Prioritization of habitat construction materials on Mars based on multi-criteria decision-making

Mars is the most accessible planet in the solar system for habitation and could serve as a base for exploring more distant planets. Space agencies and scientists worldwide continue exploring Mars to gain more geologic and atmospheric information in preparation for constructing space habitats. The harsh planetary conditions of Mars require the development of new or modified methods for building infrastructure and formulating binders. Each type of concrete has advantages and dis-advantages, and we need to find the best binder for use in construction on Mars.In this study, eight construction materials, including Ordinary Portland cement (OPC), sulfur concrete, geopolymer, sintered material, polymer-bound regolith, products of geo-thermite re-actions, regolith-based magnesium oxychloride, and microbial-induced calcite precipitation, are reviewed according to 14 criteria. The criteria are availability, shipping, water requirement, technical working conditions, curing time, temperature, total required energy, strength, dura-bility, cosmic radiation shield (density and hydrogen content), additives needed, sustainability, safety, and recyclability. We applied the Fuzzy Analytic Hierarchy Process (AHP) approach to assign a weighting to each criterion. Finally, we used three multi-criteria decision-making (MCDM) methods to determine the most suitable mortar for construction under the harsh con-ditions on Mars.The results show that if the general conditions of Mars are considered uniform such as different temperatures and geologies dependent on location, geopolymer concrete is the best material for construction based on Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), VlseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR), and Weighted Aggregates Sum Product Assessment (WASPAS) methods, and sintered material concrete and sulfur concrete are equally ranked second. Correspondingly, five concretes of Portland cement, products of geo-thermite reactions, regolith-based magnesium oxychloride, polymer-bound regolith, and microbial-induced calcite precipitation are the most efficient construction materials, respectively. In addition, using the Fuzzy AHP method, the criteria of shipping and sustainability have the highest and lowest weighting, respectively, in the decision-making process. The use of MCDM methods and inductive analysis provides a scientific approach that enables the comparison of the potential of several space concrete materials for better decision making in future research and construction within the next 10-20 years.