2020 Volume 63 Issue 4 Pages 189-194
Hayabusa2 explored a near-Earth C-type asteroid (162173) Ryugu for 17 months (June 2018–November 2019) including two landing operations for sample collection. Ryugu has a top shape with an equatorial ridge, and its bulk density of 1.19±0.03 g cm－3 suggests that Ryugu is a rubble-pile body with a large macro-porosity of ∼50–60%. The surface has a very low geometric albedo (∼0.02), darker than most of meteorite samples, and shows a weak but ubiquitous 2.72-µm absorption feature of hydrous minerals. The surface samples will be delivered to the Earth at the end of 2020. Detailed analysis of Ryugu samples will reveal the history of Ryugu and the Solar System from the beginning to the present.