Research activity information

• Giant impact on early Ganymede and its subsequent reorientation

  Naoyuki Hirata

  Abstract Ganymede has an ancient impact structure called a furrow system. The furrow system is the largest impact structure in the outer solar system, and the impact should have significantly affected Ganymede’s early history; however, its effects are poorly understood. No attention has been given to the center of the furrow system coinciding with Ganymede's tidal axis, indicating that mass redistribution induced by the furrow-forming impact caused a reorientation (true polar wander) of Ganymede. We propose that the impact ejecta created a mass anomaly that reoriented the impact site toward the tidal axis. We found that an impactor with a radius of 150 km and an incidence angle between 60° and 90° most accurately reproduces the current location of the furrow system. We predict that future explorations would reveal remnant topographic profiles or gravity anomalies associated with the furrow-forming impact and reorientation. Additionally, various possible explanations for the reorientation of Ganymede, such as an impactor-origin mascon beneath the basin or a thickness variation in the lithosphere, should be studied.

  Springer Science and Business Media LLC, Sep. 2024, Scientific Reports, 14(1) (1), English

  [Refereed]

  Scientific journal


• Gravitational disturbance on asteroidal ring systems by close encounter with a small object

  Ren Ikeya, Naoyuki Hirata

  Last, Elsevier BV, Aug. 2024, Icarus, 418, 116153 - 116153, English

  [Refereed]

  Scientific journal


• Investigation of boulder distribution in (1) Ceres and insight into its surface evolution

  Mitsuha Noma, Naoyuki Hirata

  Corresponding, Elsevier BV, May 2024, Icarus, 414, 116031 - 116031, English

  [Refereed]

  Scientific journal


• Secondary Cratering From Rheasilvia as the Possible Origin of Vesta's Equatorial Troughs

  Naoyuki Hirata

  American Geophysical Union (AGU), Mar. 2023, Journal of Geophysical Research: Planets, 128(3) (3), English

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Soluble organic molecules in samples of the carbonaceous asteroid (162173) Ryugu

  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

  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.

  American Association for the Advancement of Science (AAAS), Feb. 2023, Science, 379(6634) (6634)

  [Refereed]

  Scientific journal


• Macromolecular organic matter in samples of the asteroid (162173) Ryugu.

  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 Jr, 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

  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.

  Feb. 2023, Science (New York, N.Y.), 379(6634) (6634), eabn9057, English, International magazine

  [Refereed]

  Scientific journal


• Noble gases and nitrogen in samples of asteroid Ryugu record its volatile sources and recent surface evolution

  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

  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 measured noble gas and nitrogen isotopes in Ryugu samples and found that they are dominated by presolar 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 different abundances among the samples. Our measurements support a close relationship between Ryugu and CI chondrites. Noble gases produced by galactic cosmic rays, indicating a ~5 million year exposure, and from implanted solar wind record the recent irradiation history of Ryugu after it migrated to its current orbit.

  American Association for the Advancement of Science (AAAS), Feb. 2023, Science, 379(6634) (6634)

  [Refereed]

  Scientific journal


• Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meteorites

  Tetsuya Yokoyama, Kazuhide Nagashima, Izumi Nakai, Edward D. Young, 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, 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, Frédéric Moynier, 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, Shigekazu Yoneda, Hiroharu Yui, Ai-Cheng Zhang, Harold C. Connolly, Dante S. Lauretta, Tomoki Nakamura, Hiroshi Naraoka, Takaaki Noguchi, Ryuji Okazaki, Kanako Sakamoto, Hikaru Yabuta, 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, Hirotaka Sawada, Hiroki Senshu, Yuri Shimaki, Kei Shirai, Seiji Sugita, Yuto Takei, Hiroshi Takeuchi, Satoshi Tanaka, Eri Tatsumi, Fuyuto Terui, Yuichi Tsuda, Ryudo Tsukizaki, Koji Wada, Sei-ichiro Watanabe, 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 Suzuki, Toru Yada, Daiki Yamamoto, Kasumi Yogata, Miwa Yoshitake, Shogo Tachibana, Hisayoshi Yurimoto

  Carbonaceous meteorites are thought to be fragments of C-type (carbonaceous) asteroids. Samples of the C-type asteroid (162173) Ryugu were retrieved by the Hayabusa2 spacecraft. We measured the mineralogy and bulk chemical and isotopic compositions of Ryugu samples. The samples are mainly composed of materials similar to those of carbonaceous chondrite meteorites, particularly the CI (Ivuna-type) group. The samples consist predominantly of minerals formed in aqueous fluid on a parent planetesimal. The primary minerals were altered by fluids at a temperature of 37° ± 10°C, about million (statistical) or million (systematic) years after the formation of the first solids in the Solar System. After aqueous alteration, the Ryugu samples were likely never heated above ~100°C. The samples have a chemical composition that more closely resembles that of the Sun’s photosphere than other natural samples do.

  American Association for the Advancement of Science (AAAS), Feb. 2023, Science, 379(6634) (6634)

  [Refereed]

  Scientific journal


• A dehydrated space-weathered skin cloaking the hydrated interior of Ryugu.

  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 Jr, 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

  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.

  2023, Nature astronomy, 7(2) (2), 170 - 181, English, International magazine

  [Refereed]

  Scientific journal


• First asteroid gas sample delivered by the Hayabusa2 mission: A treasure box from Ryugu

  Ryuji Okazaki, Yayoi N. Miura, Yoshinori Takano, Hirotaka Sawada, Kanako Sakamoto, Toru Yada, Keita Yamada, Shinsuke Kawagucci, Yohei Matsui, Ko Hashizume, Akizumi Ishida, Michael W. Broadley, Bernard Marty, David Byrne, Evelyn Füri, Alex Meshik, Olga Pravdivtseva, Henner Busemann, My E.I. Riebe, Jamie Gilmour, Jisun Park, Ken-ichi Bajo, Kevin Righter, Saburo Sakai, Shun Sekimoto, Fumio Kitajima, Sarah A. Crowther, Naoyoshi Iwata, Naoki Shirai, Mitsuru Ebihara, Reika Yokochi, Kunihiko Nishiizumi, Keisuke Nagao, Jong Ik Lee, Patricia Clay, Akihiro Kano, Marc W. Caffee, Ryu Uemura, Makoto Inagaki, Daniela Krietsch, Colin Maden, Mizuki Yamamoto, Lydia Fawcett, Thomas Lawton, Tomoki Nakamura, Hiroshi Naraoka, Takaaki Noguchi, Hikaru Yabuta, Hisayoshi Yurimoto, Yuichi Tsuda, Sei-ichiro Watanabe, 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, Trevor Ireland, Harold C. Connolly, Dante S. Lauretta, Shogo Tachibana

  The Hayabusa2 spacecraft returned to Earth from the asteroid 162173 Ryugu on 6 December 2020. One day after the recovery, the gas species retained in the sample container were extracted and measured on-site and stored in gas collection bottles. The container gas consists of helium and neon with an extraterrestrial ³ He/ ⁴ He and ²⁰ Ne/ ²² Ne ratios, along with some contaminant terrestrial atmospheric gases. A mixture of solar and Earth’s atmospheric gas is the best explanation for the container gas composition. Fragmentation of Ryugu grains within the sample container is discussed on the basis of the estimated amount of indigenous He and the size distribution of the recovered Ryugu grains. This is the first successful return of gas species from a near-Earth asteroid.

  American Association for the Advancement of Science (AAAS), Nov. 2022, Science Advances, 8(46) (46)

  [Refereed]

  Scientific journal


• A pristine record of outer Solar System materials from asteroid Ryugu’s returned sample

  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

  Oct. 2022, Nature Astronomy, 6(10) (10), 1163 - 1171

  [Refereed]

  Scientific journal


• On the origin and evolution of the asteroid Ryugu: A comprehensive geochemical perspective

  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

  Japan Academy, Jun. 2022, Proceedings of the Japan Academy, Series B, 98(6) (6), 227 - 282

  [Refereed]

  Scientific journal


• Site selection for the Hayabusa2 artificial cratering and subsurface material sampling on Ryugu

  Shota Kikuchi, Sei-ichiro Watanabe, Koji Wada, Takanao Saiki, Hikaru Yabuta, Seiji Sugita, Masanao Abe, Masahiko Arakawa, Yuichiro Cho, Masahiko Hayakawa, Naoyuki Hirata, Naru Hirata, Chikatoshi Honda, Rie Honda, Ko Ishibashi, Yoshiaki Ishihara, Takahiro Iwata, Toshihiko Kadono, Shingo Kameda, Kohei Kitazato, Toru Kouyama, Koji Matsumoto, Moe Matsuoka, Tatsuhiro Michikami, Yuya Mimasu, Akira Miura, Tomokatsu Morota, Tomoki Nakamura, Satoru Nakazawa, Noriyuki Namiki, Rina Noguchi, Kazunori Ogawa, Naoko Ogawa, Tatsuaki Okada, Go Ono, Naoya Sakatani, Hirotaka Sawada, Hiroki Senshu, Yuri Shimaki, Kei Shirai, Shogo Tachibana, Yuto Takei, Satoshi Tanaka, Eri Tatsumi, Fuyuto Terui, Manabu Yamada, Yukio Yamamoto, Yasuhiro Yokota, Kent Yoshikawa, Makoto Yoshikawa, Yuichi Tsuda

  Elsevier BV, Jun. 2022, Planetary and Space Science, 219, 105519 - 105519

  [Refereed]

  Scientific journal


• Kilometer-scale crater size-frequency distributions on Ceres

  Kosei Toyokawa, Junichi Haruyama, Naoyuki Hirata, Sayuri Tanaka, Takahiro Iwata

  Elsevier BV, May 2022, Icarus, 377, 114909 - 114909, English

  [Refereed]

  Scientific journal


• Disruption of Saturn's ring particles by thermal stress

  Naoyuki Hirata, Ryuji Morishima, Keiji Ohtsuki, Akiko M. Nakamura

  Elsevier BV, May 2022, Icarus, 378, 114919 - 114919, English

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Dust release from cold ring particles as a mechanism of spoke formation in Saturn's rings

  Naoyuki Hirata, Hiroshi Kimura, Keiji Ohtsuki

  Elsevier BV, May 2022, Icarus, 378, 114920 - 114920, English

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Electrostatic dust ejection from asteroid (3200) Phaethon with the aid of mobile alkali ions at perihelion

  Hiroshi Kimura, Katsuhito Ohtsuka, Shota Kikuchi, Keiji Ohtsuki, Tomoko Arai, Fumi Yoshida, Naoyuki Hirata, Hiroki Senshu, Koji Wada, Takayuki Hirai, Peng K. Hong, Masanori Kobayashi, Ko Ishibashi, Manabu Yamada, Takaya Okamoto

  Elsevier BV, Apr. 2022, Icarus, 382, 115022 - 115022, English

  [Refereed]

  Scientific journal


• Pebbles and sand on asteroid (162173) Ryugu: In situ observation and particles returned to Earth

  S. Tachibana, H. Sawada, R. Okazaki, Y. Takano, K. Sakamoto, Y. N. Miura, C. Okamoto, H. Yano, S. Yamanouchi, P. Michel, Y. Zhang, S. Schwartz, F. Thuillet, H. Yurimoto, T. Nakamura, T. Noguchi, H. Yabuta, H. Naraoka, A. Tsuchiyama, N. Imae, K. Kurosawa, A. M. Nakamura, K. Ogawa, S. Sugita, T. Morota, R. Honda, S. Kameda, E. Tatsumi, Y. Cho, K. Yoshioka, Y. Yokota, M. Hayakawa, M. Matsuoka, N. Sakatani, M. Yamada, T. Kouyama, H. Suzuki, C. Honda, T. Yoshimitsu, T. Kubota, H. Demura, T. Yada, M. Nishimura, K. Yogata, A. Nakato, M. Yoshitake, A. I. Suzuki, S. Furuya, K. Hatakeda, A. Miyazaki, K. Kumagai, T. Okada, M. Abe, T. Usui, T. R. Ireland, M. Fujimoto, T. Yamada, M. Arakawa, H. C. Connolly, A. Fujii, S. Hasegawa, N. Hirata, N. Hirata, C. Hirose, S. Hosoda, Y. Iijima, H. Ikeda, M. Ishiguro, Y. Ishihara, T. Iwata, S. Kikuchi, K. Kitazato, D. S. Lauretta, G. Libourel, B. Marty, K. Matsumoto, T. Michikami, Y. Mimasu, A. Miura, O. Mori, K. Nakamura-Messenger, N. Namiki, A. N. Nguyen, L. R. Nittler, H. Noda, R. Noguchi, N. Ogawa, G. Ono, M. Ozaki, H. Senshu, T. Shimada, Y. Shimaki, K. Shirai, S. Soldini, T. Takahashi, Y. Takei, H. Takeuchi, R. Tsukizaki, K. Wada, Y. Yamamoto, K. Yoshikawa, K. Yumoto, M. E. Zolensky, S. Nakazawa, F. Terui, S. Tanaka, T. Saiki, M. Yoshikawa, S. Watanabe, Y. Tsuda

  The Hayabusa2 spacecraft investigated the C-type (carbonaceous) asteroid (162173) Ryugu. The mission performed two landing operations to collect samples of surface and subsurface material, the latter exposed by an artificial impact. We present images of the second touchdown site, finding that ejecta from the impact crater was present at the sample location. Surface pebbles at both landing sites show morphological variations ranging from rugged to smooth, similar to Ryugu’s boulders, and shapes from quasi-spherical to flattened. The samples were returned to Earth on 6 December 2020. We describe the morphology of >5 grams of returned pebbles and sand. Their diverse color, shape, and structure are consistent with the observed materials of Ryugu; we conclude that they are a representative sample of the asteroid.

  American Association for the Advancement of Science (AAAS), Mar. 2022, Science, 375(6584) (6584), 1011 - 1016

  [Refereed]

  Scientific journal


• Preliminary analysis of the Hayabusa2 samples returned from C-type asteroid Ryugu

  Toru Yada, Masanao Abe, Tatsuaki Okada, Aiko Nakato, Kasumi Yogata, Akiko Miyazaki, Kentaro Hatakeda, Kazuya Kumagai, Masahiro Nishimura, Yuya Hitomi, Hiromichi Soejima, Miwa Yoshitake, Ayako Iwamae, Shizuho Furuya, Masayuki Uesugi, Yuzuru Karouji, Tomohiro Usui, Tasuku Hayashi, Daiki Yamamoto, Ryota Fukai, Seiji Sugita, Yuichiro Cho, Koki Yumoto, Yuna Yabe, Jean-Pierre Bibring, Cedric Pilorget, Vincent Hamm, Rosario Brunetto, Lucie Riu, Lionel Lourit, Damien Loizeau, Guillaume Lequertier, Aurelie Moussi-Soffys, Shogo Tachibana, Hirotaka Sawada, Ryuji Okazaki, Yoshinori Takano, Kanako Sakamoto, Yayoi N. Miura, Hajime Yano, Trevor R. Ireland, Tetsuya Yamada, Masaki Fujimoto, Kohei Kitazato, Noriyuki Namiki, Masahiko Arakawa, Naru Hirata, Hisayoshi Yurimoto, Tomoki Nakamura, Takaaki Noguchi, Hikaru Yabuta, Hiroshi Naraoka, Motoo Ito, Eizo Nakamura, Kentaro Uesugi, Katsura Kobayashi, Tatsuhiro Michikami, Hiroshi Kikuchi, Naoyuki Hirata, Yoshiaki Ishihara, Koji Matsumoto, Hirotomo Noda, Rina Noguchi, Yuri Shimaki, Kei Shirai, Kazunori Ogawa, Koji Wada, Hiroki Senshu, Yukio Yamamoto, Tomokatsu Morota, Rie Honda, Chikatoshi Honda, Yasuhiro Yokota, Moe Matsuoka, Naoya Sakatani, Eri Tatsumi, Akira Miura, Manabu Yamada, Atsushi Fujii, Chikako Hirose, Satoshi Hosoda, Hitoshi Ikeda, Takahiro Iwata, Shota Kikuchi, Yuya Mimasu, Osamu Mori, Naoko Ogawa, Go Ono, Takanobu Shimada, Stefania Soldini, Tadateru Takahashi, Yuto Takei, Hiroshi Takeuchi, Ryudo Tsukizaki, Kent Yoshikawa, Fuyuto Terui, Satoru Nakazawa, Satoshi Tanaka, Takanao Saiki, Makoto Yoshikawa, Sei-ichiro Watanabe, Yuichi Tsuda

  Feb. 2022, Nature Astronomy, 6(2) (2), 214 - 220, English

  [Refereed]

  Scientific journal


• Photometric behavior of Ryugu's NIR spectral parameters

  A. Longobardo, E. Palomba, A. Galiano, F. Dirri, A. Zinzi, M. D'Amore, D. Domingue, K. Kitazato, Y. Yokota, S. E. Schroeder, 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, N. Hirata, K. Matsumoto, Y. Tsuda

  2022, Astronomy and Astrophysics, 666

  [Refereed]

  Scientific journal


• Alignment determination of the Hayabusa2 laser altimeter (LIDAR)

  Hirotomo Noda, Hiroki Senshu, Koji Matsumoto, Noriyuki Namiki, Takahide Mizuno, Seiji Sugita, Shinsuke Abe, Hiroshi Araki, Kazuyoshi Asari, Yuichiro Cho, Atsushi Fujii, Masahiko Hayakawa, Arika Higuchi, Naoyuki Hirata, Naru Hirata, Chikatoshi Honda, Rie Honda, Yoshiaki Ishihara, Shingo Kameda, Shota Kikuchi, Toru Kouyama, Moe Matsuoka, Yuya Mimasu, Tomokatsu Morota, Satoru Nakazawa, Kazunori Ogawa, Naoko Ogawa, Go Ono, Shoko Oshigami, Takanao Saiki, Naoya Sakatani, Sho Sasaki, Hirotaka Sawada, Makoto Shizugami, Hidehiko Suzuki, Tadateru Takahashi, Yuto Takei, Satoshi Tanaka, Eri Tatsumi, Fuyuto Terui, Yuichi Tsuda, Seiitsu Tsuruta, Sei-ichiro Watanabe, Manabu Yamada, Ryuhei Yamada, Tomohiro Yamaguchi, Keiko Yamamoto, Yasuhiro Yokota, Fumi Yoshida, Kent Yoshikawa, Makoto Yoshikawa, Kazuo Yoshioka

  In this study, we determined the alignment of the laser altimeter aboard Hayabusa2 with respect to the spacecraft using in-flight data. Since the laser altimeter data were used to estimate the trajectory of the Hayabusa2 spacecraft, the pointing direction of the altimeter needed to be accurately determined. The boresight direction of the receiving telescope was estimated by comparing elevations of the laser altimeter data and camera images, and was confirmed by identifying prominent terrains of other datasets. The estimated boresight direction obtained by the laser link experiment in the winter of 2015, during the Earth’s gravity assist operation period, differed from the direction estimated in this study, which fell on another part of the candidate direction; this was not selected in a previous study. Assuming that the uncertainty of alignment determination of the laser altimeter boresight was 4.6 pixels in the camera image, the trajectory error of the spacecraft in the cross- and/or along-track directions was determined to be 0.4, 2.1, or 8.6 m for altitudes of 1, 5, or 20 km, respectively.

  Springer Science and Business Media LLC, Dec. 2021, Earth, Planets and Space, 73(1) (1)

  [Refereed]

  Scientific journal


• Surface environment of Phobos and Phobos simulant UTPS

  Hideaki Miyamoto, Takafumi Niihara, Koji Wada, Kazunori Ogawa, Hiroki Senshu, Patrick Michel, Hiroshi Kikuchi, Ryodo Hemmi, Tomoki Nakamura, Akiko M. Nakamura, Naoyuki Hirata, Sho Sasaki, Erik Asphaug, Daniel T. Britt, Paul A. Abell, Ronald-Louis Ballouz, Olivier S. Banouin, Nicola Baresi, Maria A. Barucci, Jens Biele, Matthias Grott, Hideitsu Hino, Peng K. Hong, Takane Imada, Shingo Kameda, Makito Kobayashi, Guy Libourel, Katsuro Mogi, Naomi Murdoch, Yuki Nishio, Shogo Okamoto, Yuichiro Ota, Masatsugu Otsuki, Katharina A. Otto, Naoya Sakatani, Yuta Shimizu, Tomohiro Takemura, Naoki Terada, Masafumi Tsukamoto, Tomohiro Usui, Konrad Willner

  Springer Science and Business Media LLC, Dec. 2021, Earth, Planets and Space, 73(1) (1), English

  [Refereed]

  Scientific journal


• Spectrally blue hydrated parent body of asteroid (162173) Ryugu

  Eri Tatsumi, Naoya Sakatani, Lucie Riu, Moe Matsuoka, Rie Honda, Tomokatsu Morota, Shingo Kameda, Tomoki Nakamura, Michael Zolensky, Rosario Brunetto, Takahiro Hiroi, Sho Sasaki, Sei’ichiro Watanabe, Satoshi Tanaka, Jun Takita, Cédric Pilorget, Julia de León, Marcel Popescu, Juan Luis Rizos, Javier Licandro, Ernesto Palomba, Deborah Domingue, Faith Vilas, Humberto Campins, Yuichiro Cho, Kazuo Yoshioka, Hirotaka Sawada, Yasuhiro Yokota, Masahiko Hayakawa, Manabu Yamada, Toru Kouyama, Hidehiko Suzuki, Chikatoshi Honda, Kazunori Ogawa, Kohei Kitazato, Naru Hirata, Naoyuki Hirata, Yuichi Tsuda, Makoto Yoshikawa, Takanao Saiki, Fuyuto Terui, Satoru Nakazawa, Yuto Takei, Hiroshi Takeuchi, Yukio Yamamoto, Tatsuaki Okada, Yuri Shimaki, Kei Shirai, Seiji Sugita

  Abstract Ryugu is a carbonaceous rubble-pile asteroid visited by the Hayabusa2 spacecraft. Small rubble pile asteroids record the thermal evolution of their much larger parent bodies. However, recent space weathering and/or solar heating create ambiguities between the uppermost layer observable by remote-sensing and the pristine material from the parent body. Hayabusa2 remote-sensing observations find that on the asteroid (162173) Ryugu both north and south pole regions preserve the material least processed by space weathering, which is spectrally blue carbonaceous chondritic material with a 0–3% deep 0.7-µm band absorption, indicative of Fe-bearing phyllosilicates. Here we report that spectrally blue Ryugu’s parent body experienced intensive aqueous alteration and subsequent thermal metamorphism at 570–670 K (300–400 °C), suggesting that Ryugu’s parent body was heated by radioactive decay of short-lived radionuclides possibly because of its early formation 2–2.5 Ma. The samples being brought to Earth by Hayabusa2 will give us our first insights into this epoch in solar system history.

  Springer Science and Business Media LLC, Dec. 2021, Nature Communications, 12(1) (1), 5837 - 5837, English, International magazine

  [Refereed]

  Scientific journal


• Hayabusa2 pinpoint touchdown near the artificial crater on Ryugu: Trajectory design and guidance performance

  Shota Kikuchi, Takanao Saiki, Yuto Takei, Fuyuto Terui, Naoko Ogawa, Yuya Mimasu, Go Ono, Kent Yoshikawa, Hirotaka Sawada, Hiroshi Takeuchi, Hitoshi Ikeda, Atsushi Fujii, Seiji Sugita, Tomokatsu Morota, Manabu Yamada, Rie Honda, Yasuhiro Yokota, Naoya Sakatani, Shingo Kameda, Toru Kouyama, Naru Hirata, Naoyuki Hirata, Kei Shirai, Kohei Kitazato, Satoru Nakazawa, Makoto Yoshikawa, Satoshi Tanaka, Koji Wada, Sei ichiro Watanabe, Yuichi Tsuda

  Oct. 2021, Advances in Space Research, 68(8) (8), 3093 - 3140

  [Refereed]

  Scientific journal


• Ejecta emplacement as the possible origin of Ryugu's equatorial ridge

  Ren Ikeya, Naoyuki Hirata

  Corresponding, Elsevier BV, Oct. 2021, Icarus, 367, 114590 - 114590

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Resurfacing processes on asteroid (162173) Ryugu caused by an artificial impact of Hayabusa2's Small Carry-on Impactor

  Rie Honda, Masahiko Arakawa, Yuri Shimaki, Kei Shirai, Yasuhiro Yokota, Toshihiko Kadono, Koji Wada, Kazunori Ogawa, Ko Ishibashi, Naoya Sakatani, Satoru Nakazawa, Minami Yasui, Tomokatsu Morota, Shingo Kameda, Eri Tatsumi, Manabu Yamada, Toru Kouyama, Yuichiro Cho, Moe Matsuoka, Hidehiko Suzuki, Chikatoshi Honda, Masahiko Hayakawa, Kazuo Yoshioka, Naru Hirata, Naoyuki Hirata, Hirotaka Sawada, Seiji Sugita, Takanao Saiki, Hiroshi Imamura, Yasuhiko Takagi, Hajime Yano, Chisato Okamoto, Yuichi Tsuda, Yu-ichi Iijima

  Elsevier BV, Sep. 2021, Icarus, 366, 114530 - 114530, English

  [Refereed]

  Scientific journal


• Anomalously porous boulders on (162173) Ryugu as primordial materials from its parent body

  N. Sakatani, S. Tanaka, T. Okada, T. Fukuhara, L. Riu, S. Sugita, R. Honda, T. Morota, S. Kameda, Y. Yokota, E. Tatsumi, K. Yumoto, N. Hirata, A. Miura, T. Kouyama, H. Senshu, Y. Shimaki, T. Arai, J. Takita, H. Demura, T. Sekiguchi, T. G. Müller, A. Hagermann, J. Biele, M. Grott, M. Hamm, M. Delbo, W. Neumann, M. Taguchi, Y. Ogawa, T. Matsunaga, T. Wada, S. Hasegawa, J. Helbert, N. Hirata, R. Noguchi, M. Yamada, H. Suzuki, C. Honda, K. Ogawa, M. Hayakawa, K. Yoshioka, M. Matsuoka, Y. Cho, H. Sawada, K. Kitazato, T. Iwata, M. Abe, M. Ohtake, S. Matsuura, K. Matsumoto, H. Noda, Y. Ishihara, K. Yamamoto, A. Higuchi, N. Namiki, G. Ono, T. Saiki, H. Imamura, Y. Takagi, H. Yano, K. Shirai, C. Okamoto, S. Nakazawa, Y. Iijima, M. Arakawa, K. Wada, T. Kadono, K. Ishibashi, F. Terui, S. Kikuchi, T. Yamaguchi, N. Ogawa, Y. Mimasu, K. Yoshikawa, T. Takahashi, Y. Takei, A. Fujii, H. Takeuchi, Y. Yamamoto, C. Hirose, S. Hosoda, O. Mori, T. Shimada, S. Soldini, R. Tsukizaki, M. Ozaki, S. Tachibana, H. Ikeda, M. Ishiguro, H. Yabuta, M. Yoshikawa, S. Watanabe, Y. Tsuda

  Aug. 2021, Nature Astronomy, 5(8) (8), 766 - 774

  [Refereed]

  Scientific journal


• Ejecta distribution from impact craters on Ryugu: Possible origin of the bluer units

  Naoyuki Hirata, Ren Ikeya

  Elsevier BV, Aug. 2021, Icarus, 364, 114474 - 114474

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Ballistic deployment of the Hayabusa2 artificial landmarks in the microgravity environment of Ryugu

  Shota Kikuchi, Naoko Ogawa, Osamu Mori, Takanao Saiki, Yuto Takei, Fuyuto Terui, Go Ono, Yuya Mimasu, Kent Yoshikawa, Stefaan Van Wal, Hiroshi Takeuchi, Hitoshi Ikeda, Atsushi Fujii, Yuki Takao, Tetsuya Kusumoto, Naru Hirata, Naoyuki Hirata, Kei Shirai, Toru Kouyama, Shingo Kameda, Manabu Yamada, Satoru Nakazawa, Makoto Yoshikawa, Satoshi Tanaka, Seiji Sugita, Sei-ichiro Watanabe, Yuichi Tsuda

  Apr. 2021, ICARUS, 358, English

  [Refereed]

  Scientific journal


• Thermally altered subsurface material of asteroid (162173) Ryugu

  K. Kitazato, R. E. Milliken, T. Iwata, M. Abe, M. Ohtake, S. Matsuura, Y. Takagi, T. Nakamura, T. Hiroi, M. Matsuoka, L. Riu, Y. Nakauchi, K. Tsumura, T. Arai, H. Senshu, N. Hirata, M. A. Barucci, R. Brunetto, C. Pilorget, F. Poulet, J.-P. Bibring, D. L. Domingue, F. Vilas, D. Takir, E. Palomba, A. Galiano, D. Perna, T. Osawa, M. Komatsu, A. Nakato, T. Arai, N. Takato, T. Matsunaga, M. Arakawa, T. Saiki, K. Wada, T. Kadono, H. Imamura, H. Yano, K. Shirai, M. Hayakawa, C. Okamoto, H. Sawada, K. Ogawa, Y. Iijima, S. Sugita, R. Honda, T. Morota, S. Kameda, E. Tatsumi, Y. Cho, K. Yoshioka, Y. Yokota, N. Sakatani, M. Yamada, T. Kouyama, H. Suzuki, C. Honda, N. Namiki, T. Mizuno, K. Matsumoto, H. Noda, Y. Ishihara, R. Yamada, K. Yamamoto, F. Yoshida, S. Abe, A. Higuchi, Y. Yamamoto, T. Okada, Y. Shimaki, R. Noguchi, A. Miura, N. Hirata, S. Tachibana, H. Yabuta, M. Ishiguro, H. Ikeda, H. Takeuchi, T. Shimada, O. Mori, S. Hosoda, R. Tsukizaki, S. Soldini, M. Ozaki, F. Terui, N. Ogawa, Y. Mimasu, G. Ono, K. Yoshikawa, C. Hirose, A. Fujii, T. Takahashi, S. Kikuchi, Y. Takei, T. Yamaguchi, S. Nakazawa, S. Tanaka, M. Yoshikawa, S. Watanabe, Y. Tsuda

  Springer Science and Business Media LLC, Mar. 2021, Nature Astronomy, 5(3) (3), 246 - 250

  [Refereed]

  Scientific journal


• Thermophysical Properties of C-Type Asteroid 162173 Ryugu Revealed by the Thermal Infrared Imager TIR on Hayabusa2

  Tatsuaki OKADA, Tetsuya FUKUHARA, Satoshi TANAKA, Makoto TAGUCHI, Takehiko ARAI, Hiroki SENSHU, Naoya SAKATANI, Yuri SHIMAKI, Hirohide DEMURA, Yoshiko OGAWA, Kohei KITAZATO, Kentaro SUKO, Tomohiko SEKIGUCHI, Toru KOUYAMA, Jun TAKITA, Tsuneo MATSUNAGA, Takeshi IMAMURA, Takehiko WADA, Sunao HASEGAWA, Jorn HELBERT, Thomas G. MUELLER, Axel HAGERMANN, Jens BIELE, Matthias GROTT, Maximilian HAMM, Marco DELBO, Naru HIRATA, Naoyuki HIRATA, Yukio YAMAMOTO, Fuyuto TERUI, Takanao SAIKI, Satoru NAKAZAWA, Makoto YOSHIKAWA, Seiichiro WATANABE, Yuichi TSUDA

  Japan Society for Aeronautical and Space Sciences, 2021, TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN, 19(5) (5), 654 - 659

  Scientific journal


• Rotational effect as the possible cause of the east-west asymmetric crater rims on Ryugu observed by LIDAR data

  Naoyuki Hirata, Noriyuki Namiki, Fumi Yoshida, Koji Matsumoto, Hirotomo Noda, Hiroki Senshu, Takahide Mizuno, Fuyuto Terui, Yoshiaki Ishihara, Ryuhei Yamada, Keiko Yamamoto, Shinsuke Abe, Rina Noguchi, Naru Hirata, Yuichi Tsuda, Sei-ichiro Watanabe

  Jan. 2021, ICARUS, 354, English

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Crater depth-to-diameter ratios on asteroid 162173 Ryugu

  Rina Noguchi, Naoyuki Hirata, Naru Hirata, Yuri Shimaki, Naoki Nishikawa, Sayuri Tanaka, Takaaki Sugiyama, Tomokatsu Morota, Seiji Sugita, Yuichiro Cho, Rie Honda, Shingo Kameda, Eri Tatsumi, Kazuo Yoshioka, Hirotaka Sawada, Yasuhiro Yokota, Naoya Sakatani, Masahiko Hayakawa, Moe Matsuoka, Manabu Yamada, Toru Kouyama, Hidehiko Suzuki, Chikatoshi Honda, Kazunori Ogawa, Masanori Kanamaru, Sei-ichiro Watanabe

  Jan. 2021, ICARUS, 354, English

  [Refereed]

  Scientific journal


• A global system of furrows on Ganymede indicative of their creation in a single impact event

  Naoyuki Hirata, Ryo Suetsugu, Keiji Ohtsuki

  Dec. 2020, ICARUS, 352, English

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Characterization of the Ryugu surface by means of the variability of the near-infrared spectral slope in NIRS3 data

  A. Galiano, E. Palomba, M. D'Amore, A. Zinzi, 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, N. Hirata, K. Matsumoto, Y. Tsuda

  Elsevier BV, Nov. 2020, Icarus, 351, 113959 - 113959

  [Refereed]

  Scientific journal


• Hayabusa2 Landing Site Selection: Surface Topography of Ryugu and Touchdown Safety

  Shota Kikuchi, Sei-ichiro Watanabe, Takanao Saiki, Hikaru Yabuta, Seiji Sugita, Tomokatsu Morota, Naru Hirata, Naoyuki Hirata, Tatsuhiro Michikami, Chikatoshi Honda, Yashuhiro Yokota, Rie Honda, Naoya Sakatani, Tatsuaki Okada, Yuri Shimaki, Koji Matsumoto, Rina Noguchi, Yuto Takei, Fuyuto Terui, Naoko Ogawa, Kent Yoshikawa, Go Ono, Yuya Mimasu, Hirotaka Sawada, Hitoshi Ikeda, Chikako Hirose, Tadateru Takahashi, Atsushi Fujii, Tomohiro Yamaguchi, Yoshiaki Ishihara, Tomoki Nakamura, Kohei Kitazato, Koji Wada, Shogo Tachibana, Eri Tatsumi, Moe Matsuoka, Hiroki Senshu, Shingo Kameda, Toru Kouyama, Manabu Yamada, Kei Shirai, Yuichiro Cho, Kazunori Ogawa, Yukio Yamamoto, Akira Miura, Takahiro Iwata, Noriyuki Namiki, Masahiko Hayakawa, Masanao Abe, Satoshi Tanaka, Makoto Yoshikawa, Satoru Nakazawa, Yuichi Tsuda

  Oct. 2020, SPACE SCIENCE REVIEWS, 216(7) (7), English

  [Refereed]


• Thermophysical properties of the surface of asteroid 162173 Ryugu: Infrared observations and thermal inertia mapping

  Yuri Shimaki, Hiroki Senshu, Naoya Sakatani, Tatsuaki Okada, Tetsuya Fukuhara, Satoshi Tanaka, Makoto Taguchi, Takehiko Arai, Hirohide Demura, Yoshiko Ogawa, Kentaro Suko, Tomohiko Sekiguchi, Toru Kouyama, Sunao Hasegawa, Jun Takita, Tsuneo Matsunaga, Takeshi Imamura, Takehiko Wada, Kohei Kitazato, Naru Hirata, Naoyuki Hirata, Rina Noguchi, Seiji Sugita, Shota Kikuchi, Tomohiro Yamaguchi, Naoko Ogawa, Go Ono, Yuya Mimasu, Kent Yoshikawa, Tadateru Takahashi, Yuto Takei, Atsushi Fujii, Hiroshi Takeuchi, Yukio Yamamoto, Manabu Yamada, Kei Shirai, Yu-ichi Iijima, Kazunori Ogawa, Satoru Nakazawa, Fuyuto Terui, Takanao Saiki, Makoto Yoshikawa, Yuichi Tsuda, Sei-ichiro Watanabe

  Sep. 2020, ICARUS, 348, English

  [Refereed]

  Scientific journal


• Size of the smallest particles in Saturn's rings

  Keiji Ohtsuki, Hiroshi Kawamura, Naoyuki Hirata, Hiroshi Daisaka, Hiroshi Kimura

  Elsevier BV, Jul. 2020, Icarus, 344, 113346 - 113346

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Global photometric properties of (162173) Ryugu

  E. Tatsumi, D. Domingue, S. Schröder, Y. Yokota, D. Kuroda, M. Ishiguro, S. Hasegawa, T. Hiroi, R. Honda, R. Hemmi, L. Le Corre, N. Sakatani, T. Morota, M. Yamada, S. Kameda, T. Koyama, H. Suzuki, Y. Cho, K. Yoshioka, M. Matsuoka, C. Honda, M. Hayakawa, N. Hirata, N. Hirata, Y. Yamamoto, F. Vilas, N. Takato, M. Yoshikawa, M. Abe, S. Sugita

  Jul. 2020, Astronomy and Astrophysics, 639

  [Refereed]

  Scientific journal


• Sample collection from asteroid (162173) Ryugu by Hayabusa2: Implications for surface evolution

  T. Morota, S. Sugita, Y. Cho, M. Kanamaru, E. Tatsumi, N. Sakatani, R. Honda, N. Hirata, H. Kikuchi, M. Yamada, Y. Yokota, S. Kameda, M. Matsuoka, H. Sawada, C. Honda, T. Kouyama, K. Ogawa, H. Suzuki, K. Yoshioka, M. Hayakawa, N. Hirata, M. Hirabayashi, H. Miyamoto, T. Michikami, T. Hiroi, R. Hemmi, O. S. Barnouin, C. M. Ernst, K. Kitazato, T. Nakamura, L. Riu, H. Senshu, H. Kobayashi, S. Sasaki, G. Komatsu, N. Tanabe, Y. Fujii, T. Irie, M. Suemitsu, N. Takaki, C. Sugimoto, K. Yumoto, M. Ishida, H. Kato, K. Moroi, D. Domingue, P. Michel, C. Pilorget, T. Iwata, M. Abe, M. Ohtake, Y. Nakauchi, K. Tsumura, H. Yabuta, Y. Ishihara, R. Noguchi, K. Matsumoto, A. Miura, N. Namiki, S. Tachibana, M. Arakawa, H. Ikeda, K. Wada, T. Mizuno, C. Hirose, S. Hosoda, O. Mori, T. Shimada, S. Soldini, R. Tsukizaki, H. Yano, M. Ozaki, H. Takeuchi, Y. Yamamoto, T. Okada, Y. Shimaki, K. Shirai, Y. Iijima, H. Noda, S. Kikuchi, T. Yamaguchi, N. Ogawa, G. Ono, Y. Mimasu, K. Yoshikawa, T. Takahashi, Y. Takei, A. Fujii, S. Nakazawa, F. Terui, S. Tanaka, M. Yoshikawa, T. Saiki, S. Watanabe, Y. Tsuda

  The near-Earth asteroid (162173) Ryugu is thought to be a primitive carbonaceous object that contains hydrated minerals and organic molecules. We report sample collection from Ryugu’s surface by the Hayabusa2 spacecraft on 21 February 2019. Touchdown images and global observations of surface colors are used to investigate the stratigraphy of the surface around the sample location and across Ryugu. Latitudinal color variations suggest the reddening of exposed surface material by solar heating and/or space weathering. Immediately after touchdown, Hayabusa2’s thrusters disturbed dark, fine grains that originate from the redder materials. The stratigraphic relationship between identified craters and the redder material indicates that surface reddening occurred over a short period of time. We suggest that Ryugu previously experienced an orbital excursion near the Sun.

  American Association for the Advancement of Science (AAAS), May 2020, Science, 368(6491) (6491), 654 - 659, English, International magazine, Co-authored internationally

  [Refereed]

  Scientific journal


• An artificial impact on the asteroid (162173) Ryugu formed a crater in the gravity-dominated regime

  M. Arakawa, T. Saiki, K. Wada, K. Ogawa, T. Kadono, K. Shirai, H. Sawada, K. Ishibashi, R. Honda, N. Sakatani, Y. Iijima, C. Okamoto, H. Yano, Y. Takagi, M. Hayakawa, P. Michel, M. Jutzi, Y. Shimaki, S. Kimura, Y. Mimasu, T. Toda, H. Imamura, S. Nakazawa, H. Hayakawa, S. Sugita, T. Morota, S. Kameda, E. Tatsumi, Y. Cho, K. Yoshioka, Y. Yokota, M. Matsuoka, M. Yamada, T. Kouyama, C. Honda, Y. Tsuda, S. Watanabe, M. Yoshikawa, S. Tanaka, F. Terui, S. Kikuchi, T. Yamaguchi, N. Ogawa, G. Ono, K. Yoshikawa, T. Takahashi, Y. Takei, A. Fujii, H. Takeuchi, Y. Yamamoto, T. Okada, C. Hirose, S. Hosoda, O. Mori, T. Shimada, S. Soldini, R. Tsukizaki, T. Iwata, M. Ozaki, M. Abe, N. Namiki, K. Kitazato, S. Tachibana, H. Ikeda, N. Hirata, N. Hirata, R. Noguchi, A. Miura

  Apr. 2020, Science, 368(6486) (6486)

  [Refereed]

  Scientific journal


• Highly porous nature of a primitive asteroid revealed by thermal imaging

  Tatsuaki Okada, Tetsuya Fukuhara, Satoshi Tanaka, Makoto Taguchi, Takehiko Arai, Hiroki Senshu, Naoya Sakatani, Yuri Shimaki, Hirohide Demura, Yoshiko Ogawa, Kentaro Suko, Tomohiko Sekiguchi, Toru Kouyama, Jun Takita, Tsuneo Matsunaga, Takeshi Imamura, Takehiko Wada, Sunao Hasegawa, Joern Helbert, Thomas G. Mueller, Axel Hagermann, Jens Biele, Matthias Grott, Maximilian Hamm, Marco Delbo, Naru Hirata, Naoyuki Hirata, Yukio Yamamoto, Seiji Sugita, Noriyuki Namiki, Kohei Kitazato, Masahiko Arakawa, Shogo Tachibana, Hitoshi Ikeda, Masateru Ishiguro, Koji Wada, Chikatoshi Honda, Rie Honda, Yoshiaki Ishihara, Koji Matsumoto, Moe Matsuoka, Tatsuhiro Michikami, Akira Miura, Tomokatsu Morota, Hirotomo Noda, Rina Noguchi, Kazunori Ogawa, Kei Shirai, Eri Tatsumi, Hikaru Yabuta, Yasuhiro Yokota, Manabu Yamada, Masanao Abe, Masahiko Hayakawa, Takahiro Iwata, Masanobu Ozaki, Hajime Yano, Satoshi Hosoda, Osamu Mori, Hirotaka Sawada, Takanobu Shimada, Hiroshi Takeuchi, Ryudo Tsukizaki, Atsushi Fujii, Chikako Hirose, Shota Kikuchi, Yuya Mimasu, Naoko Ogawa, Go Ono, Tadateru Takahashi, Yuto Takei, Tomohiro Yamaguchi, Kent Yoshikawa, Fuyuto Terui, Takanao Saiki, Satoru Nakazawa, Makoto Yoshikawa, Seiichiro Watanabe, Yuichi Tsuda

  Mar. 2020, NATURE, 579(7800) (7800), 518 - 522, English, International magazine

  [Refereed]

  Scientific journal


• Improving Hayabusa2 trajectory by combining LIDAR data and a shape model

  Koji Matsumoto, Hirotomo Noda, Yoshiaki Ishihara, Hiroki Senshu, Keiko Yamamoto, Naru Hirata, Naoyuki Hirata, Noriyuki Namiki, Toshimichi Otsubo, Arika Higuchi, Sei-ichiro Watanabe, Hitoshi Ikeda, Takahide Mizuno, Ryuhei Yamada, Hiroshi Araki, Shinsuke Abe, Fumi Yoshida, Sho Sasaki, Shoko Oshigami, Seiitsu Tsuruta, Kazuyoshi Asari, Makoto Shizugami, Yukio Yamamoto, Naoko Ogawa, Shota Kikuchi, Takanao Saiki, Yuichi Tsuda, Makoto Yoshikawa, Satoshi Tanaka, Fuyuto Terui, Satoru Nakazawa, Tomohiro Yamaguchi, Yuto Takei, Hiroshi Takeuchi, Tatsuaki Okada, Manabu Yamada, Yuri Shimaki, Kei Shirai, Kazunori Ogawa, Yu-ichi Iijima

  Mar. 2020, ICARUS, 338, English

  [Refereed]

  Scientific journal


• The spatial distribution of impact craters on Ryugu

  Naoyuki Hirata, Tomokatsu Morota, Yuichiro Cho, Masanori Kanamaru, Sei-ichiro Watanabe, Seiji Sugita, Naru Hirata, Yukio Yamamoto, Rina Noguchi, Yuri Shimaki, Eri Tatsumi, Kazuo Yoshioka, Hirotaka Sawada, Yasuhiro Yokota, Naoya Sakatani, Masahiko Hayakawa, Moe Matsuoka, Rie Honda, Shingo Kameda, Manabu Yamada, Toru Kouyama, Hidehiko Suzuki, Chikatoshi Honda, Kazunori Ogawa, Yuichi Tsuda, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Satoru Nakazawa, Shota Kikuchi, Tomohiro Yamaguchi, Naoko Ogawa, Go Ono, Yuya Mimasu, Kent Yoshikawa, Tadateru Takahashi, Yuto Takei, Atsushi Fujii, Hiroshi Takeuchi, Tatsuaki Okada, Kei Shirai, Yu-ichi Iijima

  Mar. 2020, ICARUS, 338(1) (1), 113 - 527, English

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Design and reconstruction of the hayabusa2 precision landing on ryugu

  S. Kikuchi, F. Terui, N. Ogawa, T. Saiki, G. Ono, K. Yoshikawa, Y. Takei, Y. Mimasu, H. Ikeda, H. Sawada, T. Morota, N. Hirata, N. Hirata, T. Kouyama, S. Kameda, Y. Tsuda

  2020, Advances in the Astronautical Sciences, 171, 3101 - 3120

  [Refereed]

  International conference proceedings


• Boulder size and shape distributions on asteroid Ryugu

  Tatsuhiro Michikami, Chikatoshi Honda, Hideaki Miyamoto, Masatoshi Hirabayashi, Axel Hagermann, Terunori Irie, Keita Nomura, Carolyn M. Ernst, Masaki Kawamura, Kiichi Sugimoto, Eri Tatsumi, Tomokatsu Morota, Naru Hirata, Takaaki Noguchi, Yuichiro Cho, Shingo Kameda, Toru Kouyama, Yasuhiro Yokota, Rina Noguchi, Masahiko Hayakawa, Naoyuki Hirata, Rie Honda, Moe Matsuoka, Naoya Sakatani, Hidehiko Suzuki, Manabu Yamada, Kazuo Yoshioka, Hirotaka Sawada, Ryodo Hemmi, Hiroshi Kikuch, Kazunori Ogawa, Sei-ichiro Watanabe, Satoshi Tanaka, Makoto Yoshikawa, Yuichi Tsuda, Seiji Sugita

  Oct. 2019, ICARUS, 331, 179 - 191, English

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Multivariable statistical analysis of spectrophotometry and spectra of (162173) Ryugu as observed by JAXA Hayabusa2 mission

  Barucci M. A, Hasselmann P. H, Fulchignoni M, Honda R, Yokota Y, Sugita S, Kitazato K, Deshapriya J. D. P, Perna D, Tatsumi E, Domingue D, Morota T, Kameda S, Iwata T, Abe M, Ohtake M, Matsuura S, Matsuoka M, Hiroi T, Nakamura T, Kouyama T, Suzuki H, Yamada M, Sakatani N, Honda C, Ogawa K, Hayakawa M, Yoshioka K, Cho Y, Sawada H, Takir D, Vilas F, Hirata N, Hirata N, Tanaka S, Yamamoto Y, Yoshikawa M, Watanabe S, Tsuda Y

  Context. Starting from late June 2018, the JAXA asteroid sample return mission Hayabusa2 acquired a large quantity of resolved images and spectra of the surface of the asteroid (162173) Ryugu. Aims. By studying the visible and near-infrared spectral behavior across the surface of Ryugu using a statistical analysis, we aim to distinguish spectral homogeneous groups and to detect the small heterogeneities. This allows us to better constrain the surface composition variations. Methods. In order to isolate and interpret the difference in the asteroid surface spectral behavior, we applied the G-mode multivariate statistical analysis to a set of pixels containing information of (i) the visible ONC-T spectrophotometry, and (ii) the near-infrared NIRS3 spectra thereby obtaining automatic statistical clustering at different confidence levels. Results. The analysis of both ONC-T and NIRS3 data allows us to highlight small spectral variations on the Ryugu surface. At a 3σ confidence level, only two groups are evident, while going down to 2σ more groups are obtained with differences in spectral slope and band depth. Conclusions. The identified groups have been associated with main morphological surface features. The spectral slope variations that characterize the small groups obtained by ONC-T data analysis, are interpreted as a consequence of space weathering with the presence of more or less fresh material and/or the different grain sizes of the regolith. The variations found analyzing the NIRS3 data are attributed to slightly different contents of hydrated material and different regolith sizes. The distribution on the Ryugu surface of the groups obtained by the analysis of the two instruments indicates a clear spectral dichotomy both between the east and west, and the north and south hemispheres. Small sized regolith grains associated to the redder spectra seem concentrated in the southwestern part of the body.

  EDP Sciences, Aug. 2019, ASTRONOMY & ASTROPHYSICS, 629, A13 - A13, English

  [Refereed]

  Scientific journal


• SPECTRAL CHARACTERISTICS OF ASTEROID (162173) RYUGU WITH HAYABUSA2 NIRS3

  Takir D, Kitazato K, Milliken R. E, Iwata T, Abe M, Ohtake M, Matsuura S, Arai T, Nakauchi Y, Nakamura T, Matsuoka M, Senshu H, Hirata N, Hiroi T, Pilorget C, Brnnetto R, Poulet F, Riu L, Bibring J. -P, Domingue D. L, Vilas F, Barucci M. A, Perna D, Palomba E, Galiano A, Tsumura K, Osawa T, Komatsu M, Nakato A, Arai T, Takato N, Matsunaga Y, Takagi Y, Matsumoto K, Kouyama T, Yokota Y, Tatsumi E, Sakatani N, Yamamoto Y, Okada T, Sugita S, Honda R, Morota T, Kameda S, Sawada H, Honda C, Yamada M, Suzuki H, Yoshioka K, Hayakawa M, Ogawa K, Cho Y, Shirai K, Shimaki Y, Hirata N, Yamaguchi A, Ogawa N, Terui F, Yamaguchi T, Takei Y, Saiki T, Nakazawa S, Tanaka S, Yoshikawa M, Watanabe S, Tsuda Y

  Aug. 2019, METEORITICS & PLANETARY SCIENCE, 54, ., English

  [Refereed]

  Scientific journal


• HAYABUSA2: CURRENT SUMMARY.

  Nakamura T, Watanabe S, Hirabayashi M, Hirata N, Hirata N, Noguchi R, Shimaki Y, Ikeda H, Tatsumi E, Yoshikawa M, Kikuchi S, Yabuta H, Tachibana S, Ishihara Y, Morota T, Kitazato K, Sakatani N, Matsumoto K, Wada K, Senshu H, Honda C, Michikami T, Takeuchi H, Kouyama T, Honda R, Kameda S, Fuse T, Miyamoto H, Komatsu G, Sugita S, Okada T, Namiki N, Arakawa M, Ishiguro M, Abe M, Gaskell R, Palmer E, Barnouin O. S, Michel P, French A. S, McMahon J. W, Scheeres D. J, Abell P. A, Yamamoto Y, Tanaka S, Shirai K, Matsuoka M, Yamada M, Yokota Y, Suzuki H, Yoshioka K, Cho Y, Tanaka S, Nishikawa N, Sugiyama T, Kikuchi H, Hemmi R, Yamaguchi T, Ogawa N, Ono G, Mimasu Y, Yoshikawa K, Takahashi T, Takei Y, Fujii A, Hirose C, Iwata T, Hayakawa M, Hosoda S, Mori O, Sawada H, Shimada T, Soldini S, Yano H, Tsukizaki R, Ozaki M, Iijima Y, Ogawa K, Fujimoto M, Ho T. -M, Moussi A, Jaumann R, Bibring J. -P, Krause C, Terui F, Saiki T, Nakazawa S, Tsuda Y

  Aug. 2019, METEORITICS & PLANETARY SCIENCE, 54, ., English

  [Refereed]

  Scientific journal


• RYUGU'S PARENT-BODY PROCESSES ESTIMATED FROM HAYABUSA2 MULTI-BAND OPTICAL OBSERVATIONS

  Sugita S, Honda R, Morota T, Kameda S, Tatsumi E, Honda C, Yokota Y, Yamada M, Kouyama T, Sakatani N, Suzuki H, Yoshioka K, Cho Y, Matsuoka M, Ogawa K, Domingue D, Miyamoto H, Barnouin O. S, Michel P, Ernst C. M, Hiroi T, Nakamura T, Sawada H, Hayakawa M, Hirata N, Hirata N, Kikuchi H, Hemmi R, Michikami T, Palmer Eric, Gaskell R, Hirabayashi M, Jaumann R, Otto K, Schmitz N, Schroder S. E, Komatsu G, Tanaka S, Shirai K, Yoshikawa M, Watanabe S, Tsuda Y

  Aug. 2019, METEORITICS & PLANETARY SCIENCE, 54, ., English

  [Refereed]

  Scientific journal


• Spatial Distribution of Ray Craters on Callisto: Implications for Ray Retention and Impactor Sources on Jovian Satellites

  Luyuan Xu, Naoyuki Hirata, Hideaki Miyamoto

  Jul. 2019, JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS, 124(7) (7), 1717 - 1727, English

  [Refereed]

  Scientific journal


• Hayabusa2 arrives at the carbonaceous asteroid 162173 Ryugu-A spinning top-shaped rubble pile.

  S Watanabe, M Hirabayashi, N Hirata, Na Hirata, R Noguchi, Y Shimaki, H Ikeda, E Tatsumi, M Yoshikawa, S Kikuchi, H Yabuta, T Nakamura, S Tachibana, Y Ishihara, T Morota, K Kitazato, N Sakatani, K Matsumoto, K Wada, H Senshu, C Honda, T Michikami, H Takeuchi, T Kouyama, R Honda, S Kameda, T Fuse, H Miyamoto, G Komatsu, S Sugita, T Okada, N Namiki, M Arakawa, M Ishiguro, M Abe, R Gaskell, E Palmer, O S Barnouin, P Michel, A S French, J W McMahon, D J Scheeres, P A Abell, Y Yamamoto, S Tanaka, K Shirai, M Matsuoka, M Yamada, Y Yokota, H Suzuki, K Yoshioka, Y Cho, S Tanaka, N Nishikawa, T Sugiyama, H Kikuchi, R Hemmi, T Yamaguchi, N Ogawa, G Ono, Y Mimasu, K Yoshikawa, T Takahashi, Y Takei, A Fujii, C Hirose, T Iwata, M Hayakawa, S Hosoda, O Mori, H Sawada, T Shimada, S Soldini, H Yano, R Tsukizaki, M Ozaki, Y Iijima, K Ogawa, M Fujimoto, T-M Ho, A Moussi, R Jaumann, J-P Bibring, C Krause, F Terui, T Saiki, S Nakazawa, Y Tsuda

  The Hayabusa2 spacecraft arrived at the near-Earth carbonaceous asteroid 162173 Ryugu in 2018. We present Hayabusa2 observations of Ryugu's shape, mass, and geomorphology. Ryugu has an oblate "spinning top" shape, with a prominent circular equatorial ridge. Its bulk density, 1.19 ± 0.02 grams per cubic centimeter, indicates a high-porosity (>50%) interior. Large surface boulders suggest a rubble-pile structure. Surface slope analysis shows Ryugu's shape may have been produced from having once spun at twice the current rate. Coupled with the observed global material homogeneity, this suggests that Ryugu was reshaped by centrifugally induced deformation during a period of rapid rotation. From these remote-sensing investigations, we identified a suitable sample collection site on the equatorial ridge.

  Apr. 2019, Science (New York, N.Y.), 364(6437) (6437), 268 - 272, English, International magazine

  [Refereed]

  Scientific journal


• The surface composition of asteroid 162173 Ryugu from Hayabusa2 near-infrared spectroscopy

  K. Kitazato, R. E. Milliken, T. Iwata, M. Abe, M. Ohtake, S. Matsuura, T. Arai, Y. Nakauchi, T. Nakamura, M. Matsuoka, H. Senshu, N. Hirata, T. Hiroi, C. Pilorget, R. Brunetto, F. Poulet, L. Riu, J.-P. Bibring, D. Takir, D. L. Domingue, F. Vilas, M. A. Barucci, D. Perna, E. Palomba, A. Galiano, K. Tsumura, T. Osawa, M. Komatsu, A. Nakato, T. Arai, N. Takato, T. Matsunaga, Y. Takagi, K. Matsumoto, T. Kouyama, Y. Yokota, E. Tatsumi, N. Sakatani, Y. Yamamoto, T. Okada, S. Sugita, R. Honda, T. Morota, S. Kameda, H. Sawada, C. Honda, M. Yamada, H. Suzuki, K. Yoshioka, M. Hayakawa, K. Ogawa, Y. Cho, K. Shirai, Y. Shimaki, N. Hirata, A. Yamaguchi, N. Ogawa, F. Terui, T. Yamaguchi, Y. Takei, T. Saiki, S. Nakazawa, S. Tanaka, M. Yoshikawa, S. Watanabe, Y. Tsuda

  The near-Earth asteroid 162173 Ryugu, the target of Hayabusa2 sample return mission, is thought to be a primitive carbonaceous object. We report reflectance spectra of Ryugu’s surface acquired with the Near Infrared Spectrometer (NIRS3) on Hayabusa2, to provide direct measurements of the surface composition and geological context for the returned samples. A weak, narrow absorption feature centered at 2.72 μm was detected across the entire observed surface, indicating that hydroxyl (OH)-bearing minerals are ubiquitous there. The intensity of the OH feature and low albedo are similar to thermally- and/or shock-metamorphosed carbonaceous chondrite meteorites. There are few variations in the OH-band position, consistent with Ryugu being a compositionally homogeneous rubble-pile object, generated from impact fragments of an undifferentiated aqueously altered parent body.

  American Association for the Advancement of Science (AAAS), Mar. 2019, Science, 364(6437) (6437), eaav7432 - eaav7432, English

  [Refereed]

  Scientific journal


• The geomorphology, color, and thermal properties of Ryugu: Implications for parent-body processes

  S. Sugita, R. Honda, T. Morota, S. Kameda, H. Sawada, E. Tatsumi, M. Yamada, C. Honda, Y. Yokota, T. Kouyama, N. Sakatani, K. Ogawa, H. Suzuki, T. Okada, N. Namiki, S. Tanaka, Y. Iijima, K. Yoshioka, M. Hayakawa, Y. Cho, M. Matsuoka, N. Hirata, N. Hirata, H. Miyamoto, D. Domingue, M. Hirabayashi, T. Nakamura, T. Hiroi, T. Michikami, P. Michel, R.-L. Ballouz, O. S. Barnouin, C. M. Ernst, S. E. Schröder, H. Kikuchi, R. Hemmi, G. Komatsu, T. Fukuhara, M. Taguchi, T. Arai, H. Senshu, H. Demura, Y. Ogawa, Y. Shimaki, T. Sekiguchi, T. G. Müller, A. Hagermann, T. Mizuno, H. Noda, K. Matsumoto, R. Yamada, Y. Ishihara, H. Ikeda, H. Araki, K. Yamamoto, S. Abe, F. Yoshida, A. Higuchi, S. Sasaki, S. Oshigami, S. Tsuruta, K. Asari, S. Tazawa, M. Shizugami, J. Kimura, T. Otsubo, H. Yabuta, S. Hasegawa, M. Ishiguro, S. Tachibana, E. Palmer, R. Gaskell, L. Le Corre, R. Jaumann, K. Otto, N. Schmitz, P. A. Abell, M. A. Barucci, M. E. Zolensky, F. Vilas, F. Thuillet, C. Sugimoto, N. Takaki, Y. Suzuki, H. Kamiyoshihara, M. Okada, K. Nagata, M. Fujimoto, M. Yoshikawa, Y. Yamamoto, K. Shirai, R. Noguchi, N. Ogawa, F. Terui, S. Kikuchi, T. Yamaguchi, Y. Oki, Y. Takao, H. Takeuchi, G. Ono, Y. Mimasu, K. Yoshikawa, T. Takahashi, Y. Takei, A. Fujii, C. Hirose, S. Nakazawa, S. Hosoda, O. Mori, T. Shimada, S. Soldini, T. Iwata, M. Abe, H. Yano, R. Tsukizaki, M. Ozaki, K. Nishiyama, T. Saiki, S. Watanabe, Y. Tsuda

  Mar. 2019, Science, eaaw0422, English

  [Refereed]

  Scientific journal


• The longitudinal dichotomy of 162173 Ryugu as a result of a recent difformation process

  M. Hirabayashi, E. Tatsumi, H. Miyamoto, G. Komatsu, S. Sugita, S. Watanabe, D. J. Scheeres, O. S. Barnouin, P. Michel, C. Honda, T. Michikami, Y. Cho, T. Morota, N. Hirata, N. Hirata, N. Sakatani, S. R. Schwartz, R. Honda, Y. Yokota, S. Kameda, H. Suzuki, T. Kouyama, M. Hayakawa, M. Matsuoka, K. Yoshioka, K. Ogawa, H. Sawada, M. Yoshikawa

  Mar. 2019, Proceedings of Lunar and Planetary Science Conference, 50, 1397, English

  International conference proceedings


• Topography of Large Craters of 162173 Ryugu

  Namiki, N, Mizuno, T, Senshu, H, Noda, H, Matusmoto, K, Hirata, N, Yamada, R, Ishihara, Y, Ikeda, H, Araki, H, Yamamoto, K, Abe, S, Yoshida, F, Higuchi, A, Sasaki, S, Oshigami, S, Tsuruta, S, Asari, K, Tazawa, S, Shizugami, M. Miyamoto, H, Demura, H, Kimura, J, Otsubo, T, Hirata, N, Terui, F, Watanabe, S, Saiki, T, Nakazawa, S, Yoshikawa, M, Tsuda, Y

  Mar. 2019, 50th Lunar and Planetary Science Conference, 2658, Japanese

  International conference proceedings


• The Western Bulge of 162173 Ryugu Formed as a Result of a Rotationally Driven Deformation Process

  Masatoshi Hirabayashi, Eri Tatsumi, Hideaki Miyamoto, Goro Komatsu, Seiji Sugita, Sei-ichiro Watanabe, Daniel J. Scheeres, Olivier S. Barnouin, Patrick Michel, Chikatoshi Honda, Tatsuhiro Michikami, Yuichiro Cho, Tomokatsu Morota, Naru Hirata, Naoyuki Hirata, Naoya Sakatani, Stephen R. Schwartz, Rie Honda, Yasuhiro Yokota, Shingo Kameda, Hidehiko Suzuki, Toru Kouyama, Masahiko Hayakawa, Moe Matsuoka, Kazuo Yoshioka, Kazunori Ogawa, Hirotaka Sawada, Makoto Yoshikawa, Yuichi Tsuda

  Mar. 2019, ASTROPHYSICAL JOURNAL LETTERS, 874(1) (1), English

  [Refereed]

  Scientific journal


• Shape of (101955) Bennu indicative of a rubble pile with internal stiffness

  O. S. Barnouin, M. G. Daly, E. E. Palmer, R. W. Gaskell, J. R. Weirich, C. L. Johnson, M. M. Al Asad, J. H. Roberts, M. E. Perry, H. C. M. Susorney, R. T. Daly, E. B. Bierhaus, J. A. Seabrook, R. C. Espiritu, A. H. Nair, L. Nguyen, G. A. Neumann, C. M. Ernst, W. V. Boynton, M. C. Nolan, C. D. Adam, M. C. Moreau, B. Rizk, C. Y, Drouet, D’Aubigny, E. R. Jawin, K. J. Walsh, P. Michel, S. R. Schwartz, R.-L. Ballouz, E. M. Mazarico, D. J. Scheeres, J. W. McMahon, W. F. Bottke, S. Sugita, Naru Hirata, Naoyuki Hirata, S.-i. Watanabe, K. N. Burke, D. N. DellaGiustina, C. A. Bennett, D. S. Lauretta, The OSIRIS-REx Team

  Mar. 2019, Nature Geoscience, 12, 247–252, English

  [Refereed]

  Scientific journal


• Ray craters on Ganymede: Implications for cratering apex-antapex asymmetry and surface modification processes

  Luyuan Xu, Naoyuki Hirata, Hideaki Miyamoto

  Oct. 2017, ICARUS, 295, 140 - 148, English

  [Refereed]

  Scientific journal


• Spatial distribution of impact craters on Deimos

  Naoyuki Hirata

  May 2017, ICARUS, 288(15) (15), 69 - 77, English

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Timing of the faulting on the Wispy Terrain of Dione based on stratigraphic relationships with impact craters

  Naoyuki Hirata

  Nov. 2016, JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS, 121(11) (11), 2325 - 2334, English

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Rayed craters on Dione: Implication for the dominant surface alteration process

  Naoyuki Hirata, Hideaki Miyamoto

  Aug. 2016, ICARUS, 274, 116 - 121, English

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Differential impact cratering of Saturn's satellites by heliocentric impactors

  Naoyuki Hirata

  Feb. 2016, JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS, 121(2) (2), 111 - 117, English

  [Refereed]

  Scientific journal

  Link to Kobe Univ. Repository (Kernel)


• Performance of Hayabusa-2 LIDAR in Acceptance and Verification Tests

  Namiki, N, Mizuno, T, Senshu, H, Yamada, R, Noda, H, Hirata, N, Ikeda, H, Abe, S, Matsumoto, K, Oshigami, S, Yoshida, F, Hirata, N, Miyamoto, H, Sasaki, S, Araki, H, Shizugami, M, Tazawa, S, Ishihara, Y, Kobayashi, M, Wada, K, Demura, H, Kimura, J, Mita, M, Kawahara, K, Kunimori, H, Hayakawa, M, Kobayashi, N

  The Lunar and Planetary Institute, USA, Mar. 2015, 46th Lunar and Planetary Science Conference, 1832, 1798 - 1799, English

  International conference proceedings


• Particle deposition on the saturnian satellites from ephemeral cryovolcanism on Enceladus

  Naoyuki Hirata, Hideaki Miyamoto, Adam P. Showman

  Lead, Jun. 2014, GEOPHYSICAL RESEARCH LETTERS, 41(12) (12), 4135 - 4141, English

  [Refereed]

  Scientific journal


• Development of Hayabusa-2 LIDAR

  Namiki, N, Mizuno, T, Mita, M, Kawahara, K, Kunimori, H, Senshu, H, Yamada, R, Noda, H, Shizugami, M, Hirata, N, Ikeda, H, Abe, S, Matsumoto, K, Oshigami, S, Yoshida, F, Hirata, N, Miyamoto, H, Sasaki, S, Araki, H, Tazawa, S, Ishihara, Y, Kobayashi, M, Wada, K, Demura, H, Kimura, J, Hayakawa, M, Kobayashi, N

  The Lunar and Planetary Institute, USA, Mar. 2014, 45th Lunar and Planetary Science Conference, 1777, 1922 - 1923, English

  International conference proceedings


• Planetary-science outreach in collaboration with non-academic partners (Special issue: Public relations and outreach)

  Miyamoto H., Kikuchi H., Hirata N., Kou T., Sekioka H., Dohm James M., Niihara T., Hong P. K., Hemmi R., Kiyota K., Oguma M.

  猛烈な勢いで進む太陽系探査の成果を一般に紹介することは,若い世代の知的好奇心を鼓舞するのに有効であるし,探査の意義に関する一般の理解を深める一助にもなりえる.そこで私たちは大学博物館の一員として,太陽系科学/探査に関するアウトリーチ活動を試みた.若い世代に対象を特化したスクール・モバイルミュージアムと,より多くの人材にアプローチできるアミューズメント施設における展示活動を通じて,産学官の連携によって互いにメリットがあるアウトリーチの形が存在しうることを示した.

  The Japanese Society for Planetary Sciences, 2014, Planetary People - The Japanese Society for Planetary Sciences, 23(4) (4), 323 - 329, Japanese

  [Refereed]


• Scientific Goals of Hayabusa-2 LIDAR Experiment

  Senshu, Hiroki, Namiki, N, Mizuno, T, Hirata, N, Noda, H, Yamada, R, Ikeda, H, Abe, S, Matsumoto, K, Oshigami, S, Sasaki, S, Araki, H, Tazawa, S, Shizugami, M, Kobayashi, M, Wada, K, Ishihara, Y, Miyamoto, H, Demura, H, Kimura, J, Yoshida, F, Hirata, N, Mita, M

  American Astronomical Society, USA, Oct. 2013, American Astronomical Society, Devision of Planetary Science Meeting, 45, 112, English

  International conference proceedings


• Dust levitation as a major resurfacing process on the surface of a saturnian icy satellite, Atlas

  Naoyuki Hirata, Hideaki Miyamoto

  Lead, Jul. 2012, ICARUS, 220(1) (1), 106 - 113, English

  [Refereed]

  Scientific journal

• Pre-arrival Landing Site Selection for the Martian Moons eXploration (MMX)

  和田浩二, 中村智樹, 宮本英昭, 松本晃治, 平田成, 菊地紘, 逸見良道, 清水俊輔, 菊地翔太, 森田朋代, 小林真輝人, 清水雄太, 竹村知洋, VARSHA Natarajan, 堀田啓貴, 平田直之, 松岡萌, 巽瑛理, 黒川宏之, 長勇一郎, 田畑陽久, 倉本圭, 諸田智克, 永峰健太, 大槻真嗣, 馬場満久, 小川和律, 巳谷真司, 岡田尚基, 尾川順子, 池田人, 竹尾洋介, 松本祐樹, 大野剛, 吉川健人, 安光亮一郎

  2023, 宇宙科学技術連合講演会講演集(CD-ROM), 67th


• Geology and Surface Science of Martian Satellites: Perspective for MMX mission

  宮本英昭, MICHEL Patrick, MICHEL Patrick, 和田浩二, 逸見良道, 小川和律, 新原隆史, 坂谷尚哉, 大槻真嗣, 臼井寛裕, 菊地紘, 平田直之, 亀田真吾, 中村智樹, 諸田智克, 寺田直樹, 佐々木晶, 千秋博紀, 横田勝一郎, 木村智樹, 臼井英之, 三宅洋平, 西野真木, 長勇一郎, 二穴喜文, ASPHAUG Erik, BALLOUZ Ronald-Louis, BIELE Jens, BOETTGER Ute, ERNST Carolyn, BARNOUIN Olivier, GROTT Matthias, 小林真輝人, 清水雄太, 竹村知洋, 清水俊輔

  2022, 宇宙科学技術連合講演会講演集(CD-ROM), 66th


• はやぶさ2探査と微惑星形成

  渡邊誠一郎, 安部正真, 諸田智克, 道上達弘, 平田直之, 平田成, 嶌生有理, 杉田精司, 岡田達明, 北里宏平, 竝木則行, 橘省吾, 橘省吾, 荒川政彦, 田中智

  2021, 日本惑星科学会秋季講演会予稿集(Web), 2021


• はやぶさ2SCIによる人工クレーター形成に伴う小惑星リュウグウの再表面化過程

  本田理恵, 荒川政彦, 嶌生有理, 白井慶, 横田康弘, 門野敏彦, 和田浩二, 小川和律, 石橋高, 坂谷尚哉, 中澤暁, 保井みなみ, 諸田智克, 亀田真吾, 巽瑛理, 山田学, 神山徹, 長勇一郎, 松岡萌, 鈴木秀彦, 本田親寿, 早川雅彦, 吉岡和夫, 澤田弘崇, 杉田精司, 平田成, 平田直之

  2020, 日本惑星科学会秋季講演会予稿集(Web), 2020


• はやぶさ2のリュウグウ近傍観測の科学成果

  渡邊誠一郎, 田中智, 吉川真, 杉田精司, 岡田達明, 北里宏平, 竝木則行, 荒川政彦, 橘省吾, 橘省吾, 諸田智克, 杉浦圭祐, 嶌生有理, 平田成, 平田直之

  2020, 日本惑星科学会秋季講演会予稿集(Web), 2020


• ラブルパイル小惑星リュウグウの形状と起源

  渡邊誠一郎, 渡邊誠一郎, 平林正俊, 平田成, 平田直之, 野口里奈, 嶌生有理, 池田人, 巽瑛理, 吉川真, 菊地翔太, 薮田ひかる, 中村智樹, 橘省吾, 橘省吾, 石原吉明, 諸田智克, 北里宏平, 坂谷尚哉, 松本晃治, 松本晃治, 和田浩二, 千秋博紀, 本田親寿, 道上達広, 竹内央, 神山徹, 本田理恵, GASKELL Robert, PALMER Eric, BARNOUIN Olivier S., MICHEL Patrick, ABELL Paul, 山本幸生, 田中智, 白井慶, 松岡萌, 杉田精司, 杉田精司, 岡田達明, 並木則行, 荒川政彦, 石黒正晃, 小川和律, 照井冬人, 佐伯孝尚, 中澤暁, 津田雄一

  2019, 日本地球惑星科学連合大会予稿集(Web), 2019


• Thermal Characteristics of a Crater and Ejecta Materials Generated by a SCI (Small Carry-on Impactor) Experiment and Adjacent Touchdown Area Observed by Thermal Infrared Imager (TIR) onboard HAYABUSA2

  田中智, 坂谷尚哉, 嶌生有理, 岡田達明, 福原哲哉, 千秋博紀, 荒井武彦, 神山徹, 滝田隼, 伊藤瑞生, 森川惠海, 須古健太郎, 出村裕英, 平田成, 平田直之

  2019, 日本惑星科学会秋季講演会予稿集(Web), 2019


• はやぶさ2探査機の観測に基づく小惑星リュウグウの形状

  平田成, 平田直之, 田中小百合, 西川直輝, 杉山貴亮, GASKELL R., PALMER E., 野口里奈, 嶌生有理, 杉田精司, 津田雄一, 渡邊誠一郎

  2018, 日本惑星科学会秋季講演会予稿集(Web), 2018


• はやぶさ2によるリュウグウ観測の概観

  渡邊誠一郎, 渡邊誠一郎, 吉川真, 田中智, 杉田精司, 北里宏平, 竝木則行, 岡田達明, 平田成, 平田直之, 山本幸生, 藪田ひかる, 中村智樹, 石原吉明, 佐伯孝尚, 津田雄一

  2018, 日本惑星科学会秋季講演会予稿集(Web), 2018


• JUICEレーザ高度計(GALA)による調査に向けたガニメデ表面の超高精細DEMの作成

  押上祥子, 平田直之, 木村淳, 並木則行

  2015, 日本惑星科学会秋季講演会予稿集(Web), 2015


• S01 土星氷衛星の地質学的研究に基づくエンセラダスとディオーネの熱的再活性化の発見(特別セッション(最優秀発表賞選考),口頭発表)

  平田 直之, 宮本 英昭

  日本惑星科学会, 10 Sep. 2014, 日本惑星科学会秋期講演会予稿集, 2014, S01, Japanese


• P2-19 最新のカッシーニ探査データに基づくディオーネの表層進化史(ポスターセッション2,ポスター発表)

  平田 直之, 宮本 英昭

  日本惑星科学会, 20 Nov. 2013, 日本惑星科学会秋期講演会予稿集, 2013, "P2 - 19", Japanese


• S06 土星系の衛星におけるE環粒子の堆積物からわかるE環の性質とエンセラダスの火山活動史(特別セッション:最優秀発表賞選考,口頭発表)(ポスターセッション1,ポスター発表)

  平田 直之, 宮本 英昭

  日本惑星科学会, 24 Oct. 2012, 日本惑星科学会秋期講演会予稿集, 2012, 6 - 6, Japanese


• S11-04P How to analyze levitating dust on asteroids

  Senshu Hiroki, Kobayashi Masanori, Wada Koji, Namiki Noriyuki, Hirata Naoyuki, Miyamoto Hideaki

  The Japanese Society for Planetary Sciences, 23 Oct. 2011, Abstracts Fall Meeting of the Japanese Society for Planetary Sciences, 2011, 110 - 110, Japanese


• Saturn's small satellites : Internal structures and surface processes (Special issue: Sciences toward future explorations for the Jovian and Saturnian systems)

  Hirata N., Miyamoto H.

  土星系の魅力的な衛星は,タイタンやエンセラダスだけではない.カッシーニ探査機の活躍によって得られたさまざまな知見は,その他大勢の小型衛星も,太陽系科学において極めて興味深い対象であることを示している.小型衛星は,その小さな重力場や弱い熱的変成履歴という意味で小惑星と対比できるだけでなく,その特徴的な形態や表層の状態が,ほかの衛星や周囲の環と複雑な相互作用の結果であることから,土星系における衛星や環の形成や進化の鍵を握っていると考えられる.本稿では,こうした多様性に富む土星系小型衛星の姿と推定される内部構造,さらには進化史について概説するとともに,今後の探査で期待される観測について議論する.

  The Japanese Society for Planetary Sciences, 2011, Planetary People - The Japanese Society for Planetary Sciences, 20(4) (4), 271 - 280, Japanese


• 119 Concentration mechanisms of sulfur on Io : Contribution of photochemical reactions

  平田 直之, 宮本 英昭

  The Japanese Society for Planetary Sciences, 06 Oct. 2010, Abstracts Fall Meeting of the Japanese Society for Planetary Sciences, 2010, 19 - 19, Japanese


• P021 Identification of an impact crater on Atlas : Implications to its resurfacing process

  平田 直之, 宮本 英昭

  The Japanese Society for Planetary Sciences, 06 Oct. 2010, Abstracts Fall Meeting of the Japanese Society for Planetary Sciences, 2010, 101 - 101, Japanese

• GanymedeのTrue Polar Wanderについての考察

  平田 直之

  日本惑星科学会秋季講演会, Oct. 2023, Japanese

  Poster presentation


• Ejecta emplacement as the possible origin of Ryugu's equatrial ridge

  Ren Ikeya, Naoyuki Hirata

  日本惑星科学会秋季講演会, Nov. 2020, Japanese

  Oral presentation


• Geological Characteristics and History of Asteroid Ryugu

  H. Miyamoto, R. Hemmi, H. Kikuchi, G. Komatsu, C. Honda, T. MIChikami, T. Morota, Y. Cho, P. Mitchel, O. S. Barnouin, S. Sasaki, Naoyuki Hirata, Naru Hirata, M. Hirabayashi, R. Honda, S. Kameda, E. Tatsumi, Y. Yokota, T. Kouyama, H. Suzuki, M. Yamada, N. Sakatani, M. Hayakawa, K. Yoshida, M. Matsuoka, H. Sawada, S. Sugita

  51st Lunar and Planetary Science Conference, Mar. 2020, English

  Oral presentation


• From Asteroid to Martian Moons: A Summary of Results of Hayabusa2 LIDAR

  K. Matsumoto, N. Namiki, H. Noda, H. Senshu, T. Mizuno, R. Yamada, Y. Ishihara, Naru Hirata, Naoyuki Hirata, K. Yamamoto, T. Otsubo, A. Higuchi, H. Araki, S. Abe, Y. Masuda, H. Ikeda, F. Yoshida, S. Sasaki, S. Oshigami, S. Tsuruta, K. Asari, M. Shizugami

  51st Lunar and Planetary Science Conference, Mar. 2020, English

  Poster presentation


• Comparing Crater Morphologies on Ryugu and Bennu

  C. M. Ernst, R. T. Daly, O. S. Barnouin, Y. Cho, T. Morota, Naoyuki Hirata, R. Noguchi, E. B. Bierhaus, M. G. Daly, Naru Hirata, S. Sugita, R. W. Gaskell, E. E. Palmer, J. R. Weirich, Y. Shimaki, S. Watanabe, J. Seabrook, M. Kanamaru, P. Michel, R. Honda, M. Hayakawa, K. Yoshioka, M. Matsuoka, H. Sawada, K. Ogawa, D. S. Lauretta

  51st Lunar and Planetary Science Conference, Mar. 2020, English

  Poster presentation


• Surface Flow Analysis Based on Spectral Distributions Around Large Boulders on Ryugu

  N. Takaki, E. Tatsumi, T. Morota, Y. Cho, K. Yoshioka, H. Sawada, Y. Yokota, N. Sakatani, M. Hayakawa, R. Honda, S. Kameda, M. Matsuoka, M. Yamada, C. Honda, T. Kouyama, H. Suzuki, K. Ogawa, H. Miyamoto, Naru Hirata, Naoyuki Hirata, S. Sugita

  51st Lunar and Planetary Science Conference, Mar. 2020, English

  Oral presentation


• Rotational State and Shapes of Ryugu and Bennu: Implications for Interior Structure and Strength1675

  J. H. Roberts, O. S. Barnouin, G. A. Neumann, M. C. Nolan, M. E. Perry, R. T. Daly, C. L. Johnson, M. M. Al Asad, M. G. Daly, J. A. Seabrook, R. W. Gaskell, E. E. Palmer, J. R. Weirich, K. J. Walsh, D. J. Scheeres, J. W. McMahon, S. Watanabe, Naru Hirata, Naoyuki Hirata, S. Sugita, D. S. Lauretta

  51st Lunar and Planetary Science Conference, Mar. 2020, English

  Oral presentation


• Morphological Analysis of Boulders on Asteroid Ryugu

  S. Sugita, R. Honda, T. Morota, S. Kameda, E. Tatsumi, K. Kumoto, C. Sugimoto, C. Honda, Y. Yokota, M. Yamada, T. Kouyama, N. Sakatani, H. Suzuki, K. Yoshioka, Y. Cho, M. Matsuoka, K. Ogawa, D. Domingue, H. Miyamoto, O. S. Barnouin, P. Michel, C. M. Ernst, T. Hiroi, T. Nakamura, H. Sawada, M. Hayakawa, Naru Hirata, Naoyuki Hirata, H. Kikuchi, R. Hemmi, T. Michikami, M. Hirabayashi, G. Komatsu, S. Tanaka, K. Shirai, M. Yoshikawa, S. Watanabe, Y. Tsuda

  51st Lunar and Planetary Science Conference, Mar. 2020, English

  Oral presentation


• Unveiling Highly-Porous Nature of Primitve Asteroid 162173 Ryugu by Thermal Imager on Hayabusa2

  T. Okada, T. Fukuhara, S. Tanaka, M. Taguchi, T. Arai, N. Sakatani, Y. Shimaki, H. Senshu, Y. Ogawa, H. Demura, K. Suko, K. Kitazato, T. Kouyama, T. Sekiguchi, J. Takita, S. Hasegawa, T. Matsunaga, T. Wada, T. Imamura, J. Helbert, T. G. Mueller, A. Hagermann, J. Biele, M. Grott, M. Hamm, M. Delbo, Y. Yamamoto, Naru Hirata, Naoyuki Hirata, F. Terui, T. Saiki, S. Nakazawa, M. Yoshikawa, S. Watanabe, T. Tsuda

  51st Lunar and Planetary Science Conference, Mar. 2020, English

  Oral presentation


• Color and Albedo Changes of Ryugu's Surface Observed in the Touchdown Operation of Hayabusa2

  T. Morota, S. Sugita, Y. Cho, M. Kanamaru, E. Tatsumi, N. Sakatani, R. Honda, Naoyuki Hirata, H. Kikuchi, M. Yamada, Y. Yokota, S. Kameda, M. Matsuoka, H. Sawada, C. Honda, T. Kouyama, K. Ogawa, H. Suzuki, K. Yoshioka, M. Hayakawa, Naru Hirata, M. Hirabayashi, H. Miyamoto, T. Michikami, T. Hiroi, R. Hemmi, C. M. Ernst, O. S. Barnouin, S. Watanabe

  51st Lunar and Planetary Science Conference, Mar. 2020, English

  Oral presentation


• Plans of Hayabusa2 ONC Visible Mutiband Image Archive and Public Release

  R. Honda, Y. Yokota, M. Yamada, Y. Yamamoto, S. Murakami, K. Crombie, E. Tatsumi, T. Kouyama, T. Morota, M. Matsuoka, S. Sugita, S. Kameda, H. Suzuki, N. Sakatani, Y. Cho, M. Hayakawa, C. Honda, K. Yoshioka, H. Sawada, Naru Hirata, Naoyuki Hirata, A. Miura, H. Ohtake, H. Sato, H. Kikuchi, R. Miyazaki

  51st Lunar and Planetary Science Conference, Mar. 2020, English

  Poster presentation


• Shape Reconstruction of the Asteroid Ryugu with Structure-from-Motion Method

  Naru Hirata, T. Sugiyama, Naoyuki Hirata, S. Tanaka, N. Nishikawa, R. Noguchi, Y. Shimaki, R. Gaskell, E. Palmer, K. Matsumoto, H. Senshu, Y. Yamamoto, S. Murakami, Y. Ishihara, S. Sugita, T. Morota, R. Honda, M. Arakawa, K. Ogawa, Y. Tsuda, S. Watanabe

  51st Lunar and Planetary Science Conference, Mar. 2020, English

  Poster presentation


• Paucity of Boulders in Shallow Craters on Asteroid 162173 Ryugu

  S. Watanabe, H. Akahane, T. Morota, T. Michikami, Naru Hirata, Naoyuki Hirata, Y. Shimaki, R. Noguchi, R. Honda, S. Kameda, M. Yamada, N. Sakatani, K. Ogawa, E. Tatsumi, T. Kouyama, Y. Yokota, Y. Cho, H. Suzuki, M. Hayakawa, M. Matsuoka, C. Honda, K. Yoshioka, H. Sawada, S. Sugita, M. Arakawa, Hayabusa2 Science Team

  51st Lunar and Planetary Science Conference, Mar. 2020, English

  Oral presentation


• Visible Color of the Artificial Crater on Ryugu Created by Small Carry-On Impactor

  Yokota, Y. Cho, C. Honda, M. Matsuoka, M. Hayakawa, H. Suzuki, K. Yoshioka, H. Sawada, K. Ogawa, Naru Hirata, Naoyuki Hirata, T. Saiki, H. Imamura, Y. Takagi, H. Yano, Y. Tsuda, S. Nakazawa, K. Kitazato, T. Kadono, K. Wada, M. Arakawa, S. Sugita, S. Watanabe

  51st Lunar and Planetary Science Conference, Mar. 2020, English

  Oral presentation


• The Effect of Sphere Packing onto the Dynamics in the Gravitational Field of Rubble-Pile Asteroids: Applications to Ryugus' Ejecta

  S. Soldini, T. Saiki, H. Ikeda, K. Wada, Y. Tsuda, M. Arakawa, Naru Hirata, Naoyuki Hirata

  51st Lunar and Planetary Science Conference, Mar. 2020, English

  Oral presentation


• Thermophysical Property of the Artificial Impact Crater on Asteroid Ryugu

  N. Sakatani, S. Tanaka, T. Okada, T. Kouyama, A. Miura, Naru Hirata, H. Senshu, T. Arai, Y. Shimaki, H. Demura, K. Suko, T. Sekiguchi, J. Takita, T. Fukuhara, M. Taguchi, T. Mueller, A. Hagermann, J. Biele, M. Grott, M. Hamm, M. Delbo, M. Ito, Naoyuki Hirata, M. Arakawa, K. Ogawa, K. Wada, T. Kadono, R. Honda, K. Shirai, T. Saiki, H. Imamura, Y. Takagi, H. Yano, M. Hayakawa, C. Okamoto, H. Sawada, S. Nakazawa, Y. Iijima, S. Sugita, T. Morota, M. Yamada, S. Kameda, E. Tatsumi, Y. Yokota, H. Suzuki, C. Honda, K. Yoshioka, M. Matsuoka, Y. Cho

  51st Lunar and Planetary Science Conference, Mar. 2020, English

  Oral presentation


• A new global database of impact craters on Ceres

  Kousei Toyokawa, Naoyuki Hirata, Sayuri Tanaka

  American Geophysical Union(AGU) Fall Meeting 2019, Dec. 2019, English

  Poster presentation


• リュウグウクレーターの東西不対称性の起源に関する理論的考察

  平田 直之

  第15回衝突研究会, Nov. 2019

  Poster presentation


• 小惑星リュウグウにおけるメートルサイズのボルダー3軸比

  道上 達広, 岡村 裕之, 諸田 智克, 横田 康弘, 本田 親寿, 巽 瑛理, 宮本 英昭, 平林 正稔, 野口 高明, 長 勇一郎, 亀田 真吾, 菊地 紘, 神山 徹, 早川 雅彦, 辺見 良道, 平田 直之, 平田 成, 本田 理恵, 松岡 萌, 坂谷 尚哉, 鈴木 秀彦, 山田 学, 吉岡 和夫, 澤田 弘崇, 杉田 精司

  第15回衝突研究会, Nov. 2019

  Oral presentation


• 小惑星Ryuguに働くYORP効果の数値計算 〜自転状態の進化史解明に向けて〜

  金丸 仁明, 佐々木 晶, 諸田 智克, 長 勇一郎, 平田 成, 平田 直之, 千秋 博紀, 嶌生 有理, 田中 智, 杉田 精司, 渡邊 誠一郎

  第15回衝突研究会, Nov. 2019

  Oral presentation


• はやぶさ2タッチダウンからあきらかになった小惑星Ryuguの表面の色変化と層序

  諸田 智克, 杉田 精司, 長勇 一郎, 金丸 仁明, 本田 理恵, 巽 瑛理, 坂谷 尚哉, 平田 直之, 亀田 真吾, 菊地 紘, 山田 学, 横田 康弘, 松岡 萌, 本田 親寿, 神山 徹, 鈴木 秀彦, 早川 雅彦, 吉岡 和夫, 小川 和律, 道上 達広, 宮本 英昭, 逸見 良道, 平林 正稔, 平田 成, 廣井 孝弘, 澤田 弘崇, はやぶさ2チーム

  日本惑星科学会2019年秋季大会, Oct. 2019

  Poster presentation


• リュウグウでみられるリニアメントの空間的特性

  菊地 紘, 逸見 良道, 宮本 英昭, 小松 吾郎, 平田 直之, 平田 成, 本田 親寿, 道上 達広, 諸田 智克, 長 勇一朗, 本田 理恵, 亀田 真吾, 巽 瑛理, 横田 康弘, 神山 徹, 鈴木 秀彦, 山田 学, 坂谷 尚哉, 早川 雅彦, 吉岡 和夫, 松岡 萌, 佐々木 晶, 平林 正稔, 澤田 弘崇, 杉田 精司

  日本惑星科学会2019年秋季大会, Oct. 2019

  Poster presentation


• Spatial distribution of the depth-diameter ratio of craters on the surface of Ryugu

  野口 里奈, 平田 成, 平田 直之, 嶌生 有理, 西川 直輝, 田中 小百合, 杉山 貴亮, 諸田 智克, 金丸 仁明, 杉田 精司, 渡邊 誠一郎

  日本惑星科学会2019年秋季大会, Oct. 2019

  Poster presentation


• 小惑星リュウグウのクレーターと周辺ボルダーの関係に着目した表層の層構造の推定

  赤羽 大貴, 渡邊 誠一郎, 諸田 智克, 道上 達広, 平田 成, 平田 直之, 嶌生 有理, 野口 里奈, 本田 理恵, 亀田 真吾, 山田 学, 坂谷 尚哉, 小川 和律, 巽 瑛理, 神山 徹, 横田 康弘, 長 勇一郎, 鈴木 秀彦, 早川 雅彦, 松岡 萌, 本田 親寿, 吉岡 和夫, 澤田 弘崇, 杉田 精司, 荒川 政彦, はやぶさ2サイエンスチーム

  日本惑星科学会2019年秋季大会, Oct. 2019

  Oral presentation


• Spectral characteristics of asteroid (162173) Ryugu with Hayabusa2 NIRS3

  D. Takir, K. Kitazato, R. E. Milliken, T. Iwata, M. Abe, M. Ohtake, S. Matsuura, T. Arai, Y. Nakauchi, T. Nakamura, M. Matsuoka, H. Senshu, N. Hirata, T. Hiroi, C. Pilorget, R. Brunetto, F. Poulet, L. Riu, J.-P. Bibring, D. L. Domingue, F. Vilas, M. A. Barucci, D. Perna, E. Palomba, A. Galiano, K. Tsumura, T. Osawa, M. Komatsu, A. Nakato, T. Arai, N. Takato, T. Matsunaga, Y. Takagi, K. Matsumoto, T. Kouyama, Y. Yokota, E. Tatsumi, N. Sakatani, Y. Yamamoto, T. Okada, S. Sugita, R. Honda, T. Morota, S. Kameda, H. Sawada, C. Honda, M. Yamada, H. Suzuki, K. Yoshioka, M. Hayakawa, K. Ogawa, Y. Cho, K. Shirai, Y. Shimaki, N. Hirata, A. Yamaguchi, N. Ogawa, F. Terui, T. Yamaguchi, Y. Takei, T. Saiki, S. Nakazawa, S. Tanaka, M. Yoshikawa, S. Watanabe, Y. Tsuda

  Annual Meetings of the Meteoritical Society, Jul. 2019, English, Sapporo, International conference

  Oral presentation


• Ryugu's parent body processes estimated from Hayabusa2 multi-band optical observations

  S. Sugita, R. Honda, T. Morota, S. Kameda, E. Tatsumi, C. Honda, Y. Yokota, M. Yamada, T. Kouyama, N. Sakatani, H. Suzuki, K. Yoshioka, Y. Cho, M. Matsuoka, K. Ogawa, D. Domingue, H. Miyamoto, O. S. Barnouin, P. Michel, C. M. Ernst, T. Hiroi, T. Nakamura, H. Sawada, M. Hayakawa, N. Hirata, N. Hirata, H. Kikuchi, R. Hemmi, T. Michikami, Eric Palmer, R. Gaskell, M. Hirabayashi, R. Jaumann, K. Otto, N. Schmitz, S. E. Schröder, G. Komatsu, S. Tanaka, K. Shirai, M. Yoshikawa, S. Watanabe, Y. Tsuda

  Annual Meetings of the Meteoritical Society, Jul. 2019, English, Sapporo, International conference

  Oral presentation


• Hayabusa2: Current Summary

  T. Nakamura, S. Watanabe, M. Hirabayashi, N. Hirata, N. Hirata, R. Noguchi, Y. Shimaki, H. Ikeda, E. Tatsumi, M. Yoshikawa, S. Kikuchi, H. Yabuta, S. Tachibana, Y. Ishihara, T. Morota, K. Kitazato, N. Sakatani, K. Matsumoto, K. Wada, H. Senshu, C. Honda, T. Michikami, H. Takeuchi, T. Kouyama, R. Honda, S. Kameda, T. Fuse, H. Miyamoto, G. Komatsu, S. Sugita, T. Okada, N. Namiki, M. Arakawa, M. Ishiguro, M. Abe, R. Gaskell, E. Palmer, O. S. Barnouin, P. Michel, A. S. French, J. W. McMahon, D. J. Scheeres, P. A. Abell, Y. Yamamoto, S. Tanaka, K. Shirai, M. Matsuoka, M. Yamada, Y. Yokota, H. Suzuki, K. Yoshioka, Y. Cho, S. Tanaka, N. Nishikawa, T. Sugiyama, H. Kikuchi, R. Hemmi, T. Yamaguchi, N. Ogawa, G. Ono, Y. Mimasu, K. Yoshikawa, T. Takahashi, Y. Takei, A. Fujii, C. Hirose, T. Iwata, M. Hayakawa, S. Hosoda, O. Mori, H. Sawada, T. Shimada, S. Soldini, H. Yano, R. Tsukizaki, M. Ozaki, Y. Iijima, K. Ogawa, M. Fujimoto, T.-M. Ho, A. Moussi, R. Jaumann, J.-P. Bibring, C. Krause, F. Terui, T. Saiki, S. Nakazawa, Y. Tsuda

  Annual Meetings of the Meteoritical Society, Jul. 2019, English, Sapporo, International conference

  Oral presentation


• Development of smooth area detection method for selection of landing site on a small body

  Yuki Fujii, Rie Honda, Tomokatsu Morota, Yasuhiro Yokota, Eri Tatsumi, Naoya Sakatani, Manabu Yamada, Shingo Kameda, Toru Kouyama, Hidehiko Suzuki, Chikatoshi Honda, Masahiko Hayakawa, Kazuo Yoshioka, Yuichiro Cho, Yukio Yamamoto, Naru Hirata, Naoyuki Hirata, Hirotaka Sawada, Seiji Sugita

  Japan Geoscience Union Meeting 2019, May 2019, Japanese, Makuhari Messe, Chiba, Domestic conference

  Poster presentation


• The shape and origin of the rubble-pile asteroid Ryugu

  Sei-ichiro Watanabe, Masatoshi Hirabayashi, Naru Hirata, Naoyuki Hirata, Rina Noguchi, Yuri Shimaki, Hitoshi Ikeda, Eri Tatsumi, Makoto Yoshikawa, Shota Kikuchi, Hikaru Yabuta, Tomoki Nakamura, Shogo Tachibana, Yoshiaki Ishihara, Tomokatsu Morota, Kohei Kitazato, Naoya Sakatani, Koji Matsumoto, Koji Wada, Hiroki Senshu, Chikatoshi Honda, Tatsuhiro Michikami, Hiroshi Takeuchi, Toru Kouyama, Rie Honda, Robert Gaskell, Eric Palmer, Olivier S. Barnouin, Patrick Michel, Paul Abell, Yukio Yamamoto, Satoshi Tanaka, Kei Shirai, Moe Matsuoka, Seiji Sugita, Tatsuaki Okada, Noriyuki Namiki, Masahiko Arakawa, Masateru Ishiguro, Kazunori Ogawa, Fuyuto Terui, Takanao Saiki, Satoru Nakazawa, Yuichi Tsuda, Hayabusa, Science Team

  Japan Geoscience Union Meeting 2019, May 2019, English, Makuhari Messe, Chiba, International conference

  [Invited]

  Invited oral presentation


• Thermal Infrared Imaging of C-type Asteroid 162173 Ryugu with Porous Surfaces

  Tatsuaki Okada, Tetsuya Fukuhara, Satoshi Tanaka, Makoto Taguchi, Takehiko Arai, Naoya Sakatani, Yuri Shimaki, Hiroki Senshu, Yoshiko Ogawa, Hirohide Demura, Kentaro Suko, Kohei Kitazato, Toru Kouyama, Tomohiko Sekiguchi, Jun Takita, Sunao Hasegawa, Tsuneo Matsunaga, Takehiko Wada, Takeshi Imamura, Jorn Helbert, Thomas G. Mueller, Axel Hagermann, Jens Biele, Matthias Grott, Maximiliam Hamm, Marco Delbo, Yukio Yamamoto, Naru Hirata, Naoyuki Hirata, Fuyuto Terui, Takanao Saiki, Satoru Nakazawa, Makoto Yoshikawa, Sei-ichiro Watanabe, Yuichi Tuda

  Japan Geoscience Union Meeting 2019, May 2019, English, Makuhari Messe, Chiba, International conference

  Poster presentation


• Size of the Smallest Particles in Saturn's Rings

  Keiji Ohtsuki, Hiroshi Kawamura, Naoyuki Hirata, Hiroshi Daisaka, Hiroshi Kimura

  Japan Geoscience Union Meeting 2019, May 2019, English, Makuhari Messe, Chiba, International conference

  Poster presentation


• Reddening process of the Ryugu surface based on the crater sie-freuency distribution

  Tomokatsu Morota, Yuichiro Cho, Masanori Kanamaru, Rie Honda, Shingo Kameda, Eri Tatsumi, Yasuhiro Yokota, Toru Kouyama, Hidehiko Suzuki, Manabu Yamada, Naoya Sakatani, Chikatoshi Honda, Masahiko Hayakawa, Kazuo Yoshioka, Moe Matsuoka, Tatsuhiro Michikami, Hideaki Miyamoto, Hiroshi Kikuchi, Ryodo Hemmi, Masatoshi Hirabayashi, Naoyuki Hirata, Naru Hirata, Carolyn Ernst, Olivier Barnouin, Hirotake Sawada, Seiji Sugita

  Japan Geoscience Union Meeting 2019, May 2019, English, Makuhari Messe, Chiba, International conference

  Oral presentation


• Preliminary report on global distribution visible spectra of asteroid Ryugu based on clustering

  Rie Honda, Yasuhiro Yokota, Eri Tatsumi, Antonella Barucci, Davide Perna, Moe Matsuoka, Deborah Domingue, Tomokatsu Morota, Shingo Kameda, Toru Kouyama, Hidehiko Suzuki, Manabu Yamada, Naoya Sakatani, Chikatoshi Honda, Lucille LeCorre, Masahiko Hayakawa, Kazuo Yoshioka, Yuichiro Cho, Yukio Yamamoto, Naru Hirata, Naoyuki Hirata, Tomoki Nakamura, Takahiro Hiroi, Hirotaka Sawada, Yuki Fujii, Seiji Sugita, Ryo Hayashi

  Japan Geoscience Union Meeting 2019, May 2019, English, Makuhari Messe, Chiba, International conference

  Oral presentation


• Improved Trajectory of Hayabusa2 by Combining LIDAR Data and a Shape Model

  Koji Matsumoto, Hirotomo Noda, Yoshiaki Ishihara, Hiroki Senshu, Keiko Yamamoto, Naru Hirata, Naoyuki Hirata, Noriyuki Namiki, Toshimichi Otsubo, Sei-ichiro Watanabe, Takahide Mizuno, Yukio Yamamoto, Hitoshi Ikeda, Naoko Ogawa, Shota Kikuchi, Takanao Saiki, Yuichi Tsuda

  Japan Geoscience Union Meeting 2019, May 2019, English, Makuhari Messe, Chiba, International conference

  Oral presentation


• Geomorphological characteristics of asteroid Ryugu: implications to its evolutional history

  Hideaki Miyamoto, Ryodo Hemmi, Hiroshi Kikuchi, Goro Komatsu, Chikatoshi Honda, Tatsuhiro Michikami, Tomokatsu Morota, Yuichiro Cho, Olivier S Barnouin, Sho Sasaki, Naru Hirata, Naoyuki Hirata, Rie Honda, Shingo Kameda, Eri Tatsumi, Yasuhiro Yokota, Toru Kouyama, Hidehiko Suzuki, Manabu Yamada, Naoya Sakatani, Masahiko Hayakawa, Kazuo Yoshioka, Moe Matsuoka, Masatoshi Hirabayashi, Hirotaka Sawada, Seiji Sugita

  Japan Geoscience Union Meeting 2019, May 2019, English, Makuhari Messe, Chiba, International conference

  Oral presentation


• Timescale of reddening process of the Ryugu surface based on the crater size frequency distribution

  T. Morota, Y. Cho, M. Kanamaru, R. Honda, S. Kameda, E. Tatsumi, Y. Yokota, T. Kouyama, H. Suzuki, M. Yamada, N. Sakatani, C. Honda, M. Hayakawa, K. Yoshioka, M. Matsuoka, T. Michikami, H. Miyamoto, H. Kikuchi, R. Hemmi, M. Hirabayashi, C. M. Ernst, O. Barnouin, Naoyuki Hirata, Naru Hirata, H. Sawada, S. Sugita

  50th Lunar and Planetary Science Conference, Mar. 2019, English, The Woodlands Waterway Marriott Hotel and Convention Center, Texas, International conference

  Oral presentation


• The longitudinal dichotomy of 162173 Ryugu as a result of recent deformation

  M. Hirabayashi, E. Tatsumi, H. Miyamoto, G. Komatsu, S. Sugita, S. Watanabe, D. J. Scheeres, O. S. Barnouin, P. Michel, C. Honda, T. Michikami, Y. Cho, T. Morota, N. Hirata, N. Hirata, N. Sakatani, S. R. Schwartz, R. Honda, Y. Yokota, S. Kameda, H. Suzuki, T. Kouyama, M. Hayakawa, M. Matsuoka, K. Yoshioka, K. Ogawa, H. Sawada, M. Yoshikawa, Y. Tsuda

  Lunar and Planetary Science Conference, Mar. 2019, English, The Woodlands Waterway Marriott Hotel and Convention Center, Texas, International conference

  Poster presentation


• The evolution of Ryugu's parent body constrained by Hayabusa2 imaging observations

  S. Sugita, R. Honda, T. Morota, S. Kameda, E. Tatsumi, C. Honda, Y. Yokota, M. Yamada, T. Kouyama, N. Sakatani, H. Suzuki, K. Yoshioka, Y. Cho, M. Matsuoka, K. Ogawa, D. Domingue, H. Miyamoto, O. S. Barnouin, P. Michel, C. M. Ernst, T. Hiroi, T. Nakamura, H. Sawada, M. Hayakawa, Naru Hirata, Naoyuki Hirata, H. Kikuchi, R. Hemmi, T. Michikami, E. Palmer, R. Gaskell, M. Hirabayashi, R. Jaumann, K. Otto, N. Schmitz, S. E. Schröder, G. Komatsu, S. Tanaka, K. Shirai, M. Yoshikawa, S. Watanabe, Y. Tsuda

  50th Lunar and Planetary Science Conference, Mar. 2019, English, Houston, International conference

  Oral presentation


• The distribution of crater morphologies across Ryugu

  C.M. Ernst, Y. Cho, T. Morota, M. Kanamaru, O. S. Barnouin, Naoyuki Hirata, Naru Hirata, S. Sugita, S. Watanabe, R. W. Gaskell, E. E. Palmer, P. Michel, R. Honda, S. Kameda, E. Tatsumi, Y. Yokota, T. Kouyama, H. Suzuki, M. Yamada, N. Sakatani, C. Honda, M. Hayakawa, K. Yoshioka, M. Matsuoka, H. Sawada

  50th Lunar and Planetary Science Conference, Mar. 2019, English, The Woodlands Waterway Marriott Hotel and Convention Center, Texas, International conference

  Poster presentation


• Spatial distribution and morphology of craters on Ryugu: Implications for surface processes on the asteroid

  Y. Cho, T. Morota, M. Kanamaru, C. M. Ernst, O. S. Barnouin, E. Tatsumi, M. Hirabayashi, K. A. Otto, N. Schmitz, R. J. Wagner, R. Jaumann, H. Miyamoto, H. Kikuchi, R. Hemmi, R. Honda, S. Kameda, Y. Yokota, T. Kouyama, H. Suzuki, M. Yamada, N. Sakatani, C. Honda, M. Hayakawa, K. Yoshioki, M. Matsuoka, T. Michikami, N. Hirata, H. Sawada, S. Sugita

  50th Lunar and Planetary Science Conference, Mar. 2019, English, The Woodlands Waterway Marriott Hotel and Convention Center, Texas, International conference

  Oral presentation


• Shape reconstruction of the asteroid Ryugu by structure-from-motion technique in Hayabusa2 mission

  T. Sugiyama, Naru Hirata, Naoyuki Hirata, S. Watanabe, R. Noguchi, Y. Shimaki, S. Sugita

  50th Lunar and Planetary Science Conference, Mar. 2019, English, The Woodlands Waterway Marriott Hotel and Convention Center, Texas, International conference

  Poster presentation


• Improved trajectory of Hayabusa2 by combining LIDAR data and a shape model

  K. Matsumoto, H. Noda, Y. Ishihara, H. Senshu, K. Yamamoto, Naru Hirata, Naoyuki Hirata, N. Namiki, T. Otsubo, S. Watanabe, T. Mizuno, Y. Yamamoto, H. Ikeda, N. Ogawa, S. Kikuchi, T. Saiki, Y. Tsuda

  50th Lunar and Planetary Science Conference, Mar. 2019, English, The Woodlands Waterway Marriott Hotel and Convention Center, Texas, International conference

  Poster presentation


• Impact velocity between particles in saturn's rings

  H. Kawamura, K. Ohtsuki, N. Hirata, H. Daisaka

  50th Lunar and Planetary Science Conference, Mar. 2019, English, The Woodlands Waterway Marriott Hotel and Convention Center, Texas, International conference

  Oral presentation


• High porosity nature of the top-shape C-type asterroid 162173 Ryugu as observed by Hayabusa2

  S. Watanabe, M. Hirabayashi, N. Hirata, Naoyuki. Hirata, R. Noguchi, Y. Shimaki, H. Ikeda, E. Tatsumi, M. Yoshikawa, S. Kikuchi, H. Yabuta, T. Nakamura, S. Tachibana, Y. Ishihara, T. Morota, K. Kitazato, N. Sakatani, K. Matsumoto, K. Wada, H. Senshu, C. Honda, T. Michikami, H. Takeuchi, T. Kouyama, R. Honda, S. Kameda, T. Fuse, H. Miyamoto, G. Komatsu, S. Sugita, T. Okada, N. Namiki, M. Arakawa, M. Ishiguro, M. Abe, R. Gaskell, E. Palmer, O. S. Barnouin, P. Michel, A. S. French, J. W. McMahon, D. J. Scheeres, P. A. Abell, Y. Yamamoto, S. Tanaka, K. Shirai, M. Matsuoka, M. Yamada, Y. Yokota, H. Suzuki, K. Yoshioka, Y. Cho, S. Tanaka, N. Nishikawa, T. Sugiyama, H. Kiku-chi, R. Hemmi, T. Yamaguchi, N. Ogawa, G. Ono, Y. Mimasu, K. Yoshikawa, T. Takahashi, Y. Takei, A. Fujii, C. Hirose, T. Iwata, M. Hayakawa, S. Hosoda, O. Mori, H. Sawada, T. Shimada, S. Soldini, H. Yano, R. Tsukizaki, M. Ozaki, Y. Iijima, K. Ogawa, M. Fujimoto, T.-M. Ho, A. Moussi, R. Jaumann, J.-P. Bibring, C. Krause, F. Terui, T. Saiki, S. Nakazawa, Y. Tsuda

  50th Lunar and Planetary Science Conference, Mar. 2019, English, The Woodlands Waterway Marriott Hotel and Convention Center, Texas, International conference

  Oral presentation


• High porosity nature of the top-shape C-type asteroid 162173 Ryugu as observed by Hayabusa2

  S. Watanabe, M. Hirabayashi, N. Hirata, N. Hirata, R. Noguchi, Y. Shimaki, H. Ikeda, E. Tatsumi, M. Yoshikawa, S. Kikuchi, H. Yabuta, T. Nakamura, S. Tachibana, Y. Ishihara, T. Morota, K. Kitazato, N. Sakatani, K. Matsumoto, K. Wada, H. Senshu, C. Honda, T. Michikami, H. Takeuchi, T. Kouyama, R. Honda, S. Kameda, T. Fuse, H. Miyamoto, G. Komatsu, S. Sugita, T. Okada, N. Namiki, M. Arakawa, M. Ishiguro, M. Abe, R. Gaskell, E. Palmer, O. S. Barnouin, P. Michel, A. S. French, J. W. McMahon, D. J. Scheeres, P. A. Abell, Y. Yamamoto, S. Tanaka, K. Shirai, M. Matsuoka, M. Yamada, Y. Yokota, H. Suzuki, K. Yoshioka, Y. Cho, S. Tanaka, N. Nishikawa, T. Sugiyama, H. Kikuchi, R. Hemmi, T. Yamaguchi, N. Ogawa, G. Ono, Y. Mimasu, K. Yoshikawa, T. Takahashi, Y. Takei, A. Fujii, C. Hirose, T. Iwata, M. Hayakawa, S. Hosoda, O. Mori, H. Sawada, T. Shimada, S. Soldini, H. Yano, R. Tsukizaki, M. Ozaki, Y. Iijima, K. Ogawa, M. Fujimoto, T.-M. Ho, A. Moussi, R. Jaumann, J.-P. Bibring, C. Krause, F. Terui, T. Saiki, S. Nakazawa, Y. Tsuda

  Lunar and Planetary Science Conference, Mar. 2019, English, Houston, International conference

  Oral presentation


• Hayabusa2's multiband disk-integrated photometry of 162173 Ryugu

  D. Domingue, E. Tatsumi, Y. Yokota, S. Sugita, R. Honda, Naru Hirata, Naoyuki Hirata, Y. Yamamoto, T. Morota, S. Kameda, T. Kouyama, H. Suzuki, M. Yamada, N. Sakatani, C. Honda, M. Hayakawa, K. Yoshioka, M. Matsuoka, Y. Cho, H. Sawada, M. Ishiguro, L. LeCorre, F. Vilas

  50th Lunar and Planetary Science Conference, Mar. 2019, English, The Woodlands Waterway Marriott Hotel and Convention Center, Texas, International conference

  Poster presentation


• Geomorphological characteristics of asteroid Ryugu and its preliminary geologic map

  H. Miyamoto, R. Hemmi, H. Kikuchi, G. Komatsu, C. Honda, T. Michikami, T. Morota, Y. Cho, O. S. Barnouin, S.Sasak, Naoyuki Hirata, Naru Hirata, R. Honda, S. Kameda, E. Tatsumi, Y. Yokota, T. Kouyama, H. Suzuki, M. Yamada, N. Sakatani, M. Hayakawa, K. Yoshioka, M. Matsuoka, M. Hirabayashi, H. Sawada, S. Sugita

  50th Lunar and Planetary Science Conference, Mar. 2019, English, The Woodlands Waterway Marriott Hotel and Convention Center, Texas, International conference

  Poster presentation


• Clustering analysis of visible spectra of asteroid Ryugu and its preliminary global spectrum map

  R. Honda, Y. Yokota, E. Tatsumi, R. Hayashi, A. Barucci, D. Perna, M. Matsuoka, D. Domingue, T. Morota, S. Kameda, T. Kouyama, H. Suzuki, M. Yamada, N. Sakatani, C. Honda, L. LeCorre, M. Hayakawa, K. Yoshioka, Y. Cho, Y. Yamamoto, Naru Hirata, Naoyuki Hirata, Y. Fujii, T. Nakamura, T. Hiroi, H. Sawada, S. Sugita

  50th Lunar and Planetary Science Conference, Mar. 2019, English, The Woodlands Waterway Marriott Hotel and Convention Center, Texas, International conference

  Oral presentation


• 3D mapping of structural features on Ryugu

  H. Kikuchi, R. Hemmi, G. Komatsu, H. Miyamoto, Naoyuki Hirata, Naru Hirata, C. Honda, T. Michikami, Y. Cho, T. Morota, R. Honda, S. Kameda, E. Tatsumi, Y. Yokota, T. Kouyama, H. Suzuki, M. Yamada, N. Sakatani, M. Hayakawa, K. Yoshioka, M. Matsuoka, O. S. Barnouin, S. Sasaki, M. Hirabayashi, H. Sawada, S. Sugita

  50th Lunar and Planetary Science Conference, Mar. 2019, English, The Woodlands Waterway Marriott Hotel and Convention Center, Texas, International conference

  Poster presentation


• We performed crater size-frequency measurement on Ryugu using high-resolution images obtained by Hayabusa2. Using Ryugu cratering chronology model, the surface age of Ryugu was estimated to be 0.1 to 1 billion years from the density of craters larger than

  Tomokatsu Morota, Yuichiro Cho, Masanori Kanamaru, Rie Honda, Shingo Kameda, Eri Tatsumi, Yasuhiro Yokota, Toru Kouyama, Hidehiko Suzuki, Manabu Yamada, Naoya Sakatani, Chikatoshi Honda, Masahiko Hayakawa, Kazuo Yoshioka, Moe Matsuoka, Tatsuhiro Michikami, Hideaki Miyamoto, Hiroshi Kikuchi, Ryodo Hemmi, Masatoshi Hirabayashi, Carolyn M Ernst, Olivier S Barnouin, Naoyuki Hirata, Naru Hirata, Hirotaka Sawada, Seiji Sugita

  American Geophysical Union(AGU) Fall Meeting 2018, Dec. 2018, English, Washington, D.C., International conference

  Poster presentation


• Visible spectrophotometry of 162173 Ryugu

  Eri Tatsumi, Seiji Sugita, Rie Honda, Tomokatsu Morota, Toru Kouyama, Yasuhiro Yokota, Deborah Lorin Domingue, Hidehiko Suzuki, Shingo Kameda, Manabu Yamada, Naru Hirata, Naoyuki Hirata, Naoya Sakatani, Kazuo Yoshioka, Chikatoshi Honda, Masahiko Hayakawa, Moe Matsuoka, Yuichiro Cho, M. Antonietta Barucci, Lucille Le Corre, Sho Sasaki, Takahiro Hiroi, Masatoshi Hirabayashi, Hirotaka Sawada

  American Geophysical Union(AGU) Fall Meeting 2018, Dec. 2018, English, Washington, D.C., International conference

  Oral presentation


• The distribution of crater morphologies across Ryugu: Implications for seismic shaking

  Carolyn M Ernst, Yuichiro Cho, Tomokatsu Morota, Olivier S Barnouin, Naoyuki Hirata, Naru Hirata, Seiji Sugita, Seiichiro Watanabe, Robert W Gaskell, Eric E Palmer, Patrick Michel, Rie Honda, Shingo Kameda, Eri Tatsumi, Yasuhiro Yokota, Toru Kouyama, Hidehiko Suzuki, Manabu Yamada, Naoya Sakatani, Chikatoshi Honda, Masahiko Hayakawa, Kazuo Yoshioka, Moe Matsuoka, Hirotaka Sawada, Masanori Kanamaru

  American Geophysical Union(AGU) Fall Meeting 2018, Dec. 2018, English, Washington, D.C., International conference

  Poster presentation


• Shape and geophysical properties of the asteroid Ryugu from initial observations by Hayabusa2

  Naru Hirata, Naoyuki Hirata, Sayuri Tanaka, Naoki Nishikawa, Takaaki Sugiyama, Robert W Gaskell, Eric E Palmer, Rina Noguchi, Yuri Shimaki, Koji Matsumoto, Hiroki Senshu, Yukio Yamamoto, Shin-ya Murakami, Yoshiaki Ishihara, Seiji Sugita, Yuichi Tsuda, Seiichiro Watanabe

  American Geophysical Union(AGU) Fall Meeting 2018, Dec. 2018, English, Washington, D.C., International conference

  Oral presentation


• Preliminary geomorphological map of asteroid Ryugu

  Hideaki Miyamoto, Ryodo Hemmi, Hiroshi Kikuchi, Goro Komatsu, Chikatoshi Honda, Tatsuhiro Michikami, Tomokatsu Morota, Yuichiro Cho, Olivier S Barnouin, Sho Sasaki, Naoyuki Hirata, Naru Hirata, Rie Honda, Shingo Kameda, Eri Tatsumi, Yasuhiro Yokota, Toru Kouyama, Hidehiko Suzuki, Manabu Yamada, Naoya Sakatani, Masahiko Hayakawa, Kazuo Yoshioka, Moe Matsuoka, Masatoshi Hirabayashi, Hirotaka Sawada, Seiji Sugita

  American Geophysical Union(AGU) Fall Meeting 2018, Dec. 2018, English, Washington, D.C., International conference

  Poster presentation


• Overview of proximity operations at asteroid Ryugu by Hayabusa2 spacecraft

  Seiichiro Watanabe, Makoto Yoshikawa, Satoshi Tanaka, Seiji Sugita, Kohei Kitazato, Noriyuki Namiki, Tatsuaki Okada, Shogo Tachibana, Ralf Jaumann, J.-P. Bibring, Naru Hirata, Naoyuki Hirata, Hitoshi Ikeda, Yukio Yamamoto, Fuyuto Terui, Takanao Saiki, Satoru Nakazawa, Yuichi Tsuda

  American Geophysical Union(AGU) Fall Meeting 2018, Dec. 2018, English, Washington, D.C., International conference

  Poster presentation


• Global distribution of lineaments on Ryugu

  Hiroshi Kikuchi, Goro Komatsu, Hideaki Miyamoto, Ryodo Hemmi, Naoyuki Hirata, Naru Hirata, Chikatoshi Honda, Tatsuhiro Michikami, Yuichiro Cho, Tomokatsu Morota, Rie Honda, Shingo Kameda, Eri Tatsumi, Yasuhiro Yokota, Toru Kouyama, Hidehiko Suzuki, Manabu Yamada, Naoya Sakatani, Masahiko Hayakawa, Kazuo Yoshioka, Moe Matsuoka, Olivier S Barnouin, Sho Sasaki, Masatoshi Hirabayashi, Hirotaka Sawada, Seiji Sugita

  American Geophysical Union(AGU) Fall Meeting 2018, Dec. 2018, English, Washington, D.C., International conference

  Poster presentation


• Geology on asteroid Ryugu revealed by Hayabusa2 visible multi-band imaging observations

  S. Sugita, R. Honda, T. Morota, S. Kameda, E. Tatsumi, Y. Yokota, H. Miyamoto, T. Kouyama, D. L. Domingue, H. Suzuki, M. Yamada, N. Sakatani, K. Ogawa, C. Honda, M. Hayakawa, G. Komatsu, H. Kikuchi, R. Hemmi, T. Michikami, Naru Hirata, Naoyuki Hirata, O. S Barnouin, C. M Ernst, E. E Palmer, R. W Gaskell, P. Michel, M. Hirabayashi, R. Jaumann, N. Schmitz, K. A. Otto, M. Matsuoka, L. Le Corre, T. Hiroi, T. Nakamura, Y. Tsuda, M. Yoshikawa, S. Tanaka, K. Shirai, S. Watanabe

  American Geophysical Union Fall Meeting 2018, Dec. 2018, English, Washington, D.C., International conference

  Poster presentation


• Distribution and morphology of craters on asteroid Ryugu

  Yuichiro Cho, Tomokatsu Morota, Masanori Kanamaru, Rie Honda, Shingo Kameda, Eri Tatsumi, Yasuhiro Yokota, Toru Kouyama, Hidehiko Suzuki, Manabu Yamada, Naoya Sakatani, Chikatoshi Honda, Masahiko Hayakawa, Kazuo Yoshioka, Moe Matsuoka, Tatsuhiro Michikami, Hideaki Miyamoto, Hiroshi Kikuchi, Ryodo Hemmi, Masatoshi Hirabayashi, Carolyn M Ernst, Olivier S Barnouin, Katharina A. Otto, Nicole Schmitz, Roland J Wagner, Ralf Jaumann, Naoyuki Hirata, Naru Hirata, Hirotaka Sawada, Seiji Sugita

  American Geophysical Union(AGU) Fall Meeting 2018, Dec. 2018, English, Washington, D.C., International conference

  Oral presentation


• Comparison of color maps of asteroids Ryugu and Bennu from the approach phase of Hayabusa2 and OSIRIS-REx missions

  Lucille Le Corre, Adriana Macieira Mitchell, Olivier S Barnouin, Kris Becker, Carina Bennett, Humberto Campins, Yuichiro Cho, Beth Clark, Daniella N DellaGiustina, Christian d'Aubigny, Carolyn M Ernst, Robert W Gaskell, Dathon R Golish, Masahiko Hayakawa, Naoyuki Hirata, Naru Hirata, Chikatoshi Honda, Rie Honda, Shingo Kameda, Toru Kouyama, Dante S Lauretta, Jian-Yang Li, Moe Matsuoka, Tomokatsu Morota, Michael C Nolan, Eric E Palmer, Bashar Rizk, Naoya Sakatani, Hirotaka Sawada, Peter H Smith, Seiji Sugita, Hidehiko Suzuki, Eri Tatsumi, Seiichiro Watanabe, John R Weirich, Manabu Yamada, Yasuhiro Yokota, Kazuo Yoshioka

  American Geophysical Union(AGU) Fall Meeting 2018, Dec. 2018, English, Washington, D.C., International conference

  Oral presentation


• Clustering analysis of visible spectra of asteroid Ryugu

  Rie Honda, Yasuhiro Yokota, Eri Tatsumi, Ryo Hayashi, M. Antonietta Barucci, Davide Perna, Deborah Lorin Domingue, Tomokatsu Morota, Shingo Kameda, Toru Kouyama, Hidehiko Suzuki, Manabu Yamada, Naoya Sakatani, Chikatoshi Honda, Masahiko Hayakawa, Kazuo Yoshioka, Moe Matsuoka, Yuichiro Cho, Yukio Yamamoto, Naru Hirata, Naoyuki Hirata, Yuki Fujii, Hirotaka Sawada, Seiji Sugita

  American Geophysical Union(AGU) Fall Meeting 2018, Dec. 2018, English, Washington, D.C., International conference

  Poster presentation


• 土星環粒子に働く熱応力と粒径進化

  平田 直之, 大槻 圭史

  日本惑星科学会2018年秋季講演会, Oct. 2018, Japanese, 旭川市科学館サイパル, Domestic conference

  Oral presentation


• 小惑星リュウグウの岩塊サイズ分布の初期解析結果

  道上 達広, 本田 親寿, 川村 真輝, 杉本 貴一, 巽 瑛理, 宮本 英昭, 平林 正稔, 諸田 智克, 野口 高明, 長 勇一郎, 亀田 真吾, 菊地 紘, 神山 徹, 早川 雅彦, 辺見 良道, 平田 直之, 平田 成, 本田 理恵, 松岡 萌, 坂谷 尚哉, 鈴木 秀彦, 横田 康弘, 山田 学, 吉岡 和夫, 澤田 弘崇, 杉田 精

  日本惑星科学会2018年秋季講演会, Oct. 2018, Japanese, 旭川市科学館サイパル, Domestic conference

  Oral presentation


• 小惑星Ryugu の形状モデル作成

  田中 小百合, 西川 直輝, 平田 直之, 平田 成, 邊 誠一郎, 野口 里奈, 杉田 精司, 嶌生 有理

  日本惑星科学会2018年秋季講演会, Oct. 2018, Japanese, 旭川市科学館サイパル, Domestic conference

  Poster presentation


• 小惑星Ryugu のクレータサイズ頻度分布と表面年代

  諸田 智克, 長 勇一郎, 金丸 仁明, 本田 理恵, 亀田 真吾, 巽 瑛理, 横田 康弘, 神山 徹, 鈴木 秀彦, 山田 学, 坂谷 尚哉, 本田 親寿, 早川 雅彦, 吉岡 和夫, 松岡 萌, 道上 達広, 宮本 英昭, 菊地 紘, 逸見 良道, 平林 正稔, 平田 直之, 平田 成, 澤田 弘崇, 杉田 精司

  日本惑星科学会2018年秋季講演会, Oct. 2018, Japanese, 旭川市科学館サイパル, Domestic conference

  Oral presentation


• 画像データを用いた小惑星(162173)リュウグウの形状モデル作成及び物理的諸量の推定

  西川 直輝, 田中 小百合, 平田 直之, 平田 成, 渡邊 誠一郎, 野口 里奈, 杉田 精司, 嶌生 有理

  日本惑星科学会2018年秋季講演会, Oct. 2018, Japanese, 旭川市科学館サイパル, Domestic conference

  Poster presentation


• はやぶさ2 探査機の観測に基づく小惑星リュウグウの形状

  平田 成, 田中 小百合, 平田 直之, 西川 直輝, 杉山 貴亮, R. Gaskell, E. Palmer, 野口 里奈, 嶌生 有理, 杉田 精司, 津田 雄一, 渡邊 誠一郎

  日本惑星科学会2018年秋季講演会, Oct. 2018, Japanese, 旭川市科学館サイパル, Domestic conference

  Oral presentation


• はやぶさ2 によるリュウグウ観測の概観

  渡邊 誠一郎, 吉川真, 田中 智, 杉田 精司, 北里 宏平, 竝木 則行, 岡田 達明, 平田 直之, 山本 幸生, 藪田 ひかる, 中村 智樹, 石原 吉明, 佐伯 孝尚, 津田 雄一, はやぶさ, サイエンスチーム

  日本惑星科学会2018年秋季講演会, Oct. 2018, Japanese, 旭川市科学館サイパル, Domestic conference

  Oral presentation


• 土星リング粒子の衝突速度と最小粒子サイズ

  川村 浩司, 大槻 圭史, 平田 直之, 台坂 博

  日本天文学会2018年秋季年会, Sep. 2018, Japanese, 兵庫県立大学 姫路工学キャンパス, Domestic conference

  Oral presentation


• The Formation of Spokes: The Role of Cohesion

  Naoyuki Hirata, Hiroshi Kimura, Keiji Ohtsuki

  Asia Oceania Geosciences Society(AOGS) 15th Annual Meeting, Jun. 2018, English, Honolulu, Hawaii, International conference

  Poster presentation


• Impact velocity between particles in Saturn’s rings and implications for the minimum particle size

  Keiji Ohtsuki, Hiroshi Kawamura, Naoyuki Hirata, Hiroshi Daisaka

  Asia Oceania Geosciences Society(AOGS) 15th Annual Meeting, Jun. 2018, English, Honolulu, Hawaii, International conference

  Poster presentation


• 土星環粒子・氷衛星上のボルダーに働く熱応力とその寿命

  平田 直之, 大槻 圭史

  日本地球惑星科学連合2018年大会, May 2018, Japanese, 幕張メッセ, Domestic conference

  Poster presentation


• Shape model reconstruction of Ryugoid using Stereophotoclinometry

  Sayuri Tanaka, Naoyuki Hirata, Naru Hirata, Naoki Nishikawa, Sei-ichiro Watanabe, Yoshiaki Ishihara, Satoshi Tanaka, Tomohiro Yamaguchi, Akira Miura, Yukio Yamamoto

  Japan Geoscience Union Meeting 2018, May 2018, English, Makuhari Messe, Chiba, International conference

  Poster presentation


• An Estimate of rotational prosperities of asteroid Ryugu using simulated image data

  Naoki Nishikawa, Naoyuki Hirata, Naru Hirata, Tanaka Sayuri, Sei-ichiro Watanabe, Yoshiaki Ishihara, Satoshi Tanaka, Tomohiro Yamaguchi, Akira Miura, Yukio Yamamoto

  Japan Geoscience Union Meeting 2018, May 2018, English, Makuhari Messe;Chiba, International conference

  Poster presentation


• ガニメデ上のFurrow構造の起源に関する研究

  HIRATA NAOYUKI

  日本惑星科学会2017年度秋季講演会, Sep. 2017, Japanese, 大阪大学 豊中キャンパス, Domestic conference

  Oral presentation


• 木星衛星ガニメデの画像データの再解析

  HIRATA NAOYUKI

  JpGU-AGU Joint Meeting 2017, May 2017, Japanese, 幕張メッセ, International conference

  Oral presentation


• Physical properties of Phobos surface for landing mission

  K. Ogawa, H. Miyamoto, K. Wada, N. Sakatani, N. Hirata, H. Kikuchi, S. Yokota

  JpGU-AGU Joint Meeting 2017, May 2017, English, 幕張メッセ, International conference

  Oral presentation

• はやぶさ２画像データをつかった、現在・過去の自転状態の解析と表層進化の解明

  平田 直之

  日本学術振興会, 科学研究費助成事業 若手研究, 若手研究, 神戸大学, 01 Apr. 2020 - 31 Mar. 2023

  小惑星探査機はやぶさ２の画像データを解析し、リュウグウの自転状態およびその自転の変化によって生じる様々な表面現象についてその一端を明らかにする。小惑星は赤外線放射によって自転が暴走加速することがしられており、リュウグウは過去に自転周期が3時間を超えるほど早く自転していたらしい。リュウグウはそのような高速自転小惑星を詳細な画像データを使うことで解析ができる初めての例である。このリュウグウの現在の自転状態を解析し、さらにそのような高速自転がリュウグウの形状や表層進化にどのような影響を与えるのかを画像データの解析によって明らかにすることで、小惑星の軌道進化やそれによる太陽系初期の微惑星の集合や合体による惑星形成、地球への衝突過程などへの知見に発展させる。その具体的取り組みとして自転の加速によってクレーターなどの地形や地質にどのような影響が出るかを調査する。前年度の解析の結果、自転が加速するとクレーター地形に東西不対称性が生じること、それらが起きうる条件は自転周期が３．５時間以上の場合に限ることを発見した。さらに、赤道上に青い色を帯びた領域があることがしられていたがこれも自転が加速した場合のエジェクタの分布で説明できることがわかった。今年度は前年度の解析手法を応用することで、リュウグウのそろばん型の形状そのものがクレーターエジェクタの降り積もりで説明できることが明らかになり、新たに１報の論文の受理に至った。


• カッシーニ画像データ解析による土星中型氷衛星の熱進化史の解明

  平田 直之

  日本学術振興会, 科学研究費助成事業 新学術領域研究(研究領域提案型), 新学術領域研究(研究領域提案型), 神戸大学, 01 Apr. 2020 - 31 Mar. 2022

  土星や木星の氷衛星は内部に液体の水からなる内部海を持っているとされ、これらの氷衛星の内部海も生命誕生の場として有望と見なされている。これら氷衛星の内部状態の推定のために、土星中型衛星ディオーネおよびレアのWispy構造と呼ばれる正断層地形に着目する。衛星内部の温度変化、内部海の凍結などによって体積が変化すると、表面に正断層性の地溝帯が形成されることが知られている。そのためこれらの各地溝帯の形成年代や、形成時に衛星がどの程度の体積が膨張したかを定量的に推定することができれば衛星の内部の温度変化量や、内部海の規模の推定に一定の制約を与えることができると考えられる。そこで土星探査機カッシーニー画像データを解析し、土星中型衛星の表面にある正断層性の地溝帯を調査した。今年度の作業によって土星衛星ディオーネ・レアの地形状の解析が進展した。新規に作成されたDTMは過去のものと比較しても１０倍を超える高い精度を有しておりこれらのDTMではWispy地形が極めて明瞭に見えている。DTMの簡易な調査によるとおおよそ衛星ディオーネの全周が１－２㎞程度伸びたことが明らかとなった。これは衛星の半径に換算すると、200-400mほどディオーネが膨張したことがわかる。次年度以降はより精度の高いディオーネの膨張の計測を行う。またレアの解析を進めレアの膨張量の測定を行う。これらの膨張度を、衛星の熱進化モデルに内挿することによって熱進化史に制約をあたえ国際学会誌にて論文を投稿することを目指す。


• -

  Hyogo Science and Technology Association, 学術研究助成事業, Apr. 2020 - Mar. 2021, Principal investigator


• Satellite systems in the Solar System: Origin of their characteristics and diversity

  Ohtsuki Keiji

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B), Grant-in-Aid for Scientific Research (B), Kobe University, 01 Apr. 2015 - 31 Mar. 2019

  Observations by the Cassini spacecraft brought abundant new insights about the origin and evolution of ring-satellite systems of giant planets. With these new data in hand, we carried out theoretical studies on ring-satellite systems of giant planets. We developed a new model for the origin of Saturn's F ring and its shepherd satellites, and also carried out new simulations for the origin of rings of giant planets as well as rings of Centaurs. We also found that the gas disk around a growing giant planet can capture building blocks of regular satellites, but that it is difficult to explain the origin of irregular satellites by this mechanism alone. In relation to the origin of irregular satellites of giant planets, we also examined surface properties of small bodies in the outer Solar System using data obtained by the Subaru Telescope, and obtained results that support transportation of small icy bodies from the trans-Neptunian region into the giant planet region.

  Competitive research funding


• 熱的活動の前駆的現象に着目した氷衛星熱進化史の新展開：衛星系共進化の理解へ

  平田 直之

  日本学術振興会, 科学研究費助成事業 特別研究員奨励費, 特別研究員奨励費, 神戸大学, 24 Apr. 2015 - 31 Mar. 2018

  研究計画書にある後半部分（ディオーネのDark TerrainとWispy structuresの年代比較に関するカラー比・地形解析）に取り組んでいた。前年度、基礎部分として衛星の地理情報データ解析のための技術的手法・画像データの収集・解析が概ね完了していたのに続いて、今年度は、Dione表面に認められるWispy構造の斜面上のDark terrain堆積物の定量的な調査をおこなった。より具体的に述べると、土星衛星DioneにはWispy構造と呼ばれる正断層帯が存在している。このWispy近辺にはDark material と呼ばれる暗い堆積物が降り積もっている。前年度において、このうちDark materialの年代が１－５０Maであることがレイクレーターの研究から明らかにできている。本年度はまずWispy構造がDark terrain堆積物によって汚染されているか否かについて調査を行う予定であった。当初の予定では、カラー比・スペクトル調査を行うことで、汚染の強さの定量的な評価ができると考えていた。しかし、地形データの解析にあたっては精度面で難点があることがわかった。一方で、これと並行して、クレーターの切った切られたの関係に基づく年代測定法を用いた、Wispy構造の年代制約にも取り組んでいた。この方法は、衝突クレーターは衝突地点とその周囲を破壊してしまうことに着目した手法である。もし正断層帯が出来た後にクレーターが生じた場合、そのクレーター近傍では正断層斜面が損傷を受けているはずである。逆の場合、クレーターは損傷を受けていない正断層帯によって切られているはずである。この解析は、かなり順調に推移し、すでに論文としてまとめ、査読付き国際誌において受理された。


• 小型衛星の表層進化に着目した土星系化学的分別過程の解明：太陽系初期進化の理解へ

  平田 直之

  日本学術振興会, 科学研究費助成事業 特別研究員奨励費, 特別研究員奨励費, 東京大学, 01 Apr. 2012 - 31 Mar. 2015

  本研究では、環の起源や進化を解明するために、力学や性質や組成などの研究に取り込んだ。そのためにＮ体数値シミュレーションを用いた環粒子の挙動解析や画像解析を用いたスペクトル調査等を行った。その一方で、これまで高解像度データが得られている全ての小型衛星に対して、綿密な地質調査を初めて実施した。一連の調査の結果として、環が小型衛星の表層進化に著しい影響を及ぼしているという知見を得ることができた。この結果は、小型衛星は過去に存在した（現在では観測のできない）環の情報を記録している可能性があるという点で重要である。なぜなら、環は比較的速やかに拡散し消滅してしまうが、小型衛星の表面に定着した環の痕跡は遥かに長期間安定して存在できるためである。そこから土星系の環および衛星系の進化を解明する上で必要な情報を実際に得ることができた。その具体例として、主要環、E環、およびヤヌス-エピメテウス環の研究を推進した。これらの成果のうちの一つが国際誌に掲載されており、さらに一報を改訂中である。 これらの研究を踏まえて得た知見に基づいて、あらたに有望な研究対象を見つけるに至った。Ｅ環は土星系で最も注目度の高いエンセラダスを起源とする。エンセラダスは活発な火山活動を有する衛星であり、内部には液体の水からなる海が存在していると考えられている。この活動期間がどの程度続いているのかがこれまで不明だった。本研究は活動的であるがゆえに過去の痕跡が残らないエンセラダス本体では無く、このE環と相互作用を受けた小型衛星を調べることで、逆にエンセラダスの火山活動を制約できることを示し、その活動期間がたったの数千万年～数億年と短期間であったことを明らかにした。