An artificial impact on the asteroid (162173) Ryugu formed a crater in the gravity-dominated regime
Masahiko Arakawa, Takanao Saiki, Koji Wada, Kazunori Ogawa, Toshihiko Kadono, K. Shirai, Hirotaka Sawada, Ko Ishibashi, Rie Honda, Naoya Sakatani, Y. Iijima, Chisato Okamoto, Hajime Yano, Y. Takagi, Masahiko Hayakawa, Patrick Michel, Martin Jutzi, Yuri Shimaki, Shinichi Kimura, Yuya Mimasu, Tomoaki Toda, Hiroshi IMAMURA, Satoru Nakazawa, H. Hayakawa, Seiji Sugita, Tomokatsu Morota, Shingo Kameda, Eri Tatsumi, Yuichiro Cho, Kazuo Yoshioka, Y. Yokota, M. Matsuoka, Manabu Yamada, Toru Kouyama, Chikatoshi Honda, Yuichi Tsuda, Sei‐ichiro Watanabe, Makoto Yoshikawa, Satoshi Tanaka, Fuyuto Terui, Shota Kikuchi, Tomohiro Yamaguchi, Naoko Ogawa, Go Ono, Kent Yoshikawa, T. Takahashi, Yuto Takei, Atsushi Fujii, Hiroshi Takeuchi, Yukio Yamamoto, Tatsuaki Okada, Chikako Hirose, S Hosoda, Osamu Mori, Takanobu Shimada, Stefania Soldini, Ryudo Tsukizaki, Takahiro Iwata, Masanobu Ozaki, Masanao Abe, Noriyuki Namiki, K. Kitazato, Shogo Tachibana, Hitoshi Ikeda, Naru Hirata, N. Hirata, Rina Noguchi, Akira Miura
Abstract
The Hayabusa2 spacecraft investigated the small asteroid Ryugu, which has a rubble-pile structure. We describe an impact experiment on Ryugu using Hayabusa2's Small Carry-on Impactor. The impact produced an artificial crater with a diameter >10 meters, which has a semicircular shape, an elevated rim, and a central pit. Images of the impact and resulting ejecta were recorded by the Deployable CAMera 3 for >8 minutes, showing the growth of an ejecta curtain (the outer edge of the ejecta) and deposition of ejecta onto the surface. The ejecta curtain was asymmetric and heterogeneous and it never fully detached from the surface. The crater formed in the gravity-dominated regime; in other words, crater growth was limited by gravity not surface strength. We discuss implications for Ryugu's surface age.