[M-IS03] Astrobiology

[MIS03-P07] Collisional evolution of carbon-rich asteroids and inter-asteroid materials mixing

*Seiji Sugita¹ (1.Department of Earth and Planetary Science, Graduate School of Science Sciece, The University of Tokyo)

Relation between the parent body(s) of Near-Earth asteroids Ryugu and Bennu are a subject of great controversy and has important implications for interpretations of geochemical analyses of returned samples. Initial global observations have shown that Ryugu and Bennu possess similar albedo, visible spectra, and geologic properties but have near infrared spectra with contrasting difference. More recently, exogenic boulders with different spectral properties were found on the two asteroids, indicating that the two asteroids experienced different collisional histories. However, this does not rule out the common original parent body because the exogenic boulders could be implanted in collision events after the catastrophic disruption (CD) of the parent body forming its family. Nevertheless, further studies have estimated volumetric mixing ratios of these exogenic boulders, making it possible to assess what conditions of collisional history from the parent body(s) to the current km to sub-km bodies can quantitatively reproduce observed abundances of exogenic boulders. In this study, we conduct such assessment in aid of 3-D impact simulations and Monte Carlo model calculations in order to place further constraints on the parent-body commonality of Ryugu and Bennu.