A Review of Lunar Regolith Radiation Shielding Using In Situ Resource Utilization

Sustained human operations on the lunar surface require robust radiation protection, as the Moon lacks both a substantial atmosphere and a global magnetosphere, leaving crews exposed to galactic cosmic rays (GCR) and solar energetic particle (SEP) events. The surface radiation field is also influenced by albedo secondaries, particularly neutrons and gamma rays produced when primary particles interact with lunar regolith. These secondaries can contribute substantially to biological dose. This review synthesizes lunar and orbital measurements, radiation transport modeling, and experimental beam and neutron transmission studies to evaluate lunar regolith as an in situ resource utilization shielding material for surface habitats. Across published simulations, the first few tens of grams per square centimeter of regolith often reduce dose equivalent by fragmenting high linear energy transfer ions and lowering the average quality factor. At greater thicknesses, additional shielding can yield diminishing returns as secondary neutron production increases. Hybrid shielding strategies that place a hydrogen-rich material as an interior liner generally outperform shielding strategies with only regolith. Experimental results broadly support these trends and show that benchmarked Monte Carlo configurations can reproduce measured effects.