研究者業績

津田 雄一

ツダ ユウイチ  (Yuichi Tsuda)

基本情報

所属
国立研究開発法人宇宙航空研究開発機構 宇宙科学研究所 宇宙飛翔工学研究系 教授
東京大学 大学院工学系研究科 航空宇宙工学専攻 教授
学位
博士(工学)(2003年3月 東京大学)

J-GLOBAL ID
200901005218518613
researchmap会員ID
5000069162

外部リンク

学歴

 3

主要な受賞

 29

論文

 427
  • Yuto TAKEI, Takanao SAIKI, Roger GUTIERREZ RAMON, Naoko OGAWA, Akira MIURA, Yuya MIMASU, Maiko YAMAKAWA, Yusuke MARU, Yuichi TSUDA
    Journal of Evolving Space Activities 1 2023年6月12日  査読有り
  • Shota Kikuchi, Yuya Mimasu, Yuto Takei, Takanao Saiki, Daniel J. Scheeres, Masatoshi Hirabayashi, Koji Wada, Makoto Yoshikawa, Sei-ichiro Watanabe, Satoshi Tanaka, Yuichi Tsuda
    Acta Astronautica 2023年6月  
  • 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
    2023年5月25日  
    <p id="p1">The elastic property of asteroids is one of the paramount parameters forunderstanding their physical nature. For example, the rigidity enablesus to discuss the asteroid’s shape and surface features such as cratersand boulders, leading to a better understanding of geomorphological andgeological features on small celestial bodies. The sound velocity allowsus to construct an equation of state that is the most fundamental stepto simulate the formation of small bodies numerically. Moreover, seismicwave velocities and attenuation factors are useful to account forresurfacing caused by impact-induced seismic shaking. The elasticproperty of asteroids thus plays an important role in elucidating theasteroid’s evolution and current geological processes. The Hayabusa2spacecraft brought back the rock samples from C-type asteroid (162173)Ryugu in December 2020. As a part of the initial analysis of returnedsamples, we measured the seismic wave velocity of the Ryugu samplesusing the pulse transmission method. We found that P- and S-wavevelocities 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. Acomparison of the derived parameters with those of carbonaceouschondrites showed that the Ryugu samples have a similar elastic propertyto the Tagish Lake meteorite, which may have come from a D-typeasteroid. Both Ryugu and Tagish Lake show a high degree of aqueousalteration and few high-temperature components such as chondrules,indicating that they formed in the outer region of the solar system.</p>
  • Naotaka Tomioka, Akira Yamaguchi, Motoo Ito, Masayuki Uesugi, Naoya Imae, Naoki Shirai, Takuji Ohigashi, Makoto Kimura, Ming-Chang Liu, Richard C. Greenwood, Kentaro Uesugi, Aiko Nakato, Kasumi Yogata, Hayato Yuzawa, Yu Kodama, Kaori Hirahara, Ikuya Sakurai, Ikuo Okada, Yuzuru Karouji, Keishi Okazaki, Kosuke Kurosawa, Takaaki Noguchi, Akira Miyake, Masaaki Miyahara, Yusuke Seto, Toru Matsumoto, Yohei Igami, Satoru Nakazawa, Tatsuaki Okada, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Makoto Yoshikawa, Akiko Miyazaki, Masahiro Nishimura, Toru Yada, Masanao Abe, Tomohiro Usui, Sei-ichiro Watanabe, Yuichi Tsuda
    Nature Astronomy 7(6) 669-677 2023年4月20日  
    Abstract Micrometeorites, a possible major source of Earth’s water, are thought to form from explosive dispersal of hydrated chondritic materials during impact events on their parental asteroids. However, this provenance and formation mechanism have yet to be directly confirmed using asteroid returned samples. Here, we report evidence of mild shock metamorphism in the surface particles of asteroid Ryugu based on electron microscopy. All particles are dominated by phyllosilicates but lack dehydration textures, which are indicative of shock-heating temperatures below ~500 °C. Microfault-like textures associated with extensively shock-deformed framboidal magnetites and a high-pressure polymorph of Fe–Cr–sulfide have been identified. These findings indicate that the average peak pressure was ~2 GPa. The vast majority of ejecta formed during impact on Ryugu-like asteroids would be hydrated materials, larger than a millimetre, originating far from the impact point. These characteristics are inconsistent with current micrometeorite production models, and consequently, a new formation mechanism is required.
  • Laurette Piani, Kazuhide Nagashima, Noriyuki Kawasaki, Naoya Sakamoto, Ken-ichi Bajo, Yoshinari Abe, Jérôme Aléon, Conel M. O’D. Alexander, Sachiko Amari, Yuri Amelin, Martin Bizzarro, Audrey Bouvier, Richard W. Carlson, Marc Chaussidon, Byeon-Gak Choi, Nicolas Dauphas, Andrew M. Davis, Tommaso Di Rocco, Wataru Fujiya, Ryota Fukai, Ikshu Gautam, Makiko K. Haba, Yuki Hibiya, Hiroshi Hidaka, Hisashi Homma, Peter Hoppe, Gary R. Huss, Kiyohiro Ichida, Tsuyoshi Iizuka, Trevor R. Ireland, Akira Ishikawa, Shoichi Itoh, Noriko T. Kita, Kouki Kitajima, Thorsten Kleine, Shintaro Komatani, Alexander N. Krot, Ming-Chang Liu, Yuki Masuda, Kevin D. McKeegan, Mayu Morita, Kazuko Motomura, Frédéric Moynier, Izumi Nakai, Ann Nguyen, Larry Nittler, Morihiko Onose, Andreas Pack, Changkun Park, Liping Qin, Sara S. Russell, Maria Schönbächler, Lauren Tafla, Haolan Tang, Kentaro Terada, Yasuko Terada, Tomohiro Usui, Sohei Wada, Meenakshi Wadhwa, Richard J. Walker, Katsuyuki Yamashita, Qing-Zhu Yin, Tetsuya Yokoyama, Shigekazu Yoneda, Edward D. Young, Hiroharu Yui, Ai-Cheng Zhang, Tomoki Nakamura, Hiroshi Naraoka, Ryuji Okazaki, Kanako Sakamoto, Hikaru Yabuta, Masanao Abe, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Tatsuaki Okada, Toru Yada, Kasumi Yogata, Satoru Nakazawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Yuichi Tsuda, Sei-ichiro Watanabe, Makoto Yoshikawa, Shogo Tachibana, Hisayoshi Yurimoto
    The Astrophysical Journal Letters 946(2) L43-L43 2023年4月1日  査読有り
    Abstract Rock fragments of the Cb-type asteroid Ryugu returned to Earth by the JAXA Hayabusa2 mission share mineralogical, chemical, and isotopic properties with the Ivuna-type (CI) carbonaceous chondrites. Similar to CI chondrites, these fragments underwent extensive aqueous alteration and consist predominantly of hydrous minerals likely formed in the presence of liquid water on the Ryugu parent asteroid. Here we present an in situ analytical survey performed by secondary ion mass spectrometry from which we have estimated the D/H ratio of Ryugu’s hydrous minerals, D/HRyugu, to be [165 ± 19] × 10−6, which corresponds to δDRyugu = +59 ± 121‰ (2σ). The hydrous mineral D/HRyugu’s values for the two sampling sites on Ryugu are similar; they are also similar to the estimated D/H ratio of hydrous minerals in the CI chondrites Orgueil and Alais. This result reinforces a link between Ryugu and CI chondrites and an inference that Ryugu’s samples, which avoided terrestrial contamination, are our best proxy to estimate the composition of water at the origin of hydrous minerals in CI-like material. Based on this data and recent literature studies, the contribution of CI chondrites to the hydrogen of Earth’s surficial reservoirs is evaluated to be ∼3%. We conclude that the water responsible for the alteration of Ryugu’s rocks was derived from water ice precursors inherited from the interstellar medium; the ice partially re-equilibrated its hydrogen with the nebular H2 before being accreted on the Ryugu’s parent asteroid.
  • Eric T. Parker, Hannah L. McLain, Daniel P. Glavin, Jason P. Dworkin, Jamie E. Elsila, José C. Aponte, Hiroshi Naraoka, Yoshinori Takano, Shogo Tachibana, Hikaru Yabuta, Hisayoshi Yurimoto, Kanako Sakamoto, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Satoru Nakazawa, Yuichi Tsuda, Fuyuto Terui, Takaaki Noguchi, Ryuji Okazaki, Sei-ichiro Watanabe, Tomoki Nakamura
    Geochimica et Cosmochimica Acta 347 42-57 2023年4月  
  • Takuya Ishizaki, Hosei Nagano, Satoshi Tanaka, Naoya Sakatani, Tomoki Nakamura, Tatsuaki Okada, Ryohei Fujita, Abdulkareem Alasli, Tomoyo Morita, Mizuha Kikuiri, Kana Amano, Eiichi Kagawa, Hisayoshi Yurimoto, Takaaki Noguchi, Ryuji Okazaki, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Shogo Tachibana, Sei ichiro Watanabe, Yuichi Tsuda
    International Journal of Thermophysics 44(4) 2023年4月  査読有り
    The thermophysical properties of small Solar System bodies are essential to be determined, on which the thermal evolution of small bodies largely depends. The carbonaceous asteroid Ryugu is one of the small undifferentiated bodies formed in the early Solar System. Hayabusa2 explored the asteroid Ryugu and returned the surface samples in 2020 for detailed on-ground investigation, including measurements of thermal properties. Because the available sample amount was limited, this study developed a novel method to measure the thermal diffusivity of small and irregularly shaped samples of about 1 mm in diameter by combining lock-in thermography and periodic heating methods on the microscale. This method enables us to measure the thermal diffusivity of both flat-plate and granular shape samples by selecting the suitable detecting direction of the temperature response. Especially, when the sample has a flat-plate shape, the anisotropic distribution of the in-plane thermal diffusivity can be evaluated. This method was applied to six Ryugu samples, and the detailed anisotropic distribution of the thermal diffusivity was obtained. The measurement results showed that the samples show local thermal anisotropy caused by cracks and voids. The average thermal diffusivity among all samples was (2.8 to 5.8) × 10−7 m2·s. Based on the density and specific heat of the samples obtained independently, the thermal effusivity was estimated to be 791 J·(s1/2·m2·K) to 1253 J·(s1/2·m2·K), which is defined as the resistance of surface temperature to the change of thermal input. The determined thermal effusivity, often called thermal inertia in planetary science, is larger than the observed value of 225 ± 45 J· (s1/2·m2·K) of the asteroid Ryugu's surface, obtained from the diurnal temperature change of the rotating asteroid by a thermal infrared camera onboard Hayabuas2. This difference is likely to be attributed to the difference in the analytical scale between the sample and the surface boulders compared with the thermal diffusion length. Consequently, it was found that the present result is more representative of the thermal diffusivity and thermal inertia of local part of individual Ryugu particles.
  • Yasuhiro Oba, Toshiki Koga, Yoshinori Takano, Nanako O. Ogawa, Naohiko Ohkouchi, Kazunori Sasaki, Hajime Sato, Daniel P. Glavin, Jason P. Dworkin, Hiroshi Naraoka, Shogo Tachibana, Hisayoshi Yurimoto, Tomoki Nakamura, Takaaki Noguchi, Ryuji Okazaki, Hikaru Yabuta, Kanako Sakamoto, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Satoru Nakazawa, Sei-ichiro Watanabe, Yuichi Tsuda
    Nature Communications 14(1) 2023年3月21日  
    Abstract The pristine sample from the near-Earth carbonaceous asteroid (162173) Ryugu collected by the Hayabusa2 spacecraft enabled us to analyze the pristine extraterrestrial material without uncontrolled exposure to the Earth’s atmosphere and biosphere. The initial analysis team for the soluble organic matter reported the detection of wide variety of organic molecules including racemic amino acids in the Ryugu samples. Here we report the detection of uracil, one of the four nucleobases in ribonucleic acid, in aqueous extracts from Ryugu samples. In addition, nicotinic acid (niacin, a B3 vitamer), its derivatives, and imidazoles were detected in search for nitrogen heterocyclic molecules. The observed difference in the concentration of uracil between A0106 and C0107 may be related to the possible differences in the degree of alteration induced by energetic particles such as ultraviolet photons and cosmic rays. The present study strongly suggests that such molecules of prebiotic interest commonly formed in carbonaceous asteroids including Ryugu and were delivered to the early Earth.
  • Akira Yamaguchi, Naotaka Tomioka, Motoo Ito, Naoki Shirai, Makoto Kimura, Richard C. Greenwood, Ming-Chang Liu, Kaitlyn A. McCain, Nozomi Matsuda, Masayuki Uesugi, Naoya Imae, Takuji Ohigashi, Kentaro Uesugi, Aiko Nakato, Kasumi Yogata, Hayato Yuzawa, Yu Kodama, Kaori Hirahara, Ikuya Sakurai, Ikuo Okada, Yuzuru Karouji, Satoru Nakazawa, Tatsuaki Okada, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Makoto Yoshikawa, Akiko Miyazaki, Masahiro Nishimura, Toru Yada, Masanao Abe, Tomohiro Usui, Sei-ichiro Watanabe, Yuichi Tsuda
    Nature Astronomy 2023年3月20日  
  • Christian Potiszil, Tsutomu Ota, Masahiro Yamanaka, Chie Sakaguchi, Katsura Kobayashi, Ryoji Tanaka, Tak Kunihiro, Hiroshi Kitagawa, Masanao Abe, Akiko Miyazaki, Aiko Nakato, Satoru Nakazawa, Masahiro Nishimura, Tatsuaki Okada, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Yuichi Tsuda, Tomohiro Usui, Sei-ichiro Watanabe, Toru Yada, Kasumi Yogata, Makoto Yoshikawa, Eizo Nakamura
    Nature Communications 14(1) 2023年3月17日  
    Abstract All life on Earth contains amino acids and carbonaceous chondrite meteorites have been suggested as their source at the origin of life on Earth. While many meteoritic amino acids are considered indigenous, deciphering the extent of terrestrial contamination remains an issue. The Ryugu asteroid fragments (JAXA Hayabusa2 mission), represent the most uncontaminated primitive extraterrestrial material available. Here, the concentrations of amino acids from two particles from different touchdown sites (TD1 and TD2) are reported. The concentrations show that N,N-dimethylglycine (DMG) is the most abundant amino acid in the TD1 particle, but below detection limit in the other. The TD1 particle mineral components indicate it experienced more aqueous alteration. Furthermore, the relationships between the amino acids and the geochemistry suggest that DMG formed on the Ryugu progenitor body during aqueous alteration. The findings highlight the importance of aqueous chemistry for defining the ultimate concentrations of amino acids in primitive extraterrestrial samples.
  • Toru Matsumoto, Takaaki Noguchi, Akira Miyake, Yohei Igami, Mitsutaka Haruta, Yusuke Seto, Masaaki Miyahara, Naotaka Tomioka, Hikaru Saito, Satoshi Hata, Dennis Harries, Aki Takigawa, Yuusuke Nakauchi, Shogo Tachibana, Tomoki Nakamura, Megumi Matsumoto, Hope Ishii, John Bradley, Kenta Ohtaki, Elena Dobrică, Hugues Leroux, Corentin Le Guillou, Damien Jacob, Francisco de la Peña, Sylvain Laforet, Maya Marinova, Falko Langenhorst, Pierre Beck, Thi Phan, Rolando Rebois, Neyda Abreu, Jennifer Gray, Thomas Zega, Pierre-Marie Zanetta, Michelle Thompson, Rhonda Stroud, Katherine Burgess, Brittany Cymes, John Bridges, Leon Hicks, Martin Lee, Luke Daly, Phil Bland, Michael Zolensky, David Frank, James Martinez, Akira Tsuchiyama, Masahiro Yasutake, Junya Matsuno, Shota Okumura, Itaru Mitsukawa, Kentaro Uesugi, Masayuki Uesugi, Akihisa Takeuchi, Mingqi Sun, Satomi Enju, Tatsuhiro Michikami, Hisayoshi Yurimoto, 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, Satoshi Tanaka, Fuyuto Terui, Satoru Nakazawa, Sei-ichiro Watanabe, Yuichi Tsuda
    2023年3月16日  
  • M. W. Broadley, D. J. Byrne, E. Füri, L. Zimmermann, B. Marty, R. Okazaki, T. Yada, F. Kitajima, S. Tachibana, K. Yogata, K. Sakamoto, H. Yurimoto, T. Nakamura, T. Noguchi, H. Naraoka, H. Yabuta, S. Watanabe, Y. Tsuda, M. Nishimura, A. Nakato, A. Miyazaki, M. Abe, T. Okada, T. Usui, M. Yoshikawa, T. Saiki, S. Tanaka, F. Terui, S. Nakazawa, H. Busemann, K. Hashizume, J. D. Gilmour, A. Meshik, M. E.I. Riebe, D. Krietsch, C. Maden, A. Ishida, P. Clay, S. A. Crowther, L. Fawcett, T. Lawton, O. Pravdivtseva, Y. N. Miura, J. Park, K. Bajo, Y. Takano, K. Yamada, S. Kawagucci, Y. Matsui, M. Yamamoto, K. Righter, S. Sakai, N. Iwata, N. Shirai, S. Sekimoto, M. Inagaki, M. Ebihara, R. Yokochi, K. Nishiizumi, K. Nagao, J. I. Lee, A. Kano, M. W. Caffee, R. Uemura
    Geochimica et Cosmochimica Acta 345 62-74 2023年3月15日  
    Carbonaceous chondrites are considered to have originated from C-type asteroids and represent some of the most primitive material in our solar system. Furthermore, since carbonaceous chondrites can contain significant quantities of volatile elements, they may have played a crucial role in supplying volatiles and organic material to Earth and other inner solar system bodies. However, a major challenge of unravelling the volatile composition of chondritic meteorites is distinguishing between which features were inherited from the parent body, and what may be a secondary feature attributable to terrestrial weathering. In December 2020, the Hayabusa2 mission of the Japan Aerospace Exploration Agency (JAXA) successfully returned surface material from the C-type asteroid (162173) Ryugu to Earth. This material has now been classified as closely resembling CI-type chondrites, which are the most chemically pristine meteorites. The analysis of material from the surface of Ryugu therefore provides a unique opportunity to analyse the volatile composition of material that originated from a CI-type asteroid without the complications arising from terrestrial contamination. Given their highly volatile nature, the noble gas and nitrogen inventories of chondrites are highly sensitive to different alteration processes on the asteroid parent body, and to terrestrial contamination. Here, we investigate the nitrogen and noble gas signature of two pelletized grains collected from the first and second touchdown sites (Okazaki et al., 2022a), to provide an insight into the formation and alteration history of Ryugu. The concentration of trapped noble gas in the Ryugu samples is greater than the average composition of previously measured CI chondrites and are primarily derived from phase Q, although a significant contribution of presolar nanodiamond Xe-HL is noted. The large noble gas concentrations coupled with a significant contribution of presolar nanodiamonds suggests that the Ryugu samples may represent some of the most primitive unprocessed material from the early solar system. In contrast to the noble gases, the abundance of nitrogen and δ15N composition of the two Ryugu pellets are lower than the average CI chondrite value. We attribute the lower nitrogen abundances and δ15N measured in this study to the preferential loss of a 15N-rich phase from our samples during aqueous alteration on the parent planetesimal. The analyses of other grains returned from Ryugu have shown large variations in nitrogen concentrations and δ15N indicating that alteration fluids heterogeneously interacted with material now present on the surface of Ryugu. Finally, the ratio of trapped noble gases to nitrogen is higher than CI chondrites, and is closer to refractory phase Q and nanodiamonds. This indicates that Ryugu experienced aqueous alteration that led to the significant and variable loss of nitrogen, likely from soluble organic matter, without modification of the noble gas budget, which is primarily hosted in insoluble organic matter and presolar diamonds and is therefore more resistant to aqueous alteration.
  • Takanao SAIKI, Yuya MIMASU, Yuto TAKEI, Hiroshi TAKEUCHI, Kazutaka NISHIYAMA, Takaaki KATO, Yuichi TSUDA
    Journal of Evolving Space Activities 1 2023年3月  査読有り
  • Emmanuel Dartois, Yoko Kebukawa, Hikaru Yabuta, Jérémie Mathurin, Cécile Engrand, Jean Duprat, Laure Bejach, Alexandre Dazzi, Ariane Deniset-Besseau, Lydie Bonal, Eric Quirico, Christophe Sandt, Ferenc Borondics, Jens Barosch, George D. Cody, Brad T. De Gregorio, Minako Hashiguchi, David A.L. Kilcoyne, Mutsumi Komatsu, Zita Martins, Megumi Matsumoto, Gilles Montagnac, Smail Mostefaoui, Larry R. Nittler, Takuji Ohigashi, Taiga Okumura, Laurent Remusat, Scott Sandford, Miho Shigenaka, Rhonda Stroud, Hiroki Suga, Yoshio Takahashi, Yasuo Takeichi, Yusuke Tamenori, Maximilien Verdier-Paoletti, Shohei Yamashita, Tomoki Nakamura, Tomoyo Morita, Mizuha Kikuiri, Kana Amano, Eiichi Kagawa, Takaaki Noguchi, Hiroshi Naraoka, Ryuji Okazaki, Kanako Sakamoto, Hisayoshi Yurimoto, Masanao Abe, Kanami Kamide, Akiko Miyazaki, Aiko Nakato, Satoru Nakazawa, Masahiro Nishimura, Tatsuaki Okada, Takanao Saiki, Shogo Tachibana, Satoshi Tanaka, Fuyuto Terui, Yuichi Tsuda, Tomohiro Usui, Sei Ichiro Watanabe, Toru Yada, Kasumi Yogata, Makoto Yoshikawa
    Astronomy and Astrophysics 671 2023年3月1日  査読有り
    Context. The current period is conducive to exploring our Solar System's origins with recent and future space sample return missions, which provide invaluable information from known Solar System asteroids and comets The Hayabusa2 mission of the Japan Aerospace Exploration Agency (JAXA) recently brought back samples from the surface of the Ryugu carbonaceous asteroid. Aims. We aim to identify the different forms of chemical composition of organic matter and minerals that constitute these Solar System primitive objects, to shed light on the Solar System's origins. Methods. In this work, we recorded infrared (IR) hyper-spectral maps of whole-rock Ryugu asteroid samples at the highest achievable spatial resolution with a synchrotron in the mid-IR (MIR). Additional global far-IR (FIR) spectra of each sample were also acquired. Results. The hyper-spectral maps reveal the variability of the functional groups at small scales and the intimate association of phyl-losilicates with the aliphatic components of the organic matter present in Ryugu. The relative proportion of column densities of the identified IR functional groups (aliphatics, hydroxyl + interlayer and/or physisorbed water, carbonyl, carbonates, and silicates) giving access to the composition of the Ryugu samples is estimated from these IR hyper-spectral maps. Phyllosilicate spectra reveal the presence of mixtures of serpentine and saponite. We do not detect anhydrous silicates in the samples analysed, at the scales probed. The carbonates are dominated by dolomite. Aliphatics organics are distributed over the whole samples at the micron scale probed with the synchrotron, and intimately mixed with the phyllosilicates. The aromatic C=C contribution could not be safely deconvolved from OH in most spectra, due to the ubiquitous presence of hydrated minerals. The peak intensity ratios of the organics methylene to methyl (CH2/CH3) of the Ryugu samples vary between about 1.5 and 2.5, and are compared to the ratios in chondrites from types 1 to 3. Overall, the mineralogical and organic characteristics of the Ryugu samples show similarities with those of CI chondrites, although with a noticeably higher CH2/CH3 in Ryugu than generally measured in C1 chondrites collected on Earth, and possibly a higher carbonate content.
  • J.-C. Viennet, M. Roskosz, T. Nakamura, P. Beck, B. Baptiste, B. Lavina, E.E. Alp, M.Y. Hu, J. Zhao, M. Gounelle, R. Brunetto, H. Yurimoto, T. Noguchi, R. Okazaki, H. Yabuta, H. Naraoka, K. Sakamoto, S. Tachibana, T. Yada, M. Nishimura, A. Nakato, A. Miyazaki, K. Yogata, M. Abe, T. Okada, T. Usui, M. Yoshikawa, T. Saiki, S. Tanaka, F. Terui, S. Nakazawa, S.-I. Watanabe, Y. Tsuda
    Geochemical Perspectives Letters 25 8-12 2023年3月  
  • Hikaru Yabuta, George D. Cody, Cécile Engrand, Yoko Kebukawa, Bradley De Gregorio, Lydie Bonal, Laurent Remusat, Rhonda Stroud, Eric Quirico, Larry Nittler, Minako Hashiguchi, Mutsumi Komatsu, Taiga Okumura, Jérémie Mathurin, Emmanuel Dartois, Jean Duprat, Yoshio Takahashi, Yasuo Takeichi, David Kilcoyne, Shohei Yamashita, Alexandre Dazzi, Ariane Deniset-Besseau, Scott Sandford, Zita Martins, Yusuke Tamenori, Takuji Ohigashi, Hiroki Suga, Daisuke Wakabayashi, Maximilien Verdier-Paoletti, Smail Mostefaoui, Gilles Montagnac, Jens Barosch, Kanami Kamide, Miho Shigenaka, Laure Bejach, Megumi Matsumoto, Yuma Enokido, Takaaki Noguchi, Hisayoshi Yurimoto, Tomoki Nakamura, Ryuji Okazaki, Hiroshi Naraoka, Kanako Sakamoto, Harold C. Connolly, Dante S. Lauretta, Masanao Abe, Tatsuaki Okada, Toru Yada, Masahiro Nishimura, Kasumi Yogata, Aiko Nakato, Miwa Yoshitake, Ayako Iwamae, Shizuho Furuya, Kentaro Hatakeda, Akiko Miyazaki, Hiromichi Soejima, Yuya Hitomi, Kazuya Kumagai, Tomohiro Usui, Tasuku Hayashi, Daiki Yamamoto, Ryota Fukai, Seiji Sugita, Kohei Kitazato, Naru Hirata, Rie Honda, Tomokatsu Morota, Eri Tatsumi, Naoya Sakatani, Noriyuki Namiki, Koji Matsumoto, Rina Noguchi, Koji Wada, Hiroki Senshu, Kazunori Ogawa, Yasuhiro Yokota, Yoshiaki Ishihara, Yuri Shimaki, Manabu Yamada, Chikatoshi Honda, Tatsuhiro Michikami, Moe Matsuoka, Naoyuki Hirata, Masahiko Arakawa, Chisato Okamoto, Masateru Ishiguro, Ralf Jaumann, Jean-Pierre Bibring, Matthias Grott, Stefan Schröder, Katharina Otto, Cedric Pilorget, Nicole Schmitz, Jens Biele, Tra-Mi Ho, Aurélie Moussi-Soffys, Akira Miura, Hirotomo Noda, Tetsuya Yamada, Keisuke Yoshihara, Kosuke Kawahara, Hitoshi Ikeda, Yukio Yamamoto, Kei Shirai, Shota Kikuchi, Naoko Ogawa, Hiroshi Takeuchi, Go Ono, Yuya Mimasu, Kent Yoshikawa, Yuto Takei, Atsushi Fujii, Yu-ichi Iijima, Satoru Nakazawa, Satoshi Hosoda, Takahiro Iwata, Masahiko Hayakawa, Hirotaka Sawada, Hajime Yano, Ryudo Tsukizaki, Masanobu Ozaki, Fuyuto Terui, Satoshi Tanaka, Masaki Fujimoto, Makoto Yoshikawa, Takanao Saiki, Shogo Tachibana, Sei-ichiro Watanabe, Yuichi Tsuda
    Science 379(6634) 2023年2月24日  
    Samples of the carbonaceous asteroid (162173) Ryugu were collected and brought to Earth by the Hayabusa2 spacecraft. We investigated the macromolecular organic matter in Ryugu samples and found that it contains aromatic and aliphatic carbon, ketone, and carboxyl functional groups. The spectroscopic features of the organic matter are consistent with those in chemically primitive carbonaceous chondrite meteorites that experienced parent-body aqueous alteration (reactions with liquid water). The morphology of the organic carbon includes nanoglobules and diffuse carbon associated with phyllosilicate and carbonate minerals. Deuterium and/or nitrogen-15 enrichments indicate that the organic matter formed in a cold molecular cloud or the presolar nebula. The diversity of the organic matter indicates variable levels of aqueous alteration on Ryugu’s parent body.
  • Hiroshi Naraoka, Yoshinori Takano, Jason P. Dworkin, Yasuhiro Oba, Kenji Hamase, Aogu Furusho, Nanako O. Ogawa, Minako Hashiguchi, Kazuhiko Fukushima, Dan Aoki, Philippe Schmitt-Kopplin, José C. Aponte, Eric T. Parker, Daniel P. Glavin, Hannah L. McLain, Jamie E. Elsila, Heather V. Graham, John M. Eiler, Francois-Regis Orthous-Daunay, Cédric Wolters, Junko Isa, Véronique Vuitton, Roland Thissen, Saburo Sakai, Toshihiro Yoshimura, Toshiki Koga, Naohiko Ohkouchi, Yoshito Chikaraishi, Haruna Sugahara, Hajime Mita, Yoshihiro Furukawa, Norbert Hertkorn, Alexander Ruf, Hisayoshi Yurimoto, Tomoki Nakamura, Takaaki Noguchi, Ryuji Okazaki, Hikaru Yabuta, Kanako Sakamoto, Shogo Tachibana, Harold C. Connolly, Dante S. Lauretta, Masanao Abe, Toru Yada, Masahiro Nishimura, Kasumi Yogata, Aiko Nakato, Miwa Yoshitake, Ayako Suzuki, Akiko Miyazaki, Shizuho Furuya, Kentaro Hatakeda, Hiromichi Soejima, Yuya Hitomi, Kazuya Kumagai, Tomohiro Usui, Tasuku Hayashi, Daiki Yamamoto, Ryota Fukai, Kohei Kitazato, Seiji Sugita, Noriyuki Namiki, Masahiko Arakawa, Hitoshi Ikeda, Masateru Ishiguro, Naru Hirata, Koji Wada, Yoshiaki Ishihara, Rina Noguchi, Tomokatsu Morota, Naoya Sakatani, Koji Matsumoto, Hiroki Senshu, Rie Honda, Eri Tatsumi, Yasuhiro Yokota, Chikatoshi Honda, Tatsuhiro Michikami, Moe Matsuoka, Akira Miura, Hirotomo Noda, Tetsuya Yamada, Keisuke Yoshihara, Kosuke Kawahara, Masanobu Ozaki, Yu-ichi Iijima, Hajime Yano, Masahiko Hayakawa, Takahiro Iwata, Ryudo Tsukizaki, Hirotaka Sawada, Satoshi Hosoda, Kazunori Ogawa, Chisato Okamoto, Naoyuki Hirata, Kei Shirai, Yuri Shimaki, Manabu Yamada, Tatsuaki Okada, Yukio Yamamoto, Hiroshi Takeuchi, Atsushi Fujii, Yuto Takei, Kento Yoshikawa, Yuya Mimasu, Go Ono, Naoko Ogawa, Shota Kikuchi, Satoru Nakazawa, Fuyuto Terui, Satoshi Tanaka, Takanao Saiki, Makoto Yoshikawa, Sei-ichiro Watanabe, Yuichi Tsuda
    Science 379(6634) 2023年2月24日  
    The Hayabusa2 spacecraft collected samples from the surface of the carbonaceous near-Earth asteroid (162173) Ryugu and brought them to Earth. The samples were expected to contain organic molecules, which record processes that occurred in the early Solar System. We analyzed organic molecules extracted from the Ryugu surface samples. We identified a variety of molecules containing the atoms CHNOS, formed by methylation, hydration, hydroxylation, and sulfurization reactions. Amino acids, aliphatic amines, carboxylic acids, polycyclic aromatic hydrocarbons, and nitrogen-heterocyclic compounds were detected, which had properties consistent with an abiotic origin. These compounds likely arose from an aqueous reaction on Ryugu’s parent body and are similar to the organics in Ivuna-type meteorites. These molecules can survive on the surfaces of asteroids and be transported throughout the Solar System.
  • Daisuke Nakashima, Tomoki Nakamura, Mingming Zhang, Noriko T. Kita, Takashi Mikouchi, Hideto Yoshida, Yuma Enokido, Tomoyo Morita, Mizuha Kikuiri, Kana Amano, Eiichi Kagawa, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Satoru Nakazawa, Fuyuto Terui, Hisayoshi Yurimoto, Takaaki Noguchi, Hikaru Yabuta, Hiroshi Naraoka, Ryuji Okazaki, Kanako Sakamoto, Sei-ichiro Watanabe, Shogo Tachibana, Yuichi Tsuda
    Nature Communications 14(1) 532-532 2023年2月16日  
    Abstract Chondrule-like objects and Ca-Al-rich inclusions (CAIs) are discovered in the retuned samples from asteroid Ryugu. Here we report results of oxygen isotope, mineralogical, and compositional analysis of the chondrule-like objects and CAIs. Three chondrule-like objects dominated by Mg-rich olivine are 16O-rich and -poor with Δ17O (=δ17O – 0.52 × δ18O) values of ~ –23‰ and ~ –3‰, resembling what has been proposed as early generations of chondrules. The 16O-rich objects are likely to be melted amoeboid olivine aggregates that escaped from incorporation into 16O-poor chondrule precursor dust. Two CAIs composed of refractory minerals are 16O-rich with Δ17O of ~ –23‰ and possibly as old as the oldest CAIs. The discovered objects (&lt;30 µm) are as small as those from comets, suggesting radial transport favoring smaller objects from the inner solar nebula to the formation location of the Ryugu original parent body, which is farther from the Sun and scarce in chondrules. The transported objects may have been mostly destroyed during aqueous alteration in the Ryugu parent body.
  • Marine Paquet, Frederic Moynier, Tetsuya Yokoyama, Wei Dai, Yan Hu, Yoshinari Abe, Jérôme Aléon, Conel M. Conel, Sachiko Amari, Yuri Amelin, Ken ichi Bajo, Martin Bizzarro, Audrey Bouvier, Richard W. Carlson, Marc Chaussidon, Byeon Gak Choi, Nicolas Dauphas, Andrew M. Davis, Tommaso Di Rocco, Wataru Fujiya, Ryota Fukai, Ikshu Gautam, Makiko K. Haba, Yuki Hibiya, Hiroshi Hidaka, Hisashi Homma, Peter Hoppe, Gary R. Huss, Kiyohiro Ichida, Tsuyoshi Iizuka, Trevor R. Ireland, Akira Ishikawa, Motoo Ito, Shoichi Itoh, Noriyuki Kawasaki, Noriko T. Kita, Kouki Kitajima, Thorsten Kleine, Shintaro Komatani, Alexander N. Krot, Ming Chang Liu, Yuki Masuda, Kevin D. McKeegan, Mayu Morita, Kazuko Motomura, Izumi Nakai, Kazuhide Nagashima, David Nesvorný, Ann N. Nguyen, Larry Nittler, Morihiko Onose, Andreas Pack, Changkun Park, Laurette Piani, Liping Qin, Sara S. Russell, Naoya Sakamoto, Maria Schönbächler, Lauren Tafla, Haolan Tang, Kentaro Terada, Yasuko Terada, Tomohiro Usui, Sohei Wada, Meenakshi Wadhwa, Richard J. Walker, Katsuyuki Yamashita, Qing Zhu Yin, Shigekazu Yoneda, Edward D. Young, Hiroharu Yui, Ai Cheng Zhang, Tomoki Nakamura, Hiroshi Naraoka, Takaaki Noguchi, Ryuji Okazaki, Kanako Sakamoto, Hikaru Yabuta, Masanao Abe, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Tatsuaki Okada, Toru Yada, Kasumi Yogata, Satoru Nakazawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Yuichi Tsuda, Sei ichiro Watanabe, Makoto Yoshikawa, Shogo Tachibana, Hisayoshi Yurimoto
    Nature Astronomy 7(2) 182-189 2023年2月  
    Initial analyses showed that asteroid Ryugu’s composition is close to CI (Ivuna-like) carbonaceous chondrites (CCs) – the chemically most primitive meteorites, characterized by near-solar abundances for most elements. However, some isotopic signatures (for example, Ti, Cr) overlap with other CC groups, so the details of the link between Ryugu and the CI chondrites are not yet fully clear. Here we show that Ryugu and CI chondrites have the same zinc and copper isotopic composition. As the various chondrite groups have very distinct Zn and Cu isotopic signatures, our results point at a common genetic heritage between Ryugu and CI chondrites, ruling out any affinity with other CC groups. Since Ryugu’s pristine samples match the solar elemental composition for many elements, their Zn and Cu isotopic compositions likely represent the best estimates of the solar composition. Earth’s mass-independent Zn isotopic composition is intermediate between Ryugu/CC and non-carbonaceous chondrites (NCs), suggesting a contribution of Ryugu-like material to Earth’s budgets of Zn and other moderately volatile elements.
  • Elena Dobrică, Hope A. Ishii, John P. Bradley, Kenta Ohtaki, Adrian J. Brearley, Takaaki Noguchi, Toru Matsumoto, Akira Miyake, Yohei Igami, Mitsutaka Haruta, Hikaru Saito, Satoshi Hata, Yusuke Seto, Masaaki Miyahara, Naotaka Tomioka, Hugues Leroux, Corentin Le Guillou, Damien Jacob, Francisco de la Peña, Sylvain Laforet, Maya Marinova, Falko Langenhorst, Dennis Harries, Pierre Beck, Thi H. V. Phan, Rolando Rebois, Neyda M. Abreu, Jennifer Gray, Thomas Zega, Pierre-M. Zanetta, Michelle S. Thompson, Rhonda Stroud, Kate Burgess, Brittany A. Cymes, John C. Bridges, Leon Hicks, Martin R. Lee, Luke Daly, Phil A. Bland, Michael E. Zolensky, David R. Frank, James Martinez, Akira Tsuchiyama, Masahiro Yasutake, Junya Matsuno, Shota Okumura, Itaru Mitsukawa, Kentaro Uesugi, Masayuki Uesugi, Akihisa Takeuchi, Mingqi Sun, Satomi Enju, Aki Takigawa, Tatsuhiro Michikami, Tomoki Nakamura, Megumi Matsumoto, Yusuke Nakauchi, Hisayoshi Yurimoto, Ryuji Okazaki, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Shogo Tachibana, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Satoru Nakazawa, Sei-ichiro Watanabe, Yuichi Tsuda
    Geochimica et Cosmochimica Acta 346 65-75 2023年2月  
  • D. Loizeau, C. Pilorget, L. Riu, R. Brunetto, J.-P. Bibring, A. Nakato, A. Aléon-Toppani, K. Hatakeda, K. Yogata, J. Carter, T. Le Pivert-Jolivet, T. Yada, T. Okada, T. Usui, Y. Langevin, C. Lantz, D. Baklouti, A. Miyazaki, M. Nishimura, K. Nagashima, K. Kumagai, Y. Hitomi, M. Abe, T. Saiki, S. Tanaka, S. Nakazawa, Y. Tsuda, S. Watanabe
    Nature Astronomy 2023年1月12日  
  • Kaitlyn A. McCain, Nozomi Matsuda, Ming-Chang Liu, Kevin D. McKeegan, Akira Yamaguchi, Makoto Kimura, Naotaka Tomioka, Motoo Ito, Naoya Imae, Masayuki Uesugi, Naoki Shirai, Takuji Ohigashi, Richard C. Greenwood, Kentaro Uesugi, Aiko Nakato, Kasumi Yogata, Hayato Yuzawa, Yu Kodama, Kaori Hirahara, Ikuya Sakurai, Ikuo Okada, Yuzuru Karouji, Satoru Nakazawa, Tatsuaki Okada, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Makoto Yoshikawa, Akiko Miyazaki, Masahiro Nishimura, Toru Yada, Masanao Abe, Tomohiro Usui, Sei-ichiro Watanabe, Yuichi Tsuda
    Nature Astronomy 2023年1月12日  
  • Stefano Rubino, Zélia Dionnet, Alice Aléon-Toppani, Rosario Brunetto, Tomoki Nakamura, Donia Baklouti, Zahia Djouadi, Cateline Lantz, Obadias Mivumbi, Ferenc Borondics, Stephane Lefrançois, Christophe Sandt, Francesco Capitani, Eva Héripré, David Troadec, Megumi Matsumoto, Kana Amano, Tomoyo Morita, Hisayoshi Yurimoto, Takaaki Noguchi, Ryuji Okazaki, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Shogo Tachibana, Seiichiro Watanabe, Yuichi Tsuda
    Earth, Planets and Space 75(1) 2023年1月9日  
    Abstract Sample-return missions allow the study of materials collected directly from celestial bodies, unbiased by atmospheric entry effects and/or terrestrial alteration and contamination phenomena, using state-of-the-art techniques which are available only in a laboratory environment—but only if the collected material stays pristine. The scarcity of outer-space unaltered material recovered until now makes this material extremely precious for the potential scientific insight it can bring. To maximize the scientific output of current and future sample-return missions, the scientific community needs to plan for ways of storing, handling, and measuring this precious material while preserving their pristine state for as long as the ‘invasiveness’ of measurements allows. In July 2021, as part of the Hayabusa2 (JAXA) “Stone” preliminary examination team, we received several microscopic particles from the asteroid Ryugu, with the goal of performing IR hyper-spectral imaging and IR micro-tomography studies. Here, we describe the sample transfer, handling methods and analytical pipeline we implemented to study this very precious material while minimizing and surveilling their alteration history on Earth. Graphical Abstract
  • Yuto Takei, Shintaro Nishihira, Atsushi Harayama, Yuya Mimasu, Takanao Saiki, Satoru Nakazawa, Makoto Yoshikawa, Yuichi Tsuda
    Proceedings of the International Astronautical Congress, IAC 2023-October 2023年  
    After experiencing a series of mission failures from the late 1990s to the early 2000s, the Japan Aerospace Exploration Agency (JAXA) implemented a reform focusing on strengthening and promoting systems engineering and project management (SE/PM) in 2005. Since then, the occurrence rate of mission failures has decreased significantly for a while. Following the in-orbit failure of a flagship X-ray observatory that occurred in 2016, a cross-organizational reform of project management was implemented in 2017 to ensure development and create value. However, five years after this reform, the current new issues are becoming apparent. In parallel, a Japanese asteroid sample return probe “Hayabusa2” was developed and launched in December 2014. Overcoming the unexpectedly rough terrain of its target asteroid 162173 Ryugu, the probe marked a great success including two touchdowns to collect the asteroid's surface/underground soil and safe return to Earth on December 5th, 2020. This paper first reviews the two reforms and then takes up Hayabusa2's good practices to extract clues for solving current issues.
  • 竝木芳, 高尾勇輝, 森下直樹, 菊地翔太, 菊地翔太, 丸祐介, 森治, 津田雄一, 澤井秀次郎
    航空宇宙技術(Web) 22 51-61 2023年  
  • Alexander Meshik, Olga Pravdivtseva, Ryuji Okazaki, Kasumi Yogata, Toru Yada, Fumio Kitajima, Hisayoshi Yurimoto, Tomoki Nakamura, Takaaki Noguchi, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Shogo Tachibana, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Makoto Yoshikawa, Takanao Sakai, Satoshi Tanaka, Fuyuto Terui, Satoru Nakazawa, Seiichiro Watanabe, Yuichi Tsuda, Hayabusa2 Initial Analysis Volatile Team
    Journal of Analytical Atomic Spectrometry 2023年  
    Mass spectrometry of noble gas isotopes from the asteroid materials delivered by robotic space missions requires high sensitivity, high ion transmission, low detection limit, and other characteristics not readily available in commercial instruments.
  • Maiko YAMAKAWA, Yusuke MARU, Mitsuhisa BABA, Yu DAIMON, Kazuhisa FUJITA, Shujiro SAWAI, Osamu MORI, Yuichi TSUDA
    TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN 21 29-35 2023年  
  • Shuya KASHIOKA, Genki OHIRA, Yuki TAKAO, Taketoshi IYOTA, Yuichi TSUDA
    TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN 21 19-28 2023年  
  • Richard C. Greenwood, Ian A. Franchi, Ross Findlay, James A. Malley, Motoo Ito, Akira Yamaguchi, Makoto Kimura, Naotaka Tomioka, Masayuki Uesugi, Naoya Imae, Naoki Shirai, Takuji Ohigashi, Ming-Chang Liu, Kaitlyn A. McCain, Nozomi Matsuda, Kevin D. McKeegan, Kentaro Uesugi, Aiko Nakato, Kasumi Yogata, Hayato Yuzawa, Yu Kodama, Akira Tsuchiyama, Masahiro Yasutake, Kaori Hirahara, Akihisa Tekeuchi, Shun Sekimoto, Ikuya Sakurai, Ikuo Okada, Yuzuru Karouji, Satoru Nakazawa, Tatsuaki Okada, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Makoto Yoshikawa, Akiko Miyazaki, Masahiro Nishimura, Toru Yada, Masanao Abe, Tomohiro Usui, Sei-ichiro Watanabe, Yuichi Tsuda
    Nature Astronomy 7(1) 29-38 2022年12月19日  査読有り
    Abstract The delivery of water to the inner Solar System, including Earth, is still a debated topic. A preferential role for hydrated asteroids in this process is supported by isotopic measurements. Carbonaceous chondrite (CC) meteorites represent our main source of information about these volatile-rich asteroids. However, the destruction of weaker materials during atmospheric entry creates a bias in our CC data. The return of surface materials from the C-type asteroid 162173 Ryugu by the Hayabusa2 spacecraft provides a unique opportunity to study high-porosity, low-density, primitive materials, unrepresented in the meteorite record. We measured the bulk oxygen isotope composition from four Ryugu particles and show that they most closely resemble the rare CI (CC Ivuna-type) chondrites, but with some differences that we attribute to the terrestrial contamination of the CI meteorites. We suggest that CI-related material is widespread among carbonaceous asteroids and a more important source of Earth’s water and other volatiles than its limited presence in our meteoritic collection indicates.
  • Takaaki Noguchi, Toru Matsumoto, Akira Miyake, Yohei Igami, Mitsutaka Haruta, Hikaru Saito, Satoshi Hata, Yusuke Seto, Masaaki Miyahara, Naotaka Tomioka, Hope A. Ishii, John P. Bradley, Kenta K. Ohtaki, Elena Dobrică, Hugues Leroux, Corentin Le Guillou, Damien Jacob, Francisco de la Peña, Sylvain Laforet, Maya Marinova, Falko Langenhorst, Dennis Harries, Pierre Beck, Thi H. V. Phan, Rolando Rebois, Neyda M. Abreu, Jennifer Gray, Thomas Zega, Pierre-M. Zanetta, Michelle S. Thompson, Rhonda Stroud, Kate Burgess, Brittany A. Cymes, John C. Bridges, Leon Hicks, Martin R. Lee, Luke Daly, Phil A. Bland, Michael E. Zolensky, David R. Frank, James Martinez, Akira Tsuchiyama, Masahiro Yasutake, Junya Matsuno, Shota Okumura, Itaru Mitsukawa, Kentaro Uesugi, Masayuki Uesugi, Akihisa Takeuchi, Mingqi Sun, Satomi Enju, Aki Takigawa, Tatsuhiro Michikami, Tomoki Nakamura, Megumi Matsumoto, Yusuke Nakauchi, Masanao Abe, Masahiko Arakawa, Atsushi Fujii, Masahiko Hayakawa, Naru Hirata, Naoyuki Hirata, Rie Honda, Chikatoshi Honda, Satoshi Hosoda, Yu-ichi Iijima, Hitoshi Ikeda, Masateru Ishiguro, Yoshiaki Ishihara, Takahiro Iwata, Kousuke Kawahara, Shota Kikuchi, Kohei Kitazato, Koji Matsumoto, Moe Matsuoka, Yuya Mimasu, Akira Miura, Tomokatsu Morota, Satoru Nakazawa, Noriyuki Namiki, Hirotomo Noda, Rina Noguchi, Naoko Ogawa, Kazunori Ogawa, Tatsuaki Okada, Chisato Okamoto, Go Ono, Masanobu Ozaki, Takanao Saiki, Naoya Sakatani, Hirotaka Sawada, Hiroki Senshu, Yuri Shimaki, Kei Shirai, Seiji Sugita, Yuto Takei, Hiroshi Takeuchi, Satoshi Tanaka, Eri Tatsumi, Fuyuto Terui, Ryudo Tsukizaki, Koji Wada, Manabu Yamada, Tetsuya Yamada, Yukio Yamamoto, Hajime Yano, Yasuhiro Yokota, Keisuke Yoshihara, Makoto Yoshikawa, Kent Yoshikawa, Ryohta Fukai, Shizuho Furuya, Kentaro Hatakeda, Tasuku Hayashi, Yuya Hitomi, Kazuya Kumagai, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Hiromichi Soejima, Ayako I. Suzuki, Tomohiro Usui, Toru Yada, Daiki Yamamoto, Kasumi Yogata, Miwa Yoshitake, Harold C. Connolly, Dante S. Lauretta, Hisayoshi Yurimoto, Kazuhide Nagashima, Noriyuki Kawasaki, Naoya Sakamoto, Ryuji Okazaki, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Shogo Tachibana, Sei-ichiro Watanabe, Yuichi Tsuda
    Nature Astronomy 2022年12月19日  
    Abstract Without a protective atmosphere, space-exposed surfaces of airless Solar System bodies gradually experience an alteration in composition, structure and optical properties through a collective process called space weathering. The return of samples from near-Earth asteroid (162173) Ryugu by Hayabusa2 provides the first opportunity for laboratory study of space-weathering signatures on the most abundant type of inner solar system body: a C-type asteroid, composed of materials largely unchanged since the formation of the Solar System. Weathered Ryugu grains show areas of surface amorphization and partial melting of phyllosilicates, in which reduction from Fe3+ to Fe2+ and dehydration developed. Space weathering probably contributed to dehydration by dehydroxylation of Ryugu surface phyllosilicates that had already lost interlayer water molecules and to weakening of the 2.7 µm hydroxyl (–OH) band in reflectance spectra. For C-type asteroids in general, this indicates that a weak 2.7 µm band can signify space-weathering-induced surface dehydration, rather than bulk volatile loss.
  • Yuto Takei, Takanao Saiki, Yuichi Tsuda
    Frontiers in Space Technologies 3 2022年12月8日  
    There are a number of deep space probes that are currently in operation with diverse destinations and objectives. For example, the Japanese Hayabusa2 and the U.S. OSIRIS-REx missions are both sample returns, targeting different near-Earth asteroids. Europe’s ExoMars and the U.S. Perseverance are orbiting and roving Mars as precursors of future manned explorations. Conventionally, deep space missions require dedicated launch vehicles for each mission. The interplanetary Earth departure trajectory from the low Earth orbit (LEO) usually lacks flexibility and efficiency. Furthermore, innovative and reusable launch systems have been researched and developed by multiple organizations including private sector organizations such as SpaceX and Blue Origin. It is expected that the unit cost per launch weight to LEO be significantly reduced by rideshare mass transportation executed by using reusable mega launchers in the near future. This study aims to fill the transportation gap between LEO and deep space by realizing a flexible and economical interplanetary Earth departure without sacrificing the arbitrariness of LEO, target V-infinity vector, and target Earth departure epoch. Thus, the one-revolution Earth free-return orbit (1rEFRO) and the consequent Earth gravity assist (EGA) are introduced to separate the velocity increment and direction adjustment. The planetary free-return and EGAs are common in interplanetary missions; however, a comprehensive study on the flexibility, economic efficiency, and arbitrariness of the sequence (1rEFRO + EGA) originating from LEO was not explicitly found. After describing the necessary coordinate frames, LEO’s orbital elements, 1rEFRO, and the terms ‘flexibility’ and ‘economic efficiency’ are defined in Section 2. Then in Section 3, the two-body-based preliminary orbit design method is proposed and formulated. Section 4 aims to reveal LEO’s comprehensiveness as efficient parking orbits when adopting the 1rEFRO + EGA sequence, using the newly proposed “ LEO i-Ω diagram”. Section 5 describes a detailed orbit design constructed based on multi-body propagation and optimization to confirm the feasibility, flexibility, and economics of the solution and the usefulness of the initial solution given by the preliminary design method formulated in Section 3.
  • Noriyuki Kawasaki, Kazuhide Nagashima, Naoya Sakamoto, Toru Matsumoto, Ken Ichi Bajo, Sohei Wada, Yohei Igami, Akira Miyake, Takaaki Noguchi, Daiki Yamamoto, Sara S. Russell, Yoshinari Abe, Jérôme Aléon, Conel M.O’D Alexander, Sachiko Amari, Yuri Amelin, Martin Bizzarro, Audrey Bouvier, Richard W. Carlson, Marc Chaussidon, Byeon Gak Choi, Nicolas Dauphas, Andrew M. Davis, Tommaso Di Rocco, Wataru Fujiya, Ryota Fukai, Ikshu Gautam, Makiko K. Haba, Yuki Hibiya, Hiroshi Hidaka, Hisashi Homma, Peter Hoppe, Gary R. Huss, Kiyohiro Ichida, Tsuyoshi Iizuka, Trevor R. Ireland, Akira Ishikawa, Motoo Ito, Shoichi Itoh, Noriko T. Kita, Kouki Kitajima, Thorsten Kleine, Shintaro Komatani, Alexander N. Krot, Ming Chang Liu, Yuki Masuda, Kevin D. McKeegan, Mayu Morita, Kazuko Motomura, Frédéric Moynier, Izumi Nakai, Ann Nguyen, Larry Nittler, Morihiko Onose, Andreas Pack, Changkun Park, Laurette Piani, Liping Qin, Maria Schönbächler, Lauren Tafla, Haolan Tang, Kentaro Terada, Yasuko Terada, Tomohiro Usui, Meenakshi Wadhwa, Richard J. Walker, Katsuyuki Yamashita, Qing Zhu Yin, Tetsuya Yokoyama, Shigekazu Yoneda, Edward D. Young, Hiroharu Yui, Ai Cheng Zhang, Tomoki Nakamura, Hiroshi Naraoka, Ryuji Okazaki, Kanako Sakamoto, Hikaru Yabuta, Masanao Abe, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Tatsuaki Okada, Toru Yada, Kasumi Yogata, Satoru Nakazawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Yuichi Tsuda, Sei Ichiro Watanabe, Makoto Yoshikawa, Shogo Tachibana, Hisayoshi Yurimoto
    Science Advances 8(50) 2022年12月  
    The extraterrestrial materials returned from asteroid (162173) Ryugu consist predominantly of low-temperature aqueously formed secondary minerals and are chemically and mineralogically similar to CI (Ivuna-type) carbonaceous chondrites. Here, we show that high-temperature anhydrous primary minerals in Ryugu and CI chondrites exhibit a bimodal distribution of oxygen isotopic compositions: 16O-rich (associated with refractory inclusions) and 16O-poor (associated with chondrules). Both the 16O-rich and 16O-poor minerals probably formed in the inner solar protoplanetary disk and were subsequently transported outward. The abundance ratios of the 16O-rich to 16O-poor minerals in Ryugu and CI chondrites are higher than in other carbonaceous chondrite groups but are similar to that of comet 81P/Wild2, suggesting that Ryugu and CI chondrites accreted in the outer Solar System closer to the accretion region of comets.
  • K. Ogawa, N. Sakatani, T. Kadono, M. Arakawa, R. Honda, K. Wada, K. Shirai, Y. Shimaki, K. Ishibashi, Y. Yokota, T. Saiki, H. Imamura, Y. Tsuda, S. Nakazawa, Y. Takagi, M. Hayakawa, H. Yano, C. Okamoto, Y. Iijima, T. Morota, S. Kameda, E. Tatsumi, Y. Cho, K. Yoshioka, H. Sawada, M. Matsuoka, M. Yamada, T. Kouyama, H. Suzuki, C. Honda, S. Sugita
    Earth, Planets and Space 74(1) 2022年12月  
    Japanese Hayabusa2 spacecraft has successfully carried out an impact experiment using a small carry-on impactor (SCI) on an asteroid (162173) Ryugu. We examine the size distribution of particles inside and outside an artificial impact crater (the SCI crater) based on the images taken by the optical navigation camera onboard the Hayabusa2 spacecraft. The circumferential variation in particle size distribution inside the SCI crater is recognized and we interpret that major circumferential variation is caused by the large boulders inside the SCI crater that existed prior to the impact. The size distribution inside the SCI crater also shows that the subsurface layer beneath the SCI impact site had a large number of particles with a characteristic size of – 9 cm, which is consistent with the previous evaluations. On the other hand, the size distribution outside the SCI crater exhibits the radial variation, implying that the deposition of ejecta from the SCI crater is involved. The slope of the size distribution outside the crater at small sizes differs from the slope of the size distribution on the surface of Ryugu by approximately 1 or slightly less. This is consistent with the claim that some particles are buried in fine particles of the subsurface origin included in ejecta from the SCI crater. Thus, the particle size distributions inside and outside the SCI crater reveal that the subsurface layer beneath the SCI impact site is rich in fine particles with – 9 cm in size while the particles on the surface have a size distribution of a power-law form with shallower slopes at small sizes due to the deposition of fine ejecta from the subsurface layer. Finally, we discuss a process responsible for this difference in particle size distribution between the surface and the subsurface layers. The occurrence of segregation in the gravitational flow of particles on the surface of Ryugu is plausible. Graphical Abstract: [Figure not available: see fulltext.].
  • Pieter Tack, Ella De Pauw, Beverley Tkalcec, Miles Lindner, Benjamin Bazi, Bart Vekemans, Frank Brenker, Marco Di Michiel, Masayuki Uesugi, Hisayoshi Yurimoto, Tomoki Nakamura, Kana Amano, Megumi Matsumoto, Yuri Fujioka, Yuma Enokido, Daisuke Nakashima, Takaaki Noguchi, Ryuji Okazaki, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Shogo Tachibana, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Satoru Nakazawa, Sei Ichiro Watanabe, Yuichi Tsuda, Laszlo Vincze
    Earth, Planets and Space 74(1) 2022年12月  
    Millimetre-sized primordial rock fragments originating from asteroid Ryugu were investigated using high energy X-ray fluorescence spectroscopy, providing 2D and 3D elemental distribution and quantitative composition information on the microscopic level. Samples were collected in two phases from two sites on asteroid Ryugu and safely returned to Earth by JAXA’s asteroid explorer Hayabusa2, during which time the collected material was stored and maintained free from terrestrial influences, including exposure to Earth’s atmosphere. Several grains of interest were identified and further characterised to obtain quantitative information on the rare earth element (REE) content within said grains, following a reference-based and computed-tomography-assisted fundamental parameters quantification approach. Several orders of magnitude REE enrichments compared to the mean CI chondrite composition were found within grains that could be identified as apatite phase. Small enrichment of LREE was found for dolomite grains and slight enrichment or depletion for the general matrices within the Ryugu rock fragments A0055 and C0076, respectively. Graphical Abstract: [Figure not available: see fulltext.]
  • Stefania Soldini, Takanao Saiki, Yuichi Tsuda
    Frontiers in Space Technologies 3 2022年11月23日  
    On 5 April 2019, the Hayabusa 2 spacecraft performed the first successful artificial impact experiment on an asteroid. The Small Carry-on Impactor (SCI) device was deployed at an altitude of 500 m above Ryugu’s surface. The 2 kg copper projectile hit Ryugu’s surface in 40 min and caused the formation of an artificial crater 14.5 m in diameter. Once the SCI was deployed, the Hayabusa 2 spacecraft performed a two-week escape trajectory reaching altitudes as far as 120 km from Ryugu. The spacecraft then returned to its nominal position at 20 km altitude (Home-Position) from Ryugu for hovering control. This was done to prevent ejecta particles from seriously damaging the spacecraft and compromising its functionality. In this article, we present a method to forecast the daily probability of spacecraft damage along the selected nominal escape trajectory due to the debris cloud formed by an artificial impact. The result of the damage analysis confirmed that the selected escape trajectory experienced a small number of particle collisions under the design threshold, which would not have resulted in damage. Indeed, no damage was reported on the Hayabusa 2 spacecraft and it kept operating normally after the SCI operation. The method here presented serves as a guideline for post-impact mission operations to forecast and estimate the probability of damage to spacecraft or CubeSats operating near a small celestial body after an artificial impact experiment has occurred.
  • Benjamin Bazi, Pieter Tack, Miles Lindner, Bart Vekemans, Ella De Pauw, Beverley Tkalcec, Frank E. Brenker, Jan Garrevoet, Gerald Falkenberg, Hikaru Yabuta, Hisayoshi Yurimoto, Tomoki Nakamura, Kana Amano, Megumi Matsumoto, Yuri Fujioka, Yuma Enokido, Daisuke Nakashima, Masayuki Uesugi, Hiroshi Naraoka, Takaaki Noguchi, Ryuji Okazaki, Kanako Sakamoto, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Satoru Nakazawa, Shogo Tachibana, Sei-ichiro Watanabe, Yuichi Tsuda, Laszlo Vincze
    Earth, Planets and Space 74(1) 2022年11月4日  
    Abstract A fundamental parameter-based quantification scheme for confocal XRF was applied to sub-micron synchrotron radiation X-ray fluorescence (SR-XRF) data obtained at the beamline P06 of the Deutsches Elektronen-Synchrotron (DESY, Hamburg, Germany) from two sections C0033-01 and C0033-04 that were wet cut from rock fragment C0033 collected from Cb-type asteroid (162173) Ryugu by JAXA’s Hayabusa2 mission. Trace-element quantifications show that C0033 bulk matrix is CI-like, whereas individual mineral grains (i.e., magnetite, pyrrhotite, dolomite, apatite and breunnerite) show, depending on the respective phase, minor to strong deviations. The non-destructive nature of SR-XRF coupled with a new PyMca (a Python toolkit for XRF data analysis)-based quantification approach, performed in parallel with the synchrotron experiments, proves to be an attractive tool for the initial analysis of samples from return missions, such as Hayabusa2 and OSIRIS-REx, the latter returning material from a B-type asteroid (101955) Bennu in 2023. Graphical Abstract
  • Timo Hopp, Nicolas Dauphas, Yoshinari Abe, Jérôme Aléon, Conel M.O.D. Alexander, Sachiko Amari, Yuri Amelin, Ken Ichi Bajo, Martin Bizzarro, Audrey Bouvier, Richard W. Carlson, Marc Chaussidon, Byeon Gak Choi, Andrew M. Davis, Tommaso Di Rocco, Wataru Fujiya, Ryota Fukai, Ikshu Gautam, Makiko K. Haba, Yuki Hibiya, Hiroshi Hidaka, Hisashi Homma, Peter Hoppe, Gary R. Huss, Kiyohiro Ichida, Tsuyoshi Iizuka, Trevor R. Ireland, Akira Ishikawa, Motoo Ito, Shoichi Itoh, Noriyuki Kawasaki, Noriko T. Kita, Kouki Kitajima, Thorsten Kleine, Shintaro Komatani, Alexander N. Krot, Ming Chang Liu, Yuki Masuda, Kevin D. McKeegan, Mayu Morita, Kazuko Motomura, Frédéric Moynier, Izumi Nakai, Kazuhide Nagashima, David Nesvorný, Ann Nguyen, Larry Nittler, Morihiko Onose, Andreas Pack, Changkun Park, Laurette Piani, Liping Qin, Sara S. Russell, Naoya Sakamoto, Maria Schönbächler, Lauren Tafla, Haolan Tang, Kentaro Terada, Yasuko Terada, Tomohiro Usui, Sohei Wada, Meenakshi Wadhwa, Richard J. Walker, Katsuyuki Yamashita, Qing Zhu Yin, Tetsuya Yokoyama, Shigekazu Yoneda, Edward D. Young, Hiroharu Yui, Ai Cheng Zhang, Tomoki Nakamura, Hiroshi Naraoka, Takaaki Noguchi, Ryuji Okazaki, Kanako Sakamoto, Hikaru Yabuta, Masanao Abe, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Tatsuaki Okada, Toru Yada, Kasumi Yogata, Satoru Nakazawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Yuichi Tsuda, Sei Ichiro Watanabe, Makoto Yoshikawa, Shogo Tachibana, Hisayoshi Yurimoto
    Science Advances 8(46) 2022年11月  
    Little is known about the origin of the spectral diversity of asteroids and what it says about conditions in the protoplanetary disk. Here, we show that samples returned from Cb-type asteroid Ryugu have Fe isotopic anomalies indistinguishable from Ivuna-type (CI) chondrites, which are distinct from all other carbonaceous chondrites. Iron isotopes, therefore, demonstrate that Ryugu and CI chondrites formed in a reservoir that was different from the source regions of other carbonaceous asteroids. Growth and migration of the giant planets destabilized nearby planetesimals and ejected some inward to be implanted into the Main Belt. In this framework, most carbonaceous chondrites may have originated from regions around the birthplaces of Jupiter and Saturn, while the distinct isotopic composition of CI chondrites and Ryugu may reflect their formation further away in the disk, owing their presence in the inner Solar System to excitation by Uranus and Neptune.
  • Masahiko Sato, Yuki Kimura, Satoshi Tanaka, Tadahiro Hatakeyama, Seiji Sugita, Tomoki Nakamuna, Shogo Tachibana, 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
    Journal of Geophysical Research: Planets 127(11) 2022年11月  
  • Ryuji Okazaki, Bernard Marty, Henner Busemann, Ko Hashizume, Jamie D. Gilmour, Alex Meshik, Toru Yada, Fumio Kitajima, Michael W. Broadley, David Byrne, Evelyn Füri, My E. I. Riebe, Daniela Krietsch, Colin Maden, Akizumi Ishida, Patricia Clay, Sarah A. Crowther, Lydia Fawcett, Thomas Lawton, Olga Pravdivtseva, Yayoi N. Miura, Jisun Park, Ken-ichi Bajo, Yoshinori Takano, Keita Yamada, Shinsuke Kawagucci, Yohei Matsui, Mizuki Yamamoto, Kevin Righter, Saburo Sakai, Naoyoshi Iwata, Naoki Shirai, Shun Sekimoto, Makoto Inagaki, Mitsuru Ebihara, Reika Yokochi, Kunihiko Nishiizumi, Keisuke Nagao, Jong Ik Lee, Akihiro Kano, Marc W. Caffee, Ryu Uemura, Tomoki Nakamura, Hiroshi Naraoka, Takaaki Noguchi, Hikaru Yabuta, Hisayoshi Yurimoto, Shogo Tachibana, Hirotaka Sawada, Kanako Sakamoto, Masanao Abe, Masahiko Arakawa, Atsushi Fujii, Masahiko Hayakawa, Naoyuki Hirata, Naru Hirata, Rie Honda, Chikatoshi Honda, Satoshi Hosoda, Yu-ichi Iijima, Hitoshi Ikeda, Masateru Ishiguro, Yoshiaki Ishihara, Takahiro Iwata, Kosuke Kawahara, Shota Kikuchi, Kohei Kitazato, Koji Matsumoto, Moe Matsuoka, Tatsuhiro Michikami, Yuya Mimasu, Akira Miura, Tomokatsu Morota, Satoru Nakazawa, Noriyuki Namiki, Hirotomo Noda, Rina Noguchi, Naoko Ogawa, Kazunori Ogawa, Tatsuaki Okada, Chisato Okamoto, Go Ono, Masanobu Ozaki, Takanao Saiki, Naoya Sakatani, Hiroki Senshu, Yuri Shimaki, Kei Shirai, Seiji Sugita, Yuto Takei, Hiroshi Takeuchi, Satoshi Tanaka, Eri Tatsumi, Fuyuto Terui, Ryudo Tsukizaki, Koji Wada, Manabu Yamada, Tetsuya Yamada, Yukio Yamamoto, Hajime Yano, Yasuhiro Yokota, Keisuke Yoshihara, Makoto Yoshikawa, Kent Yoshikawa, Shizuho Furuya, Kentaro Hatakeda, Tasuku Hayashi, Yuya Hitomi, Kazuya Kumagai, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Hiromichi Soejima, Ayako Iwamae, Daiki Yamamoto, Kasumi Yogata, Miwa Yoshitake, Ryota Fukai, Tomohiro Usui, Harold C. Connolly, Dante Lauretta, Sei-ichiro Watanabe, Yuichi Tsuda
    Science 379(6634) 2022年10月20日  
    The near-Earth carbonaceous asteroid (162173) Ryugu is expected to contain volatile chemical species that could provide information on the origin of Earth’s volatiles. Samples of Ryugu were retrieved by the Hayabusa2 spacecraft. We measure noble gas and nitrogen isotopes in Ryugu samples, finding they are dominated by pre-solar and primordial components, incorporated during Solar System formation. Noble gas concentrations are higher than those in Ivuna-type carbonaceous (CI) chondrite meteorites. Several host phases of isotopically distinct nitrogen have heterogeneous abundances between the samples. Our measurements support a close relationship between Ryugu and CI chondrites. Noble gases produced by galactic cosmic rays, indicating ~5 Myr exposure, and from implanted solar wind, record the recent irradiation history of Ryugu after it migrated to its current orbit.
  • F. Moynier, W. Dai, T. Yokoyama, Y. Hu, M. Paquet, Y. Abe, J. Aléon, C.M.O'D Alexander, S. Amari, Y. Amelin, K.-I. Bajo, M. Bizzarro, A. Bouvier, R.W. Carlson, M. Chaussidon, B.-G. Choi, N. Dauphas, A.M. Davis, T. Di Rocco, W. Fujiya, R. Fukai, I. Gautam, M.K. Haba, Y. Hibiya, H. Hidaka, H. Homma, P. Hoppe, G.R. Huss, K. Ichida, T. Iizuka, T.R. Ireland, A. Ishikawa, M. Ito, S. Itoh, N. Kawasaki, N.T. Kita, K. Kitajima, T. Kleine, S. Komatani, A.N. Krot, M.-C. Liu, Y. Masuda, K.D. McKeegan, M. Morita, K. Motomura, I. Nakai, K. Nagashima, D. Nesvorný, A. Nguyen, L. Nittler, M. Onose, A. Pack, C. Park, L. Piani, L. Qin, S.S. Russell, N. Sakamoto, M. Schönbächler, L. Tafla, H. Tang, K. Terada, Y. Terada, T. Usui, S. Wada, M. Wadhwa, R.J. Walker, K. Yamashita, Q.-Z. Yin, S. Yoneda, E.D. Young, H. Yui, A.-C. Zhang, T. Nakamura, H. Naraoka, T. Noguchi, R. Okazaki, K. Sakamoto, H. Yabuta, M. Abe, A. Miyazaki, A. Nakato, M. Nishimura, T. Okada, T. Yada, K. Yogata, S. Nakazawa, T. Saiki, S. Tanaka, F. Terui, Y. Tsuda, S.-I. Watanabe, M. Yoshikawa, S. Tachibana, H. Yurimoto
    Geochemical Perspectives Letters 24 1-6 2022年10月  
  • T. Nakamura, M. Matsumoto, K. Amano, Y. Enokido, M. E. Zolensky, T. Mikouchi, H. Genda, S. Tanaka, M. Y. Zolotov, K. Kurosawa, S. Wakita, R. Hyodo, H. Nagano, D. Nakashima, Y. Takahashi, Y. Fujioka, M. Kikuiri, E. Kagawa, M. Matsuoka, A. J. Brearley, A. Tsuchiyama, M. Uesugi, J. Matsuno, Y. Kimura, M. Sato, R. E. Milliken, E. Tatsumi, S. Sugita, T. Hiroi, K. Kitazato, D. Brownlee, D. J. Joswiak, M. Takahashi, K. Ninomiya, T. Takahashi, T. Osawa, K. Terada, F. E. Brenker, B. J. Tkalcec, L. Vincze, R. Brunetto, A. Aléon-Toppani, Q. H. S. Chan, M. Roskosz, J.-C. Viennet, P. Beck, E. E. Alp, T. Michikami, Y. Nagaashi, T. Tsuji, Y. Ino, J. Martinez, J. Han, A. Dolocan, R. J. Bodnar, M. Tanaka, H. Yoshida, K. Sugiyama, A. J. King, K. Fukushi, H. Suga, S. Yamashita, T. Kawai, K. Inoue, A. Nakato, T. Noguchi, F. Vilas, A. R. Hendrix, C. Jaramillo-Correa, D. L. Domingue, G. Dominguez, Z. Gainsforth, C. Engrand, J. Duprat, S. S. Russell, E. Bonato, C. Ma, T. Kawamoto, T. Wada, S. Watanabe, R. Endo, S. Enju, L. Riu, S. Rubino, P. Tack, S. Takeshita, Y. Takeichi, A. Takeuchi, A. Takigawa, D. Takir, T. Tanigaki, A. Taniguchi, K. Tsukamoto, T. Yagi, S. Yamada, K. Yamamoto, Y. Yamashita, M. Yasutake, K. Uesugi, I. Umegaki, I. Chiu, T. Ishizaki, S. Okumura, E. Palomba, C. Pilorget, S. M. Potin, A. Alasli, S. Anada, Y. Araki, N. Sakatani, C. Schultz, O. Sekizawa, S. D. Sitzman, K. Sugiura, M. Sun, E. Dartois, E. De Pauw, Z. Dionnet, Z. Djouadi, G. Falkenberg, R. Fujita, T. Fukuma, I. R. Gearba, K. Hagiya, M. Y. Hu, T. Kato, T. Kawamura, M. Kimura, M. K. Kubo, F. Langenhorst, C. Lantz, B. Lavina, M. Lindner, J. Zhao, B. Vekemans, D. Baklouti, B. Bazi, F. Borondics, S. Nagasawa, G. Nishiyama, K. Nitta, J. Mathurin, T. Matsumoto, I. Mitsukawa, H. Miura, A. Miyake, Y. Miyake, H. Yurimoto, R. Okazaki, H. Yabuta, H. Naraoka, K. Sakamoto, S. Tachibana, H. C. Connolly, D. S. Lauretta, M. Yoshitake, M. Yoshikawa, K. Yoshikawa, K. Yoshihara, Y. Yokota, K. Yogata, H. Yano, Y. Yamamoto, D. Yamamoto, M. Yamada, T. Yamada, T. Yada, K. Wada, T. Usui, R. Tsukizaki, F. Terui, H. Takeuchi, Y. Takei, A. Iwamae, H. Soejima, K. Shirai, Y. Shimaki, H. Senshu, H. Sawada, T. Saiki, M. Ozaki, G. Ono, T. Okada, N. Ogawa, K. Ogawa, R. Noguchi, H. Noda, M. Nishimura, N. Namiki, S. Nakazawa, T. Morota, A. Miyazaki, A. Miura, Y. Mimasu, K. Matsumoto, K. Kumagai, T. Kouyama, S. Kikuchi, K. Kawahara, S. Kameda, T. Iwata, Y. Ishihara, M. Ishiguro, H. Ikeda, S. Hosoda, R. Honda, C. Honda, Y. Hitomi, N. Hirata, N. Hirata, T. Hayashi, M. Hayakawa, K. Hatakeda, S. Furuya, R. Fukai, A. Fujii, Y. Cho, M. Arakawa, M. Abe, S. Watanabe, Y. Tsuda
    Science 379(6634) 2022年9月22日  
    Samples of the carbonaceous asteroid Ryugu were brought to Earth by the Hayabusa2 spacecraft. We analyzed seventeen Ryugu samples measuring 1-8 mm. CO 2 -bearing water inclusions are present within a pyrrhotite crystal, indicating that Ryugu’s parent asteroid formed in the outer Solar System. The samples contain low abundances of materials that formed at high temperatures, such as chondrules and Ca, Al-rich inclusions. The samples are rich in phyllosilicates and carbonates, which formed by aqueous alteration reactions at low temperature, high pH, and water/rock ratios &lt; 1 (by mass). Less altered fragments contain olivine, pyroxene, amorphous silicates, calcite, and phosphide. Numerical simulations, based on the mineralogical and physical properties of the samples, indicate Ryugu’s parent body formed ~ 2 million years after the beginning of Solar System formation.
  • Ming-Chang Liu, Kaitlyn A. McCain, Nozomi Matsuda, Akira Yamaguchi, Makoto Kimura, Naotaka Tomioka, Motoo Ito, Masayuki Uesugi, Naoya Imae, Naoki Shirai, Takuji Ohigashi, Richard C. Greenwood, Kentaro Uesugi, Aiko Nakato, Kasumi Yogata, Hayato Yuzawa, Yu Kodama, Kaori Hirahara, Ikuya Sakurai, Ikuo Okada, Yuzuru Karouji, Satoru Nakazawa, Tatsuaki Okada, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Makoto Yoshikawa, Akiko Miyazaki, Masahiro Nishimura, Toru Yada, Masanao Abe, Tomohiro Usui, Sei-ichiro Watanabe, Yuichi Tsuda
    Nature Astronomy 6(10) 1172-1177 2022年9月1日  
  • Daisuke Nakashima, Tomoki Nakamura, Mingming Zhang, Noriko Kita, Takashi Mikouchi, Hideto Yoshida, Yuma Enokido, Tomoyo Morita, Mizuha Kikuiri, Kana Amano, Eiichi Kagawa, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Satoru Nakazawa, Fuyuto Terui, Hisayoshi Yurimoto, Takaaki Noguchi, Hikaru Yabuta, Hiroshi Naraoka, Ryuji Okazaki, Kanako Sakamoto, Sei-ichiro Watanabe, Shogo Tachibana, Yuichi Tsuda
    2022年8月29日  
    Abstract Chondrule-like objects and Ca-Al-rich inclusions (CAIs) are discovered in the retuned samples from asteroid Ryugu. Three chondrule-like objects, which are 16O-rich and -poor with D17O (= d17O – 0.52 × d18O) values of ~ − 23‰ and ~ − 3‰, are dominated by Mg-rich olivine, resembling what proposed as earlier generations of chondrules. The 16O-rich objects are likely to be melted amoeboid olivine aggregates that escaped from incorporation into 16O-poor chondrule precursor dust. Two CAIs composed of spinel, hibonite, and perovskite are 16O-rich with D17O of ~ − 23‰ and possibly as old as the oldest CAIs. The chondrule-like objects and CAIs (&lt; 30 µm) are as small as those from comets, suggesting radial transport favoring smaller objects from the inner solar nebula to the formation location of the Ryugu original parent body, which is farther from the Sun and scarce in chondrules. The transported objects may have been mostly destroyed during aqueous alteration.
  • Motoo Ito, Naotaka Tomioka, Masayuki Uesugi, Akira Yamaguchi, Naoki Shirai, Takuji Ohigashi, Ming-Chang Liu, Richard C. Greenwood, Makoto Kimura, Naoya Imae, Kentaro Uesugi, Aiko Nakato, Kasumi Yogata, Hayato Yuzawa, Yu Kodama, Akira Tsuchiyama, Masahiro Yasutake, Ross Findlay, Ian A. Franchi, James A. Malley, Kaitlyn A. McCain, Nozomi Matsuda, Kevin D. McKeegan, Kaori Hirahara, Akihisa Takeuchi, Shun Sekimoto, Ikuya Sakurai, Ikuo Okada, Yuzuru Karouji, Masahiko Arakawa, Atsushi Fujii, Masaki Fujimoto, Masahiko Hayakawa, Naoyuki Hirata, Naru Hirata, Rie Honda, Chikatoshi Honda, Satoshi Hosoda, Yu-ichi Iijima, Hitoshi Ikeda, Masateru Ishiguro, Yoshiaki Ishihara, Takahiro Iwata, Kosuke Kawahara, Shota Kikuchi, Kohei Kitazato, Koji Matsumoto, Moe Matsuoka, Tatsuhiro Michikami, Yuya Mimasu, Akira Miura, Osamu Mori, Tomokatsu Morota, Satoru Nakazawa, Noriyuki Namiki, Hirotomo Noda, Rina Noguchi, Naoko Ogawa, Kazunori Ogawa, Tatsuaki Okada, Chisato Okamoto, Go Ono, Masanobu Ozaki, Takanao Saiki, Naoya Sakatani, Hirotaka Sawada, Hiroki Senshu, Yuri Shimaki, Kei Shirai, Seiji Sugita, Yuto Takei, Hiroshi Takeuchi, Satoshi Tanaka, Eri Tatsumi, Fuyuto Terui, Ryudo Tsukizaki, Koji Wada, Manabu Yamada, Tetsuya Yamada, Yukio Yamamoto, Hajime Yano, Yasuhiro Yokota, Keisuke Yoshihara, Makoto Yoshikawa, Kent Yoshikawa, Ryota Fukai, Shizuho Furuya, Kentaro Hatakeda, Tasuku Hayashi, Yuya Hitomi, Kazuya Kumagai, Akiko Miyazaki, Masahiro Nishimura, Hiromichi Soejima, Ayako Iwamae, Daiki Yamamoto, Miwa Yoshitake, Toru Yada, Masanao Abe, Tomohiro Usui, Sei-ichiro Watanabe, Yuichi Tsuda
    Nature Astronomy 6(10) 1163-1171 2022年8月15日  
    Abstract Volatile and organic-rich C-type asteroids may have been one of the main sources of Earth’s water. Our best insight into their chemistry is currently provided by carbonaceous chondritic meteorites, but the meteorite record is biased: only the strongest types survive atmospheric entry and are then modified by interaction with the terrestrial environment. Here we present the results of a detailed bulk and microanalytical study of pristine Ryugu particles, brought to Earth by the Hayabusa2 spacecraft. Ryugu particles display a close compositional match with the chemically unfractionated, but aqueously altered, CI (Ivuna-type) chondrites, which are widely used as a proxy for the bulk Solar System composition. The sample shows an intricate spatial relationship between aliphatic-rich organics and phyllosilicates and indicates maximum temperatures of ~30 °C during aqueous alteration. We find that heavy hydrogen and nitrogen abundances are consistent with an outer Solar System origin. Ryugu particles are the most uncontaminated and unfractionated extraterrestrial materials studied so far, and provide the best available match to the bulk Solar System composition.
  • Aiko NAKATO, Toru Yada, Masahiro Nishimura, Kasumi Yogata, Akiko Miyazaki, Kana Nagashima, Kentaro Hatakeda, Kazuya Kumagai, Yuya Hitomi, Hiromichi Soejima, Jean-Pierre Bibring, Cedric Pilorget, Vincent Hamm, Rosario Brunetto, Lucie Riu, Lionel Lourit, Damien Loizeau, Tania Le Pivert-Jolivet, Guillaume Lequertier, Aurelie Moussi-Soffys, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Satoru Nakazawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Makoto Yoshikawa, Sei-ichiro Watanabe, Yuichi Tsuda
    2022年8月3日  
    Abstract Hayabusa2 spacecraft successfully collected rock samples through two touchdowns from the surface of C-type near-Earth asteroid 162173 Ryugu and brought them back to Earth in 2020. At the Extraterrestrial Sample Curation Center in JAXA, we performed initial description to all samples to obtain the fundamental information and prepare the database for sample allocation. We propose morphological classifications for the returned samples based on the initial description of 205 grains described in the first 6 months. The returned samples can be distinguished by four morphological characteristics: dark, glossy, bright, and white. According to coordinated study of initial description and detailed investigation by scanning electron microscopy and X-ray diffraction analysis in this study, these features reflect the differences in the degree of space weathering and mineral assemblages. The degree of space weathering of the four studied grains is heterogeneous: weak for A0042 (dark group) and C0041 (white group); moderate for C0094 (glossy); and severe for A0017 (bright). The white phase in a grain belonging to white group is identified as large carbonate minerals. This is the first effort to classify Ryugu returned samples. Based on these results, researchers can estimate sample characteristics only from the information on the JAXA curation public database. It could be an important reference for sample selection for further investigation.
  • A. Galiano, E. Palomba, F. Dirri, A. Longobardo, K. Kitazato, T. Iwata, M. Matsuoka, T. Hiroi, D. Takir, T. Nakamura, M. Abe, M. Ohtake, S. Matsuura, S. Watanabe, M. Yoshikawa, T. Saiki, S. Tanaka, T. Okada, Y. Yamamoto, Y. Takei, K. Shirai, N. Hirata, K. Matsumoto, Y. Tsuda
    Monthly Notices of the Royal Astronomical Society 514(4) 6173-6182 2022年8月1日  
    The JAXA Hayabusa2 mission accomplished the formation of an artificial crater on the asteroid Ryugu. The aim of this work is to analyse the area surrounding the artificial crater and reveal spectral variability compared to the same region before the crater formation, to mineralogically and physically characterize the subsurface exposed material. The crater's investigation focused on the analysis of two regions corresponding to the inner part of crater (the pit and the crater wall/floor), two areas related to ejecta deposited close to the crater, two areas of ejecta moved far from the crater, and two external areas. Each area was investigated both before and after the crater formation, by the study of the photometrically corrected spectral parameters: the 1.9 μm reflectance, the near-infrared spectral slope, and the depth of the bands at 2.7 and 2.8 μm. The subsurface material of the post-crater areas shows deeper absorption bands, a decrease in reflectance, and a reddening in spectral slope with respect to the surface material of pre-crater areas. The subsurface regolith could have experienced a lower OH devolatilization due to space weathering and/or could be composed of finer dark grains than the surface layer. The ejecta reached distances of ~20 m from the impact point, mainly moving in the northern direction; nevertheless, a few ejecta also reached the south-eastern part of crater.
  • Minako Hashiguchi, Dan Aoki, Kazuhiko Fukushima, Hiroshi Naraoka, Yoshinori Takano, Dworkin P. Jason, Aponte C. Jose, Elsila E. Jamie, Eiler M. John, Yoshihiro Furukawa, Aogu Furusho, Glavin P. Daniel, Heather V. Graham, Kenji Hamase, Hertkorn Norbert, Junko Isa, Toshiki Koga, McLain L. Hannah, Hajime Mita, Yasuhiro Oba, Nanako O. Ogawa, Naohiko Ohkouchi, Francois-Regis Orthous-Daunay, Eric T. Parker, Ruf Alexander, Saburo Sakaki, Schmitt-Kopplin Philippe, Haruna Sugahara, Thissen Roland, Vuitton Véronique, Cédric Wolters, Toshihiro Yoshimura, Hisayoshi Yurimoto, Tomoki Nakamura, Takaaki Noguchi, Ryuji Okazaki, Hikaru Yabuta, Kanako Sakamoto, Shogo Tachibana, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tomohiro Usui, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Satoru Nakazawa, Sei-ichiro Watanabe, Yuichi Tsuda
    2022年7月25日  
    Abstract We performed in-situ analysis on a ~1 mm-sized Ryugu grain A0080 returned by the Hayabusa2 spacecraft to investigate the relationship of soluble organic matter (SOM) to minerals. The DESI-HRMS (desorption electrospray ionization-high resolution mass spectrometry) imaging using methanol spray identified more than 200 soluble organic compounds, which were assigned as CHN, CHO, CHO-Na (sodium adducted), and CHNO in molecular composition. Heterogeneous spatial distribution was observed for different compound classes of SOM as well as among the same alkylated homologues on the sample surface. The A0080 sample showed similar mineralogy to that of CI chondrite and contained two different lithologies, which are rich in magnetite, pyrrhotite, and dolomite (lithology 1) and poor in those minerals (lithology 2). CHN compounds were relatively concentrated in lithology 1 than in lithology 2, on the other hand, CHO, CHO-Na, and CHNO compounds were distributed in both lithologies. Such different spatial distribution of SOM is the result of interaction of the SOM with minerals, during precipitation of the SOM via fluid activity, or could be due to difference in transportation efficiencies of SOMs in aqueous fluid. However, organic-related ions measured by ToF-SIMS did not coincide with the spatial distribution revealed by DESI-HRMS imaging, indicating that the ToF-SIMS data would be mainly derived from methanol-insoluble organic matter in A0080. Alkylated homologues of CHN compounds with large C number appeared more abundant in lithology 2 than lithology 1. In contrast, fragments of the Murchison meteorite showed different features to of A0080, implying different formation or growth mechanisms for the alkylated CHN compounds by interaction with fluid and minerals on Murchison parent body and asteroid Ryugu. This difference might be mainly attributed to the carbonate grains, which would have played as a catalyst for CH2 growth of CHN compounds. Future in-situ analysis of CI chondrite will provide more reliable constraints for the history of soluble organic compounds in asteroid Ryugu.
  • Tatsuhiro Michikami, Axel Hagermann, Tomokatsu Morota, Yasuhiro Yokota, Seitaro Urakawa, Hiroyuki Okamura, Naoya Tanabe, Koki Yumoto, Tatsuki Ebihara, Yuichiro Cho, Carolyn M. Ernst, Masahiko Hayakawa, Masatoshi Hirabayashi, Naru Hirata, Chikatoshi Honda, Rie Honda, Shingo Kameda, Masanori Kanamaru, Hiroshi Kikuchi, Shota Kikuchi, Toru Kouyama, Moe Matsuoka, Hideaki Miyamoto, Takaaki Noguchi, Rina Noguchi, Kazunori Ogawa, Tatsuaki Okada, Naoya Sakatani, Sho Sasaki, Hirotaka Sawada, Chiho Sugimoto, Hidehiko Suzuki, Satoshi Tanaka, Eri Tatsumi, Akira Tsuchiyama, Yuichi Tsuda, Sei ichiro Watanabe, Manabu Yamada, Makoto Yoshikawa, Kazuo Yoshioka, Seiji Sugita
    Icarus 381 2022年7月15日  査読有り
    Over a broad size range, the shapes of impact fragments from catastrophic disruptions are distributed around the mean axial ratio 2: √2: 1, irrespective of experimental conditions and target materials. Although most blocks on asteroids are likely to be impact fragments, there is not enough quantitative data for reliable statistics on their three-axial lengths and/or ratios because it is difficult to precisely estimate the heights of the blocks. In this study, we evaluate the heights of blocks on asteroid Ryugu by measuring their shadows. The three-axial ratios of ~4100 small blocks with diameters from 5.0 cm to 7.6 m in Ryugu's equatorial region are investigated using eight close-up images of narrower localities taken at altitudes below 500 m, i.e. at <5.4 cm/pixel resolution, obtained immediately before the second touch-down of the Hayabusa2 spacecraft. The purpose of this study is to investigate the block shape distribution, which is important for understanding the geological history of asteroid Ryugu. Specifically, the shape distribution is compared to laboratory impact fragments. Our observations indicate that the shape distributions of blocks smaller than 1 m on Ryugu are consistent with laboratory impact fragment shape distributions, implying that the dominant shape-determining process for blocks on Ryugu was impact fragmentation. Blocks several meters in size in the equatorial region seem to be slightly flatter than the rest, suggesting that some blocks are partly buried in a bed of regolith. In conclusion, the shape distributions of blocks from several-cm to several-m in the equatorial region of asteroid Ryugu suggest that these are mainly fragments originating from the catastrophic disruption of their parent body and/or from a later impact.
  • Eizo NAKAMURA, Katsura KOBAYASHI, Ryoji TANAKA, Tak KUNIHIRO, Hiroshi KITAGAWA, Christian POTISZIL, Tsutomu OTA, Chie SAKAGUCHI, Masahiro YAMANAKA, Dilan M. RATNAYAKE, Havishk TRIPATHI, Rahul KUMAR, Maya-Liliana AVRAMESCU, Hidehisa TSUCHIDA, Yusuke YACHI, Hitoshi MIURA, Masanao ABE, Ryota FUKAI, Shizuho FURUYA, Kentaro HATAKEDA, Tasuku HAYASHI, Yuya HITOMI, Kazuya KUMAGAI, Akiko MIYAZAKI, Aiko NAKATO, Masahiro NISHIMURA, Tatsuaki OKADA, Hiromichi SOEJIMA, Seiji SUGITA, Ayako SUZUKI, Tomohiro USUI, Toru YADA, Daiki YAMAMOTO, Kasumi YOGATA, Miwa YOSHITAKE, Masahiko ARAKAWA, Atsushi FUJII, Masahiko HAYAKAWA, Naoyuki HIRATA, Naru HIRATA, Rie HONDA, Chikatoshi HONDA, Satoshi HOSODA, Yu-ichi IIJIMA, Hitoshi IKEDA, Masateru ISHIGURO, Yoshiaki ISHIHARA, Takahiro IWATA, Kosuke KAWAHARA, Shota KIKUCHI, Kohei KITAZATO, Koji MATSUMOTO, Moe MATSUOKA, Tatsuhiro MICHIKAMI, Yuya MIMASU, Akira MIURA, Tomokatsu MOROTA, Satoru NAKAZAWA, Noriyuki NAMIKI, Hirotomo NODA, Rina NOGUCHI, Naoko OGAWA, Kazunori OGAWA, Chisato OKAMOTO, Go ONO, Masanobu OZAKI, Takanao SAIKI, Naoya SAKATANI, Hirotaka SAWADA, Hiroki SENSHU, Yuri SHIMAKI, Kei SHIRAI, Yuto TAKEI, Hiroshi TAKEUCHI, Satoshi TANAKA, Eri TATSUMI, Fuyuto TERUI, Ryudo TSUKIZAKI, Koji WADA, Manabu YAMADA, Tetsuya YAMADA, Yukio YAMAMOTO, Hajime YANO, Yasuhiro YOKOTA, Keisuke YOSHIHARA, Makoto YOSHIKAWA, Kent YOSHIKAWA, Masaki FUJIMOTO, Sei-ichiro WATANABE, Yuichi TSUDA
    Proceedings of the Japan Academy, Series B 98(6) 227-282 2022年6月10日  
  • Kaitlyn McCain, Nozomi Matsuda, Ming-Chang Liu, Kevin McKeegan, Akira Yamaguchi, Makoto Kimura, Naotaka Tomioka, Motoo Ito, Naoya Imae, Masayuki Uesugi, Naoki Shirai, Takuji Ohigashi, Richard Greenwood, Kentaro Uesugi, Aiko Nakato, Kasumi Yogata, Hayato Yuzawa, Yu Kodama, Kaori Hirahara, Ikuya Sakurai, Ikuo Okada, Yuzuru Karouji, Satoru Nakazawa, Tatsuaki Okada, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Makoto Yoshikawa, Akiko Miyazaki, Masahiro Nishimura, Toru Yada, Masanao Abe, Tomohiro Usui, Sei-ichiro Watanabe, Yuichi Tsuda
    2022年6月8日  

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