[P-PS03] Regolith Science

[PPS03-P04] Ryugu's surface change formed by SCI forward debris

*嶌生 有理¹、横田 康弘¹、本田 理恵²、荒川 政彦³、和田 浩二⁴、門野 敏彦⁵、白井 慶³、小川 和律⁶、坂谷 尚哉⁷、石橋 高⁴、佐伯 孝尚¹、今村 裕志¹、中澤 暁¹、早川 雅彦¹、矢野 創¹、高木 靖彦⁸、平田 成⁹、澤田 弘崇¹、杉田 精司¹⁰、諸田 智克¹⁰、亀田 真吾⁷、巽 瑛理¹¹、山田 学⁴、神山 徹¹²、長 勇一郎¹⁰、松岡 萌¹、吉岡 和夫¹⁰、鈴木 秀彦¹³、本田 親寿⁹ (1.宇宙航空研究開発機構宇宙科学研究所、2.高知大学、3.神戸大学、4.千葉工業大学惑星探査研究センター、5.産業医科大学、6.宇宙航空研究開発機構国際宇宙探査センター、7.立教大学、8.愛知東邦大学、9.会津大学、10.東京大学、11.カナリア天体物理学研究所、12.産業技術総合研究所、13.明治大学)

キーワード：はやぶさ２、クレーター形成、小惑星リュウグウ

The small carry-on impactor (SCI) on the Hayabusa2 spacecraft is designed to create an artificial crater on an asteroid surface for the collection of sub-surface materials and validation of crater scaling laws [1]. The SCI launches a hollow hemisphere copper liner with a diameter of 13 cm at a velocity of 2 km/s, accompanied by numerous debris [2]. In the ground tests, the SCI forward debris generated concentric damage on the target surface. The SCI successfully created an artificial crater on the surface of Ryugu in 2019 [3]. Besides the artificial crater, surface changes around the crater, such as rim formation, boulder movement, and the emergence of new boulders were observed by the optical navigation camera telescope (ONC-T) [4]. Additionally, concentric surface changes were observed ~70 m distance from the artificial crater, created by the SCI forward debris. Here we report the distribution of the surface changes formed by the SCI forward debris both in the ground test and Ryugu. Based on the SCI detonation position [5], we found that the polar angle of the forward debris in the ground tests is ~11°, whereas that in Ryugu is ~15°, probably due to the absence of ambient pressure.

[1] Arakawa et al. (2017), Space Science Review 208, 187–212. [2] Saiki et al. (2017), Space Science Review 208, 165–186. [3] Arakawa et al. (2020), Science 368, 67-71. [4] Honda et al., submitted to Icarus. [5] Saiki et al. (2020), Astrodynamics 4, 289–308.