Caption: asteroid 162173 Ryugu seen in rotation (rotation period 7.627(7) h) assembled from images by the Hayabusa2 (2014--2020) spacecraft taken 2018 Jul10. The images were taken by the Hayabusa2's Optical Navigation Camera - Telescopic (ONC-T) at a distance of probably 20 kilometers (12 miles). Ryugu is the 23rd minor planet studied by a spacecraft in situ and is the target of the second sample-return mission to an asteroid (i.e., Hayabusa2's sample-return mission).

Features:

1. Ryugu was discovered in 1999. Its mean orbital radius is 1.1896 AU with eccentricity 0.1902 (i.e., 19.02 %). Its orbital period is 1.30 yr (474 d). See Wikipedia: 162173 Ryugu: Side table.

2. Ryugu's mean diameter is 0.865(15) km and its equatorial surface gravity is (1/80,000) g ≅ 1.25*10**(-4) m/s**2. See Wikipedia: 162173 Ryugu: Side table.

3. As one can see, Ryugu has a typical airless world look: heavily impact cratered with a smooth look caused by space weathering which coats the surface with regolith. See space_weathering.html for more on space weathering and regolith. However, despite superficial appearances, the surface has no or little dust (see Wikipedia: 162173 Ryugu: Surface).

4. Ryugu is actually a rubble pile: "about 50% of its volume being empty space" (see Wikipedia: 162173 Ryugu: Physical).

   Rubble pile astro-bodies are probably only marginally gravitationally-bound by self-gravity.