Carbonaceous chondrites are visible in the photographs transmitted to Earth by the Japanese Hayabusa-2 probe. This is a fairly common type of meteorite, but it is the first time they have been observed in the “natural environment”.
Chondrites are a type of meteorite that contains chondrules: spherical or elliptical inclusions about a millimeter in size or slightly larger. Most often they are composed of silicates, although different options are possible.
The chemical composition of chondrites as a whole repeats the composition of the “heavy” fraction of the Sun (that is, without hydrogen and helium), therefore it is believed that they (or those bodies from which they were subsequently knocked out) were formed simultaneously with our star.
Carbonaceous chondrites are characterized by a high content of iron (in various silicates) and carbon. Variants are possible with the latter; it can also be found in its pure form, like graphite. A characteristic feature of carbonaceous chondrites is a dark color. Apparently, she made it possible to identify them in the photos with Ryugu.
The discovery is not surprising when you remember that Ryugu himself belongs to spectral class C – it is a carbonaceous asteroid.
The photographs of its surface and the stones lying on it were taken by the MASCOT robot, which “landed” on the surface of Ryugu on October 3, 2018, and worked there for 17 hours.