The assessment of the criticality of raw materials allows the identification of the likelihood of a supply disruption of a material and the vulnerability of a system (e.g. a national economy, technology, or company) to this disruption. Inconclusive outcomes of various studies suggest that criticality assessments would benefit from the identification of best practices. To prepare the field for such guidance, this paper aims to clarify the mechanisms that affect methodological choices which influence the results of a study. This is achieved via literature review and round table discussions among international experts. The paper demonstrates that criticality studies are divergent in the system under study, the anticipated risk, the purpose of the study, and material selection. These differences in goal and scope naturally result in different choices regarding indicator selection, the required level of aggregation as well as the subsequent choice of aggregation method, and the need for a threshold value. However, this link is often weak, which suggests a lack of understanding of cause-and-effect mechanisms of indicators and outcomes. Data availability is a key factor that limits the evaluation of criticality. Furthermore, data quality, including both data uncertainty and data representativeness, is rarely addressed in the interpretation and communication of results. Clear guidance in the formulation of goals and scopes of criticality studies, the selection of adequate indicators and aggregation methods, and the interpretation of the outcomes, are important initial steps in improving the quality of criticality assessments.

In terms of space architecture, the biggest technological challenges towards manned missions on Mars, are radiation protection as well as the use of ISRU. The design for a space habitat therefore calls for a technology driven design, often using material sciences as starting point. However, the use of this methodology can overlook architectural aspects that are important for the well-being of the crew, which is, in turn, critical for the completion of the mission. This project focusses on the beneficial aspect of introducing daylight in a working/living environment. Therefore, a preliminary research tested the translucency of different materials in extreme cold [-40°C] to simulate the Martian environment. The use of two distinct materials were found to comply well to all the qualitative as well as the quantitative requirements. These two materials form the structural element for the hybrid habitat as well as form a radiation protection for the crew. The first material is found abundantly on Mars and is the main structural element: ice. As first barrier with the Martian environment, the translucent material will let daylight in the habitat, meaning that day and night changes can be felt by the crew which will reduce their overall anxiety and homesickness. Ice also has peculiar properties that can reinforce the structural elements of the habitat depending on the outdoor climate. It also has repairing properties that no other material possess which is critical for a redundant design. The second material will ensure most of the thermal insulation as well as the secondary structure of the habitat. This material is not found on Mars but can be sourced from the atmosphere using ISRU: polycarbonate (PC). This secondary structure consist of the finished interior walls and windows, as PC resists well under low temperatures and is relatively easy to make as no high pressure is required. Both the ice and PC are excellent against radiation, especially PC which traps secondary radiation. As the indoor partition walls are made from PC, this will increase the radiation protection within the core of the habitat. By cleverly designing the functions and layout, less materials are needed to build this hybrid habitat. Most importantly, as these PC walls are also translucent, shadows will be seen from one room to another. This will improve the overall comfort of the crew as they interact both with themselves and with the outdoor environment via the radiation shielding windows.