The Itokawa regolith simulant IRS-1 as an S-type asteroid surface analogue

Abstract Asteroid regolith simulants (i.e., substitute materials for asteroid surface regoliths) are useful for the preparation of asteroid landing and/or sample-return missions. In this study, we report a new Itokawa asteroid Regolith Simulant (called IRS-1) as an S-type asteroid surface analogue for China's upcoming asteroid exploration. The IRS-1 simulant was developed from mixing terrestrial minerals with appropriate particle size distributions, based on the currently available mineralogy data of S-type asteroid 25143 Itokowa and a LL6 chondrite Sulagiri. Multiple properties of this simulant are well-characterized, including mineralogy, bulk chemistry, particle size, density, mechanical properties, reflectance spectra, thermal properties, thermogravimetry, and hygroscopicity. These results demonstrate that the IRS-1 simulant has similar mineralogy, bulk chemistry, and physical properties to the target materials (i.e., Itokowa samples and LL6 chondrite Sulagiri), making this simulant a reasonable surface analogue of S-type asteroids. Based on the investigation of mechanical properties of the IRS-1 simulant and two other prepared regolith samples (i.e., L-chondrite-like IRS-1 L and H-chondrite-like IRS 1H), we found that the mineralogical variations on S-type asteroids have a relatively large influence on the mechanical properties of S-type asteroid regoliths. Our studies show that the IRS-1 simulant will be appropriate for a number of scientific and engineering-based investigations where a large amount (few kilograms to hundreds of kilograms) of sample is required (e.g., technology development, hardware testing, and drilling). This study also provides an effective production approach for the future development of asteroid regolith simulants for different types of asteroid regoliths and associated applications.