Global properties | |||
Measured | Eccentricity | 0.190208 | |
Semi-major axis | 1.189555 | AU | |
Inclination | 5.883556 | ° | |
Period | 473.8878 | Days | |
Perihelion | 0.963292 | AU | |
Aphelion | 1.415819 | AU | |
Rotation period | 7.6326 | h | |
Pole direction in ecliptic coordinates (lambda, beta) | (310–340, − 40 ± 15) | ° | |
Shape | Almost spherical | ||
Volume-equivalent diameter | 850–880 | m | |
Phase function (Lommel-Seeliger model) | see Table 2 | ||
Geometric and bond albedos | see Table 3 | ||
Spectral type | C-type, see also Table 4 | ||
Derived | Composition (meteorite spectral counterpart) | heated CM, CM2, or CI | |
Predicted | Satellite | no | |
Dust around Ryugu | no or little | ||
Boulders: power law exponent of cumulative SFD | − 3 | ||
Crater density | more than Itokawa, less than Toutatis | ||
Surface roughness at meter scales | like Eros and Itokawa | ||
Origin | Originated in the inner main asteroid belt, between ~ 2.1 and 2.5 AU, and reached the ν_{6} by inward Yarkovsky drift | ||
Regolith thermophysical properties | |||
Measured | Thermal inertia | 150–300, typically 200 | J m^{−2} s^{−1/2} K^{−1} |
Maximum surface temperature | 320–375 | K | |
Roughness (the rms of surface slopes) | < 0.1 | ||
Derived | Regolith thermal conductivity | 0.020–0.108, most likely 0.042 | W m^{−1} K^{−1} |
Typical particle size in diameter | 3–30 most likely 6–10 (2.2–5 by Gundlach and Blum 2013 model) | mm | |
Predicted | Regolith heat capacity at 300 K | 758 | J kg^{−1} K^{−1} |
Regolith emissivity | 0.9 | ||
Regolith thermal albedo | 0.019 | ||
Regolith bulk density | 1100–1500 | kg m^{−3} | |
Regolith mechanical properties | |||
Predicted | Regolith porosity | ~ 0.4–0.5 | |
Regolith cohesion | 100 | Pa | |
Regolith angle of friction | 33 | ° | |
Regolith tensile strength | < 1000 | Pa | |
Inter-grain friction angle | 40–50 | ° | |
Regolith bearing strength | < a few 1000 | Pa | |
Compressive strength of rock | 15–30 | MPa | |
Tensile strength of rock | < 1 | MPa | |
Presence of ponds | Possible, there are compositions being expected to be significantly different from that of the bulk asteroid |