[P-PS04] Regolith Science

[PPS04-03] The size of ejecta particles of the artificial impact crater formed by Hayabusa2 Small Carry-on Impactor

*和田 浩二¹、石橋 高¹、木村 宏¹、荒川 政彦²、澤田 弘崇³、小川 和律^3,2、白井 慶²、本田 理恵⁴、飯島 祐一³、門野 敏彦⁵、坂谷 尚哉³、三桝 裕也³、戸田 知朗³、嶌生 有理³、中澤 暁³、早川 基³、佐伯 孝尚³、高木 靖彦⁶、今村 裕志³、岡本 千里²、早川 雅彦³、平田 成⁷、矢野 創³ (1.千葉工業大学惑星探査研究センター、2.神戸大学、3.宇宙航空研究開発機構、4.高知大学、5.産業医科大学、6.愛知東邦大学、7.会津大学)

キーワード：はやぶさ２、小型搭載型衝突装置、分離カメラ3、リュウグウ、衝突クレーター、イジェクタ

A projectile accelerated by Hayabusa2 Small Carry-on Impactor succeeded in producing an artificial impact crater with a diameter of >10 m on the surface of the asteroid Ryugu on April 5, 2019. At the time of cratering, Deployable Camera 3 (DCAM3) took clear images of ejecta curtain emerged from the crater. Comparing the ejecta curtain images to a theoretical model of ejecta curtain, we infer the size of the particles composing the ejecta curtain. Since almost of the ejecta particles come from the underground, we can discuss about the particle size distribution of the subsurface layer of Ryugu and the evolution process of Ryugu’s surface layer. As a result, the typical size range of the ejecta particles is estimated to be ~cm to several 10 cm, although it depends on the assumed size distribution. This typical size is relatviely small compared to the boulder size on the uppermost surface, suggesting some kind of surface process occured in the past.