Three-axial shape distributions of pebbles, cobbles and boulders smaller than a few meters on asteroid Ryugu

• Published in: Icarus (New York, N.Y. 1962) N.Y. 1962), 2022-07, Vol.381, p.115007, Article 115007
• Main Authors: Michikami, Tatsuhiro, Hagermann, Axel, Morota, Tomokatsu, Yokota, Yasuhiro, Urakawa, Seitaro, Okamura, Hiroyuki, Tanabe, Naoya, Yumoto, Koki, Ebihara, Tatsuki, Cho, Yuichiro, Ernst, Carolyn M., Hayakawa, Masahiko, Hirabayashi, Masatoshi, Hirata, Naru, Honda, Chikatoshi, Honda, Rie, Kameda, Shingo, Kanamaru, Masanori, Kikuchi, Hiroshi, Kikuchi, Shota, Kouyama, Toru, Matsuoka, Moe, Miyamoto, Hideaki, Noguchi, Takaaki, Noguchi, Rina, Ogawa, Kazunori, Okada, Tatsuaki, Sakatani, Naoya, Sasaki, Sho, Sawada, Hirotaka, Sugimoto, Chiho, Suzuki, Hidehiko, Tanaka, Satoshi, Tatsumi, Eri, Tsuchiyama, Akira, Tsuda, Yuichi, Watanabe, Sei-ichiro, Yamada, Manabu, Yoshikawa, Makoto, Yoshioka, Kazuo, Sugita, Seiji
• Format: Article
• Language: English
• Subjects: Asteroid Ryugu; Asteroids; Atmosfärsvetenskap; Atmospheric science; Impact process; Regolith; Sciences of the Universe; Surfaces
• ISSN: 0019-1035; 1090-2643; 1090-2643
• DOI: 10.1016/j.icarus.2022.115007

Over a broad size range, the shapes of impact fragments from catastrophic disruptions are distributed around the mean axial ratio 2: √2: 1, irrespective of experimental conditions and target materials. Although most blocks on asteroids are likely to be impact fragments, there is not enough quantitative data for reliable statistics on their three-axial lengths and/or ratios because it is difficult to precisely estimate the heights of the blocks. In this study, we evaluate the heights of blocks on asteroid Ryugu by measuring their shadows. The three-axial ratios of ~4100 small blocks with diameters from 5.0 cm to 7.6 m in Ryugu's equatorial region are investigated using eight close-up images of narrower localities taken at altitudes below 500 m, i.e. at