Lunar Construction Research Articles

Preparation and evaluation of geopolymer based on BH-2 lunar regolith simulant under lunar surface temperature and vacuum condition

The construction of a lunar base and habitation on the moon has always been of great significance to utilizing lunar resources and deep space exploration. In this paper, a new type of lunar regolith simulant denoted as BH-2 of similar compositions and particle size distribution with real one was developed and used for geopolymer synthesis under simulated lunar surface temperature and vacuum conditions. The geopolymer products were characterized by compressive strength test, Mercury Intrusion Porosimetry (MIP), Scanning Electron Microscope coupled, and 29Si magic angle spinning-nuclear magnetic resonance (29Si MAS-NMR). The results showed that BH-2 lunar regolith simulant could be used to synthesize geopolymer. And the 72-h compressive strength of the geopolymer cured at the temperature of group C, corresponding to the 324–384 h of one lunar day, could reach 38.2 MPa, which was advantageous in the early stages of lunar construction because no additional curing equipment is required. The pores originated from lunar regolith simulant and caused by incomplete geopolymerization resulted in decreased compressive strength of the resulting geopolymer. Vacuum conditions on the moon favored the preparation of lunar geopolymers due to the lack of carbon dioxide weakening the efflorescence effect. This study benefits to lunar base construction with in-situ resource.

Microstructural, mechanical, and thermal properties of microwave-sintered KLS-1 lunar regolith simulant

KLS-1 Lunar regolith simulant was microwave sintered to explore its potential applicability in future lunar construction. The effects of sintering temperature on linear shrinkage, density, porosity, and microstructural, mechanical, and thermal properties were investigated. As the sintering temperature increased, linear shrinkage and density increased and porosity decreased. Structural evolution in the sintered samples was characterized by scanning electron microscopy and X-ray diffraction. Unconfined compressive strength testing showed that mechanical strength increased significantly with increasing sintering temperature, with 1120 °C giving the highest strength of 37.0 ± 4.8 MPa. The sintered samples exhibited a coefficient of thermal expansion of approximately 5 × 10−6 °C−1, which was well-maintained even after cyclic temperature stress between −100 and 200 °C. Therefore, this microwave processing appears promising for the fabrication of building material with sufficient mechanical strength and thermal durability for lunar construction.

Sintered or melted regolith for lunar construction: state-of-the-art review and future research directions

Low-cost robust processes are needed to produce construction materials for habitats and civil infrastructure in the early stages of the development of a permanent base on the moon. Sintered or melted regolith (SoMR) is an attractive solution as it requires only regolith and solar energy as inputs, both of which are readily available on the moon. This paper presents a review of SoMR technologies. It also provides an evaluation of the different technologies based on the results of 53 experimental studies of SoMR production which were identified in the literature. The key outcomes of these experimental trials are summarised, and the viability of each process for the production of lunar construction materials is evaluated. Finally, future research which would address current technical challenges and uncertainties is suggested.

Regolith-based magnesium oxychloride composites doped by graphene: Novel high-performance building materials for lunar constructions

In our study, we demonstrated a novel approach in the field of lunar construction materials. The prepared composite materials are based on magnesium oxychloride cement (MOC), which is currently broadly studied and is coming back to the foreground as an ecological alternative to commonly used building materials. To improve the properties of the matrix, graphene was used as an additive. The addition of graphene has previously shown enormous improvement of the mechanical properties of MOC. As a filler, the regolith simulant in the form of powder was used in a high percentage in order to reduce the amount of imported raw materials. The prepared samples were characterized by a wide range of analytical methods, identifying the phase and chemical composition, microstructure, mechanical properties and other. To evaluate the endurance of the materials, they were subjected to thermal treatment simulating the conditions on the Moon. The mechanical properties were only slightly reduced after the thermal treatment even for the samples with a very high content of regolith. The compressive strength reached an unbelievably high value of 67 MPa for the sample with 50 wt% of regolith. The prepared composite materials show the application potential for the lunar infrastructure constructions.

Prediction of micrometeoroid damage to lunar construction materials using numerical modeling of hypervelocity impact events

The use of Lunar regolith for the creation of construction materials to build habitats and other infrastructure required for a Lunar base is an example of in situ resource utilization (ISRU), an important strategy for minimizing the launch mass associated with a NASA mission to the Moon. One class of solidified regolith, Biopolymer-bound Soil Composites (BSC), consists of regolith mixed with a small amount of biopolymer binding agent (10% w/w). This paper characterizes BSC's micrometeoroid impact performance using experimental and numerical methods. Micrometeoroids are a notable hazard of the Lunar environment and pose a challenging design consideration. A total of 17 hypervelocity impact experiments were conducted on BSC targets at NASA's White Sands Testing Facility. Numerical simulations of the hypervelocity impact experiments were carried out using CTH, a shock physics code developed by Sandia National Laboratories. Comparisons between the experimental craters and the simulation results indicate that there is good agreement between crater dimensions of the hypervelocity impact experiments and the CTH model. The CTH model developed in this paper provides (1) a damage prediction tool that allows for the necessary extrapolation of micrometeoroid impact velocities beyond what is experimentally achievable and into the velocity regime that is relevant for micrometeoroids and (2) a material design tool that is capable of varying material parameters computationally, ultimately allowing for the engineering and optimization of BSC's performance under impact loading.

Utilization of urea as an accessible superplasticizer on the moon for lunar geopolymer mixtures

Abstract When developing materials for lunar construction, it is essential to minimize the weight of components that have to be brought in from Earth. All necessary ingredients for geopolymers could potentially be sourced on the lunar surface, which is why the material might be an efficient construction material for infrastructure on the moon. Finding a chemical admixture that can be easily obtained on the moon, which can increase the workability while utilizing less water, would be highly beneficial for utilizing lunar regolith geopolymers for lunar 3D printing. Urea can break hydrogen bonds, and therefore reduces the viscosities of many aqueous mixtures. Since urea is the second most abundant component in urine (after water), it is readily available anywhere there are humans. We have therefore explored the possibility of utilizing urea as a chemical admixture for lunar geopolymers. Addition of urea has been compared with polycarboxylate and naphthalene based superplasticizers, and with a control mixture without superplasticizer. When curing the sample containing urea at 80 °C, the initial setting time became longer. The samples containing urea or naphthalene-based superplasticizers could bear heavy weights shortly after mixing, while keeping an almost stable shape. Samples without superplasticizer or containing the polycarboxylate-based admixture were too stiff for mold-shaped formation after casting. Samples containing urea and naphthalene-based admixtures could be used to build up a structure without any noticeable deformation. Initial compressive strength of the samples with urea was higher than for the two other specimens containing superplasticizers, and it continued to rise even after 8 freeze-thaw cycles. Microstructural studies revealed that superplasticizers can influence the formation of additional air voids within the samples.

Preparation of autoclave concrete from basaltic lunar regolith simulant: Effect of mixture and manufacture process

Abstract To build a permanently inhabited base on the Moon is a vitally important step to developing lunar exploration and deep space detection. Indigenous materials become a significant requirement for lunar construction as transporting construction materials from Earth is extremely expensive. Fortunately, construction materials can be fabricated by utilizing in situ materials on the Moon surface. Autoclaving technology is a feasible method for lunar construction material manufacture. In this study, basaltic lunar regolith simulant (LRS) was utilized to imitate the lunar regolith as major raw material. Firstly, Ca(OH)2 and PI 52.5 were compared to choose better calcareous material. In addition, the influence of calcareous material ratio, LRS fineness, briquetting pressure value and autoclaving craft on mechanical property were discussed to determine an appropriate material system and manufacture process. Furthermore, strength effect mechanism was expounded by the investigation of pore characteristics and hydration products. The results indicated that Ca(OH)2 was more effective in producing better performance LRS autoclaved concrete and introducing appropriate amount of Ca(OH)2 can improve the strength and promote target hydration products generation effectively. Meanwhile, the increasing of LRS fineness resulted in weakening of compressive strength which was ascribe to the increasing pore volume caused by the arch effect during briquetting process with finer LRS particles. Moreover, augmentation of briquetting pressure value made significant improvement in compactness of rough-body and autoclaved specimens and finally resulted in increment of density and enhancement of strength. On the other hand, the extension of saturated vapor pressure duration time enhanced the compressive strength by promoting hydrothermal synthesis reaction and generating of target hydration products.

A structural assessment of unrefined sintered lunar regolith simulant

The potential of utilizing lunar regolith as the raw material for manufacturing structural members is very appealing for future exploration and settlement of the Moon. Future lunar missions will depend on in-situ resource utilization (ISRU) for structural components, among other things. Sintered lunar regolith has been proposed as a structural material. In general, it has been assumed that the regolith would be at least minimally processed before use. We propose the possibility of manufacturing structural components directly using unrefined sintered lunar regolith with the advantage of requiring fewer specialized material processing equipment.Our purpose in this study was the quantification of the material properties of unrefined sintered lunar regolith simulant. Two batches of sintered lunar regolith simulant JSC-1A samples, with porosities of 1.44% and 11.78%, underwent compression testing using an Instron series 4500 Universal Test System machine. Material properties were evaluated from the acquired load vs. deflection data. Stress vs. strain, modulus of elasticity, toughness, bulk modulus and compressive strength were evaluated as a function of porosity. The average compressive strength of the 1.44% porosity material was 218.8 MPa, and 84.6 MPa for the 11.78% porosity material. Our tests show that even unrefined sintered 11.78% porosity lunar regolith holds the possibility of being a useful structural material for lunar construction. Comparing our experimental results with those of other ISRU derived structural materials, unrefined sintered lunar regolith is expected to be one of the strongest material derived from lunar sources.

Solar bricks for lunar construction

A novel brick manufacturing technique is described, whereby natural mineral soil and added thermoplastic polymer particles are mixed, heated, and allowed to cool, to enable polymeric bonding of the soil grains. Experimental results indicate that the gradation of the soil plays a significant role on the compression strength of the manufactured bricks. This is because gradation controls fabric in highly compacted granular soils. A fabric that features pore filling by progressively smaller grains results in an increased likelihood of added polymer localization at intergranular contacts and therefore high strength. A conventional convection oven and a solar oven were used independently to implement the heat treatment; the comparison reveals the potential use of the latter for low energy cost brick construction in remote locations and nontraditional environments such as the Moon.

Microwave processing of lunar soil for supporting longer-term surface exploration on the Moon

The future of human space exploration will inevitably involve longer-term stays and possibly permanent settlement on the surfaces of other planetary bodies. It will, therefore, be advantageous or perhaps even necessary to utilise local resources for building an infrastructure for human habitation on the destination planetary body. In this context human lunar exploration is the next obvious step. Lunar soil is regarded as an ideal feedstock for lunar construction materials. However, significant gaps remain in our knowledge and understanding of certain chemical and physical properties of lunar soil, which need to be better understood in order to develop appropriate construction techniques and materials for lunar applications.This article reviews our current understanding of the dielectric behaviour of lunar soil in the microwave spectrum, which is increasingly recognised as an important topic of research in the Space Architecture field. Although the coupling between the lunar soil and microwave energy is already recognised, considerable challenges must be overcome before microwave processing could be used as a main fabrication method for producing robust structures on the Moon. We also review the existing literature on the microwave processing of lunar soil and identify three key research areas where future efforts are needed to make significant advances in understanding the potential of microwave processing of lunar soil for construction purposes.

Development of near-zero water consumption cement materials via the geopolymerization of tektites and its implication for lunar construction.

The environment on the lunar surface poses some difficult challenges to building long-term lunar bases; therefore, scientists and engineers have proposed the creation of habitats using lunar building materials. These materials must meet the following conditions: be resistant to severe lunar temperature cycles, be stable in a vacuum environment, have minimal water requirements, and be sourced from local Moon materials. Therefore, the preparation of lunar building materials that use lunar resources is preferred. Here, we present a potential lunar cement material that was fabricated using tektite powder and a sodium hydroxide activator and is based on geopolymer technology. Geopolymer materials have the following properties: approximately zero water consumption, resistance to high- and low-temperature cycling, vacuum stability and good mechanical properties. Although the tektite powder is not equivalent to lunar soil, we speculate that the alkali activated activity of lunar soil will be higher than that of tektite because of its low Si/Al composition ratio. This assumption is based on the tektite geopolymerization research and associated references. In summary, this study provides a feasible approach for developing lunar cement materials using a possible water recycling system based on geopolymer technology.

CyGaMEs Selene player log dataset: Gameplay assessment, flow dimensions and non‐gameplay assessments

AbstractThe Selene: A Lunar Construction GaME instructional video game is a robust research environment (institutional review board approved) for investigating learning, affect, and the CyGaMEs Metaphorics approach to instructional video game design, embedded assessment, and informatics analysis and reporting. CyGaMEs applies analogical reasoning theory to translate fundamental scientific phenomena into embodied, procedural, goal‐driven, instructional gameplay and concurrent metrics of learning. Selene also collects integrated measures of affect operationalized as flow dimensions skill and challenge. Selene is a free, online Flash/Flex game available 24/7 to registered players. The player (agemean = 13; N = 3882; nfemale = 1915; nmale = 1908; nSpanish‐language version = 157) dataset, collected between April 6, 2010 and May 30, 2014, is anonymized, open and downloadable within Wheeling Jesuit University's data repository. Dataset files contain timestamped, tab‐delimited, player log data for gesture‐level gameplay; Timed Report progress toward each game/learning goal; flow dimensions; non‐gameplay assessments; demographics; paradata; and repository lexicons. Dataset analyses using traditional statistical methods (eg, multilevel modeling, interrupted time‐series) study learning trajectories, learning moments, affect (flow dimensions), persistence, gender differences, dashboard effects and the interactions among them. CyGaMEs Selene translates Timed Reports into real‐time, online dashboard report visualizations players and their registered educators can understand and use.

Evaluation of lunar regolith geopolymer binder as a radioactive shielding material for space exploration applications

Future manned missions to the moon will require the ability to build structures using the moon’s natural resources. The geopolymer binder described in this paper (Lunamer) is a construction material that consists of up to 98% lunar regolith, drastically reducing the amount of material that must be carried from Earth in the event of lunar construction. This material could be used to fabricate structural panels and interlocking blocks that have radiation shielding and thermal insulation characteristics. These panels and blocks could be used to construct living quarters and storage facilities on the lunar surface, or as shielding panels to be installed on crafts launched from the moon surface to deep-space destinations. Lunamer specimens were manufactured in the laboratory and compressive strength results of up to 16MPa when cast with conventional methods and 37MPa when cast using uniaxial pressing were obtained. Simulation results have shown that the mechanical and chemical properties of Lunamer allow for adequate radiation shielding for a crew inside the lunar living quarters without additional requirements.

Video game learning dynamics: Actionable measures of multidimensional learning trajectories

AbstractValid, accessible, reusable methods for instructional video game design and embedded assessment can provide actionable information enhancing individual and collective achievement. Cyberlearning through game‐based, metaphor‐enhanced learning objects (CyGaMEs) design and embedded assessment quantify player behavior to study knowledge discovery and application. CyGaMEs is grounded by analogical reasoning theory, cognitive task analysis and knowledge representation. A construct representation argument for validity using evidence‐centered design warrants CyGaMEs, its web‐based learning environment, Selene: A Lunar Construction GaME, its embedded assessment, and a learning dynamics approach to student, measurement and statistical models. Two studies (US volunteers, Study 1: n = 267, mean (M)age = 15; Study 2: n = 90, Mage = 12) cross‐validate learning dynamics (learner progress, rate of progress and changes in that rate) for Selene's multidimensional goals while players learn and apply standard‐based science about fundamental geology and space science concepts. Gameplay data analyzed using regression, calculus and hierarchical linear modeling exhibit overall relatively high standardized rates of progress toward each goal statistically higher than zero. For example, adjusting for nesting within individual players, average rate of progress toward the goal of accreting lunar mass is a z‐score of 1.4 (99% confidence interval = 1.40lower, 1.48upper) or 1.4 standard deviations above zero.

Robotic Construction by Contour Crafting: The Case of Lunar Construction

Contour Crafting is a digitally controlled construction process invented by Professor Behrokh Khoshnevis that fabricates components directly from computer models, using layered fabrication technology. By obviating the need for formwork used in traditional concrete construction, CC can reduce costs and construction times significantly. The technique has great potential as a robotic form of construction reliant on relatively minimal human labor as a form of construction in relatively hazardous environments, such as the Moon with its radiation levels that can prove highly damaging. Current research funded by NASA has been exploring the potential for using CC on the Moon to build structures making use of readily available regolith that is found in great abundance on the surface of the Moon. This article offers an overview of this research and evaluates the merits of using CC on the Moon.

Optimization of the self-propagating high-temperature process for the fabrication in situ of Lunar construction materials

The highly exothermic self-propagating thermite reduction of ilmenite (FeTiO3) is systematically investigated for the in situ fabrication of composite ceramics in Lunar environment. Because of its relatively lower volatility, Al is preferred to Mg as reducing agent. A self-propagating (SHS) behavior is displayed only if the Al/FeTiO3 molar ratio is higher than 0.9. In addition, when the amount of the reducing metal in the mixture is increased, the reactive process proceeds faster and the combustion temperature becomes higher, as a consequence of the increased system exothermicity. Correspondingly, the maximum amount of Lunar regolith (containing up to 20wt.% ilmenite) to be possibly reacted with additional FeTiO3 and Al is identified. The obtained product, consisting of a complex mixture of various Al-, Ti-, Mg-, and Ca-oxides along with metallic and intermetallic phases, displays good compressive strength properties (25.8–27.2MPa) that make it promising as construction material. Parabolic flight experiments evidenced that neither SHS process dynamics nor product characteristics are significantly affected by gravity. All the obtained findings allows us to conclude that the optimal conditions identified during terrestrial experiments are also valid for in situ applications in Lunar environment, with the only exception for the slight overpressure (few Torr) required for limiting Al vaporization during SHS.

Power Requirements for the Construction and Operation of a Lunar Oxygen Plant

AbstractConstruction work and machines required to build lunar facilities including an oxygen plant were specified, and power requirements for the construction and operation of these facilities were estimated based on a proposed evolutional scenario. Individual components of lunar facilities such as habitat/laboratory modules, corridor modules, and connection/evacuation modules were designed, and specifications of lunar construction machines were determined. A realistic oxygen plant was also designed by referring to the experimental and analytical results of hydrogen reduction of ilmenite processes. The energy required for soil work is estimated to exceed the energy for a construction facility, and the covering of facilities with regolith is expected to be the most energy-consuming work. Estimated power demands for construction in the evolutional Phases 1, 2, and 3 were 75, 75, and 155 kW, whereas those for operation of the oxygen plant were 2.3, 31, and 761 kW, respectively.

Sulfur “concrete” for lunar applications – Sublimation concerns

Melting sulfur and mixing it with an aggregate to form “concrete” is commercially well established and constitutes a material that is particularly well-suited for use in corrosive environments. Discovery of the mineral troilite (FeS) on the moon poses the question of extracting the sulfur for use as a lunar construction material. This would be an attractive alternative to conventional concrete as it does not require water. However, the viability of sulfur concrete in a lunar environment, which is characterized by lack of an atmosphere and extreme temperatures, is not well understood. Here it is assumed that the lunar ore can be mined, refined, and the raw sulfur melded with appropriate lunar regolith to form, for example, bricks. This study evaluates pure sulfur and two sets of small sulfur concrete samples that have been prepared using JSC-1 lunar stimulant and SiO 2 powder as aggregate additions. Each set was subjected to extended periods in a vacuum environment to evaluate sublimation issues. Results from these experiments are presented and discussed within the context of the lunar environment.

Experimental simulation of tensile behavior of lunar soil simulant JSC-1

The return of humans to the Moon, which includes construction and infrastructure development remain a national priority for exploration of space. Thus, a thorough understanding of lunar soil properties for purposes of engineering design is required. In the past lunar soil (regolith) simulant JSC-1 has been widely used by investigators in feasibility studies to device preliminary concepts, where basic strength, compaction and stiffness behavior are of importance. While the tensile strength of granular soils is customarily assumed to be insignificant or zero in terrestrial engineering design, tensile strength behavior may be of greater importance in lunar construction. Experimental studies have shown that the tensile strength of regolith, specifically JSC-1 is substantial and reliable techniques for assessing behavior are needed. A direct tension device was recently developed to determine tensile strength properties of granular soils for a wide range of packing densities, and experiments were conducted on JSC-1 to determine ranges of tensile strength. The specimens were prepared by a miniature compaction technique. This paper presents tensile strength results for JSC-1, which may be of importance for future infrastructure designs and development of in situ resource utilization on the Moon.

Engineering, Design and Construction of Lunar Bases

How do we begin to expand our civilization to the Moon? What are the technical issues that infrastructural engineers, in particular, must address? This paper has the goal of introducing this fascinating area of structural mechanics, design, and construction. Published work of the past several decades about lunar bases is summarized. Additional emphasis is placed on issues related to regolith mechanics and robotic construction. Although many hundreds of papers have been written on these subjects, and only a few tens of these have been referred to here, it is believed that a representative view has been created. This summary includes environmental issues, a classification of structural types being considered for the Moon, and some possible usage of in situ resources for lunar construction. An appendix provides, in tabular form, an overview of structural types and their lunar applications and technology drivers.