TERRAPUB Geochemical Journal

Geochemical Journal, Vol. 55, 2021

Assessing the debris generated by the small carry-on impactor operated from the Hayabusa2 mission

Motoo Ito1*, Yoshinori Takano2, Yoko Kebukawa3, Takuji Ohigashi4, Moe Matsuoka5, Kento Kiryu3, Masayuki Uesugi6, Tomoki Nakamura7, Hayato Yuzawa4, Keita Yamada8, Hiroshi Naraoka9, Toru Yada5, Masanao Abe5, Masahiko Hayakawa5, Takanao Saiki5, Shogo Tachibana5,10, and Hayabusa2 Project Team

1Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), B200 Monobe, Nankoku, Kochi 783-8502, Japan
2Biogeochemistry Research Center (BGC), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima, Yokosuka 237-0061, Japan
3Graduate School of Engineering Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
4UVSOR Synchrotron Facility, Institute for Molecular Science, 38 Nishigo-naka, Myodaiji, Okazaki, Aichi 444-8585, Japan
5Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara, Kanagawa 252-5210, Japan
6Japan Synchrotron Radiation Research Institute (JASRI/SPring-8), 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan
7Department of Earth Science, Graduate School of Science, Tohoku University, Aoba, Sendai, Miyagi 980-8578, Japan
8Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology (TIT), Yokohama 226-8502, Japan
9Department of Earth and Planetary Sciences, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
10UTokyo Organization for Planetary and Space Science (UTOPS), University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033, Japan.

(Received February 19, 2021; Accepted May 8, 2021)

Abstract: We have analyzed the carbonaceous materials generated by the explosion of an High-melting explosive mixture in an Ar atmosphere in a laboratory simulation of the small carry-on impactor experiment. We used both non-destructive and destructive analytical techniques to identify the chemical nature of the materials. From SEM-EDS, we found the materials to be composed mainly of carbon, nitrogen, and oxygen, with a detectable amount of metals. Suitable parameters for identifying these materials are a FTIR peak at 1520 cm-1, low reflectance and gentle red slope of FTIR spectrum compared with the Murchison CM2 chondrite, the Raman D and G bands, and the hydrogen, carbon, and nitrogen isotopic compositions and their spatial distributions. The scanning transmission X-ray microscopy (STXM)-XANES results provided information about the molecular nature of these highly aromatic materials, which was supported by results from TD-GC/MS. These results suggest that it is possible to distinguish Ryugu samples from SCI potential contaminants in a sample container by using proper combinations of analytical techniques. This assessment provides information that will be useful for the analysis of the Ryugu asteroidal samples.
Key words: C-type asteroid Ryugu, Hayabusa2 mission, Off-nominal assessment, Small carry-on Impactor, Carbonaceous materials

*Corresponding author E-mail: motoo@jamstec.go.jp