Table 1 Summary of the findings of the Hayabusa2 orbiter, MASCOT, and the returned samples

Particle size frequency distribution

Power index -2.65 for boulder > 5 m (Michikami et al. 2019)^b

No particles observed^b

Power index -3.88 for particles > 1 mm (Yada et al. 2022)^b

Inclusions

Inclusions below detection limit

Bright inclusions of (0.63 ± 0.91) mm in size (Schröder et al. 2021)^b

No inclusions (chondrules/CAI) observed but sub-millimetre sized grains of specific colour found (Pilorget et al. 2022)^b

Surface structure/

pebbles/boulders

Four types of boulders (dark and rugged, bright and smooth, bright and mottled, and Otohime Saxum) (Sugita et al. 2019), elongated impact fragments (Michikami et al. 2019) for metre sized boulders^a

Two types of boulders (smooth, rough), locally rough surface texture (fractal dimension 1.18 (Otto et al. 2020))^a

Rugged and smooth as well as angular and round particles (Yada et al. 2022) elongated and sub-equant blocks with concave portions (Tsuchiyama et al. 2022; Tachibana et al. 2022b) in predominantly millimetre scale, flat saponite-rich surface layers (Nakamura et al. 2022)^a

Colour in visible wavelength range

Consistent with C-complex asteroids (Sugita et al. 2019; Tatsumi et al. 2020)^a

Neutral spectrum with individual inclusions with red or blue spectral slopes (Schröder et al. 2021)^a

Overall slightly reddish slope, but with individual particles also being blue, consistent with C/Cb-type asteroids (Yumoto et al. 2022)^a

Reflectance/albedo

Geometric albedo of 0.045 ± 0.002 (Sugita et al. 2019)/0.040 ± 0.005 at 0.55 µm (Tatsumi et al. 2020), Bond albedo of 0.014 ± 0.01 (Tatsumi et al. 2020)^a

I/F of 0.034 ± 0.003 at 0.53 µm and phase angle 4.5° ± 0.1°, consistent with geometric albedo of 0.045 (Schröder et al. 2021)^a

I/F at 0.55 µm and 30° phase angle is 30–70% higher than remote sensing observations, but darker than CI meteorites (Yumoto et al. 2022; Yada et al. 2022)^b

Meteorite analogue

Thermally metamorphosed CI and/or shocked CM

carbonaceous chondrites (Kitazato et al. 2019; Sugita et al. 2019)^a

CI or CM carbonaceous chondrites based on inclusions characterization (Jaumann et al. 2019; Schröder et al. 2021; Otto et al. 2021), similar to CI based on thermal modelling (Hamm et al. 2022)^a

CI chondrites but with lower albedo, higher porosity and more fragile characteristics as well as a lag of sulfates, ferrihydrites and interlayer water (Tanaka et al. 2022; Yada et al. 2022; Yokoyama et al. 2022; Ito et al. 2022)^a

Thermal inertia

(225 ± 45)J m⁻² K⁻¹ s^−1/2 (Okada et al. 2020; Shimaki et al. 2020)^a

(256 ±  34) J m⁻² K⁻¹ s^−1/2 at 230 K (Hamm et al. 2022)^a

892 J m⁻² K⁻¹ s^−1/2 at a temperature of 298 K (Tanaka et al. 2022)^b

Tensile strength

 ~ 229 kPa following the approach from Grott et al. (2019) (L ≈ 10 cm) ; Okada et al. (2020); Shimaki et al. (2020)^a

200–280 kPa at a scale of  ~ 10 cm assuming a Young’s modulus representative of carbonaceous chondrites (Grott et al. 2019)^a

4900 kPa (Tanaka et al. 2022) at a scale of 3 × 3 mm^2b

Density¹

Asteroid bulk density including microporosity of (1190 ± 20)kg/m³ (Watanabe et al. 2019)^a

Grain density of (2848 ± 152) kg/m³, bulk density of (1424 ± 135) kg/m³ (Grott et al. 2020) and (1380 ± 70) kg/m³ (Herbst et al. 2021) based on semi-empirical mixing models^a

Sample bulk density of (1282 ± 231 )kg/m³ (Yada et al. 2022) and (1790 ± 80) kg/m³ considering the full 3D structure (Nakamura et al. 2022)^a

Porosity

Globally 0.3–0.5 (Okada et al. 2020), boulders with > 0.7 found on the floor of fresh craters (Sakatani et al. 2021)^a

0.5 ± 0.02 (Grott et al. 2020) based on semi-empirical mixing models. 0.46 (Hamm et al. 2022) based on the model by Krause et al. (2011)^a

Higher than CI chondrites, 0.46 based on typical CI grain densities (Yada et al. 2022; Nakamura et al. 2022)^a

Homogeneous magnetization scale

n.a.^c

Less than centimetre scale

(Hercik et al. 2020)^a

Roughly several 100s of micrometres (Sato et al. 2022; Nakamura et al. 2022)^a

‍Specific magnetic moment

n.a.^c

10^–5 Am²/kg for decimetre sized particles (Hercik et al. 2020)^a

10^–2 Am²/kg for 0.1–1 mm sized particles

(Sato et al. 2022)^a