave radiometers (MRM), which supplied unique passive microwave data, supplementing visible, thermal infrared, and radar data in current lunar studies. However, the application of MRM data is constrained by the limited amount of the original dataset, which cannot express spatial variations at given local times. In this study, we present a novel approach to constructing a local-time brightness temperature (TB) model using barycentric interpolation based on Delaunay tetrahedralization. This model enables the generation of a complete TB dataset, producing TB maps that are both continuous and self-consistent in both spatial and temporal domains. Compared to the traditional methods, those generated in this work avoid a ~7-K bias on a global scale. Furthermore, the interpolated maps offer superior representations of the TB over time for various lunar surfaces. The preliminary evaluations on global and regional scales hint important application of MRM data in studying the geological features of the Moon.
... The maximum percentage of 24.5 and 9.0 for FeO and TiO 2 was found for Taurus-Littrow Valley, with a regolith thickness around 8 m. While for Descartes crater, FeO percentage was 5.55 at the depth of 12.5 m (Fa and Jin 2010c). Physical temperature and dielectric constant are other decisive factor here. ...
... Even though the laboratory measurements of 56 Apollo samples exhibit that there is a very small concentration 57 of helium-3 enriched in the lunar regolith with an average 58 concentration of about 3.59 ppb [14], it is still triggered a 59 great interest for scientists [16]. The discovery of the lunar 60 helium-3 resources, which is a candidate material for nuclear 61 fusion and may provide new supplies for future Earth's energy 62 shortage [17], [18], [19], [20]. The total helium-3 reservoir in 63 the entire Moon is strongly associated with the thickness of 64 the lunar regolith [11]. ...
... On the 68 other hand, it is assumed that the concentration of helium-3 69 in the lunar regolith decreases with depth. The total content 70 of the helium-3 was calculated to be ∼6.6 × 10 8 kg on the 71 entire Moon by the Chinese Chang'E-1 microwave radiometer 72 observation [11], [18]. According to the above remote sensing 73 results, the total helium-3 reservoir in the whole Moon is at 74 least 660,000 tons, but the total reservoir of that on Earth is 75 only 20 tons [11]. ...
... situ helium-3 estimation has not been reported. The estimation 80 of the global helium-3 reservoir is observed by space-borne 81 instruments, e.g., Clementine's spectrometer and the Chang'E-82 1 microwave radiometer [9], [18]. However, these space-borne 83 instruments usually have a low spatial resolution, e.g., the 84 Chang'E-1 microwave radiometer has a spatial resolution of 85 30-50 km [18]. ...
The Moon-based Ground Penetrating Radar (GPR) carried by the Yutu rover performed in-situ radar measurements to explore extraterrestrial objects, which provides an unprecedented opportunity to study the shallow subsurface structure of the Moon and its internal resources. Exploiting lunar resources might be one of the solutions to the Earth's energy shortage in the future. In this paper, firstly, the thickness distribution of the lunar regolith at the Chang'E-3 landing site is derived using the high-frequency Yutu radar observation data. Secondly, the surface concentration of helium-3 is determined based on the surface TiO
$_{2}$
content of the lunar regolith. Finally, the reservoir of helium-3 resources in the lunar regolith is estimated. Our result suggests that the helium-3 reservoir along the Yutu rover traveling route from the navigation points N105 to N208 (
$\sim$
445 m
$^{2}$
) is
$\sim$
37–51 g, and its helium-3 content per unit area is
$\sim$
0.083–0.114 g/m
${^{2}}$
, which is at least 5 times higher than that of the global average. Currently, the nuclear fusion experiment is facing a severe shortage of tritium fuel. We discuss the possibility of replacing it with lunar helium-3 as the fuel for nuclear fusion. Meanwhile, we also suggest that the Chang'E-3 landing area can be a potential site selection for the exploitation of the lunar helium-3 in the future. Our results will provide a valuable reference to evaluate the economics and feasibility of mining in-situ helium-3 resources on the Moon.
... The maximum percentage of 24.5 and 9.0 for FeO and TiO 2 was found for Taurus-Littrow Valley, with a regolith thickness around 8 m. While for Descartes crater, FeO percentage was 5.55 at the depth of 12.5 m (Fa and Jin 2010c). Physical temperature and dielectric constant are other decisive factor here. ...
... Scientists believe that there may be areas of higher concentration on the Moon. The results [39,40] of the Change-1 probe indicate that there may be regions with 3 He concentrations of 80 ppb/m 2 and higher on the Moon. In conclusion, the development of cheap, clean, and ecological fusion energy requires the development of space mining and the commencement of the exploitation of helium-3 deposits on the Moon. ...
The global climate crisis forces the search for new ecological sources of energy and mining methods. Space mining can solve those problems, but, first, wide geological surveying space missions using drilling methods are necessary. Additionally, drilling methods will be important in geological, life searching, geoengineering, and many other studies of extraterrestrial objects. Space is becoming a new area of possible drilling applications. Designing future space drilling missions requires adapting drilling technologies, not only to the conditions of the space environment, but also to the economic and technological realities of the space industry. The possibility of constructing low mass coring devices with energy consumption below 100 W was investigated in this paper. Minimization of energy consumption and mass of a coring is essential for the device to be used in space missions, when lander instruments supplied by low power electric battery are expected to work reliably and the launch cost (depending of mass) at an economically acceptable level. Some similar devices investigated for the future space missions are known from papers listed in the references. To answer whether or not it is possible to build such devices, the authors performed initial drillability tests. The obtained results are presented in this paper.
... Although, the amount of 3 2 He on the surface of Earth is limited, as discussed in [48], this value is well below the maximum availability in human hands [49]. Moreover, there is a large source of extractable 3 2 He (10 9 kg) on the lunar surface that has been deposited by solar wind for more than 4 ⋅ 10 9 years [50][51][52]. It is worth mentioning that one of the objectives of the NASA Artemis Program is the search of 3 2 He on the lunar surface [53]. ...
The main purpose of this work is to perform an analysis of realistic new trajectories for a robotic mission to Saturn’s largest moon, Titan, in order to demonstrate the great advantages related to the Direct Fusion Drive (DFD). The DFD is a D -23He fuelled, aneutronic, thermonuclear fusion propulsion system (Cohen et al., 2019). This fusion propulsion concept is based on a magnetically confined field reversed configuration plasma, where the deuterium propellant is heated by fusion products, and then expanded into a magnetic nozzle, providing both thrust and electrical energy to the spacecraft. The trajectories calculations and analysis for the Titan mission are obtained based on the characteristics provided by the PPPL (Cohen et al., 2019) for a 2 MW-class DFD engine. Two different profile missions are considered: the first one is a thrust-coast-thrust profile with constant thrust and specific impulse, the second scenario is a continuous and constant thrust profile mission. Each mission study is divided into four different phases, starting from the initial low Earth orbit departure, the interplanetary trajectory, Saturn orbit insertion, and the Titan orbit insertion. For all mission phases, maneuver time and propellant consumption are calculated. The results of calculations and mission analysis offer a complete overview of the advantages in term of payload mass and travel time. It is important to emphasize that the deceleration capability is one of the DFD game changers: in fact, the DFD performance allows to rapidly reach high velocities and decelerate in even shorter time period. This capability results in a total trip duration of 2.6 years for the thrust-coast-thrust profile and less than 2 years for the continuous thrust profile. The high payload enabling capability, combined with the huge electrical power available from the fusion reactor leads to a tremendous advantage compared to present technology.
... The global inventory of He-3 on the Moon was estimated to be 7.1 Â 10 8 kg (Taylor, 1994). Based on Chang'E1 measurements of the regolith thickness, the global 3 He inventory on the Moon was re-estimated to be 6.6 Â 10 8 kg by Fa and Jin (2010). A similar estimation of the inventory of 3 He in the regolith of the Moon of about 10 9 kg was given earlier by Wittenberg et al. (1991). ...
A global map of the ³He content of the lunar regolith has been constructed. Detailed studies (³He, TiO2, FeO content, slope maps) of several regions with highest predicted ³He content such as the craters Grimaldi and Riccioli, Mare Moscoviense, the southern-western part of Oceanus Procellarum, the northern-western part of Mare Tranquillitatis, and the northern-eastern part of Mare Fecundidatis were performed. These regions are located on flat mare surfaces and have a high TiO2 content. The studied regions, especially craters Grimaldi and Riccioli, were selected as candidate landing sites for missions aimed at extracting ³He from the lunar regolith. The suggested sites may be further re-examined by the Korean Pathfinder Lunar Orbiter during the nominal 1-year mission period in 2021.
... However, the Moon has been subjected to a large quantile bombardment of 3 He by the solar wind since its origin. Eventually, up to ~20 ppb (by weight) of 3 He have been implanted in some of the lunar soils, making them suitable candidates for future lunar mining operations (Fa & Jin, 2007;Fa & Jin, 2010;. ...
The Moon serves as an attic to the Earth’s treasure by preserving the volatile repository from the harsh space environment. The exposure of the lunar surface to the solar wind plasma results in the implantation of potential 3He into the top 1 mm of the regolith. The retention of the 3He primarily depends on the regional ilmenite content and maturation subject to the solar wind plasma supply. In the present research, an attempt is made to explore the influence of petrophysical properties of the regolith on the retained 3He using multisensor approach. The retention framework is improved by incorporating the associated effects of space weathering on the regolith materials, which are represented by spectral parameters. The integration of the spectral parameters, plasma flux, and ilmenite content leads to a novel hybrid variable that is directly compared with the in-situ 3He measurements at the Apollo and Luna landing sites. Considering the independence of the space weathering processes, the correlation analysis suggests that the predicted 3He contents are in close agreement with the actual abundance. However, all the weathering processes lead to the reduction of Fe2+ into the nanophase metallic iron particles, thereby interrelating to each other. The applicability of the weighted average linear combination is utilized to model the unknown inherent relationship between the weathering trends. Upon comparing with the in-situ 3He, the RMSE reduces to 1.17 ppb compared to the independent approach. The empirical relationship is applied to the Vallis Schroteri region, wherein the high 3He abundant regions emerge out to be pyroclastic deposits and localized hotspots near the primary rille and Agricola Mountains. It is also observed that the two dominant processes governing the abundance are attenuation of the mafic absorption band depths and reddening of the soil. However, a different scenario all together appears for the 3He abundance per unit area, wherein the soil chemistry proves to be a deciding factor. The spatial variability of the 3He abundant regolith is found to be aligned with the episodic space weathering events over the geological timescale, clearly indicated by the cyclic behaviour of the variogram trends. Moreover, the highly retained 3He content may be oriented at around 135º relative to other directions. The lower cutoff and width increases the spatial variability of the deposition. The retention of the 3He is found to be associated with the petrophysical properties of the soil. This is clearly illustrated by comparing the retrieved scattering mechanisms, dielectric content, and geotechnical variations. In the research, the utility of the radar backscatter is modelled as a function of incidence angle, dielectric constant and surface roughness. The sensitivity analysis is performed, which provides the bounding limits of the realistic surface parameters and radar configuration. This is fed into the multilayer perceptron neural network for performing the inversion based on multivariate regression. The inverted dielectric constant shows an RMSE of 0.26. The retrieval process is applied to the monostatic data of the landing sites, wherein the inverted values are in close agreement with the actual values. Upon testing the study site, the pyroclastic regoliths are associated with high dielectric constant and increased surface scattering mechanisms. The regolith is also characterized by lower void spaces between the grains and higher relative density. Due to the freshly formed microcraters, the excavation of the rocks from the interior lowers the penetration of the radar wave, thereby increasing the granular packing of the gardened regolith. As the dielectric contrast increases, the retention of the lower 3He ejecta regolith increases, attributing to the roughness variations. The observation is also aligned with the CPR. Moreover, the abundance is negatively correlated with the void ratio for shorter lag distances. On the contrary, the higher abundant pyroclastic regolith relates well with the surface scattering mechanisms associated with cyclicity. An opposition is also observed in this to the bistatic angle with a more significant exponential depth profile. Furthermore, retention modelling provides new insights into the potential mining operations for the lunar outposts. The study recommends deeper exploration of the pyroclastic regoliths, thereby contributing to the lunar mining and remote sensing paradigms.
