Dark Primitive Asteroids: Results From Hayabusa2 and OSIRIS-REx Missions

Dark primitive asteroids are believed to have preserved materials that witnessed the condensation of the early phases of the formation of the solar system. These objects may also contain pre-solar grains that retain information on the interstellar medium (ISM) and even their genesis in evolved stars. They offer clues to the chemical mixture from which the planets formed some 4.6 billion years ago. Hayabusa2 and OSIRIS-REx, respectively JAXA and NASA mission, have the objective of return samples from the primitive asteroids C-type (162173) Ryugu and B-type (101955) Bennu. Analysis of data obtained so far shows two objects with different compositional and geomorphological properties. Some similarity with CM and CI carbonaceous chondrite meteorites were observed but also higher content of water-bearing minerals and other peculiarities. The samples returned to Earth from the two asteroids will allow us to better understand the origin of the solar system and will represent invaluable ground-truth for laboratory experiments and ground observations. Here we present the status of the two missions as well the obtained results from remote sensing observation and Hayabusa2 returned samples.