Preliminary analysis of the Hayabusa2 samples returned from C-type asteroid Ryugu

Abstract C-type asteroids 1 are considered to be primitive small Solar System bodies enriched in water and organics, providing clues the origin evolution of building blocks life. asteroid 162173 Ryugu has been characterized by remote sensing 2–7 on-asteroid measurements 8,9 with Hayabusa2 (ref. 10 ). However, ground truth provided laboratory analysis returned samples is invaluable determine fine properties other planetary bodies. We report preliminary results analyses on from particle size distribution, density porosity, spectral textural properties, a search for Ca–Al-rich inclusions (CAIs) chondrules. The bulk sample mainly consists rugged smooth particles millimetre submillimetre size, confirming that physical chemical were not altered during return asteroid. power index its distribution shallower than surface boulder observed 11 , indicating differences samples. average estimated densities 1,282 ± 231 kg m −3 which lower meteorites 12 suggesting high microporosity down scale, extending centimetre-scale estimates thermal 5,9 . extremely dark optical near-infrared reflectance profile weak absorptions at 2.7 3.4 μm imply carbonaceous composition indigenous aqueous alteration, matching global 3,4 representative Together absence CAIs chondrules, these features indicate most similar CI chondrites but albedo, higher porosity more fragile characteristics.