Feasibility Study of Biomass Production at a Lunar Base Using a Mass Cost Model

In 2021, Japan's Ministry of Agriculture, Forestry, and Fisheries selected the Space Foodsphere Association as the contractor for a government-led strategic project called "Development of an Advanced Resource-Recycling Food System that Supports Long-Term Stays on the Moon." The authors of this paper, Space Foodsphere Association members, launched a conceptual design study of a ground-based test facility consisting of a crop/microalgae/meat cultivation area, a habitation area, a resource recycling facility, and an environmental control area. This report describes the results of the study for comparing the mass cost of open- and closed-loop systems under various conditions using a biomass production mass cost model. To evaluate the economic advantages of a closed-loop system for long-duration missions, this study examined how many years it would take for the total mass of supplies transported from Earth to sustain an open-loop system to exceed the system mass and supply mass required for implementing a closed-loop system. Specifically, the study compared the cumulative total mass cost, consisting of system mass and supply mass, from two perspectives: the power supply of solar and nuclear power systems, and the cultivation of four low-caloric crops or the cultivation of both four low-caloric crops and four high-caloric crops. The results showed the economic rationality of a resource recycling food supply system under two scenarios. One is when growing only low-calorie crops (fresh vegetables such as lettuce, cucumbers, tomatoes, and strawberries), but food self-sufficiency is not 100%. The other is 100% food self-sufficient through the production of high-calorie crops, but a power supply system with low mass cost and lightweight outer shell structures (e.g., meteorite and radiation protection provided by local building materials) must be available.