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Elastic Property of Returned Samples From Asteroid (162173) Ryugu
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  • Keisuke Onodera,
  • Yuta Ino,
  • Satoshi Tanaka,
  • Taichi Kawamura,
  • Rei Kanemaru,
  • Takuya Ishizaki,
  • Ryota Fukai,
  • Takeshi Tsuji,
  • Tomoki Nakamura,
  • Daisuke Nakashima,
  • Masayuki Uesugi,
  • Shogo Tachibana,
  • Seiji Sugita,
  • Hisayoshi Yurimoto,
  • Takaaki Noguchi,
  • Ryuji Okazaki,
  • Hikaru Yabuta,
  • Hiroshi Naraoka,
  • Kanako Sakamoto,
  • Toru Yada,
  • Masahiro Nishimura,
  • Aiko Nakato,
  • Akiko Miyazaki,
  • Kasumi Yogata,
  • Masanao Abe,
  • Tatsuaki Okada,
  • Tomohiro Usui,
  • Makoto Yoshikawa,
  • Takanao Saiki,
  • Satoru Nakazawa,
  • Fuyuto Terui,
  • Sei-ichiro Watanabe,
  • Yuichi Tsuda
Keisuke Onodera
The University of Tokyo

Corresponding Author:[email protected]

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Yuta Ino
Kwansei Gakuin University
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Satoshi Tanaka
JAXA ISAS
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Taichi Kawamura
Université Paris Cité, Institut de physique du globe de Paris, CNRS
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Rei Kanemaru
Japan Aerospace Exploration Agency
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Takuya Ishizaki
Japan Aerospace Exploration Agency
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Ryota Fukai
Japan Aerospace Exploration Agency
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Takeshi Tsuji
University of Tokyo
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Tomoki Nakamura
Tohoku University
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Daisuke Nakashima
Tohoku University
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Masayuki Uesugi
Japan Synchrotron Radiation Research Institute (JASRI), SPring-8
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Shogo Tachibana
University of Tokyo
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Seiji Sugita
University of Tokyo
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Hisayoshi Yurimoto
Earth and Planetary Sciences
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Takaaki Noguchi
Kyoto University
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Ryuji Okazaki
Kyushu University
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Hikaru Yabuta
Hiroshima Universtity
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Hiroshi Naraoka
Kyushu University
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Kanako Sakamoto
Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA)
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Toru Yada
Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA)
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Masahiro Nishimura
Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA)
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Aiko Nakato
Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA)
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Akiko Miyazaki
Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA)
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Kasumi Yogata
Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA)
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Masanao Abe
Japan Aerospace Exploration Agency
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Tatsuaki Okada
JAXA
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Tomohiro Usui
Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency
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Makoto Yoshikawa
Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA)
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Takanao Saiki
Japan Aerospace Exploration Agency
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Satoru Nakazawa
Japan Aerospace Exploration Agency
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Fuyuto Terui
Kanagawa Institute of Technology
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Sei-ichiro Watanabe
Nagoya University
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Yuichi Tsuda
Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency
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Abstract

The elastic property of asteroids is one of the paramount parameters for understanding their physical nature. For example, the rigidity enables us to discuss the asteroid’s shape and surface features such as craters and boulders, leading to a better understanding of geomorphological and geological features on small celestial bodies. The sound velocity allows us to construct an equation of state that is the most fundamental step to simulate the formation of small bodies numerically. Moreover, seismic wave velocities and attenuation factors are useful to account for resurfacing caused by impact-induced seismic shaking. The elastic property of asteroids thus plays an important role in elucidating the asteroid’s evolution and current geological processes. The Hayabusa2 spacecraft brought back the rock samples from C-type asteroid (162173) Ryugu in December 2020. As a part of the initial analysis of returned samples, we measured the seismic wave velocity of the Ryugu samples using the pulse transmission method. We found that P- and S-wave velocities of the Ryugu samples were about 2.1 km/s and 1.2 km/s, respectively. We also estimated Young’s modulus of 6.0 – 8.0 GPa. A comparison of the derived parameters with those of carbonaceous chondrites showed that the Ryugu samples have a similar elastic property to the Tagish Lake meteorite, which may have come from a D-type asteroid. Both Ryugu and Tagish Lake show a high degree of aqueous alteration and few high-temperature components such as chondrules, indicating that they formed in the outer region of the solar system.
24 May 2023Submitted to ESS Open Archive
25 May 2023Published in ESS Open Archive