3D Tomographic Analysis of Regolith Simulants Enabling Multidimensional Particle-Discrete Characterization

Lunar in-situ Resource Utilisation (ISRU) has become a rapidly growing field within the last decade. In this context, the extraction of oxygen directly from lunar regolith is one of the major challenges as starting point for a successful exploration of the Moon and beyond. This publication is part of a series of talks on Universal Predictors of Regolith Behavior (UPREB) which address a framework to develop a deeper understanding of the source material, regolith, to successfully process it on the Moon. The particulate material brought back to Earth by the lunar missions can only be used for validation due to limited quantities. To close the knowledge gap regarding the behaviour of this material in the lunar environment, simulants are used to try to reproduce real regolith in terms of mineralogical composition, chemical composition and particle size distribution. Most analyses, both of simulants and real regolith, do not provide any information on particle descriptors on a single-particle basis. However, this kind of data is essential to correlate particle descriptors multidimensionally, e.g., for particle size and particle shape, which cannot be considered independently of each other in mechanical processes like sieving. Only particle-discrete data enables reliable statistical models (e.g., digital twins of the regolith particle systems) and simulations (e.g., flow behaviour of the bulk material using Discrete Element Modelling - DEM). In the following we will focus on the analyses of various regolith simulants using 3D X-ray Microtomography. We show special aspects of sample preparation, measurement, and image post-processing, which are essential to extract valid particle-discrete data. With the proposed workflow it is possible to create a valid and statistically significant data basis for subsequent virtual materials testing. This will enable the reproduction of the fundamentally different lunar conditions compared to the Earth's environment, facilitating preparations for new missions.