Developing and Characterizing a New‐generation Regolith Simulant “IGCAS‐AST01” for the Tianwen‐2 Target Asteroid (469219) Kamoʻoalewa

Abstract

China plans to return samples from the near‐Earth asteroid (469219) Kamoʻoalewa, which we previously identified as an LL‐chondrite‐compositional, highly space‐weathered object with fine‐grained regolith. In this study, we developed 10 mL of Kamoʻoalewa regolith simulant, designated “IGCAS‐AST01,” by irradiating LL5/6 chondrite (Kheneg Ljouâd) powder with a high‐energy pulsed laser. We then analyzed the composition, grain size distribution, density, porosity, visible to near‐infrared reflectance spectrum, emission spectrum (approximated as 1–Reflectance), thermal diffusivity, specific heat capacity, and microstructural features of both the fresh (unirradiated) powder and IGCAS‐AST01. IGCAS‐AST01 is composed of 57.8 vol.% olivine, 19.9 vol.% orthopyroxene, 5.6 vol.% diopside, 12.2 vol.% plagioclase, 2.6 vol.% troilite, and minor amounts of other phases. It has a mean size of 26.99 μm, a median size of 23.19 μm, a density of 1196.8 kg m ⁻³ , and a porosity of 64.3%. Additionally, IGCAS‐AST01 exhibits a low reflectance of 0.1 at 0.55 μm and an extremely steep spectral slope. In the temperature range of 253.15–473.15 K, its thermal diffusivity and specific heat capacity range from 3.6–4.7 × 10 ⁻⁶  m ²  s ⁻¹ and 718.43–890.20 J kg ⁻¹  K ⁻¹ , respectively. Furthermore, thick amorphous rims and abundant nanophase metallic iron particles are observed in olivine and pyroxene grains of IGCAS‐AST01. These results could support the Tianwen‐2 mission's payload calibration, sampling operations, on‐orbit scientific data interpretation, and future sample analysis.