[U-04] Capture the fast process in Earth and planetary science

[U04-07] Chemical reaction processes bridge between asteroid Ryugu and early evolution of Earth

★Invited Papers

*Seiji Sugita^1,3, Hideharu Kuwahara², Kosuke Kurosawa³ (1.Department of Earth and Planetary Science, Graduate School of Science Sciece, The University of Tokyo, 2.Ehime University, 3.Chiba Institute of Technology)

Keywords:Asteroid missions, Hypervelocity impacts, Impact vapor clouds, Atmospheric entry physics

JAXA's Hayabusa2 has arrived at asteroid Ryugu and is uncovering many new aspects of the primitive asteroid, such as extremly low albedo (4.5+/- 0.1%), flat spectra (Cb type), young resurfacing age (<10^6 yr for the top 1 m layer), high boulder number dentity (x2 of Itokawa) and low abundance of hydrated minerals. These pieces of information is very importance for understanding the early evolution of inner solar system and Earth's surface environment. In particular, what happens upon hypervelocity impacts of such bodies is important for understading the atmospheric chemistry of early Earth. In this study, we review atmospheric entry processes, high-temperature chemistry processes, and discuss the implications of recent results on asteroid missions, such as Hayabusa2 and OSIRIS-REx, for Earth's early evolution.