Additive manufacturing (AM) is one of the most promising techniques for on-site manufacturing on extraterrestrial bodies. In this investigation, layerwise solar sintering under ambient and vacuum conditions targeting lunar exploration and a moon base was studied. A solar simulator was used in order to enable AM of interlockable building elements ou...
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... began prevented the use of a turbo-molecular pump to reach a higher vacuum level. The gas pressure within the chamber initially increased rapidly to over 200 mbar. Following this, the pressure increased linearly, at a rate of approximately 2.3 mbar=s until the end of the process. The pressure evolution graph during the AM process is shown in Fig. 5. ...
To satisfy the essential needs, including energy requirements, for human and robotic space explorations on planetary objects like Moon, Mars and asteroids, the proper exploitation of resources available in-situ represents a crucial issue. Along this line, the present work investigates the potential of a sintered lunar regolith simulant (JSC-1A) for possible solar energy harvesting and thermal energy storage applications. Regolith simulant powders are first consolidated by Spark Plasma Sintering (SPS) at 700 and 900 °C to produce bulk samples with different relative densities, i.e. 86 and 98%, respectively, and surface porosities. Negligible changes from the compositional point of view are induced by SPS at 700 °C, whereas a decrease of the original glassy phase content is observed when operating at 900 °C. The optical properties of sintered samples and pristine regolith powders are compared, considering the spectral absorptance/emittance, the integrated solar absorptance and the integrated thermal emittance estimated in a temperature range representative for the ISRU application, i.e. from 100 to 1300 K. We found that sintering changes the optical properties of regolith in a process-dependent way, with an increased solar absorptance and thermal emittance shown by sintered pellets with respect to pristine powders.
Lunar regolith is the most abundant natural resource on Moon's surface. It is the intensively studied prime candidate for in-situ fabrication and repair (ISFR) technologies for future crewed exploration and resource harvesting missions on the Moon. Additive manufacturing with lunar regolith is a promising ISFR method that can be used for sustainable local production of engineering tools and components. This method requires little quantities of extra materials delivered from Earth, but, like many other prospective ISFR technologies, is sensible to the quality of the pre-processed regolith powders that are used as the primary source materials. The evolution of properties of highland and mare lunar regolith simulants concerning grinding-based pre-processing was studied in this work. The effect of regolith grinding was studied for the processes, relevant to stereolithography-based additive manufacturing. Particle size distribution, mean particle size, UV–Vis, XRD and XRF spectra were acquainted from the samples, ground in a ball mill at various grinding times (to different fraction sizes). The photopolymerization efficiency was assessed for lunar simulant-infilled resins prepared from lunar regolith simulants ground with different parameters. It was found that the grinding time of lunar regolith simulants strongly influences their optical properties – the light absorption in the far UV increased by 5.5 times. Based on the measured photo-polymerization depth, the optimal grinding procedure for mare and highland lunar regolith simulants was determined.
The next step for the exploration of space seems to require the human participation by means of a long-lasting lunar outpost. Therefore, this paper attempts to review the up-to-date knowledge regarding prominent issues surrounding the construction stage of a permanent base on the Moon in the light of the 3D printing process. In this context, a number of significant and specific issues are presented and discussed in a detailed manner to determine both the state-of-the-art position of the related literature and the relevant fields for improvement and implications. As a result, the use of heterogeneous and collective swarms of ground robots through a decentralized approach seems reasonable for the 3D printing tasks. However, as it is an emerging technology, it has to be improved further and tested in a terrestrial context as well as on the Moon. In this regard, it is a must to investigate precisely if the solar energy will be adequate for the operation of robots during preparation, transportation, and printing processes of local and Earth-based construction materials. In terms of structural needs, a composite shelter, including (i) an inner inflatable shell with a three-layer membrane, (ii) an outer concrete layer with regolith, polymer, and reinforcing fibers, and (iii) an outermost shield with raw regolith, will likely be viable. However, sieving and binding issues during the preparation phase of concrete under vacuum and microgravity conditions must be solved efficiently.
The distinct difference between the lunar surface (Moon) and the Earth forced space research organizations (SRO) and researchers to study the geotechnical properties of the lunar soils for the successful execution of lunar missions. The planned Chandrayaan Missions of the Indian Space Research Organization include constructing lunar structures on the lunar surface for the future Moon colonization. The stability of such lunar structures is completely dependent upon the foundation systems adopted. The foundation systems of these lunar structures are expected to encounter various types of vibrations due to moonquakes on the lunar surface. The analysis and design of a foundation system with respect to ground motion and vibration rely on the dynamic properties of the lunar soil. Also, the characterization of dynamic soil properties like shear modulus, damping ratio, and Poisson's ratio is essential for the safe design of foundation systems. Therefore, it is imperative to evaluate the dynamic properties of the lunar soil against moonquake-induced vibrations. Past research has utilized lunar soil simulants were used to assess the lunar soil's geotechnical properties. In that order, this study explains the dynamic properties of the new lunar highland simulant LSS-ISAC-1 under simulated moonquake conditions using cyclic triaxial tests. The shear modulus and damping ratio were determined from the cyclic triaxial tests for the different relative densities (30%, 63%, and 80%), confining pressures (5 kPa–75 kPa), and frequencies to represent the loose, medium, and dense states of the lunar surface. The bender element test is also done to find the shear wave velocity and maximum shear modulus. The results were compared with the lunar soil simulant CAS-1 and lunar soils to show the reliability of the obtained test results of LSS-ISAC-1.
Scientific exploration of extraterrestrial planets has gripped human imagination since the advent of space travel. Human missions to Mars could produce insight into the essential questions of how, when and where life began on Earth. Such missions would only be feasible using local space resources materials, a concept called in situ resource utilization (ISRU). In the absence of organic materials from plants, the globally available oxidic surface minerals (regolith) are the only viable resource for large-scale construction efforts such as habitats, greenhouses, landing pads and equipment building. This review provides the first comprehensive literature review of ISRU materials research employing Martian simulants. It gives a detailed overview of all Mars simulants, their history, properties, and challenges, introducing a generational concept for simulants development. The available Mars simulant processing literature (including selected work on lunar simulants) is categorized into seven regolith bonding concepts. The state-of-the-art on additive manufacturing (AM) in ISRU research is discussed. Detailed feasibility assessments for all processing approaches are given, including overview graphs comparing the mechanical performance of each fusion concept with feedstock availability on the surface of Mars. Finally, major open questions and future challenges of materials processing for early Mars missions is examined.
In this article we present a design principle based on segmenting a structure into a set of topologically or geometrically interlocked elements. None of these designs was borrowed from Nature and yet there are some parallels between these structures born in the minds of researchers and Nature’s designs. We give some historical background, describe the different kinds of interlocking structures, and discuss the ways in which they can be generated. Based on the beneficial features of the proposed structures, such as a great tolerance to local failures, enhanced bending compliance, high sound and energy absorption, ease of assembly and disassembly, and nearly full recyclability, we discuss possible applications of the concept of topological and geometrical interlocking design.