| Abstract |
I will review the scientific results of the Hayabusa2 mission, a sample return mission from the C-type asteroid Ryugu. Analysis of the samples revealed that Ryugu has a CI chondrite composition. It has become clear that Ryugu/CI chondrites are distinct from non-carbonaceous (NC) and carbonaceous meteorites (CC), highlighting the isotopic trichotomy of Solar System materials. Using Mn-Cr extinct radionuclide dating and thermal history calculations, it is estimated that Ryugu's parent body was an icy planetesimal formed in the outer Solar System about 2 million years after the formation of CAIs (Calcium-Aluminum-rich Inclusions). It underwent intense metamorphism due to melted water 4 to 7 million years after the CAI formation, resulting in secondary minerals such as phyllosilicates, carbonates, and magnetite. The strong disk magnetic field recorded in the magnetite particles suggests that Ryugu's parent body may have migrated to the inner Solar System by the time of aqueous alteration. I will organize the information extracted from Ryugu samples and discuss how these findings constrain theories on the Solar System formation. |
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