Anatomy of Lunar Regolith: The Moon’s Surface Material

28 August 2025

Space is a rare lecture topic, but Hong Kong plays a role in the netional programme.

Around 25 members listened to Dr Zhao, of the Hong Kong PolyTechnic University discussing their research on lunar soil samples returned by the Chinese Chang’e-5 mission. To analyse these samples, they used advanced 3D X-ray computed tomography (CT) scanning combined with machine learning techniques. This allowed them to examine over 700,000 lunar soil particles and determine their physical and mineralogical properties in a non-destructive way. The analysis revealed that the Chang’e-5 soil grains are generally smaller and have more complex shapes compared to samples collected by earlier US and Soviet missions. By processing the CT images, we determined the approximate composition of the lunar soil: about 46% glass and plagioclase, around 50% pyroxene and olivine, and roughly 5% ilmenite. Based on these findings, they developed a high-fidelity lunar soil simulant called PolyU-1. This simulant closely matches the real lunar samples in both grain size distribution and mineral composition. Using PolyU-1, they conducted tests to measure key mechanical properties of lunar regolith, such as friction angle and cohesion. Understanding these properties is crucial for predicting how lunar soil will behave during landing, drilling, excavation, and other engineering activities on the Moon. Lastly, Dr Qi will discuss potential ways to use materials found on the Moon to support future missions and infrastructure.

Dr. Qi Zhao is an Associate Professor in the Department of Civil and Environmental Engineering at The Hong Kong Polytechnic University (PolyU). He obtained his PhD from the University of Toronto and subsequently worked as a postdoctoral researcher at both the University of Toronto and UC Berkeley before joining PolyU. He is a recipient of the Leopold Müller Award from the Austrian Society for Geomechanics and the Dr. N.G.W. Cook PhD Dissertation Award from the American Rock Mechanics Association (ARMA). In 2021, he was selected as a Future Leader of ARMA. Dr. Zhao is a founding management committee member of the Research Centre for Deep Space Explorations (RCDSE) at PolyU. His research focuses on developing novel geomechanics and geophysics solutions for sustainable urban development and deep space exploration. He is currently participating in the Chang’e-8 project, developing a probe for in situ measurement of the dielectric constant of lunar regolith at the south pole of the Moon.