Review of space resources processing for Mars missions: Martian simulants, regolith bonding concepts and additive manufacturing

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.