The spatial distribution of impact craters on Ryugu
Abstract
Asteroid 162173 Ryugu has numerous craters. The initial measurement of impact craters on Ryugu, by Sugita et al. (2019), is based on Hayabusa2 ONC images obtained during the first month after the arrival of Hayabusa2 in June 2018. Utilizing new images taken until February 2019, we constructed a global impact crater catalogue of Ryugu, which includes all craters larger than 20 m in diameter on the surface of Ryugu. As a result, we identified 77 craters on the surface of Ryugu. Ryugu shows variation in crater density which cannot be explained by the randomness of cratering; there are more craters at lower latitudes and fewer at higher latitudes, and fewer craters in the western bulge (160 E - 290 E) than in the region around the meridian (300 E - 30 E). This variation implies a complicated geologic history for Ryugu. It seems that the longitudinal variation in crater density simply indicates variation in the crater ages; the cratered terrain around the meridian seems to be geologically old while the western bulge is relatively young. The latitudinal variation in crater density suggests that the equatorial ridge of Ryugu is a geologically old structure; however, this could be alternatively explained by a collision with many fission fragments during a short rotational period of Ryugu in the past.
Keywords
Cite
@article{arxiv.2205.05818,
title = {The spatial distribution of impact craters on Ryugu},
author = {Naoyuki Hirata and Tomokatsu Morota and Yuichiro Cho and Masanori Kanamaru and Sei-ichiro Watanabe and Seiji Sugita and Naru Hirata and Yukio Yamamoto and Rina Noguchi and Yuri Shimaki and Eri Tatsumi and Kazuo Yoshioka and Hirotaka Sawada and Yasuhiro Yokota and Naoya Sakatani and Masahiko Hayakawa and Moe Matsuoka and Rie Honda and Shingo Kameda and Mamabu Yamada and Toru Kouyama and Hidehiko Suzuki and Chikatoshi Honda and Kazunori Ogawa and Yuichi Tsuda and Makoto Yoshikawa and Takanao Saiki and Satoshi Tanaka and Fuyuto Terui and Satoru Nakazawa and Shota Kikuchi and Tomohiro Yamaguchi and Naoko Ogawa and Go Ono and Yuya Mimasu and Kent Yoshikawa and Tadateru Takahashi and Yuto Takei and Atsushi Fujii and Hiroshi Takeuchi and Tatsuaki Okada and Kei Shirai and Yu-ichi Iijima},
journal= {arXiv preprint arXiv:2205.05818},
year = {2022}
}
Comments
18 pages 3 figures