[P-PS03] Small Solar System Bodies: New perspectives on the origin and evolution of the Solar System

[PPS03-07] Elastic property of Ryugu samples: Preliminary summary

★Invited Papers

*Keisuke Onodera¹, Yuta Ino², Satoshi Tanaka³, Taichi Kawamura⁴, Rei Kanemaru³, Takuya Ishizaki³, Ryota Fukai³, Takeshi Tsuji⁵, Tomoki Nakamura⁶, Masayuki Uesugi⁷, Hisayoshi Yurimoto⁸, Takaaki Noguchi⁹, Ryuji Okazaki¹⁰, Hikaru Yabuta¹¹, Hiroshi Naraoka¹⁰, Sakamoto Kanako³, Shogo Tachibana⁵, Sei-ichiro Watanabe¹², Yuichi Tsuda^3,5, Hayabusa2 Initial Sample-Analysis Team (1.Earthquake Research Institute / The University of Tokyo, 2.Kwansei Gakuin University, 3.Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 4.Institut de Physique du Globe de Paris, Université Paris Cité, 5.The University of Tokyo, 6.Tohoku University, 7.Japan Synchrotron Radiation Research Institute, 8.Hokkaido University, 9.Kyoto University, 10.Kyushu University, 11.Hiroshima University, 12.Nagoya University)

Keywords:Hayabusa2, Ryugu, Elastic wave velocity, Asteroid seismology

Elastic property is one of the most fundamental parameters to characterize planetary bodies. In the case of asteroids, elastic parameters such as rigidity and seismic wave velocity play an important role in explaining surface morphology, impact phenomena, and physical weathering (e.g., Arakawa et al., 2020; Cho et al., 2021; Honda et al., 2021; Takaki et al., 2022). Also, these parameters are crucial constraints for numerical studies of asteroid formation (e.g., Nakamura et al., 2022). Therefore, the measurement of elastic property is pivotal to deepen our understanding of both current phenomena as well as past evolution processes of asteroids.

In the framework of Hayabusa2 initial sample analysis, we measured the seismic wave velocity of the Ryugu particles labeled as C0002-No3 and C0002-No4, which were retrieved from the second touch-down site (i.e., near the artificially formed crater; Arakawa et al., 2020; Morota et al., 2020). Moreover, by combining the previously measured density value (Nakamura et al., 2022), we estimated Young’s modulus as well. While Nakamura et al. (2022) showed the averaged elastic parameters, we take a closer look at each sample and try to understand the variations among particles. Furthermore, in comparison with other carbonaceous chondrites, we investigate which type of meteorite shows similar elastic features to those of Ryugu samples.

In the presentation, we will show the seismic wave velocity and Young’s modulus of the returned Ryugu samples, and discuss how these parameters are different from other carbonaceous chondrites.


References
- Arakawa et al. (2020), Science, 368, 67.
- Cho et al. (2021), JGR: Planets, 126, e2020JE006572.
- Honda et al. (2021), Icarus, 366, 114530.
- Morota et al. (2020), Science, 368, 654.
- Nakamura et al. (2022), Science, 10.1126/science.abn8671.
- Takaki et al. (2022), Icarus, 377, 114911.