Establishing a permanent, self-sufficient habitat for humans on planetary bodies is critical for successful space exploration. In-situ resource utilisation (ISRU) of locally available resources offers the possibility of an energy-efficient and cost-effective approach. This paper considers the high-temperature processing of molten lunar regolith under conditions which represent the lunar environment, namely low gravity, low temperature, and negligible atmospheric pressure. The rheological properties of the low-titanium lunar mare regolith simulant JSC-1A are measured using concentric cylinder rheometry and these results are used to explore the influence of viscosity on processing operations involving the flow of molten regolith for fabricating construction components on the Moon surface. These include the delivery of molten regolith within an extrusion-based 3D printing technique and the ingress of molten regolith into porous structures. The energy and power required to establish and maintain sufficiently high temperatures for the regolith to remain in the liquid state are also considered and discussed in the context of lunar construction.

Commercial lunar resource extraction activities could become a reality in the mid to long term. Under the existing Outer Space Treaty, there is ambiguity regarding the legal context within which such activities could occur. The Artemis Accords, signed in 2020, are proposed as a mechanism by which space resource extraction activities could take place, with a key proposal of the Accords being the use of Safety Zones to facilitate lunar resource extraction. Whilst the use of Safety Zones is ostensibly proposed for small scale In Situ Resource Utilisation (ISRU) activities focussed on lunar water production, messaging around the Artemis Accords has indicated that there may be an intent to use them to set precedent for longer term, larger scale commercial resource activity. This article explores the practicability of using Safety Zones for large scale commercial lunar resource extraction from the perspective of the commercial entities that could undertake such activities. Conceptual long term demand for water sourced from ice contained in the lunar Permanently Shadowed Regions (PSRs) is derived, and the surface area required to produce sufficient water to meet this market demand determined. Due to the potential characteristics of water ice occurrence in the lunar PSRs, the footprint of operations could be substantial, and virtually without precedent in the terrestrial extractive resource industries. The article concludes that the use of the Safety Zones proposed in the Artemis Accords could be impractical for the governance of large scale commercial lunar resource production. It is suggested that whilst small scale ISRU activities take place under the auspices of the Artemis Accords, efforts are continued to develop a multilateral governance framework acceptable to both the international community and to the commercial sector for the potential large scale development of lunar resources.(c) 2022 Elsevier Ltd. All rights reserved.

Space Resource Utilisation (SRU) or In Situ Resource Utilisation (ISRU) is the use of natural resources from the Moon, Mars and other bodies for use in situ or elsewhere in the Solar System. The implementation of SRU technologies will provide the breakthrough for humankind to explore further into space. A range of extraction processes to produce useable resources have been proposed, such as oxygen production from lunar regolith, extraction of lunar ice and construction of habitation by 3D printing. Practical and successful implementation of SRU requires that all the stages of the process flowsheet (excavation, beneficiation and extraction) are considered. This requires a complete 'mine-to-market' type approach, analogous to that of terrestrial mineral extraction. One of the key challenges is the unique cross-disciplinary nature of SRU; it integrates space systems, robotics, materials handling and beneficiation, and chemical process engineering. This is underpinned by knowledge of the lunar or planetary geology, including mineralogy, physical characteristics, and the variability in local materials. Combining such diverse fields in a coordinated way requires the use of a universal framework. The framework will enable integration of operations and comparison of technologies, and will define a global terminology to be used across all fields. In this paper, a universal SRU flowsheet and terminology are described, and a matrix approach to describing regolith characteristics specifically for SRU is proposed. This is the first time that such an approach has been taken to unify this rapidly-developing sector.