¹Pengfei Zhang (>10)
Journal of Geophysical Research: Planets (in Press) Link to Article [DOI: 10.1029/2026JE009859]
¹Center for Lunar and Planetary Sciences, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, China
Published by arrangement with John Wiley & Sons

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  m² 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.

^1,2M. Kołodziej, ³B. Pieterek, ⁴G. Zieliński, ¹K. Załęski, ¹E. Coy
Journal of Geophysical Research: Planets (in Press) Open Source Link to Article [DOI: 10.1029/2026JE009937]
¹NanoBioMedical Centre, Adam Mickiewicz University in Poznan, Poznan, Poland
²Institute of Molecular Physics, Polish Academy of Sciences, Poznan, Poland
³Geohazard Research Unit, Institute of Geology, Adam Mickiewicz University in Poznan, Poznan, Poland
⁴Micro-area Analysis Laboratory, Polish Geological Institute—National Research Institute, Warsaw, Poland
Published by arrangement with John Wiley & Sons

Meteorites serve as an exceptional source of insight into our planet and the Solar System. Most meteorite fragments were recovered hundreds to thousands of years after their fall, and therefore exhibit varying degrees of terrestrial weathering, which has altered or completely removed weather-sensitive mineral phases. This study focuses on two aubrites—NWA 14582 and Ribbeck—examining the differences in their mineral composition. The NWA 14582 was collected in a desert long after its fall and has undergone significantly greater shock metamorphic alteration than the Ribbeck meteorite. The alterations are evidenced by the structural changes in its enstatite and diopside, along with the absence of feldspars, which have transformed into maskelynite. The Ribbeck meteorite, recovered shortly after its descent, revealed several mineral phases not present in NWA 14582. Electron microprobe investigations confirmed that minerals such as troilite, daubréelite, schreibersite, and kamacite exhibit resistance to weathering. Conversely, the observed minerals, such as heideite, caswellsilverite, oldhamite, pentlandite, and alabandite, appear to be particularly susceptible to terrestrial weathering processes. Our observations further indicate that the climate at the fall site can have a substantial impact on the preservation of primary mineral phases and the formation of secondary weathering products. We additionally report a Cu-based iodide in an early sample preparation that was not preserved in subsequently prepared mounts, as well as a rare Al–Cu–Zn alloy in Ribbeck. Further microchemical and isotopic analyses are required to determine the provenance of these phases.