Characterization and Comparative Analysis of the Electrostatic Properties of Different Lunar Regolith Simulants

In pursuing sustainable lunar exploration and habitation, understanding the electrostatic and electromagnetic behavior of lunar dust and regolith particles is receiving significant interest. However, the limited number of lunar regolith samples collected during the Apollo missions is insufficient to sustain the large number of current lunar experimental studies. Therefore, many lunar simulants have been fabricated using terrestrial materials to emulate the properties of lunar dust and regolith particles. Different lunar regolith simulants are used to represent different moon regions and for different applications. In this work, we study the electrostatic properties of the particles of two lunar simulants: JSC-l A and NU - LHT-4 M. JSC-lA is a simulant for the lunar mare regions, the dark areas of the moon, whereas NU-LHT-4M is a highland simulant, the lighter or brighter parts of the moon. Both simulants have particles with stable 3D shapes and have been used in a wide range of experiments. Utilizing advanced 3D X-ray tomography, we imaged the 3D particle shapes of thousands of particles from each simulant with sub-micron resolution. Using the open-source SCUFF-EM package, a Method of Moments (MOM)-based tool, we calculated the electrostatic polarizability tensors of the particles in each simulant. The particles were assigned a relative dielectric permittivity of 9.8 following: Grant Heiken, David Vaniman, and Bevan M. French, Lunar sourcebook: A user's guide to the Moon, No. 1259, Cup Archive, 1991. The electrostatic polarizability describes the electric dipole moment acquired by the particle when exposed to electric fields of different directions. After calculating the polarizability tensor, its eigenvalues are calculated and arranged in decreasing order
$P_{1}\geq P_{2}$
2: P3. Our quantitative analysis shows significant differences between the polarizability values of the NU-LHT-4M and JSC-IA simulants. Averaging 5000 particles from each simulant, NU-LHT-4M yielded average polarizability values
$(P_{1}=240,527,\ P_{2}=169,075,\ P_{3}=111,707)$
whereas the average JSC I-A values were
$(P_{1}=127,243,\ P_{2}=93,879,\ P_{3}=69,671)$
. Comparisons with previously published polarizability results from actual lunar regolith particles collected in the Apollo missions will be presented.