Geotechnical characterisation of two new low-fidelity lunar regolith analogues (UoM-B and UoM-W) for use in large-scale engineering experiments

Engineering experiments regarding excavation, sampling, or mobility for rocky planetary surface exploration (Moon, asteroids, the moons of Mars, Mars) often require large test beds filled with hundreds of kilograms of soil. Specifically engineered regolith simulants are costly and often not available in large enough quantities due to limited production rates. The use of low-fidelity analogues is reasonable, but their geotechnical properties have to be reported in order to be able to calculate excavation and traction forces, as well as to make results comparable and repeatable. This necessary characterisation step is often overlooked in studies regarding regolith handling and excavation. Two readily available low-fidelity analogue materials, we term UoM-B and UoM-W, have been identified and their geotechnical characteristics investigated. The chemical composition, particle morphology, particle size distribution, specific gravity, maximum and minimum densities, and shear strength parameters have been determined. These parameters can be seen as standard metrics in the characterisation of planetary regolith simulants or analogues. The obtained results are compared to values known for five relevant lunar regolith simulants and data from Apollo lunar regolith samples. Although the materials are fundamentally chemically different to Apollo lunar regolith, both materials showed promising characteristics for use as low-fidelity analogues in large-scale engineering experiments; their mechanical properties, crucial for engineering experiments, were found to be similar to lunar regolith and its simulants.