A Critical Review of the Engineering Properties of Extraterrestrial Regolith

ABSTRACT Deep space exploration is the frontier of the development of humanity. Investigators worldwide have conducted extensive research on the engineering characteristics and mineralogical composition of surface materials on the Moon, Mars, and asteroids, which have significant implications for future large-scale spacecraft soft landings and the construction of permanent bases. This work analyzes and summarizes a volume of previous findings on the engineering properties of the regolith of the Moon, Mars, and asteroid Ryugu, including the particle size distribution, bulk density, internal friction angle, cohesion, and presence of water ice. The methods used to obtain these properties are critically reviewed. We discuss their advantages and disadvantages and identify the potential new techniques that can be used to better constrain these engineering properties. This study can help researchers to understand the research progress on extraterrestrial regolith in the engineering properties, as well as prospective research directions in deep space exploration. INTRODUCTION Major government space agencies and private companies around the world, such as NASA, CNSA, and SpaceX, have launched ambitious deep space exploration programs to explore the evolution of the solar system and find a potential new habitat for mankind (Wu et al., 2012). Among the extraterrestrial celestial bodies in the solar system, Mars is the focus of the scientific community's attention due to its similarities to Earth (Li et al., 2021). Some key findings concerning Mars have been revealed by a series of probes, especially the landed ones such as InSight and Tianwen-1 (Zou et al., 2021). Due to the remote distance between Mars and Earth, the Moon is considered to be a springboard for Mars exploration (Crawford & Joy, 2014). Lunar exploration is the focus of current deep space exploration programs, including the Artemis program of the United States (Smith et al., 2020), the Chang’e (CE) Project of China (Li et al., 2019), and the Luna program of Russia (Djachkova et al., 2017). In addition, many asteroids have also attracted great interest from researchers, such as Ryugu, Bennu, 2016HO3, etc. (Zhang et al., 2022), and they also have a great chance to contribute to the solution to the evolution of the solar system.