Elastic Properties of Returned Samples From Asteroid (162173) RyuguOPEN ACCESS

14/10/2025 14:36 · by karmaka · in asteroid, carbonaceous chondrite, CI, Hayabusa-2 / 162173 Ryugu, surface, Tagish Lake, Tarda, ungrouped, witnessed fall

Keisuke Onodera, Yuta Ino, Satoshi Tanaka, Taichi Kawamura, Takuya Ishizaki, Rei Kanemaru, 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, Fuyuto Terui, Satoru Nakazawa, Sei-ichiro Watanabe, Yuichi Tsuda

JGR Planets, First Published: 9 October 2025

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“Key Points

We provide an initial summary of the elastic properties of asteroid (162173) Ryugu samples brought by Hayabusa2
The measured elastic parameters were compared with those of carbonaceous chondrite meteorites, such as Ivuna, Tagish Lake, and Tarda
We find that Ryugu’s elasticity is distinctly lower than that of Ivuna, which is chemically and mineralogically similar to Ryugu”

“The successful sample return from asteroid (162173) Ryugu by Hayabusa2 has contributed to our understanding of the solar system evolution. Over the course of the initial sample analysis, various measurements were conducted, such as mineralogical observation, chemical analysis, and mechanical property measurement. These pieces of information allow us to give constraints on the essential conditions of Ryugu’s formation and evolution processes (e.g., thermal environment, aqueous alteration, formation of a rubble-pile body), leading to a clearer view of the early solar system. Here, we report the initial results of the elastic properties of Ryugu particles (e.g., P- and S-wave velocities and Young’s modulus) obtained via ultrasonic pulse transmission measurement. Our measurement results showed 2.15 0.05 km/s and 1.25 0.05 km/s for the compressional and shear waves, respectively. Regarding Young’s modulus, we obtained 7.1 0.6 GPa, consistent with the previously measured value via a nanoindentation test. Compared with the elastic properties of other carbonaceous chondrites (Tagish Lake, Tarda, Ivuna, and Murchison meteorites), we found that Ryugu had distinctly lower rigidity than Ivuna—the most similar material to Ryugu with respect to chemical and mineralogical features. Instead, Tagish Lake showed the closest elastic properties to Ryugu samples. The affinities in chemical and mineralogical features indicate the genetic relationship between Ryugu and Ivuna. On the other hand, the difference in elastic properties might indicate their formation and evolution processes proceeded differently (e.g., formation depth, degree of alteration).”