The PubMed review on lunar regolith radiation shielding (PMID 42296993) synthesizes lunar and orbital measurements, transport simulations, and beam/neutron transmission experiments for surface habitats, and reports that the first few tens of grams per square centimetre of regolith often reduce dose equivalent by fragmenting high-LET ions and lowering average quality factor.[1] It also finds that at greater thicknesses, additional regolith gives diminishing returns because secondary neutron production rises, while hybrid designs with a hydrogen-rich interior liner generally outperform regolith-only shielding.[1]
For lunar habitation, the engineering lesson is decisive: regolith is useful as bulk mass, but it is not sufficient as the only radiation barrier, especially once shield thickness reaches the regime where secondaries dominate.[1] A layered system that combines regolith with low-atomic-number, hydrogen-rich materials better addresses both galactic cosmic rays and secondary neutron buildup, which directly affects crew dose, material preservation, and mission duration resilience.[1]
Ark priority: evaluate hybrid wall stacks, not monolithic regolith berms, and benchmark them against dose-equivalent targets using transport models and physical test data.[1] The team should track hydrogen-rich liners, structural/regolith composites, and interior anti-neutron layers as near-term integration candidates, because the review indicates these configurations consistently beat regolith alone.[1]