Morphological characteristics and digital generation of millimeter-scale particles in the lunar soil of Chang'e-5

The millimeter-scale lunar soil particles from the CE-5 mission exhibit a complex morphology, including pronounced angularity and particle agglomeration caused by high-temperature sintering during space weathering. This distinctive particle morphology has a significant impact on the physical and mechanical properties of its assemblages, serving as a critical factor influencing the engineering behavior and resource utilization of lunar soil. Accurately reproducing this complex shape remains challenging but is critical for particle-scale simulations and weathering layer mechanics studies. In this study, we quantitatively characterise the morphology of CE-5 particles via five shape descriptors, including a five-dimensional morphological framework of particle size, sphericity, convexity, aspect ratio, and Wadell roundness, to systematically quantify the shape of lunar soil particles. A digital particle generation procedure based on database matching and a complex Fourier descriptor (CFD), which is capable of creating nonsingular digital particles with target shape characteristics, was developed. The mean values of particle size, sphericity, convexity, aspect ratio and roundness for real particles were 0.84, 0.78, 0.92, 0.76 and 0.12, respectively, whereas the corresponding parameters for generated particles were 0.86, 0.82, 0.96, 0.80 and 0.15, respectively. In the normalised morphometric five-dimensional feature space, the overall Wasserstein distance is as low as 0.014, indicating that the generated particles are in good agreement with the real samples and that their morphological parameters are highly matched with the measured data. These findings demonstrate the effectiveness of CFD-based replication of lunar weathering layer morphology and provide a practical way to generate particles for lunar modelling and engineering applications.