Motion reconstruction of the small carry-on impactor aboard Hayabusa2
small body exploration, Hayabusa2, kinetic impact, artificial crater, motion reconstruction
Subsurface exploration is one of the most ambitious scientific objectives of the Hayabusa2 mission. A small device called small carry-on impactor (SCI) was developed to create an artificial crater on the surface of asteroid Ryugu. This enables us to sample subsurface materials, which will provide a window to the past. The physical properties of the resulting crater are also useful for understanding the internal structure of Ryugu. Accurate understanding of the crater and ejecta properties, including the depth of excavation of subsurface materials, requires accurate information on impact conditions. In particular, the impact angle is a critical factor because it greatly influences the size and shape of the crater. On April 5, 2019, the Hayabusa2 spacecraft deployed the SCI at 500 m of altitude above the asteroid surface. The SCI gradually reduced its altitude, and it shot a 2 kg copper projectile into the asteroid 40 min after separation. Estimating the position of the released SCI is essential for determining the impact angle. This study describes the motion reconstruction of the SCI based on the actual operation data. The results indicate that the SCI was released with high accuracy.
Tsinghua University Press
Takanao Saiki, Yuya Mimasu, Yuto Takei, Manabu Yamada, Hirotaka Sawada, Kazunori Ogawa, Naoko Ogawa, Hiroshi Takeuchi, Akira Miura, Yuri Shimaki, Koji Wada, Rie Honda, Yasuhiro Yokota, Kei Shirai, Naruhisa Sano, Hirohito Ohtsuka, Go Ono, Kent Yoshikawa, Shota Kikuchi, Chikako Hirose, Yukio Yamamoto, Takahiro Iwata, Masahiko Arakawa, Seiji Sugita, Satoshi Tanaka, Fuyuto Terui, Makoto Yoshikawa, Satoru Nakazawa, Sei-ichiro Watanabe, Yuichi Tsuda. Motion reconstruction of the small carry-on impactor aboard Hayabusa2. Astrodynamics 2020, 4(4): 289-308.