Particle Morphology Controls the Bulk Mechanical Behavior of Far-Side Lunar Regolith from Chang’e-6 Samples and Deep Learning

Abstract

Lunar far-side samples returned by the Chang'e-6 mission offer unprecedented insights into regolith properties within the South Pole-Aitken basin, essential for advancing lunar exploration and in situ resource utilization. This paper presents an integrated characterization framework combining high-resolution x-ray micro-computed tomography with semisupervised machine learning to reconstruct and analyze 349,740 individual particles at high throughput. Morphological analysis demonstrates that far-side regolith exhibits greater irregularity than previously characterized near-side samples, with a median particle diameter of 60.51 μm and a mean 3-dimensional sphericity of 0.74-values distinct from those reported for Apollo and Chang'e-5 materials. Discrete element method simulations incorporating these high-fidelity morphologies under representative lunar surface confining pressures (5 to 15 kPa) reveal a high internal friction angle of 47.96° and a cohesion of 1.08 kPa. These parameters exceed Surveyor mission estimates and align with the upper range of Apollo program values, indicating enhanced mechanical strength and cohesion in far-side regolith. The superior mechanical properties arise primarily from pronounced particle irregularity promoting strong mechanical interlocking, potentially augmented by cementation from abundant glassy agglutinate phases. These findings establish critical geotechnical benchmarks for lunar far-side materials, providing essential design parameters for future robotic and crewed missions, landing site selection, and infrastructure development.