Lunar Poles Research Articles

Space War and the Regressive Development of the Principle of Common Heritage of Humankind: Legal vs. Technological Weapons

Deep under the waters, HMS Challenger discovered the polymetallic nodules during its scientific expeditions in the Kara Sea part of the Arctic Ocean in 1868. Whilst in the vastness of the skies above, the Clementine and Lunar Prospector indicated the existence of water ice at the lunar poles during the period of 1994 to 1999. In 2003, the SMART-1 lunar orbiter of the European Space Agency discovered the key chemical elements of the Moon. Going even further back, in 1988, NASA published a work on Helium-3 blown away by the solar wind onto the Moon, and the possibilities of harvesting it as an alternative energy source for the continuation and advancement of human race. The deep seabed and the outer space, along with their resources, are both internationally governed under the same underlying principle: the Common Heritage of Humankind. Yet, while the former has begun to take shape, the latter still has very little progress. Various factors ranging from laws to politics to economics and undeniably the advances in science and technology have hindered the development of the principle of Common Heritage of Humankind in the outer space regime. Hence, this paper is to argue on how best to reform the principle, and consequently, determining which of its elements that might be spared in order for it to eventually work in balancing the contrasting interests from diverse stake-holders: the developed and the developing countries; the sovereign and the corporations – with their respective weapons of laws or of technology.

Water extraction from icy lunar simulants using low power microwave heating

Identifying the best technique for extracting water ice deposits in permanently shadowed regions at the lunar poles will be crucial in determining how successful a long-term or permanent settlement at these locations will be for future scientific and technology missions. This study uses a low-power microwave heating method to extract water from icy lunar simulants. Samples of lunar highland and mare simulants at different water contents (3–15 wt %) were heated using 250 W, 2.45 GHz microwaves. A maximum of 67 ± 5% [2SD] of the water was extracted during heating runs of 25 min. Water was extracted more efficiently from the highland simulant than from the mare simulant. A significant reason for the different efficiency of water extraction in icy lunar simulants was the differing porosity of the samples made from different simulants. Pore space filled with ice leads to a reduced contact area between grains and an increased area of free ice, which causes poor heating performance. The results indicated that differences in chemical composition between the simulants had a negligible effect on water extraction, as the contact area between grains seems to dominate water extraction. This study found that low-power microwave heating is an effective technique for extracting water from cryogenic Icy simulants. It was also found that using a simple input energy principle (Input Energy = Absorbed Power x Heating Time) to estimate the additional heating time was sufficient to overcome inefficient heating due to differing absorbed powers. For undersaturated samples, microwave heating was an efficient heating mechanism, but is less efficient for saturated samples where alternative heating methods may be more efficient at melting free ice before employing microwave heating.

Investigating the dielectric properties of lunar surface regolith fines using Mini-RF SAR data

Polarimetric synthetic aperture radar (SAR) is an effective technique to retrieve physical properties of planetary surfaces, such as the dielectric constant and surface roughness. Dielectric properties of lunar regolith are quite attractive for future lunar SAR missions. In this paper, we investigate the dielectric properties of lunar regolith by the Mini-RF SAR data. First, a new model of dielectric constant inversion for hybrid polarimetric SAR is proposed, in which the hybrid polarimetric scattering similarity parameter is first introduced. Second, the dielectric constants of Apollo 14, 16, 17 and Chang’E-5 landing sites are estimated through the proposed model. The inversion results fit well with the laboratory measurements of lunar samples, with an estimated root mean square error (RMSE) of 0.53. In addition, we analyze the dielectric properties of regolith on crater floors in different geologic settings, including the lunar maria, highlands, and permanently shadowed regions (PSRs) near the lunar poles. The results indicate that for craters with diameters of 5–25 km, the real part of the dielectric constant of regolith fines increases with crater depth-to-diameter (d/D) ratio, while no apparent correlation is found with crater diameter. Furthermore, the average dielectric constant of regolith fines is 3.01 in PSRs, which is less than that in the lunar maria and highlands (3.43 and 4.13, respectively). This implies that craters in PSRs may possess a looser regolith material compared to the mid-latitude craters. In a word, the proposed method is useful for estimating the dielectric properties of lunar regolith, and it is promising for future lunar SAR applications.

Optimal multi-site selection for a PV-based lunar settlement based on a novel method to estimate sun illumination profiles

Recently, space organizations have considered the Moon to host lunar bases. Such bases require power and energy to function. However, the efficient and safe use of the energy resources on the Moon is a huge challenge. Space photovoltaic (PV) power systems are appealing technologies due to their maturity and high solar energy availability at some locations on the Moon. The effectiveness of these PV systems depends on their selenographic location, which might necessitate the deployment of energy storage technologies to cover the base’s energy demand. Some analysts have proposed the installation of PV modules on kilometers-tall towers near the lunar poles to harvest more solar energy and limit the need for energy storage systems (ESSs). Alternatively, this paper proposes to harvest the energy from multiple sites in the lunar South Pole region using a novel technique to compute the Sun illumination profile and the LOLA topographic databases to compute the terrain elevations. The proposed algorithm seeks the most optimal configuration of sites and tower heights to minimize the longest night period and total distance between the sites. This study assesses groups of 1 to 6 sites assuming the use of towers having heights of 10, 100, and 500 [m]. The time horizon for the analysis is one Axial Precession Cycle, which is approximately 18.6 years. According to the results, a system of two sites with a separation of 42.05 [km] and towers of 500 [m] height has a maximum darkness period of only 3 [h] while another solution proposes a system of three sites with towers of 10 [m] that removes the need of EES (solar eclipse periods by the Earth are not considered). The proposed technique is suitable for engineering applications, such as base planning and operation management.

Sunlit pathways between south pole sites of interest for lunar exploration

The lunar poles are of high interest to human and robotic exploration for their exploration potential to host volatiles useful for scientific and commercial purposes in cold permanently shadowed regions and for the rare highly-illuminated regions that can support exploration efforts. We investigate if the complex and dynamic lighting is amenable to long traverses between these sparsely-distributed, distant sites of interest. We use accurate high-resolution topographic maps of the south polar region to compute the traverse paths, and we simulate the time-varying illumination conditions along these over long time periods to determine whether such trips are possible while remaining nearly entirely sunlit. We find that long-distance sunlit pathways are possible but long in duration. These can be further optimized, and potentially significantly shortened given specific survival capabilities, such as driving through short periods of shadows.

Site selection, thermodynamics, environment and life support analysis for the PneumoPlanet inflatable lunar habitat concept

Human habitats on the lunar surface have been planned and designed already since the beginning of the space age in the early 1960's, long before the successful Apollo missions, which for the first time brought humans to the Moon and safely back to Earth. While existing plans for manned lunar stations were postponed for a long time for various reasons, the interest in building permanent research stations on the surface of the Moon re-awoke in the late 1990s and early 2000s. Hereby, the focus turned more and more towards the lunar poles, where strong indications for the existence of water ice inside permanently dark craters were found. In this study we present a design for a lunar habitat, which makes maximal use of the natural resources available on the Moon, in particular in the vicinity of the poles, while at the same time the necessary material transfer from Earth to the lunar surface is minimized. We identify and study the sites around the lunar poles (both north and south pole) and present a design for a lunar habitat consisting of up to 16 greenhouses suitable for permanently housing and nourishing up to 32 humans. The greenhouses have a toroidal shape and are connected by tunnels. The horizontally incident sunlight is re-directed by a rotating mirror towards an artificial crater and from there through a transparent foil to the interior of the greenhouses. The main feature of our design is that the walls of the greenhouses as well as the attached rooms and tunnels are made of extremely light-weight materials, which are inflated to their final size simply by applying air pressure. Effective protection against harmful cosmic radiation is reached by covering greenhouses, living areas and connecting tunnels with a several metres thick layer of loose regolith. This cover ensures also a high level of thermal isolation, which helps to avoid too fast cooling of the interior during phases of total darkness. Finite element models of the thermodynamic behaviour of the suggested design confirm that life-friendly conditions can be created and kept over long time spans by using only the available solar illumination as power source and installing a state-of-art cooling system for the interior. In contrast to other concepts, the basic building blocks of this habitat design could be transported to the lunar surface by existing rocket systems offering a medium transport capacity, like Ariane 64 , in combination with the planned European Large Logistics Lunar Lander Finally, various safety issues that might occur during setup and operation of such a lunar habitat, are discussed. • Low weight lunar habitats. • Thermo-physical modelling. • Inflatable membranes as building elements. • Mirror membranes for use of natural sunlight. • Loose regolith for protection against cosmic radiation and micro-meteorites.

Lunar Magnetic Anomalies and Polar Ice

AbstractSolar wind ion sputtering is one of several non‐negligible loss mechanisms for water ice in permanently shadowed regions (PSRs) near the lunar poles. Previous estimates of the solar wind ion flux within south polar PSRs have considered only the ambient solar wind flow and effects of topography. Here, improved maps of crustal magnetic fields in the lunar polar regions are constructed, confirming that more anomalies are present near the south pole than near the north pole. These anomalies have moderate amplitudes, occur over at least two permanently shadowed craters, and correlate approximately with the exposed water ice distribution. Because of the low angle of solar wind incidence near the poles, these anomalies are likely effective in reducing the ion flux, and any resulting water ice loss rate. These anomalies may therefore explain why more water ice is found near the south pole than near the north pole.

Double Shadows at the Lunar Poles

Topographic depressions within permanently shadowed regions (PSRs) on low-obliquity planetary bodies can be shielded not only from direct illumination, but also from scattered sunlight and thermal emission from nearby sunlit surfaces. We apply an illumination model to high-resolution topography data to produce the first map of double shadows at the lunar poles. The total doubly shadowed area resolved at the 30 m scale is 1.47 km2 in the northern hemisphere and 5.37 km2 in the southern hemisphere, predominantly contained within small craters on the floors of large permanently shadowed craters. In total, ∼0.04% of PSR area is permanently double shadowed, but the largest double shadows are nearly 600 m across, potentially large enough to be resolved in remote sensing temperature measurements. In the absence of secondary heating sources, double shadows are predicted to be significantly colder than singly shadowed areas and could sequester highly volatile compounds like carbon dioxide. Future in situ investigation of the regions identified in this work can elucidate the origin and distribution of the Moon’s most volatile deposits.

Seasons of Ice: Water Ice Migration and Seasonal Transient Shadow at the Lunar Poles

AbstractLunar water ice can be broadly categorized as belonging to one of two populations: deep, ancient, stable deposits, and shallow, transient, recent deposits. However, a third state for lunar ice is also possible. Temporary sequestration occurs when ice is deposited into a transiently shadowed region at the lunar poles. These temporarily sequestered ice deposits are unstable over geologic time scales, but in the short term, are capable of a wide range of migration, sublimation, and retention patterns due to their thermally dependent sublimation and migration rates. We developed a model to characterize the range of possible migration and retention behaviors for temporarily sequestered ice deposits within locations with dynamic illumination conditions. We found that water ice migration, sublimation, and retention varies across the lunar polar environment, with neighboring locations experiencing different illumination and thermal conditions. We found that the residence times of temporarily sequestered ice deposits in some high latitude, non‐shadowed regions can be similar to or greater than the length of time spent above the long term stability temperature of ice during lunar winter months, leading to incomplete removal of surface or near surface ice during the day. We also found that shallowly buried, unstable ice deposits take longer to sublimate than surface deposits, leading to a temporal lag in escaping ice. This work suggests that temporary sequestration can lead to complex ice migration and retention patterns at high latitudes, with ice sublimation efficiency varying across the lunar polar environment due to local, small scale differences in illumination conditions.

The Eagle Returned: Geopolitical Aspects of the New Lunar Race

ABSTRACT After 50 years, the Moon is becoming a center of attention in the geopolitical competition among space powers. The planned lunar settlements to take place starting in 2025, or soon thereafter, will hold geopolitical considerations and impacts. This paper highlights and summarizes factors that will affect the process of lunar settlement in the context of the importance of lunar poles. The poles include the location of key resources – permanent sunlight for power generation and water – for the state actors involved in the settlement projects. Access to these resources will influence relations among the actors. The paper points to the need to participate in the lunar settlement process for state actors not to be left behind or in a disadvantaged position for access to key resources. Further discussed is the geopolitical context concerning settlement of the geographically advantageous polar regions, primarily the south lunar pole. If this is undertaken by adversarial states, a space power, dependent on the outcome of that competition, would be limited in its own efforts to develop an independent settlement.

Polar Ice Accumulation from Volcanically Induced Transient Atmospheres on the Moon

Water ice exists at the lunar poles, but its origin, abundance, and distribution are not well understood. One potential source of water to the poles is the volcanic outgassing of volatiles from the lunar interior and subsequent condensation of erupted water vapor as surface ice. We investigate whether volcanic outgassing is a viable source for the accumulation of lunar polar water ice. We construct a model that accounts for volcanic outgassing, atmospheric escape to space, and surface ice accumulation over the period of peak lunar volcanic activity (4–2 Ga) and map the resulting water ice distribution and abundance using current surface temperature data from the Lunar Reconnaissance Orbiter. Our model suggests that ∼41% of the total H2O mass erupted over this period could have condensed as ice in the polar regions, with thicknesses up to several hundreds of meters. The south pole accumulates roughly twice the ice mass of the north, and the southern deposits are thicker. Typical modeled eruptions generate collisional atmospheres with lifetimes of ∼2500 yr. However, these atmospheres are episodic and generally do not persist between eruptions. Roughly 15% of an atmosphere’s water vapor mass forms a frost on the lunar nightside, while the transient atmosphere persists. Our work suggests that the volcanically active period of the early Moon would have been punctuated by short-lived, collisional atmospheres that enabled the efficient sequestration of large quantities (8.2 × 1015 kg) of water ice at the poles and the temporary diurnal availability of water ice and vapor at all latitudes.

Size–frequency measurements of meter-sized craters and boulders in the lunar polar regions for landing-site selections of future lunar polar missions

The concentrations of volatiles, especially hydrogen (or water), at the lunar poles have been reported from remote sensing data in previous studies. Many future missions are targeting to investigate the permanently shadowed regions inside polar craters, where water ice can exist because the temperature is extremely low. Accordingly, landing sites are being planned around polar craters. We conducted a geomorphological analysis of the ejecta blankets of Shackleton Crater at the South Pole (89.63°S, 130.0°E) and Whipple Crater at the North Pole (89.14 N°, 119.5°E). Size–frequency measurements of the craters and boulders were derived from high resolution (~1 m/pix) image data obtained by the Narrow Angle Camera onboard the Lunar Reconnaissance Orbiter. The number of identified craters (diameter > 10 m) and boulders (diameter > 3 m) were 35,799 and 1273, respectively, around Shackleton and 17,074 and 3092, respectively, around Whipple. The number densities of boulders around fresh craters on Shackleton and Whipple rim are lower than at the Apollo and Luna landing sites, suggesting a low production rate of boulders in these regions. The number density of small craters is lower than expected from the formation ages of Shackleton and Whipple and is strongly correlated with regional topographic slopes, implying that small craters were eliminated by resurfacing with mass wasting from the continuous ejecta of Shackleton and Whipple. Ejecta blankets from small craters may cover and preserve past subsurface accumulations of water molecules. Based on the crater counting data, we propose feasible landing sites around Shackleton Crater and scenarios for exploring local subsurface water using excavators in future missions.

Spatial Distribution and Thermal Diversity of Surface Volatile Cold Traps at the Lunar Poles

Abstract The polar regions of the Moon host some of the most extreme low temperatures in the inner solar system due to its low obliquity, lack of atmosphere, and topographic relief. Some of these regions are already confirmed to host water ice. Proposed sources of water and other volatiles include lunar volcanic outgassing, solar wind, and comet impacts. Each of these possible sources would carry a potentially identifiable compositional signature beyond water. Determining the dominant sources of lunar volatiles, therefore, requires assessing the long-term thermal stability of an array of compounds. We present results of mapping the surface thermal stability locations of multiple key volatiles, including water, from the Diviner Lunar Radiometer data from 60° to 90° latitude in both hemispheres. We find the annual maximum temperature for each pixel of interest in the map (∼300 m) to determine which volatiles of interest would be stable there. We report on the thermal stability area of each volatile, as well as the geologic context in some cases. We find that while the thermal stability area for volatiles is larger in the south pole generally, both the north pole and south pole host areas where potential tracer volatiles from lunar volcanism, solar wind, and cometary impacts would be thermally stable for billions of years if such volatiles were ever delivered. We find several areas equatorward of ∼80° on the lunar nearside that could host water ice, where future missions could potentially access volatile deposits in order to place constraints on water delivery to the Moon.

Challenges of operating a drilling instrument on a small rover at the lunar poles - LVS-PIE phase A study results

The “LVS-PIE Phase A″ project successfully investigated the feasibility of using the Lunar Volatiles Scout instrument on the ispace Polar Ice Explorer rover to search for possible cold-trapped water ice deposits at the lunar poles. The suitability of the two systems for a joint mission was studied based on identified conflicts between both initial systems, such as the envelope for integration or the power budget. The interfaces were made compatible, mechanical structure and mechanisms were updated to enable system integration and thermal simulations were performed to refine the thermal design for safe operation within the thermal limits under lunar conditions. Thermal extraction simulations for the instrument constrained the power requirement during the instrument's heating phase. Real drilling down forces and reaction torques were determined with representative experiments for both rover and instrument revealing stable conditions during the envisioned drilling process. In the developed mission scenario, operational feasibility of the LVS-PIE mission concept was demonstrated using a notional traverse, remote sensing data and investigation of technical budgets. The mission can reach sites of high scientific interest at the lunar poles and perform relevant measurements with the instrument. A joined mission consisting of an instrument package for drilling and gas analysis on a rover below 20 ​kg total mass is found to be technically feasible and scientifically valuable.

View Factor-Based Computation of Secondary Illumination Within Lunar Permanently Shadowed Regions

Permanently shadowed regions (PSRs) at the lunar poles pique scientific interest on account of their cold trapping of volatiles that is highly relevant in the current scope of lunar exploration. Interiors of PSRs are largely unknown due to the challenging illumination conditions. In this letter, we describe a method for synthesizing images at PSRs based on the knowledge of incident solar illumination geometry and local topography that reflects light into PSRs.

Selection of a Landing Site in the Permanently Shadowed Portion of Lunar Polar Regions Using DEM and Mini-RF Data

Direct sampling has never been performed in the permanently shadowed regions (PSRs) of lunar poles up to now. In the Chinese Chang’e-7 (CE-7) mission, a mini-flyer will fly from the lander in a solar illuminated region at the lunar south polar region to the nearby PSRs to collect samples for analysis. In this letter, four potential craters of the lunar south pole, including Shackleton, Shoemaker, de Gerlache, and Slater are discussed for this proposal. Design principles of the landing site, sampling site, and flight route are presented. The local surface slopes are calculated using a digital elevation model (DEM) to select a flat area as a potential landing site, which should allow ample time for solar illumination to support the rover from the lander and allow the flyer to reach the neighboring PSRs. Mini-RF data are applied for further validation of the flat landing and sampling sites, particularly for some rocky rough surfaces that are not identified in DEM and optical images of PSRs. The craters de Gerlache and Slater are found to be suitable for further analysis when high-resolution synthetic aperture radar (SAR) data are acquired by the new polarimetric SAR carried by CE-7.

Prominent volcanic source of volatiles in the south polar region of the Moon

Gas-rich discharges of magma produced pyroclastic vents on the lunar surface. Calculations suggest those pyroclastic vents repeatedly generated 1012 to 1015 g of H2O and CO + CO2 for pyroclastic volumes of 10 to 500 km3 early in lunar history, particularly during the first billion years of lunar history. Some of those volatiles migrated to the lunar poles where they could be trapped in permanently shadowed regions (PSRs). The largest indigenous source of volatiles in the south polar region was volcanism that occurred on the floor of the Schrödinger impact basin. Here a large pyroclastic vent ceased erupting ∼ 3.70 +0.02-0.03 Ga, releasing H2O, CO-CO2, F, S, and Cl vapor species, including calculated values of 3.0 × 1013 to 1.6 × 1014 g H2O. A transport and depositional model suggests 1.1 × 1010 kg (12%) of that water may have been trapped in the south polar region.

Carbon Dioxide Cold Traps on the Moon

AbstractWater ice is expected to be trapped in permanently cold regions near the lunar poles. Other ices (“super‐volatiles”) are trapped at lower temperatures, close to the lowest temperatures measured within the lunar permanently shadowed regions (PSRs). Here, the thermal stability of solid carbon dioxide in the south polar region is determined by analysis of 11 years of temperature measurements by Diviner, a radiometer onboard the Lunar Reconnaissance Orbiter. Sublimation rates averaged over a draconic year are far lower than peak sublimation rates. Small spatially contiguous pockets of CO2 ice stability are found in the craters Amundsen, Haworth, de Gerlache, and others, over a cumulative area of roughly 200 km2. The LCROSS probe impacted one of those pockets and released CO2, serving as validation of the thermal stability calculations. Future surface missions can utilize this highly localized resource for the production of fuel, steel, and biological materials.

Indirect solar receiver development for the thermal extraction of H2O(v) from lunar regolith: Heat and mass transfer modeling

A novel indirect solar receiver/volatile extractor concept was considered for thermally extracting H2O(s) from lunar regolith in the permanently shadowed regions on the Moon. The modeled indirect solar receiver/H2O(s) extractor consisted of a rigid, highly conductive chamber that was partially embedded in the lunar surface. Solar selective and non-selective absorbers were examined to efficiently capture concentrated solar irradiation and effectively transfer heat to icy regolith to drive H2O sublimation. A detailed heat and mass transfer model was developed in ANSYS Fluent to assess the feasibility of thermal extraction from permanently shadowed regions near the lunar poles with 5 wt% of H2O(s). The maximum H2O(v) collected after 10 terrestrial h of simulation time was 2789 g for the solar selective coated receiver and 1035 g for the non-selective receiver. The addition of a solar selective coating was observed to significantly enhance H2O(s) thermal extraction. The low lunar regolith thermal conductivity was shown as the major bottleneck for thermal extraction.

Analyzing Surface Ruggedness Inside and Outside of Ice Stability Zones at the Lunar Poles

Abstract We measured surface ruggedness within 12 polar craters on the Moon, six at each pole, using a variation of the Vector Ruggedness Measure (VRM*). We compare VRM* values derived within ice stability zones, where maximum surface temperatures are ≤112 K, to VRM* values from warmer surfaces where ice is not stable. Ruggedness values inside and outside of ice stability zones are statistically not from the same continuous distribution (α = 0.05). In nine of the 12 investigated craters, surfaces where ice is stable are smoother than neighboring warmer surfaces. These comparatively smooth surfaces are observed in both craters that host surface water-ice exposures and those that do not, suggesting that the presence of subsurface ice, rather than surface ice, may be responsible for the reduced surface ruggedness derived from a moving window of 3 × 3 cells applied to 120 m elevation models. Reduced ruggedness of ice stability zones is slightly greater in south polar craters and tends to correlate with enhanced hydrogen content as modeled from Lunar Prospector data. While ice stability zones may have a control on the distribution of softened topography at the lunar poles, the magnitude of this softening is small at the investigated baselines.