The Hayabusa2 mission: what will we expect from samples from C-type near-Earth asteroid (162173) Ryugu?

Primitive small bodies should record the origin and early evolution of the Solar System as well as their own evolution. The JAXA’s spacecraft Hayabusa2 investigated the C-type near-Earth asteroid (162 173) Ryugu and succeeded two landing operations for sample acquisition. Ryugu is a top-shape rubble pile body with a bulk density of 1.19 ± 0.03 g cm–3. The surface has uniformity in visible spectra with very low geometric albedo (∼0.043), darker than most of meteorite samples. A weak 2.72 μm absorption feature, observed globally, indicates the ubiquitous presence of hydrated silicates. The analysis of returned samples will reveal if this weak feature is due to thermal dehydration or to weak aqueous alteration. Ryugu samples will be investigated on ground in order to understand what C-type asteroids are and what the samples record the origin and evolution of the Solar System and the formation and evolution of Ryugu.