In situ resource utilization of structural material from planetary regolith.

Maximizing in situ resource utilization (ISRU) will be a necessary precept for all space faring nations wishing to establish a sustainable habitat on the Moon and Mars. As off-world infrastructure development advances and longer sustainable habitats are produced, what determines ISRU will also need to evolve. In this paper we explore a period in lunar colonization following the NASA Artemis program, where the available energy for manufacturing is still limited, where lunar chemical processing plants have not yet been constructed, and where the mass/weight of material transport from Earth is still confined to super heavy rockets. We present a multilayer construct, called a Regishell, that utilizes surface regolith mixed with a binder material. The Regishell is a robotic-build system that lands intact and is utilized multiple times. The focus of this paper is not the robot system but the binder materials that could be taken from the Artemis landers or produced in situ that when mixed with the regolith form a hardened structure under lunar solar radiation. The hardened material when integrated into the Regishell forms a protective structural support for a human habitat. We present examples of fused material along with measured hardness values for a polymer and a geopolymer binder. Moreover, we have conducted Monte Carlo simulations using the Regishell construct with the regolith mixture that includes a water layer to prove viability as a radiation shield. We find that the lunar regolith layer alone is adequate to substantially reduce astronaut space radiation dose due to solar particle events and galactic cosmic rays for a 14-day lunar surface mission. [ABSTRACT FROM AUTHOR]