Faculty Profiles - WATANABE, Sei-ichiro

Phosphorus-rich grains in Ryugu samples with major biochemical potential Reviewed International coauthorship International journal

Pilorget, C; Baklouti, D; Bibring, JP; Brunetto, R; Ito, M; Franchi, I; Tomioka, N; Uesugi, M; Yamaguchi, A; Greenwood, R; Okada, T; Usui, T; Yada, T; Hatakeda, K; Yogata, K; Loizeau, D; Le Pivert-Jolivet, T; Jiang, T; Carter, J; Hamm, V; Abe, M; Aléon-Toppani, A; Borondics, F; Enokido, Y; Hitomi, Y; Imae, N; Karouji, Y; Kumagai, K; Kimura, M; Langevin, Y; Lantz, C; Liu, MC; Mahlke, M; Miyazaki, A; Mughal, Z; Nagashima, K; Nakano, A; Nakata, A; Nakato, A; Nishimura, M; Ohigashi, T; Ojima, T; Poulet, F; Riu, L; Shirai, N; Sugiyama, Y; Tahara, R; Uesugi, K; Yasutake, M; Yuzawa, H; Moussi-Soffys, A; Nakazawa, S; Saiki, T; Terui, F; Yoshikawa, M; Tanaka, S; Watanabe, S; Tsuda, Y

NATURE ASTRONOMY 2024.9

Breunnerite grain and magnesium isotope chemistry reveal cation partitioning during aqueous alteration of asteroid Ryugu Reviewed International coauthorship International journal Open Access

Yoshimura, T; Araoka, D; Naraoka, H; Sakai, S; Ogawa, NO; Yurimoto, H; Morita, M; Onose, M; Yokoyama, T; Bizzarro, M; Tanaka, S; Ohkouchi, N; Koga, T; Dworkin, JP; Nakamura, T; Noguchi, T; Okazaki, R; Yabuta, H; Sakamoto, K; Yada, T; Nishimura, M; Nakato, A; Miyazaki, A; Yogata, K; Abe, M; Okada, T; Usui, T; Yoshikawa, M; Saiki, T; Tanaka, S; Terui, F; Nakazawa, S; Watanabe, S; Tsuda, Y; Tachibana, S; Takano, Y

NATURE COMMUNICATIONS Vol. 15 ( 1 ) 2024.9

Variations of organic functional chemistry in carbonaceous matter from the asteroid 162173 Ryugu Reviewed International coauthorship International journal Open Access

Bradley De Gregorio, George D. Cody, Rhonda M. Stroud, A. L. David Kilcoyne, Scott Sandford, Corentin Le Guillou, Larry R. Nittler, Jens Barosch, Hikaru Yabuta, Zita Martins, Yoko Kebukawa, Taiga Okumura, Minako Hashiguchi, Shohei Yamashita, Yasuo Takeichi, Yoshio Takahashi, Daisuke Wakabayashi, Cécile Engrand, Laure Bejach, Lydie Bonal, Eric Quirico, Laurent Remusat, Jean Duprat, Maximilien Verdier-Paoletti, Smail Mostefaoui, Mutsumi Komatsu, Jérémie Mathurin, Alexandre Dazzi, Ariane Deniset-Besseau, Emmanuel Dartois, Yusuke Tamenori, Hiroki Suga, Gilles Montagnac, Kanami Kamide, Miho Shigenaka, Megumi Matsumoto, Yuma Enokido, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Satoru Nakazawa, Tomohiro Usui, Masanao Abe, Tatsuaki Okada, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Hisayoshi Yurimoto, Tomoki Nakamura, Takaaki Noguchi, Ryuji Okazaki, Hiroshi Naraoka, Kanako Sakamoto, Shogo Tachibana, Sei-ichiro Watanabe, Yuichi Tsuda

Nature Communications Vol. 15 ( 1 ) 2024.8

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

Abstract

Primordial carbon delivered to the early earth by asteroids and meteorites provided a diverse source of extraterrestrial organics from pre-existing simple organic compounds, complex solar-irradiated macromolecules, and macromolecules from extended hydrothermal processing. Surface regolith collected by the Hayabusa2 spacecraft from the carbon-rich asteroid 162173 Ryugu present a unique opportunity to untangle the sources and processing history of carbonaceous matter. Here we show carbonaceous grains in Ryugu can be classified into three main populations defined by spectral shape: Highly aromatic (HA), Alkyl-Aromatic (AA), and IOM-like (IL). These carbon populations may be related to primordial chemistry, since C and N isotopic compositions vary between the three groups. Diffuse carbon is occasionally dominated by molecular carbonate preferentially associated with coarse-grained phyllosilicate minerals. Compared to related carbonaceous meteorites, the greater diversity of organic functional chemistry in Ryugu indicate the pristine condition of these asteroid samples.

DOI： 10.1038/s41467-024-51731-w

Other Link： https://www.nature.com/articles/s41467-024-51731-w

Asteroid Ryugu and the Hayabusa2 Mission Invited Reviewed International journal

Sei-ichiro Watanabe, Shota Kikuchi

Oxford Research Encyclopedia of Planetary Science 2024.8

Authorship：Lead author,　Corresponding author Language：English Publishing type：Part of collection (book) Publisher：Oxford University Press

The carbonaceous type (C-type) asteroid Ryugu is a near-Earth object measuring ~1 km in equatorial diameter. C-type asteroids of this size are seldom found in the near-Earth region, making Ryugu an invaluable target for a sample return mission. Studying Ryugu offers insights into the Solar System formation and the transportation of volatile components from the asteroid belt to the early Earth. The Hayabusa2 spacecraft, developed by the Japan Aerospace Explosion Agency (JAXA), was launched on an H-IIA rocket in December 2014. It reached Ryugu in June 2018, and for 17 months, it closely observed the asteroid using optical and thermal imagers, a near-infrared spectrometer, and a laser altimeter. The spacecraft deployed three small rovers and a lander onto Ryugu surface, allowing for in-depth imaging and measurements. Furthermore, Hayabusa2 executed two precise touchdowns on different regions of the asteroid for sampling and initiated an impact experiment that created an artificial crater on Ryugu. During the second touchdown, subsurface materials ejected from the artificial crater were collected. Hayabusa2 departed from Ryugu in November 2019 and returned a capsule containing Ryugu samples to Earth in December 2020. Having successfully completed its sample return mission, Hayabusa2 is now en route to its next objective: a rendezvous with a small, rapidly rotating asteroid in July 2031. Ryugu is a rubble-pile asteroid, formed through the re-accumulation of fragments of a disrupted parent asteroid in the inner main asteroid belt. Its distinct spinning-top shape was likely molded by landslides, triggered by rapid rotation about ten million years after its formation. Chemically, Ryugu’s surface material closely resembles that of CI (Ivuna-type) carbonaceous chondrites, known for their primitive compositions. The high porosity of Ryugu particles hints at a past presence of ice. Moreover, the plentiful carbonates, combined with the limited presence of high-temperature inclusions larger than 30 μm, suggest that Ryugu’s parent body originated in the outer Solar System, likely beyond the Saturn orbit. Within a few million years following the formation of the Solar System, gravitational interactions with giant planets may have scattered this parent body to the inner main asteroid belt. The decay heat from the short-lived radionuclide, 26Al, then facilitated aqueous alteration of the parent body and led to the genesis of diverse organic compounds. Many low-albedo asteroids in the main belt share spectra similarities with Ryugu. This implies that the structural water in phyllosilicates and organic matter could have been transported to the early Earth through dynamical and collisional evolution of these objects.

DOI： 10.1093/acrefore/9780190647926.013.266

Pyrrhotites in asteroid 162173 Ryugu: Records of the initial changes on their surfaces with aqueous alteration Reviewed International coauthorship International journal Open Access

Hiroharu Yui, Shu-hei Urashima, Morihiko Onose, Mayu Morita, Shintaro Komatani, Izumi Nakai, Yoshinari Abe, Yasuko Terada, Hisashi Homma, Kazuko Motomura, Kiyohiro Ichida, Tetsuya Yokoyama, Kazuhide Nagashima, 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, Wataru Fujiya, Ryota Fukai, Ikshu Gautam, Makiko K. Haba, Yuki Hibiya, Hiroshi Hidaka, Peter Hoppe, Gary R. Huss, Tsuyoshi Iizuka, Trevor R. Ireland, Akira Ishikawa, Shoichi Itoh, Noriyuki Kawasaki, Noriko T. Kita, Kouki Kitajima, Thorsten Kleine, Sasha Krot, Ming-Chang Liu, Yuki Masuda, Frédéric Moynier, Ann Nguyen, Larry Nittler, Andreas Pack, Changkun Park, Laurette Piani, Liping Qin, Tommaso Di Rocco, Sara S. Russell, Naoya Sakamoto, Maria Schönbächler, Lauren Tafla, Haolan Tang, Kentaro Terada, Tomohiro Usui, Sohei Wada, Meenakshi Wadhwa, Richard J. Walker, Katsuyuki Yamashita, Qing-Zhu Yin, Shigekazu Yoneda, Edward D. Young, Ai-Cheng Zhang, Tomoki Nakamura, Hiroshi Naraoka, Takaaki Noguchi, Ryuji Okazaki, Kanako Sakamoto, Hikaru Yabuta, Masanao Abe, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Tatsuaki Okada, Toru Yada, Kasumi Yogata, Satoru Nakazawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Yuichi Tsuda, Sei-ichiro Watanabe, Makoto Yoshikawa, Shogo Tachibana, Hisayoshi Yurimoto

Geochimica et Cosmochimica Acta Vol. 379 page： 172 - 183 2024.8

Primordial aqueous alteration recorded in water-soluble organic molecules from the carbonaceous asteroid (162173) Ryugu Reviewed International coauthorship International journal Open Access

Yoshinori Takano, Hiroshi Naraoka, Jason P. Dworkin, Toshiki Koga, Kazunori Sasaki, Hajime Sato, Yasuhiro Oba, Nanako O. Ogawa, Toshihiro Yoshimura, Kenji Hamase, Naohiko Ohkouchi, Eric T. Parker, José C. Aponte, Daniel P. Glavin, Yoshihiro Furukawa, Junken Aoki, Kuniyuki Kano, Shin-ichiro M. Nomura, Francois-Regis Orthous-Daunay, Philippe Schmitt-Kopplin, Aogu Furusho, Minako Hashiguchi, Kazuhiko Fukushima, Dan Aoki, Hannah L. McLain, Jamie E. Elsila, Heather V. Graham, John M. Eiler, Norbert Hertkorn, Alexander Ruf, Cédric Wolters, Junko Isa, Véronique Vuitton, Roland Thissen, Saburo Sakai, Haruna Sugahara, Hajime Mita, Yoshito Chikaraishi, Takaaki Yoshikawa, Satoru Tanaka, Mayu Morita, Morihiko Onose, Daisuke Araoka, Fumie Kabashima, Kosuke Fujishima, Hajime Sato, Tomoya Yamazaki, Yuki Kimura, Hisayoshi Yurimoto, Tomoki Nakamura, Takaaki Noguchi, Ryuji Okazaki, Hikaru Yabuta, Kanako Sakamoto, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Satoru Nakazawa, Sei-ichiro Watanabe, Yuichi Tsuda, Shogo Tachibana

Nature Communications Vol. 15 ( 1 ) 2024.7

Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

Abstract

We report primordial aqueous alteration signatures in water-soluble organic molecules from the carbonaceous asteroid (162173) Ryugu by the Hayabusa2 spacecraft of JAXA. Newly identified low-molecular-weight hydroxy acids (HO-R-COOH) and dicarboxylic acids (HOOC-R-COOH), such as glycolic acid, lactic acid, glyceric acid, oxalic acid, and succinic acid, are predominant in samples from the two touchdown locations at Ryugu. The quantitative and qualitative profiles for the hydrophilic molecules between the two sampling locations shows similar trends within the order of ppb (parts per billion) to ppm (parts per million). A wide variety of structural isomers, including α- and β-hydroxy acids, are observed among the hydrophilic molecules. We also identify pyruvic acid and dihydroxy and tricarboxylic acids, which are biochemically important intermediates relevant to molecular evolution, such as the primordial TCA (tricarboxylic acid) cycle. Here, we find evidence that the asteroid Ryugu samples underwent substantial aqueous alteration, as revealed by the presence of malonic acid during keto–enol tautomerism in the dicarboxylic acid profile. The comprehensive data suggest the presence of a series for water-soluble organic molecules in the regolith of Ryugu and evidence of signatures in coevolutionary aqueous alteration between water and organics in this carbonaceous asteroid.

DOI： 10.1038/s41467-024-49237-6

Other Link： https://www.nature.com/articles/s41467-024-49237-6

Microscale hydrogen, carbon, and nitrogen isotopic diversity of organic matter in asteroid Ryugu Reviewed International coauthorship International journal Open Access

Larry R Nittler, Jens Barosch, Katherine Burgess, Rhonda M Stroud, Jianhua Wang, Hikaru Yabuta, Yuma Enokido, Megumi Matsumoto, Tomoki Nakamura, Yoko Kebukawa, Shohei Yamashita, Yoshio Takahashi, Laure Bejach, Lydie Bonal, George D Cody, Emmanuel Dartois, Alexandre Dazzi, Bradley De Gregorio, Ariane Deniset-Besseau, Jean Duprat, Cécile Engrand, Minako Hashiguchi, A.L. David Kilcoyne, Mutsumi Komatsu, Zita Martins, Jérémie Mathurin, Gilles Montagnac, Smail Mostefaoui, Taiga Okumura, Eric Quirico, Laurent Remusat, Scott Sandford, Miho Shigenaka, Hiroki Suga, Yasuo Takeichi, Yusuke Tamenori, Maximilien Verdier-Paoletti, Daisuke Wakabayashi, Masanao Abe, Kanami Kamide, Akiko Miyazaki, Aiko Nakato, Satoru Nakazawa, Masahiro Nishimura, Tatsuaki Okada, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Tomohiro Usui, Toru Yada, Kasumi Yogata, Makoto Yoshikawa, Hisayoshi Yurimoto, Takaaki Noguchi, Ryuji Okazaki, Hiroshi Naraoka, Kanako Sakamoto, Shogo Tachibana, Sei-ichiro Watanabe, Yuichi Tsuda

Earth and Planetary Science Letters Vol. 637 page： 118719 - 118719 2024.7

Three-dimensional textures of Ryugu samples and their implications for the evolution of aqueous alteration in the Ryugu parent body Reviewed International coauthorship International journal Open Access

Akira Tsuchiyama, Megumi Matsumoto, Junya Matsuno, Masahiro Yasutake, Tomoki Nakamura, Takaaki Noguchi, Akira Miyake, Kentaro Uesugi, Akihisa Takeuchi, Shota Okumura, Yuri Fujioka, Mingqi Sun, Aki Takigawa, Toru Matsumoto, Satomi Enju, Itaru Mitsukawa, Yuma Enokido, Tatsuhiko Kawamoto, Takeshi Mikouchi, Tatsuhiro Michikami, Tomoyo Morita, Mizuha Kikuiri, Kana Amano, Eiichi Kagawa, Stefano Rubino, Zelia Dionnet, Alice Aléon-Toppani, Rosario Brunetto, Michael E. Zolensky, Tsukasa Nakano, Naoto Nakano, Hisayoshi Yurimoto, Ryuji Okazaki, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Satoru Nakazawa, Fuyuto Terui, Shogo Tachibana, Sei-ichiro Watanabe, Yuichi Tsuda

Geochimica et Cosmochimica Acta Vol. 375 page： 146 - 172 2024.6

Aqueous alteration in icy planetesimals: The effect of outward transport of gaseous hydrogen Reviewed International coauthorship International journal Open Access

Shibuya, T; Sekine, Y; Kikuchi, S; Kurokawa, H; Fukushi, K; Nakamura, T; Watanabe, S

GEOCHIMICA ET COSMOCHIMICA ACTA Vol. 374 page： 264 - 283 2024.6

Nonmagnetic framboid and associated iron nanoparticles with a space-weathered feature from asteroid Ryugu Reviewed International coauthorship International journal Open Access

Yuki Kimura, Takeharu Kato, Satoshi Anada, Ryuji Yoshida, Kazuo Yamamoto, Toshiaki Tanigaki, Tetsuya Akashi, Hiroto Kasai, Kosuke Kurosawa, Tomoki Nakamura, Takaaki Noguchi, Masahiko Sato, Toru Matsumoto, Tomoyo Morita, Mizuha Kikuiri, Kana Amano, Eiichi Kagawa, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Satoru Nakazawa, Hisayoshi Yurimoto, Ryuji Okazaki, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Sei-ichiro Watanabe, Yuichi Tsuda, Shogo Tachibana

Nature Communications Vol. 15 ( 1 ) 2024.4

Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

Abstract

Extraterrestrial minerals on the surface of airless Solar System bodies undergo gradual alteration processes known as space weathering over long periods of time. The signatures of space weathering help us understand the phenomena occurring in the Solar System. However, meteorites rarely retain the signatures, making it impossible to study the space weathering processes precisely. Here, we examine samples retrieved from the asteroid Ryugu by the Hayabusa2 spacecraft and discover the presence of nonmagnetic framboids through electron holography measurements that can visualize magnetic flux. Magnetite particles, which normally provide a record of the nebular magnetic field, have lost their magnetic properties by reduction via a high-velocity (>5 km s–1) impact of a micrometeoroid with a diameter ranging from 2 to 20 μm after destruction of the parent body of Ryugu. Around these particles, thousands of metallic-iron nanoparticles with a vortex magnetic domain structure, which could have recorded a magnetic field in the impact event, are found. Through measuring the remanent magnetization of the iron nanoparticles, future studies are expected to elucidate the nature of the nebular/interplanetary magnetic fields after the termination of aqueous alteration in an asteroid.

DOI： 10.1038/s41467-024-47798-0

Other Link： https://www.nature.com/articles/s41467-024-47798-0

AFM-IR nanospectroscopy of nanoglobule-like particles in Ryugu samples returned by the Hayabusa2 mission Reviewed International journal Open Access

Mathurin, J; Bejach, L; Dartois, E; Engrand, C; Dazzi, A; Deniset-Besseau, A; Duprat, J; Kebukawa, Y; Yabuta, H; Bonal, L; Quirico, E; Sandt, C; Borondics, F; Barosch, J; Beck, P; Cody, GD; De Gregorio, BT; Hashiguchi, M; Kilcoyne, DAL; Komatsu, M; Martins, Z; Matsumoto, M; Montagnac, G; Mostefaoui, S; Nittler, LR; Ohigashi, T; Okumura, T; Phan, VH; Remusat, L; Sandford, S; Shigenaka, M; Stroud, R; Suga, H; Takahashi, Y; Takeichi, Y; Tamenori, Y; Verdier-Paoletti, M; Yamashita, S; Nakamura, T; Morita, T; Kikuiri, M; Amano, K; Kagawa, E; Noguchi, T; Naraoka, H; Okazaki, R; Sakamoto, K; Yurimoto, H; Abe, M; Kamide, K; Miyazaki, A; Nakato, A; Nakazawa, S; Nishimura, M; Okada, T; Saiki, T; Tachibana, S; Tanaka, S; Terui, F; Tsuda, Y; Usui, T; Watanabe, SI; Yada, T; Yogata, K; Yoshikawa, M

ASTRONOMY & ASTROPHYSICS Vol. 684 2024.4

Correlated IR-SEM-TEM studies of three different grains from Ryugu: From the initial material to post-accretional processes Reviewed International coauthorship International journal Open Access

Alice Aléon-Toppani, Rosario Brunetto, Zélia Dionnet, Stefano Rubino, Donia Baklouti, François Brisset, Maxime Vallet, Eva Heripre, Tomoki Nakamura, Cateline Lantz, Zahia Djouadi, Ferenc Borondics, Christophe Sandt, David Troadec, Obadias Mivumbi, Megumi Matsumoto, Kana Amano, Tomoyo Morita, Hisayoshi Yurimoto, Takaaki Noguchi, Ryuji Okazaki, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Shogo Tachibana, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tatsuaki Okada, Tomohira Usui, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Satoru Nakazawa, Sei-ichiro Watanabe, Yuichi Tsuda

Geochimica et Cosmochimica Acta Vol. 371 page： 1 - 30 2024.4

Unraveling the Cr Isotopes of Ryugu: An Accurate Aqueous Alteration Age and the Least Thermally Processed Solar System Material Reviewed International coauthorship International journal Open Access

Ryoji Tanaka, Dilan M. Ratnayake, Tsutomu Ota, Noah Miklusicak, Tak Kunihiro, Christian Potiszil, Chie Sakaguchi, Katsura Kobayashi, Hiroshi Kitagawa, Masahiro Yamanaka, Masanao Abe, Akiko Miyazaki, Aiko Nakato, Satoru Nakazawa, Masahiro Nishimura, Tatsuaki Okada, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Yuichi Tsuda, Tomohiro Usui, Sei-ichiro Watanabe, Toru Yada, Kasumi Yogata, Makoto Yoshikawa, Eizo Nakamura

The Astrophysical Journal Vol. 965 ( 1 ) page： 52 - 52 2024.4

Language：English Publishing type：Research paper (scientific journal) Publisher：American Astronomical Society

Abstract

The analysis of samples returned from the C-type asteroid Ryugu has drastically advanced our knowledge of the evolution of early solar system materials. However, no consensus has been obtained on the chronological data, which is important for understanding the evolution of the asteroid Ryugu. Here, the aqueous alteration age of Ryugu particles was determined by the Mn–Cr method using bulk samples, yielding an age of 4.13 + 0.62/−0.55 Myr after the formation of Ca–Al-rich inclusions (CAI). The age corresponds to 4563.17 + 0.60/−0.67 Myr ago. The higher 55Mn/52Cr, ε 54Cr, and initial ε 53Cr values of the Ryugu samples relative to any carbonaceous chondrite samples implies that its progenitor body formed from the least thermally processed precursors in the outermost region of the protoplanetary disk. Despite accreting at different distances from the Sun, the hydrous asteroids (Ryugu and the parent bodies of CI, CM, CR, and ungrouped C2 meteorites) underwent aqueous alteration during a period of limited duration (3.8 ± 1.8 Myr after CAI). These ages are identical to the crystallization age of the carbonaceous achondirtes NWA 6704/6693 within the error. The ε 54Cr and initial ε 53Cr values of Ryugu and NWA 6704/6693 are also identical, while they show distinct Δ'17O values. This suggests that the precursors that formed the progenitor bodies of Ryugu and NWA 6703/6693 were formed in close proximity and experienced a similar degree of thermal processing in the protosolar nebula. However, the progenitor body of Ryugu was formed by a higher ice/dust ratio, than NWA6703/6693, in the outer region of the protoplanetary disk.

DOI： 10.3847/1538-4357/ad276a

Other Link： https://iopscience.iop.org/article/10.3847/1538-4357/ad276a/pdf

Pervasive aqueous alteration in the early Solar System revealed by potassium isotopic variations in Ryugu samples and carbonaceous chondrites Reviewed International coauthorship International journal Open Access

Yan Hu, Frédéric Moynier, Wei Dai, Marine Paquet, Tetsuya Yokoyama, 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, Shoichi Itoh, Noriyuki Kawasaki, Noriko T. Kita, Koki Kitajima, Thorsten Kleine, Shintaro Komatani, Alexander N. Krot, Ming-Chang Liu, Yuki Masuda, Mayu Morita, Kazuko Motomura, Izumi Nakai, Kazuhide Nagashima, David Nesvorný, Ann Nguyen, Larry Nittler, Morihiko Onose, Andreas Pack, Changkun Park, Laurette Piani, Liping Qin, Sara S. Russell, Naoya Sakamoto, Maria Schönbächler, Lauren Tafla, Haolan Tang, Kentaro Terada, Yasuko Terada, Tomohiro Usui, Sohei Wada, Meenakshi Wadhwa, Richard J. Walker, Katsuyuki Yamashita, Qing-Zhu Yin, Shigekazu Yoneda, Edward D. Young, Hiroharu Yui, Ai-Cheng Zhang, Tomoki Nakamura, Hiroshi Naraoka, Takaaki Noguchi, Ryuji Okazaki, Kanako Sakamoto, Hikaru Yabuta, Masanao Abe, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Tatsuaki Okada, Toru Yada, Kasumi Yogata, Satoru Nakazawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Yuichi Tsuda, Sei-ichiro Watanabe, Makoto Yoshikawa, Shogo Tachibana, Hisayoshi Yurimoto

Icarus Vol. 409 page： 115884 - 115884 2024.2

Microstructural and chemical features of impact melts on Ryugu particle surfaces: Records of interplanetary dust hit on asteroid Ryugu Reviewed International coauthorship International journal Open Access

Megumi Matsumoto, Junya Matsuno, Akira Tsuchiyama, Tomoki Nakamura, Yuma Enokido, Mizuha Kikuiri, Aiko Nakato, Masahiro Yasutake, Kentaro Uesugi, Akihisa Takeuchi, Satomi Enju, Shota Okumura, Itaru Mitsukawa, Mingqi Sun, Akira Miyake, Mitsutaka Haruta, Yohei Igami, Hisayoshi Yurimoto, Takaaki Noguchi, Ryuji Okazaki, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Shogo Tachibana, Michael Zolensky, Toru Yada, Masahiro Nishimura, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Satoru Nakazawa, Sei-ichiro Watanabe, Yuichi Tsuda

Science Advances Vol. 10 ( 3 ) 2024.1

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：American Association for the Advancement of Science (AAAS)

The Hayabusa2 spacecraft delivered samples of the carbonaceous asteroid Ryugu to Earth. Some of the sample particles show evidence of micrometeoroid impacts, which occurred on the asteroid surface. Among those, particles A0067 and A0094 have flat surfaces on which a large number of microcraters and impact melt splashes are observed. Two impact melt splashes and one microcrater were analyzed to unveil the nature of the objects that impacted the asteroid surface. The melt splashes consist mainly of Mg-Fe–rich glassy silicates and Fe-Ni sulfides. The microcrater trapped an impact melt consisting mainly of Mg-Fe–rich glassy silicate, Fe-Ni sulfides, and minor silica-rich glass. These impact melts show a single compositional trend indicating mixing of Ryugu surface materials and impactors having chondritic chemical compositions. The relict impactor in one of the melt splashes shows mineralogical similarity with anhydrous chondritic interplanetary dust particles having a probable cometary origin. The chondritic micrometeoroids probably impacted the Ryugu surface during its residence in a near-Earth orbit.

DOI： 10.1126/sciadv.adi7203

The thermal history of Ryugu based on Raman characterization of Hayabusa2 samples Reviewed International coauthorship International journal

Bonal, L; Quirico, E; Montagnac, G; Komatsu, M; Kebukawa, Y; Yabuta, H; Amano, K; Barosch, J; Bejach, L; Cody, GD; Dartois, E; Dazzi, A; De Gregorio, B; Deniset-Besseau, A; Duprat, J; Engrand, C; Hashiguchi, M; Kamide, K; Kilcoyne, D; Martins, Z; Mathurin, J; Mostefaoui, S; Nittler, L; Ohigashi, T; Okumura, T; Remusat, L; Sandford, S; Shigenaka, M; Stroud, R; Suga, H; Takahashi, Y; Takeichi, Y; Tamenori, Y; Verdier-Paoletti, M; Yamashita, S; Nakamura, T; Naraoka, H; Noguchi, T; Okazaki, R; Yurimoto, H; Tachibana, S; Abe, M; Miyazaki, A; Nakato, A; Nakazawa, S; Nishimura, M; Okada, T; Saiki, T; Sakamoto, K; Tanaka, S; Terui, F; Tsuda, Y; Usui, T; Watanabe, S; Yada, T; Yogata, K; Yoshikawa, M

ICARUS Vol. 408 2024.1

Polycyclic aromatic hydrocarbons in samples of Ryugu formed in the interstellar medium Reviewed International coauthorship International journal Open Access

Zeichner, SS; Aponte, JC; Bhattacharjee, S; Dong, GN; Hofmann, AE; Dworkin, JP; Glavin, DP; Elsila, JE; Graham, HV; Naraoka, H; Takano, Y; Tachibana, S; Karp, AT; Grice, K; Holman, AI; Freeman, KH; Yurimoto, H; Nakamura, T; Noguchi, T; Okazaki, R; Yabuta, H; Sakamoto, K; Yada, T; Nishimura, M; Nakato, A; Miyazaki, A; Yogata, K; Abe, M; Okada, T; Usui, T; Yoshikawa, M; Saiki, T; Tanaka, S; Terui, F; Nakazawa, S; Watanabe, S; Tsuda, Y; Hamase, K; Fukushima, K; Aoki, D; Hashiguchi, M; Mita, H; Chikaraishi, Y; Ohkouchi, N; Ogawa, NO; Sakai, S; Parker, ET; McLain, HL; Orthous-Daunay, FR; Vuitton, V; Wolters, C; Schmitt-Kopplin, P; Hertkorn, N; Thissen, R; Ruf, A; Isa, J; Oba, Y; Koga, T; Yoshimura, T; Araoka, D; Sugahara, H; Furusho, A; Furukawa, Y; Aoki, J; Kano, K; Nomura, SM; Sasaki, K; Sato, H; Yoshikawa, T; Tanaka, S; Morita, M; Onose, M; Kabashima, F; Fujishima, K; Yamazaki, T; Kimura, Y; Eiler, JM

SCIENCE Vol. 382 ( 6677 ) page： 1411 - 1415 2023.12

Nucleosynthetic s-Process Depletion in Mo from Ryugu samples returned by Hayabusa2 Reviewed International coauthorship International journal Open Access

Nakanishi, N; Yokoyama, T; Ishikawa, A; Walker, RJ; Abe, Y; Aléon, J; Alexander, CMO; Amari, S; Amelin, Y; Bajo, KI; Bizzarro, M; Bouvier, A; Carlson, RW; Chaussidon, M; Choi, BG; Dauphas, N; Davis, AM; Di Rocco, T; Fujiya, W; Fukai, R; Gautam, I; Haba, MK; Hibiya, Y; Hidaka, H; Homma, H; Hoppe, P; Huss, GR; Ichida, K; Iizuka, T; Ireland, TR; Itoh, S; Kawasaki, N; Kita, NT; Kitajima, K; Kleine, T; Komatani, S; Krot, AN; Liu, MC; Masuda, Y; Morita, M; Motomura, K; Moynier, F; Nakai, I; Nagashima, K; Nguyen, A; Nittler, L; Onose, M; Pack, A; Park, C; Piani, L; Qin, L; Russell, SS; Sakamoto, N; Schönbächler, M; Tafla, L; Tang, H; Terada, K; Terada, Y; Usui, T; Wada, S; Wadhwa, M; Yamashita, K; Yin, QZ; Yoneda, S; Young, D; Yui, H; Zhang, AC; Nakamura, T; Naraoka, H; Noguchi, T; Okazaki, R; Sakamoto, K; Yabuta, H; Abe, M; Miyazaki, A; Nakato, A; Nishimura, M; Okada, T; Yada, T; Yogata, K; Nakazawa, S; Saiki, T; Tanaka, S; Terui, F; Tsuda, Y; Watanabe, SI; Yoshikawa, M; Tachibana, S; Yurimoto, H

GEOCHEMICAL PERSPECTIVES LETTERS Vol. 28 page： 31 - 36 2023.12

Reassigning CI chondrite parent bodies based on reflectance spectroscopy of samples from carbonaceous asteroid Ryugu and meteorites Reviewed International coauthorship International journal Open Access

Kana Amano, Moe Matsuoka, Tomoki Nakamura, Eiichi Kagawa, Yuri Fujioka, Sandra M. Potin, Takahiro Hiroi, Eri Tatsumi, Ralph E. Milliken, Eric Quirico, Pierre Beck, Rosario Brunetto, Masayuki Uesugi, Yoshio Takahashi, Takahiro Kawai, Shohei Yamashita, Yuma Enokido, Taiga Wada, Yoshihiro Furukawa, Michael E. Zolensky, Driss Takir, Deborah L. Domingue, Camilo Jaramillo-Correa, Faith Vilas, Amanda R. Hendrix, Mizuha Kikuiri, Tomoyo Morita, Hisayoshi Yurimoto, Takaaki Noguchi, Ryuji Okazaki, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Shogo Tachibana, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Satoru Nakazawa, Sei-ichiro Watanabe, Yuichi Tsuda

Science Advances Vol. 9 ( 49 ) 2023.12

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：American Association for the Advancement of Science (AAAS)

The carbonaceous asteroid Ryugu has been explored by the Hayabusa2 spacecraft to elucidate the actual nature of hydrous asteroids. Laboratory analyses revealed that the samples from Ryugu are comparable to unheated CI carbonaceous chondrites; however, reflectance spectra of Ryugu samples and CIs do not coincide. Here, we demonstrate that Ryugu sample spectra are reproduced by heating Orgueil CI chondrite at 300°C under reducing conditions, which caused dehydration of terrestrial weathering products and reduction of iron in phyllosilicates. Terrestrial weathering of CIs accounts for the spectral differences between Ryugu sample and CIs, which is more severe than space weathering that likely explains those between asteroid Ryugu and the collected samples. Previous assignments of CI chondrite parent bodies, i.e., chemically most primitive objects in the solar system, are based on the spectra of CI chondrites. This study indicates that actual spectra of CI parent bodies are much darker and flatter at ultraviolet to visible wavelengths than the spectra of CI chondrites.

DOI： 10.1126/sciadv.adi3789

Influx of nitrogen-rich material from the outer Solar System indicated by iron nitride in Ryugu samples Reviewed International coauthorship International journal Open Access

Toru Matsumoto, Takaaki Noguchi, Akira Miyake, Yohei Igami, Mitsutaka Haruta, Yusuke Seto, Masaaki Miyahara, Naotaka Tomioka, Hikaru Saito, Satoshi Hata, Dennis Harries, Aki Takigawa, Yusuke Nakauchi, Shogo Tachibana, Tomoki Nakamura, Megumi Matsumoto, Hope A. Ishii, John P. Bradley, Kenta Ohtaki, Elena Dobrică, Hugues Leroux, Corentin Le Guillou, Damien Jacob, Francisco de la Peña, Sylvain Laforet, Maya Marinova, Falko Langenhorst, Pierre Beck, Thi 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, Tatsuhiro Michikami, Hisayoshi Yurimoto, Ryuji Okazaki, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Satoru Nakazawa, Sei-ichiro Watanabe, Yuichi Tsuda

Nature Astronomy 2023.11

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

Abstract

Large amounts of nitrogen compounds, such as ammonium salts, may be stored in icy bodies and comets, but the transport of these nitrogen-bearing solids into the near-Earth region is not well understood. Here, we report the discovery of iron nitride on magnetite grains from the surface of the near-Earth C-type carbonaceous asteroid Ryugu, suggesting inorganic nitrogen fixation. Micrometeoroid impacts and solar wind irradiation may have caused the selective loss of volatile species from major iron-bearing minerals to form the metallic iron. Iron nitride is a product of nitridation of the iron metal by impacts of micrometeoroids that have higher nitrogen contents than the CI chondrites. The impactors are probably primitive materials with origins in the nitrogen-rich reservoirs in the outer Solar System. Our observation implies that the amount of nitrogen available for planetary formation and prebiotic reactions in the inner Solar System is greater than previously recognized.

DOI： 10.1038/s41550-023-02137-z

Other Link： https://www.nature.com/articles/s41550-023-02137-z

Water circulation in Ryugu asteroid affected the distribution of nucleosynthetic isotope anomalies in returned sample Reviewed International coauthorship International journal Open Access

Tetsuya Yokoyama, Meenakshi Wadhwa, Tsuyoshi Iizuka, Vinai Rai, Ikshu Gautam, Yuki Hibiya, Yuki Masuda, Makiko K. Haba, Ryota Fukai, Rebekah Hines, Nicole Phelan, 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, Hiroshi Hidaka, Hisashi Homma, Peter Hoppe, Gary R. Huss, Kiyohiro Ichida, Trevor Ireland, Akira Ishikawa, Shoichi Itoh, Noriyuki Kawasaki, Noriko T. Kita, Koki Kitajima, Thorsten Kleine, Shintaro Komatani, Alexander N. Krot, Ming-Chang Liu, Kevin D. McKeegan, Mayu Morita, Kazuko Motomura, Frédéric Moynier, Izumi Nakai, Kazuhide Nagashima, Ann Nguyen, Larry Nittler, Morihiko Onose, Andreas Pack, Changkun Park, Laurette Piani, Liping Qin, Sara Russell, Naoya Sakamoto, Maria Schönbächler, Lauren Tafla, Haolan Tang, Kentaro Terada, Yasuko Terada, Tomohiro Usui, Sohei Wada, Richard J. Walker, Katsuyuki Yamashita, Qing-Zhu Yin, Shigekazu Yoneda, Edward D. Young, Hiroharu Yui, Ai-Cheng Zhang, Tomoki Nakamura, Hiroshi Naraoka, Takaaki Noguchi, Ryuji Okazaki, Kanako Sakamoto, Hikaru Yabuta, Masanao Abe, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Tatsuaki Okada, Toru Yada, Kasumi Yogata, Satoru Nakazawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Yuichi Tsuda, Sei-ichiro Watanabe, Makoto Yoshikawa, Shogo Tachibana, Hisayoshi Yurimoto

Science Advances Vol. 9 ( 45 ) 2023.11

Language：English Publishing type：Research paper (scientific journal) Publisher：American Association for the Advancement of Science (AAAS)

Studies of material returned from Cb asteroid Ryugu have revealed considerable mineralogical and chemical heterogeneity, stemming primarily from brecciation and aqueous alteration. Isotopic anomalies could have also been affected by delivery of exogenous clasts and aqueous mobilization of soluble elements. Here, we show that isotopic anomalies for mildly soluble Cr are highly variable in Ryugu and CI chondrites, whereas those of Ti are relatively uniform. This variation in Cr isotope ratios is most likely due to physicochemical fractionation between 54 Cr-rich presolar nanoparticles and Cr-bearing secondary minerals at the millimeter-scale in the bulk samples, likely due to extensive aqueous alteration in their parent bodies that occurred after Solar System birth. In contrast, Ti isotopes were marginally affected by this process. Our results show that isotopic heterogeneities in asteroids are not all nebular or accretionary in nature but can also reflect element redistribution by water.

DOI： 10.1126/sciadv.adi7048

Space weathering record and pristine state of Ryugu samples from MicrOmega spectral analysis Reviewed International coauthorship International journal

Le Pivert-Jolivet, T; Brunetto, R; Pilorget, C; Bibring, JP; Nakato, A; Hamm, V; Hatakeda, K; Lantz, C; Loizeau, D; Riu, L; Yogata, K; Baklouti, D; Poulet, F; Aleon-Toppani, A; Carter, J; Langevin, Y; Okada, T; Yada, T; Hitomi, Y; Kumagai, K; Miyazaki, A; Nagashima, K; Nishimura, M; Usui, T; Abe, M; Saiki, T; Tanaka, S; Nakazawa, S; Tsuda, Y; Watanabe, S

NATURE ASTRONOMY 2023.10

Space weathering acts strongly on the uppermost surface of Ryugu Reviewed International coauthorship International journal Open Access

Moe Matsuoka, Ei-ichi Kagawa, Kana Amano, Tomoki Nakamura, Eri Tatsumi, Takahito Osawa, Takahiro Hiroi, Ralph Milliken, Deborah Domingue, Driss Takir, Rosario Brunetto, Antonella Barucci, Kohei Kitazato, Seiji Sugita, Yuri Fujioka, Osamu Sasaki, Shiho Kobayashi, Takahiro Iwata, Tomokatsu Morota, Yasuhiro Yokota, Toru Kouyama, Rie Honda, Shingo Kameda, Yuichiro Cho, Kazuo Yoshioka, Hirotaka Sawada, Masahiko Hayakawa, Naoya Sakatani, Manabu Yamada, Hidehiko Suzuki, Chikatoshi Honda, Kazunori Ogawa, Kei Shirai, Cateline Lantz, Stefano Rubino, Hisayoshi Yurimoto, Takaaki Noguchi, Ryuji Okazaki, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Shogo Tachibana, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Satoru Nakazawa, Sei-ichiro Watanabe, Yuichi Tsuda

Communications Earth & Environment Vol. 4 ( 1 ) 2023.9

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

Abstract

Returned samples from Cb-type asteroid (162173) Ryugu exhibit very dark spectra in visible and near-infrared ranges, generally consistent with the Hayabusa2 observations. A critical difference is that a structural water absorption of hydrous silicates is around twice as deep in the returned samples compared with those of Ryugu’s surface, suggesting Ryugu surface is more dehydrated. Here we use laboratory experiments data to indicate the spectral differences between returned samples and asteroid surface are best explained if Ryugu surface has (1) higher porosity, (2) larger particle size, and (3) more space-weathered condition, with the last being the most effective. On Ryugu, space weathering by micrometeoroid bombardments promoting dehydration seem to be more effective than that by solar-wind implantation. Extremely homogeneous spectra of the Ryugu’s global surface is in contrast with the heterogeneous S-type asteroid (25143) Itokawa’s spectra, which suggests space weathering has proceeded more rapidly on Cb-type asteroids than S-type asteroids.

DOI： 10.1038/s43247-023-00991-3

Other Link： https://www.nature.com/articles/s43247-023-00991-3

Carbonate record of temporal change in oxygen fugacity and gaseous species in asteroid Ryugu Reviewed International coauthorship International journal Open Access

Wataru Fujiya, Noriyuki Kawasaki, Kazuhide Nagashima, Naoya Sakamoto, Conel M. O’D. Alexander, Noriko T. Kita, Kouki Kitajima, Yoshinari Abe, Jérôme Aléon, 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, Ryota Fukai, Ikshu Gautam, Makiko K. Haba, Yuki Hibiya, Hiroshi Hidaka, Hisashi Homma, Peter Hoppe, Gary R. Huss, Kiyohiro Ichida, Tsuyoshi Iizuka, Trevor R. Ireland, Akira Ishikawa, Shoichi Itoh, Thorsten Kleine, Shintaro Komatani, Alexander N. Krot, Ming-Chang Liu, Yuki Masuda, Kevin D. McKeegan, Mayu Morita, Kazuko Motomura, Frédéric Moynier, Izumi Nakai, Ann Nguyen, Larry Nittler, Morihiko Onose, Andreas Pack, Changkun Park, Laurette Piani, Liping Qin, Sara S. Russell, Maria Schönbächler, Lauren Tafla, Haolan Tang, Kentaro Terada, Yasuko Terada, Tomohiro Usui, Sohei Wada, Meenakshi Wadhwa, Richard J. Walker, Katsuyuki Yamashita, Qing-Zhu Yin, Tetsuya Yokoyama, Shigekazu Yoneda, Edward D. Young, Hiroharu Yui, Ai-Cheng Zhang, Tomoki Nakamura, Hiroshi Naraoka, Takaaki Noguchi, Ryuji Okazaki, Kanako Sakamoto, Hikaru Yabuta, Masanao Abe, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Tatsuaki Okada, Toru Yada, Kasumi Yogata, Satoru Nakazawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Yuichi Tsuda, Sei-ichiro Watanabe, Makoto Yoshikawa, Shogo Tachibana, Hisayoshi Yurimoto

Nature Geoscience Vol. 16 ( 8 ) page： 675 - + 2023.8

Ryugu's Anhydrous Ingredients and Their Spectral Link to Primitive Dust from the Outer Solar System Reviewed International coauthorship International journal Open Access

Brunetto R., Lantz C., Fukuda Y., Aleon-Toppani A., Nakamura T., Dionnet Z., Baklouti D., Borondics F., Djouadi Z., Rubino S., Amano K., Matsumoto M., Fujioka Y., Morita T., Kukuiri M., Kagawa E., Matsuoka M., Milliken R., Yurimoto H., Noguchi T., Okazaki R., Yabuta H., Naraoka H., Sakamoto K., Tachibana S., Yada T., Nishimura M., Nakato A., Miyazaki A., Yogata K., Abe M., Okada T., Usui T., Yoshikawa M., Saiki T., Tanaka S., Terui F., Nakazawa S., Watanabe S., Tsuda Y.

ASTROPHYSICAL JOURNAL LETTERS Vol. 951 ( 2 ) 2023.7

A history of mild shocks experienced by the regolith particles on hydrated asteroid Ryugu Reviewed International coauthorship International journal Open Access

Naotaka Tomioka, Akira Yamaguchi, Motoo Ito, Masayuki Uesugi, Naoya Imae, Naoki Shirai, Takuji Ohigashi, Makoto Kimura, Ming-Chang Liu, Richard C. Greenwood, Kentaro Uesugi, Aiko Nakato, Kasumi Yogata, Hayato Yuzawa, Yu Kodama, Kaori Hirahara, Ikuya Sakurai, Ikuo Okada, Yuzuru Karouji, Keishi Okazaki, Kosuke Kurosawa, Takaaki Noguchi, Akira Miyake, Masaaki Miyahara, Yusuke Seto, Toru Matsumoto, Yohei Igami, Satoru Nakazawa, Tatsuaki Okada, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Makoto Yoshikawa, Akiko Miyazaki, Masahiro Nishimura, Toru Yada, Masanao Abe, Tomohiro Usui, Sei-ichiro Watanabe, Yuichi Tsuda

Nature Astronomy Vol. 7 ( 6 ) page： 669 - 677 2023.6

Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

Abstract

Micrometeorites, a possible major source of Earth’s water, are thought to form from explosive dispersal of hydrated chondritic materials during impact events on their parental asteroids. However, this provenance and formation mechanism have yet to be directly confirmed using asteroid returned samples. Here, we report evidence of mild shock metamorphism in the surface particles of asteroid Ryugu based on electron microscopy. All particles are dominated by phyllosilicates but lack dehydration textures, which are indicative of shock-heating temperatures below ~500 °C. Microfault-like textures associated with extensively shock-deformed framboidal magnetites and a high-pressure polymorph of Fe–Cr–sulfide have been identified. These findings indicate that the average peak pressure was ~2 GPa. The vast majority of ejecta formed during impact on Ryugu-like asteroids would be hydrated materials, larger than a millimetre, originating far from the impact point. These characteristics are inconsistent with current micrometeorite production models, and consequently, a new formation mechanism is required.

DOI： 10.1038/s41550-023-01947-5

Other Link： https://www.nature.com/articles/s41550-023-01947-5

The spatial distribution of soluble organic matter and their relationship to minerals in the asteroid (162173) Ryugu Reviewed International coauthorship International journal Open Access

Hashiguchi Minako, Aoki Dan, Fukushima Kazuhiko, Naraoka Hiroshi, Takano Yoshinori, Dworkin Jason P., Dworkin Karin E., Aponte Jose C., Elsila Jamie E., Eiler John M., Furukawa Yoshihiro, Furusho Aogu, Glavin Daniel P., Graham Heather V., Hamase Kenji, Hertkorn Norbert, Isa Junko, Koga Toshiki, McLain Hannah L., Mita Hajime, Oba Yasuhiro, Ogawa Nanako O., Ohkouchi Naohiko, Orthous-Daunay Francois-Regis, Parker Eric T., Ruf Alexander, Sakai Saburo, Schmitt-Kopplin Philippe, Sugahara Haruna, Thissen Roland, Vuitton Veronique, Wolters Cedric, Yoshimura Toshihiro, Yurimoto Hisayoshi, Nakamura Tomoki, Noguchi Takaaki, Okazaki Ryuji, Yabuta Hikaru, Sakamoto Kanako, Tachibana Shogo, Yada Toru, Nishimura Masahiro, Nakato Aiko, Miyazaki Akiko, Yogata Kasumi, Abe Masanao, Usui Tomohiro, Yoshikawa Makoto, Saiki Takanao, Tanaka Satoshi, Terui Fuyuto, Nakazawa Satoru, Watanabe Sei-ichiro, Tsuda Yuichi

EARTH, PLANETS AND SPACE Vol. 75 ( 1 ) 2023.5

Nonequilibrium spherulitic magnetite in the Ryugu samples Reviewed International coauthorship International journal Open Access

Laforet S., Marinova M., Langenhorst F., Harries D., Beck P., Phan T. H. V., Rebois R., Abreu N. M., Gray J., Zega T., Zanetta P. -M., Thompson M. S., Stroud R., Burgess K., Cymes B. A., Bridges J. C., Hicks L., Lee M. R., Daly L., Bland P. A., Zolensky M. E., Frank D. R., Martinez J., Tsuchiyama A., Yasutake M., Matsuno J., Okumura S., Mitsukawa I., Uesugi K., Uesugi M., Takeuchi A., Sun M., Enju S., Takigawa A., Michikami T., Nakamura T., Matsumoto M., Nakauchi Y., Yurimoto H., Okazaki R., Yabuta H., Naraoka H., Sakamoto K., Tachibana S., Yada T., Nishimura M., Nakato A., Miyazaki A., Yogata K., Abe M., Okada T., Usui T., Yoshikawa M., Saiki T., Tanaka S., Terui F., Nakazawa S., Watanabe S. and Tsuda Y.

Geochimica et Cosmochimica Acta Vol. 346 page： 65 - 75 2023.4

Exploration-Based Reconstruction of Planetesimals Invited Reviewed International coauthorship

Sei-ichiro Watanabe, Masahiko Arakawa, Masatoshi Hirabayashi, Seiji Sugita, William F. Bottke, Patrick Michel

Protostars and Planets VII (Astronomical Society of the Pacific) page： 993 - 1029 2023.4

Variations of the surface characteristics of Ryugu returned samples Reviewed International coauthorship International journal Open Access

Nakato Aiko, Yada Toru, Nishimura Masahiro, Yogata Kasumi, Miyazaki Akiko, Nagashima Kana, Hatakeda Kentaro, Kumagai Kazuya, Hitomi Yuya, Soejima Hiromichi, Bibring Jean-Pierre, Pilorget Cedric, Hamm Vincent, Brunetto Rosario, Riu Lucie, Lourit Lionel, Loizeau Damien, Le Pivert-Jolivet Tania, Lequertier Guillaume, Moussi-Soffys Aurelie, Abe Masanao, Okada Tatsuaki, Usui Tomohiro, Nakazawa Satoru, Saiki Takanao, Tanaka Satoshi, Terui Fuyuto, Yoshikawa Makoto, Watanabe Sei-ichiro, Tsuda Yuichi

EARTH PLANETS AND SPACE Vol. 75 ( 1 ) 2023.3

Uracil in the carbonaceous asteroid (162173) Ryugu Reviewed International coauthorship International journal Open Access

Yasuhiro Oba, Toshiki Koga, Yoshinori Takano, Nanako O. Ogawa, Naohiko Ohkouchi, Kazunori Sasaki, Hajime Sato, Daniel P. Glavin, Jason P. Dworkin, Hiroshi Naraoka, Shogo Tachibana, Hisayoshi Yurimoto, Tomoki Nakamura, Takaaki Noguchi, Ryuji Okazaki, Hikaru Yabuta, Kanako Sakamoto, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Satoru Nakazawa, Sei-ichiro Watanabe, Yuichi Tsuda

Nature Communications Vol. 14 ( 1 ) page： 1292 2023.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

Abstract

The pristine sample from the near-Earth carbonaceous asteroid (162173) Ryugu collected by the Hayabusa2 spacecraft enabled us to analyze the pristine extraterrestrial material without uncontrolled exposure to the Earth’s atmosphere and biosphere. The initial analysis team for the soluble organic matter reported the detection of wide variety of organic molecules including racemic amino acids in the Ryugu samples. Here we report the detection of uracil, one of the four nucleobases in ribonucleic acid, in aqueous extracts from Ryugu samples. In addition, nicotinic acid (niacin, a B3 vitamer), its derivatives, and imidazoles were detected in search for nitrogen heterocyclic molecules. The observed difference in the concentration of uracil between A0106 and C0107 may be related to the possible differences in the degree of alteration induced by energetic particles such as ultraviolet photons and cosmic rays. The present study strongly suggests that such molecules of prebiotic interest commonly formed in carbonaceous asteroids including Ryugu and were delivered to the early Earth.

DOI： 10.1038/s41467-023-36904-3

Other Link： https://www.nature.com/articles/s41467-023-36904-3

Insight into multi-step geological evolution of C-type asteroids from Ryugu particles Reviewed International coauthorship International journal Open Access

Akira Yamaguchi, Naotaka Tomioka, Motoo Ito, Naoki Shirai, Makoto Kimura, Richard C. Greenwood, Ming-Chang Liu, Kaitlyn A. McCain, Nozomi Matsuda, Masayuki Uesugi, Naoya Imae, Takuji Ohigashi, Kentaro Uesugi, Aiko Nakato, Kasumi Yogata, Hayato Yuzawa, Yu Kodama, Kaori Hirahara, Ikuya Sakurai, Ikuo Okada, Yuzuru Karouji, Satoru Nakazawa, Tatsuaki Okada, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Makoto Yoshikawa, Akiko Miyazaki, Masahiro Nishimura, Toru Yada, Masanao Abe, Tomohiro Usui, Sei-ichiro Watanabe, Yuichi Tsuda

Nature Astronomy 2023.3

PAHs, hydrocarbons, and dimethylsulfides in Asteroid Ryugu samples A0106 and C0107 and the Orgueil (CI1) meteorite Reviewed International coauthorship International journal Open Access

José C. Aponte, Jason P. Dworkin, Daniel P. Glavin, Jamie E. Elsila, Eric T. Parker, Hannah L. McLain, Hiroshi Naraoka, Ryuji Okazaki, Yoshinori Takano, Shogo Tachibana, Guannan Dong, Sarah S. Zeichner, John M. Eiler, Hisayoshi Yurimoto, Tomoki Nakamura, Hikaru Yabuta, Fuyuto Terui, Takaaki Noguchi, Kanako Sakamoto, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Satoru Nakazawa, Yuichi Tsuda, Sei-ichiro Watanabe, The Hayabusa2-initial-analysis SOM team, The Hayabusa2-initial-analysis core team

Earth Planets and Space Vol. 75 ( 1 ) 2023.2

Macromolecular organic matter in samples of the asteroid (162173) Ryugu Reviewed International coauthorship Open Access

Hikaru Yabuta, George D. Cody, Cécile Engrand, Yoko Kebukawa, Bradley De Gregorio, Lydie Bonal, Laurent Remusat, Rhonda Stroud, Eric Quirico, Larry Nittler, Minako Hashiguchi, Mutsumi Komatsu, Taiga Okumura, Jérémie Mathurin, Emmanuel Dartois, Jean Duprat, Yoshio Takahashi, Yasuo Takeichi, David Kilcoyne, Shohei Yamashita, Alexandre Dazzi, Ariane Deniset-Besseau, Scott Sandford, Zita Martins, Yusuke Tamenori, Takuji Ohigashi, Hiroki Suga, Daisuke Wakabayashi, Maximilien Verdier-Paoletti, Smail Mostefaoui, Gilles Montagnac, Jens Barosch, Kanami Kamide, Miho Shigenaka, Laure Bejach, Megumi Matsumoto, Yuma Enokido, Takaaki Noguchi, Hisayoshi Yurimoto, Tomoki Nakamura, Ryuji Okazaki, Hiroshi Naraoka, Kanako Sakamoto, Harold C. Connolly, Dante S. Lauretta, Masanao Abe, Tatsuaki Okada, Toru Yada, Masahiro Nishimura, Kasumi Yogata, Aiko Nakato, Miwa Yoshitake, Ayako Iwamae, Shizuho Furuya, Kentaro Hatakeda, Akiko Miyazaki, Hiromichi Soejima, Yuya Hitomi, Kazuya Kumagai, Tomohiro Usui, Tasuku Hayashi, Daiki Yamamoto, Ryota Fukai, Seiji Sugita, Kohei Kitazato, Naru Hirata, Rie Honda, Tomokatsu Morota, Eri Tatsumi, Naoya Sakatani, Noriyuki Namiki, Koji Matsumoto, Rina Noguchi, Koji Wada, Hiroki Senshu, Kazunori Ogawa, Yasuhiro Yokota, Yoshiaki Ishihara, Yuri Shimaki, Manabu Yamada, Chikatoshi Honda, Tatsuhiro Michikami, Moe Matsuoka, Naoyuki Hirata, Masahiko Arakawa, Chisato Okamoto, Masateru Ishiguro, Ralf Jaumann, Jean-Pierre Bibring, Matthias Grott, Stefan Schröder, Katharina Otto, Cedric Pilorget, Nicole Schmitz, Jens Biele, Tra-Mi Ho, Aurélie Moussi-Soffys, Akira Miura, Hirotomo Noda, Tetsuya Yamada, Keisuke Yoshihara, Kosuke Kawahara, Hitoshi Ikeda, Yukio Yamamoto, Kei Shirai, Shota Kikuchi, Naoko Ogawa, Hiroshi Takeuchi, Go Ono, Yuya Mimasu, Kent Yoshikawa, Yuto Takei, Atsushi Fujii, Yu-ichi Iijima, Satoru Nakazawa, Satoshi Hosoda, Takahiro Iwata, Masahiko Hayakawa, Hirotaka Sawada, Hajime Yano, Ryudo Tsukizaki, Masanobu Ozaki, Fuyuto Terui, Satoshi Tanaka, Masaki Fujimoto, Makoto Yoshikawa, Takanao Saiki, Shogo Tachibana, Sei-ichiro Watanabe, Yuichi Tsuda

Science Vol. 379 ( 6634 ) 2023.2

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：American Association for the Advancement of Science (AAAS)

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.

DOI： 10.1126/science.abn9057

Soluble organic molecules in samples of the carbonaceous asteroid (162173) Ryugu Reviewed International coauthorship Open Access

Hiroshi Naraoka, Yoshinori Takano, Jason P. Dworkin, Yasuhiro Oba, Kenji Hamase, Aogu Furusho, Nanako O. Ogawa, Minako Hashiguchi, Kazuhiko Fukushima, Dan Aoki, Philippe Schmitt-Kopplin, José C. Aponte, Eric T. Parker, Daniel P. Glavin, Hannah L. McLain, Jamie E. Elsila, Heather V. Graham, John M. Eiler, Francois-Regis Orthous-Daunay, Cédric Wolters, Junko Isa, Véronique Vuitton, Roland Thissen, Saburo Sakai, Toshihiro Yoshimura, Toshiki Koga, Naohiko Ohkouchi, Yoshito Chikaraishi, Haruna Sugahara, Hajime Mita, Yoshihiro Furukawa, Norbert Hertkorn, Alexander Ruf, Hisayoshi Yurimoto, Tomoki Nakamura, Takaaki Noguchi, Ryuji Okazaki, Hikaru Yabuta, Kanako Sakamoto, Shogo Tachibana, Harold C. Connolly, Dante S. Lauretta, Masanao Abe, Toru Yada, Masahiro Nishimura, Kasumi Yogata, Aiko Nakato, Miwa Yoshitake, Ayako Suzuki, Akiko Miyazaki, Shizuho Furuya, Kentaro Hatakeda, Hiromichi Soejima, Yuya Hitomi, Kazuya Kumagai, Tomohiro Usui, Tasuku Hayashi, Daiki Yamamoto, Ryota Fukai, Kohei Kitazato, Seiji Sugita, Noriyuki Namiki, Masahiko Arakawa, Hitoshi Ikeda, Masateru Ishiguro, Naru Hirata, Koji Wada, Yoshiaki Ishihara, Rina Noguchi, Tomokatsu Morota, Naoya Sakatani, Koji Matsumoto, Hiroki Senshu, Rie Honda, Eri Tatsumi, Yasuhiro Yokota, Chikatoshi Honda, Tatsuhiro Michikami, Moe Matsuoka, Akira Miura, Hirotomo Noda, Tetsuya Yamada, Keisuke Yoshihara, Kosuke Kawahara, Masanobu Ozaki, Yu-ichi Iijima, Hajime Yano, Masahiko Hayakawa, Takahiro Iwata, Ryudo Tsukizaki, Hirotaka Sawada, Satoshi Hosoda, Kazunori Ogawa, Chisato Okamoto, Naoyuki Hirata, Kei Shirai, Yuri Shimaki, Manabu Yamada, Tatsuaki Okada, Yukio Yamamoto, Hiroshi Takeuchi, Atsushi Fujii, Yuto Takei, Kento Yoshikawa, Yuya Mimasu, Go Ono, Naoko Ogawa, Shota Kikuchi, Satoru Nakazawa, Fuyuto Terui, Satoshi Tanaka, Takanao Saiki, Makoto Yoshikawa, Sei-ichiro Watanabe, Yuichi Tsuda

Science Vol. 379 ( 6634 ) 2023.2

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：American Association for the Advancement of Science (AAAS)

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.

DOI： 10.1126/science.abn9033

Chondrule-like objects and Ca-Al-rich inclusions in Ryugu may potentially be the oldest Solar System materials Reviewed International coauthorship International journal Open Access

Daisuke Nakashima, Tomoki Nakamura, Mingming Zhang, Noriko T. Kita, Takashi Mikouchi, Hideto Yoshida, Yuma Enokido, Tomoyo Morita, Mizuha Kikuiri, Kana Amano, Eiichi Kagawa, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Satoru Nakazawa, Fuyuto Terui, Hisayoshi Yurimoto, Takaaki Noguchi, Hikaru Yabuta, Hiroshi Naraoka, Ryuji Okazaki, Kanako Sakamoto, Sei-ichiro Watanabe, Shogo Tachibana, Yuichi Tsuda

Nature Communications Vol. 14 ( 1 ) page： 532 - 532 2023.2

Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

Abstract

Chondrule-like objects and Ca-Al-rich inclusions (CAIs) are discovered in the retuned samples from asteroid Ryugu. Here we report results of oxygen isotope, mineralogical, and compositional analysis of the chondrule-like objects and CAIs. Three chondrule-like objects dominated by Mg-rich olivine are 16O-rich and -poor with Δ17O (=δ17O – 0.52 × δ18O) values of ~ –23‰ and ~ –3‰, resembling what has been proposed as early generations of chondrules. The 16O-rich objects are likely to be melted amoeboid olivine aggregates that escaped from incorporation into 16O-poor chondrule precursor dust. Two CAIs composed of refractory minerals are 16O-rich with Δ17O of ~ –23‰ and possibly as old as the oldest CAIs. The discovered objects (<30 µm) are as small as those from comets, suggesting radial transport favoring smaller objects from the inner solar nebula to the formation location of the Ryugu original parent body, which is farther from the Sun and scarce in chondrules. The transported objects may have been mostly destroyed during aqueous alteration in the Ryugu parent body.

DOI： 10.1038/s41467-023-36268-8

Other Link： https://www.nature.com/articles/s41467-023-36268-8

Contribution of Ryugu-like material to Earth’s volatile inventory by Cu and Zn isotopic analysis Reviewed International coauthorship International journal Open Access

Marine Paquet, Frederic Moynier, Tetsuya Yokoyama, Wei Dai, Yan Hu, 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, Izumi Nakai, Kazuhide Nagashima, David Nesvorný, Ann N. Nguyen, Larry Nittler, Morihiko Onose, Andreas Pack, Changkun Park, Laurette Piani, Liping Qin, Sara S. Russell, Naoya Sakamoto, Maria Schönbächler, Lauren Tafla, Haolan Tang, Kentaro Terada, Yasuko Terada, Tomohiro Usui, Sohei Wada, Meenakshi Wadhwa, Richard J. Walker, Katsuyuki Yamashita, Qing-Zhu Yin, Shigekazu Yoneda, Edward D. Young, Hiroharu Yui, Ai-Cheng Zhang, Tomoki Nakamura, Hiroshi Naraoka, Takaaki Noguchi, Ryuji Okazaki, Kanako Sakamoto, Hikaru Yabuta, Masanao Abe, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Tatsuaki Okada, Toru Yada, Kasumi Yogata, Satoru Nakazawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Yuichi Tsuda, Sei-ichiro Watanabe, Makoto Yoshikawa, Shogo Tachibana, Hisayoshi Yurimoto

Nature Astronomy Vol. 7 ( 2 ) page： 182 - 189 2023.2

Constraints on Solar System early evolution by MicrOmega analysis of Ryugu carbonates Reviewed International coauthorship

D. Loizeau, C. Pilorget, L. Riu, R. Brunetto, J.-P. Bibring, A. Nakato, A. Aléon-Toppani, K. Hatakeda, K. Yogata, J. Carter, T. Le Pivert-Jolivet, T. Yada, T. Okada, T. Usui, Y. Langevin, C. Lantz, D. Baklouti, A. Miyazaki, M. Nishimura, K. Nagashima, K. Kumagai, Y. Hitomi, M. Abe, T. Saiki, S. Tanaka, S. Nakazawa, Y. Tsuda, S. Watanabe

Nature Astronomy 2023.1

Early fluid activity on Ryugu inferred by isotopic analyses of carbonates and magnetite Reviewed International coauthorship Open Access

Kaitlyn A. McCain, Nozomi Matsuda, Ming-Chang Liu, Kevin D. McKeegan, Akira Yamaguchi, Makoto Kimura, Naotaka Tomioka, Motoo Ito, Naoya Imae, Masayuki Uesugi, Naoki Shirai, Takuji Ohigashi, Richard C. Greenwood, Kentaro Uesugi, Aiko Nakato, Kasumi Yogata, Hayato Yuzawa, Yu Kodama, Kaori Hirahara, Ikuya Sakurai, Ikuo Okada, Yuzuru Karouji, Satoru Nakazawa, Tatsuaki Okada, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Makoto Yoshikawa, Akiko Miyazaki, Masahiro Nishimura, Toru Yada, Masanao Abe, Tomohiro Usui, Sei-ichiro Watanabe, Yuichi Tsuda

Nature Astronomy 2023.1

A dehydrated space-weathered skin cloaking the hydrated interior of Ryugu Reviewed International coauthorship International journal Open Access

Takaaki Noguchi, Toru Matsumoto, Akira Miyake, Yohei Igami, Mitsutaka Haruta, Hikaru Saito, Satoshi Hata, Yusuke Seto, Masaaki Miyahara, Naotaka Tomioka, Hope A. Ishii, John P. Bradley, Kenta K. Ohtaki, Elena Dobrică, Hugues Leroux, Corentin Le Guillou, Damien Jacob, Francisco de la Peña, Sylvain Laforet, Maya Marinova, Falko Langenhorst, Dennis Harries, Pierre Beck, Thi H. V. Phan, Rolando Rebois, Neyda M. Abreu, Jennifer Gray, Thomas Zega, Pierre-M. Zanetta, Michelle S. Thompson, Rhonda Stroud, Kate Burgess, Brittany A. Cymes, John C. Bridges, Leon Hicks, Martin R. Lee, Luke Daly, Phil A. Bland, Michael E. Zolensky, David R. Frank, James Martinez, Akira Tsuchiyama, Masahiro Yasutake, Junya Matsuno, Shota Okumura, Itaru Mitsukawa, Kentaro Uesugi, Masayuki Uesugi, Akihisa Takeuchi, Mingqi Sun, Satomi Enju, Aki Takigawa, Tatsuhiro Michikami, Tomoki Nakamura, Megumi Matsumoto, Yusuke Nakauchi, Masanao Abe, Masahiko Arakawa, Atsushi Fujii, Masahiko Hayakawa, Naru Hirata, Naoyuki Hirata, Rie Honda, Chikatoshi Honda, Satoshi Hosoda, Yu-ichi Iijima, Hitoshi Ikeda, Masateru Ishiguro, Yoshiaki Ishihara, Takahiro Iwata, Kousuke Kawahara, Shota Kikuchi, Kohei Kitazato, Koji Matsumoto, Moe Matsuoka, Yuya Mimasu, Akira Miura, Tomokatsu Morota, Satoru Nakazawa, Noriyuki Namiki, Hirotomo Noda, Rina Noguchi, Naoko Ogawa, Kazunori Ogawa, Tatsuaki Okada, Chisato Okamoto, Go Ono, Masanobu Ozaki, Takanao Saiki, Naoya Sakatani, Hirotaka Sawada, Hiroki Senshu, Yuri Shimaki, Kei Shirai, Seiji Sugita, Yuto Takei, Hiroshi Takeuchi, Satoshi Tanaka, Eri Tatsumi, Fuyuto Terui, Ryudo Tsukizaki, Koji Wada, Manabu Yamada, Tetsuya Yamada, Yukio Yamamoto, Hajime Yano, Yasuhiro Yokota, Keisuke Yoshihara, Makoto Yoshikawa, Kent Yoshikawa, Ryohta Fukai, Shizuho Furuya, Kentaro Hatakeda, Tasuku Hayashi, Yuya Hitomi, Kazuya Kumagai, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Hiromichi Soejima, Ayako I. Suzuki, Tomohiro Usui, Toru Yada, Daiki Yamamoto, Kasumi Yogata, Miwa Yoshitake, Harold C. Connolly, Dante S. Lauretta, Hisayoshi Yurimoto, Kazuhide Nagashima, Noriyuki Kawasaki, Naoya Sakamoto, Ryuji Okazaki, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Shogo Tachibana, Sei-ichiro Watanabe, Yuichi Tsuda

Nature Astronomy 2022.12

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

Abstract

Without a protective atmosphere, space-exposed surfaces of airless Solar System bodies gradually experience an alteration in composition, structure and optical properties through a collective process called space weathering. The return of samples from near-Earth asteroid (162173) Ryugu by Hayabusa2 provides the first opportunity for laboratory study of space-weathering signatures on the most abundant type of inner solar system body: a C-type asteroid, composed of materials largely unchanged since the formation of the Solar System. Weathered Ryugu grains show areas of surface amorphization and partial melting of phyllosilicates, in which reduction from Fe3+ to Fe2+ and dehydration developed. Space weathering probably contributed to dehydration by dehydroxylation of Ryugu surface phyllosilicates that had already lost interlayer water molecules and to weakening of the 2.7 µm hydroxyl (–OH) band in reflectance spectra. For C-type asteroids in general, this indicates that a weak 2.7 µm band can signify space-weathering-induced surface dehydration, rather than bulk volatile loss.

DOI： 10.1038/s41550-022-01841-6

Other Link： https://www.nature.com/articles/s41550-022-01841-6

Oxygen isotope evidence from Ryugu samples for early water delivery to Earth by CI chondrites Reviewed International coauthorship Open Access

Richard C. Greenwood, Ian A. Franchi, Ross Findlay, James A. Malley, Motoo Ito, Akira Yamaguchi, Makoto Kimura, Naotaka Tomioka, Masayuki Uesugi, Naoya Imae, Naoki Shirai, Takuji Ohigashi, Ming-Chang Liu, Kaitlyn A. McCain, Nozomi Matsuda, Kevin D. McKeegan, Kentaro Uesugi, Aiko Nakato, Kasumi Yogata, Hayato Yuzawa, Yu Kodama, Akira Tsuchiyama, Masahiro Yasutake, Kaori Hirahara, Akihisa Tekeuchi, Shun Sekimoto, Ikuya Sakurai, Ikuo Okada, Yuzuru Karouji, Satoru Nakazawa, Tatsuaki Okada, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Makoto Yoshikawa, Akiko Miyazaki, Masahiro Nishimura, Toru Yada, Masanao Abe, Tomohiro Usui, Sei-ichiro Watanabe, Yuichi Tsuda

Nature Astronomy Vol. 7 ( 1 ) page： 29 - 38 2022.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

Abstract

The delivery of water to the inner Solar System, including Earth, is still a debated topic. A preferential role for hydrated asteroids in this process is supported by isotopic measurements. Carbonaceous chondrite (CC) meteorites represent our main source of information about these volatile-rich asteroids. However, the destruction of weaker materials during atmospheric entry creates a bias in our CC data. The return of surface materials from the C-type asteroid 162173 Ryugu by the Hayabusa2 spacecraft provides a unique opportunity to study high-porosity, low-density, primitive materials, unrepresented in the meteorite record. We measured the bulk oxygen isotope composition from four Ryugu particles and show that they most closely resemble the rare CI (CC Ivuna-type) chondrites, but with some differences that we attribute to the terrestrial contamination of the CI meteorites. We suggest that CI-related material is widespread among carbonaceous asteroids and a more important source of Earth’s water and other volatiles than its limited presence in our meteoritic collection indicates.

DOI： 10.1038/s41550-022-01824-7

Other Link： https://www.nature.com/articles/s41550-022-01824-7

Oxygen isotopes of anhydrous primary minerals show kinship between asteroid Ryugu and comet 81P/Wild2 Reviewed International coauthorship Open Access

Noriyuki Kawasaki, Kazuhide Nagashima, Naoya Sakamoto, Toru Matsumoto, Ken-ichi Bajo, Sohei Wada, Yohei Igami, Akira Miyake, Takaaki Noguchi, Daiki Yamamoto, Sara S. Russell, Yoshinari Abe, Jérôme Aléon, Conel M. O’D. Alexander, Sachiko Amari, Yuri Amelin, Martin Bizzarro, Audrey Bouvier, Richard W. Carlson, Marc Chaussidon, Byeon-Gak Choi, Nicolas Dauphas, Andrew M. Davis, Tommaso Di Rocco, Wataru Fujiya, Ryota Fukai, Ikshu Gautam, Makiko K. Haba, Yuki Hibiya, Hiroshi Hidaka, Hisashi Homma, Peter Hoppe, Gary R. Huss, Kiyohiro Ichida, Tsuyoshi Iizuka, Trevor R. Ireland, Akira Ishikawa, Motoo Ito, Shoichi Itoh, Noriko T. Kita, Kouki Kitajima, Thorsten Kleine, Shintaro Komatani, Alexander N. Krot, Ming-Chang Liu, Yuki Masuda, Kevin D. McKeegan, Mayu Morita, Kazuko Motomura, Frédéric Moynier, Izumi Nakai, Ann Nguyen, Larry Nittler, Morihiko Onose, Andreas Pack, Changkun Park, Laurette Piani, Liping Qin, Maria Schönbächler, Lauren Tafla, Haolan Tang, Kentaro Terada, Yasuko Terada, Tomohiro Usui, Meenakshi Wadhwa, Richard J. Walker, Katsuyuki Yamashita, Qing-Zhu Yin, Tetsuya Yokoyama, Shigekazu Yoneda, Edward D. Young, Hiroharu Yui, Ai-Cheng Zhang, Tomoki Nakamura, Hiroshi Naraoka, Ryuji Okazaki, Kanako Sakamoto, Hikaru Yabuta, Masanao Abe, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Tatsuaki Okada, Toru Yada, Kasumi Yogata, Satoru Nakazawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Yuichi Tsuda, Sei-ichiro Watanabe, Makoto Yoshikawa, Shogo Tachibana, Hisayoshi Yurimoto

Science Advances Vol. 8 ( 50 ) 2022.12

Language：English Publishing type：Research paper (scientific journal) Publisher：American Association for the Advancement of Science (AAAS)

The extraterrestrial materials returned from asteroid (162173) Ryugu consist predominantly of low-temperature aqueously formed secondary minerals and are chemically and mineralogically similar to CI (Ivuna-type) carbonaceous chondrites. Here, we show that high-temperature anhydrous primary minerals in Ryugu and CI chondrites exhibit a bimodal distribution of oxygen isotopic compositions: 16 O-rich (associated with refractory inclusions) and 16 O-poor (associated with chondrules). Both the 16 O-rich and 16 O-poor minerals probably formed in the inner solar protoplanetary disk and were subsequently transported outward. The abundance ratios of the 16 O-rich to 16 O-poor minerals in Ryugu and CI chondrites are higher than in other carbonaceous chondrite groups but are similar to that of comet 81P/Wild2, suggesting that Ryugu and CI chondrites accreted in the outer Solar System closer to the accretion region of comets.

DOI： 10.1126/sciadv.ade2067

First asteroid gas sample delivered by the Hayabusa2 mission: A treasure box from Ryugu Reviewed International coauthorship Open Access

Okazaki Ryuji, Miura Yayoi N., Takano Yoshinori, Sawada Hirotaka, Sakamoto Kanako, Yada Toru, Yamada Keita, Kawagucci Shinsuke, Matsui Yohei, Hashizume Ko, Ishida Akizumi, Broadley Michael W., Marty Bernard, Byrne David, Furi Evelyn, Meshik Alex, Pravdivtseva Olga, Busemann Henner, Riebe My E. I, Gilmour Jamie, Park Jisun, Bajo Ken-ichi, Righter Kevin, Sakai Saburo, Sekimoto Shun, Kitajima Fumio, Crowther Sarah A., Iwata Naoyoshi, Shirai Naoki, Ebihara Mitsuru, Yokochi Reika, Nishiizumi Kunihiko, Nagao Keisuke, Lee Jong Ik, Clay Patricia, Kano Akihiro, Caffee Marc W., Uemura Ryu, Inagaki Makoto, Krietsch Daniela, Maden Colin, Yamamoto Mizuki, Fawcett Lydia, Lawton Thomas, Nakamura Tomoki, Naraoka Hiroshi, Noguchi Takaaki, Yabuta Hikaru, Yurimoto Hisayoshi, Tsuda Yuichi, Watanabe Sei-Ichiro, Abe Masanao, Arakawa Masahiko, Fujii Atsushi, Hayakawa Masahiko, Hirata Naoyuki, Hirata Naru, Honda Rie, Honda Chikatoshi, Hosoda Satoshi, Iijima Yu-Ichi, Ikeda Hitoshi, Ishiguro Masateru, Ishihara Yoshiaki, Iwata Takahiro, Kawahara Kosuke, Kikuchi Shota, Kitazato Kohei, Matsumoto Koji, Matsuoka Moe, Michikami Tatsuhiro, Mimasu Yuya, Miura Akira, Morota Tomokatsu, Nakazawa Satoru, Namiki Noriyuki, Noda Hirotomo, Noguchi Rina, Ogawa Naoko, Ogawa Kazunori, Okada Tatsuaki, Okamoto Chisato, Ono Go, Ozaki Masanobu, Saiki Takanao, Sakatani Naoya, Senshu Hiroki, Shimaki Yuri, Shirai Kei, Sugita Seiji, Takei Yuto, Takeuchi Hiroshi, Tanaka Satoshi, Tatsumi Eri, Terui Fuyuto, Tsukizaki Ryudo, Wada Koji, Yamada Manabu, Yamada Tetsuya, Yamamoto Yukio, Yano Hajime, Yokota Yasuhiro, Yoshihara Keisuke, Yoshikawa Makoto, Yoshikawa Kent, Furuya Shizuho, Hatakeda Kentaro, Hayashi Tasuku, Hitomi Yuya, Kumagai Kazuya, Miyazaki Akiko, Nakato Aiko, Nishimura Masahiro, Soejima Hiromichi, Iwamae Ayako, Yamamoto Daiki, Yogata Kasumi, Yoshitake Miwa, Fukai Ryota, Usui Tomohiro, Ireland Trevor, Connolly Harold C. Jr., Lauretta Dante S., Tachibana Shogo

SCIENCE ADVANCES Vol. 8 ( 46 ) 2022.11

Ryugu’s nucleosynthetic heritage from the outskirts of the Solar System Reviewed International coauthorship Open Access

Timo Hopp, Nicolas Dauphas, Yoshinari Abe, Jérôme Aléon, Conel M. O’D. Alexander, Sachiko Amari, Yuri Amelin, Ken-ichi Bajo, Martin Bizzarro, Audrey Bouvier, Richard W. Carlson, Marc Chaussidon, Byeon-Gak Choi, Andrew M. Davis, Tommaso Di Rocco, Wataru Fujiya, Ryota Fukai, Ikshu Gautam, Makiko K. Haba, Yuki Hibiya, Hiroshi Hidaka, Hisashi Homma, Peter Hoppe, Gary R. Huss, Kiyohiro Ichida, Tsuyoshi Iizuka, Trevor R. Ireland, Akira Ishikawa, Motoo Ito, Shoichi Itoh, Noriyuki Kawasaki, Noriko T. Kita, Kouki Kitajima, Thorsten Kleine, Shintaro Komatani, Alexander N. Krot, Ming-Chang Liu, Yuki Masuda, Kevin D. McKeegan, Mayu Morita, Kazuko Motomura, Frédéric Moynier, Izumi Nakai, Kazuhide Nagashima, David Nesvorný, Ann Nguyen, Larry Nittler, Morihiko Onose, Andreas Pack, Changkun Park, Laurette Piani, Liping Qin, Sara S. Russell, Naoya Sakamoto, Maria Schönbächler, Lauren Tafla, Haolan Tang, Kentaro Terada, Yasuko Terada, Tomohiro Usui, Sohei Wada, Meenakshi Wadhwa, Richard J. Walker, Katsuyuki Yamashita, Qing-Zhu Yin, Tetsuya Yokoyama, Shigekazu Yoneda, Edward D. Young, Hiroharu Yui, Ai-Cheng Zhang, Tomoki Nakamura, Hiroshi Naraoka, Takaaki Noguchi, Ryuji Okazaki, Kanako Sakamoto, Hikaru Yabuta, Masanao Abe, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Tatsuaki Okada, Toru Yada, Kasumi Yogata, Satoru Nakazawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Yuichi Tsuda, Sei-ichiro Watanabe, Makoto Yoshikawa, Shogo Tachibana, Hisayoshi Yurimoto

Science Advances Vol. 8 ( 46 ) 2022.11

Language：English Publishing type：Research paper (scientific journal) Publisher：American Association for the Advancement of Science (AAAS)

Little is known about the origin of the spectral diversity of asteroids and what it says about conditions in the protoplanetary disk. Here, we show that samples returned from Cb-type asteroid Ryugu have Fe isotopic anomalies indistinguishable from Ivuna-type (CI) chondrites, which are distinct from all other carbonaceous chondrites. Iron isotopes, therefore, demonstrate that Ryugu and CI chondrites formed in a reservoir that was different from the source regions of other carbonaceous asteroids. Growth and migration of the giant planets destabilized nearby planetesimals and ejected some inward to be implanted into the Main Belt. In this framework, most carbonaceous chondrites may have originated from regions around the birthplaces of Jupiter and Saturn, while the distinct isotopic composition of CI chondrites and Ryugu may reflect their formation further away in the disk, owing their presence in the inner Solar System to excitation by Uranus and Neptune.

DOI： 10.1126/sciadv.add8141

Photometric behavior of Ryugu's NIR spectral parameters Reviewed International coauthorship Open Access

Longobardo A., Palomba E., Galiano A., Dirri F., Zinzi A., D'Amore M., Domingue D., Kitazato K., Yokota Y., Schroeder S. E., Iwata T., Matsuoka M., Hiroi T., Takir D., Nakamura T., Abe M., Ohtake M., Matsuura S., Watanabe S., Yoshikawa M., Saiki T., Tanaka S., Okada T., Yamamoto Y., Takei Y., Shirai K., Hirata N., Hirata N., Matsumoto K., Tsuda Y.

ASTRONOMY & ASTROPHYSICS Vol. 666 2022.10

Noble gases and nitrogen in samples of asteroid Ryugu record its volatile sources and recent surface evolution Reviewed International coauthorship Open Access

Ryuji Okazaki, Bernard Marty, Henner Busemann, Ko Hashizume, Jamie D. Gilmour, Alex Meshik, Toru Yada, Fumio Kitajima, Michael W. Broadley, David Byrne, Evelyn Füri, My E. I. Riebe, Daniela Krietsch, Colin Maden, Akizumi Ishida, Patricia Clay, Sarah A. Crowther, Lydia Fawcett, Thomas Lawton, Olga Pravdivtseva, Yayoi N. Miura, Jisun Park, Ken-ichi Bajo, Yoshinori Takano, Keita Yamada, Shinsuke Kawagucci, Yohei Matsui, Mizuki Yamamoto, Kevin Righter, Saburo Sakai, Naoyoshi Iwata, Naoki Shirai, Shun Sekimoto, Makoto Inagaki, Mitsuru Ebihara, Reika Yokochi, Kunihiko Nishiizumi, Keisuke Nagao, Jong Ik Lee, Akihiro Kano, Marc W. Caffee, Ryu Uemura, Tomoki Nakamura, Hiroshi Naraoka, Takaaki Noguchi, Hikaru Yabuta, Hisayoshi Yurimoto, Shogo Tachibana, Hirotaka Sawada, Kanako Sakamoto, Masanao Abe, Masahiko Arakawa, Atsushi Fujii, Masahiko Hayakawa, Naoyuki Hirata, Naru Hirata, Rie Honda, Chikatoshi Honda, Satoshi Hosoda, Yu-ichi Iijima, Hitoshi Ikeda, Masateru Ishiguro, Yoshiaki Ishihara, Takahiro Iwata, Kosuke Kawahara, Shota Kikuchi, Kohei Kitazato, Koji Matsumoto, Moe Matsuoka, Tatsuhiro Michikami, Yuya Mimasu, Akira Miura, Tomokatsu Morota, Satoru Nakazawa, Noriyuki Namiki, Hirotomo Noda, Rina Noguchi, Naoko Ogawa, Kazunori Ogawa, Tatsuaki Okada, Chisato Okamoto, Go Ono, Masanobu Ozaki, Takanao Saiki, Naoya Sakatani, Hiroki Senshu, Yuri Shimaki, Kei Shirai, Seiji Sugita, Yuto Takei, Hiroshi Takeuchi, Satoshi Tanaka, Eri Tatsumi, Fuyuto Terui, Ryudo Tsukizaki, Koji Wada, Manabu Yamada, Tetsuya Yamada, Yukio Yamamoto, Hajime Yano, Yasuhiro Yokota, Keisuke Yoshihara, Makoto Yoshikawa, Kent Yoshikawa, Shizuho Furuya, Kentaro Hatakeda, Tasuku Hayashi, Yuya Hitomi, Kazuya Kumagai, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Hiromichi Soejima, Ayako Iwamae, Daiki Yamamoto, Kasumi Yogata, Miwa Yoshitake, Ryota Fukai, Tomohiro Usui, Harold C. Connolly, Dante Lauretta, Sei-ichiro Watanabe, Yuichi Tsuda

SCIENCE Vol. 379 ( 6634 ) 2022.10

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：American Association for the Advancement of Science (AAAS)

The near-Earth carbonaceous asteroid (162173) Ryugu is expected to contain volatile chemical species that could provide information on the origin of Earth’s volatiles. Samples of Ryugu were retrieved by the Hayabusa2 spacecraft. We measure noble gas and nitrogen isotopes in Ryugu samples, finding they are dominated by pre-solar and primordial components, incorporated during Solar System formation. Noble gas concentrations are higher than those in Ivuna-type carbonaceous (CI) chondrite meteorites. Several host phases of isotopically distinct nitrogen have heterogeneous abundances between the samples. Our measurements support a close relationship between Ryugu and CI chondrites. Noble gases produced by galactic cosmic rays, indicating ~5 Myr exposure, and from implanted solar wind, record the recent irradiation history of Ryugu after it migrated to its current orbit.

DOI： 10.1126/science.abo0431

Incorporation of 16O-rich anhydrous silicates in the protolith of highly hydrated asteroid Ryugu Reviewed International coauthorship International journal Open Access

Ming-Chang Liu, Kaitlyn A. McCain, Nozomi Matsuda, Akira Yamaguchi, Makoto Kimura, Naotaka Tomioka, Motoo Ito, Masayuki Uesugi, Naoya Imae, Naoki Shirai, Takuji Ohigashi, Richard C. Greenwood, Kentaro Uesugi, Aiko Nakato, Kasumi Yogata, Hayato Yuzawa, Yu Kodama, Kaori Hirahara, Ikuya Sakurai, Ikuo Okada, Yuzuru Karouji, Satoru Nakazawa, Tatsuaki Okada, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Makoto Yoshikawa, Akiko Miyazaki, Masahiro Nishimura, Toru Yada, Masanao Abe, Tomohiro Usui, Sei-ichiro Watanabe, Yuichi Tsuda

Nature Astronomy Vol. 6 ( 10 ) page： 1172 - + 2022.10

A pristine record of outer Solar System materials from asteroid Ryugu’s returned sample Reviewed International coauthorship International journal Open Access

Motoo Ito, Naotaka Tomioka, Masayuki Uesugi, Akira Yamaguchi, Naoki Shirai, Takuji Ohigashi, Ming-Chang Liu, Richard C. Greenwood, Makoto Kimura, Naoya Imae, Kentaro Uesugi, Aiko Nakato, Kasumi Yogata, Hayato Yuzawa, Yu Kodama, Akira Tsuchiyama, Masahiro Yasutake, Ross Findlay, Ian A. Franchi, James A. Malley, Kaitlyn A. McCain, Nozomi Matsuda, Kevin D. McKeegan, Kaori Hirahara, Akihisa Takeuchi, Shun Sekimoto, Ikuya Sakurai, Ikuo Okada, Yuzuru Karouji, Masahiko Arakawa, Atsushi Fujii, Masaki Fujimoto, Masahiko Hayakawa, Naoyuki Hirata, Naru Hirata, Rie Honda, Chikatoshi Honda, Satoshi Hosoda, Yu-ichi Iijima, Hitoshi Ikeda, Masateru Ishiguro, Yoshiaki Ishihara, Takahiro Iwata, Kosuke Kawahara, Shota Kikuchi, Kohei Kitazato, Koji Matsumoto, Moe Matsuoka, Tatsuhiro Michikami, Yuya Mimasu, Akira Miura, Osamu Mori, Tomokatsu Morota, Satoru Nakazawa, Noriyuki Namiki, Hirotomo Noda, Rina Noguchi, Naoko Ogawa, Kazunori Ogawa, Tatsuaki Okada, Chisato Okamoto, Go Ono, Masanobu Ozaki, Takanao Saiki, Naoya Sakatani, Hirotaka Sawada, Hiroki Senshu, Yuri Shimaki, Kei Shirai, Seiji Sugita, Yuto Takei, Hiroshi Takeuchi, Satoshi Tanaka, Eri Tatsumi, Fuyuto Terui, Ryudo Tsukizaki, Koji Wada, Manabu Yamada, Tetsuya Yamada, Yukio Yamamoto, Hajime Yano, Yasuhiro Yokota, Keisuke Yoshihara, Makoto Yoshikawa, Kent Yoshikawa, Ryota Fukai, Shizuho Furuya, Kentaro Hatakeda, Tasuku Hayashi, Yuya Hitomi, Kazuya Kumagai, Akiko Miyazaki, Masahiro Nishimura, Hiromichi Soejima, Ayako Iwamae, Daiki Yamamoto, Miwa Yoshitake, Toru Yada, Masanao Abe, Tomohiro Usui, Sei-ichiro Watanabe, Yuichi Tsuda

Nature Astronomy Vol. 6 ( 10 ) page： 1163 - + 2022.10

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

Abstract

Volatile and organic-rich C-type asteroids may have been one of the main sources of Earth’s water. Our best insight into their chemistry is currently provided by carbonaceous chondritic meteorites, but the meteorite record is biased: only the strongest types survive atmospheric entry and are then modified by interaction with the terrestrial environment. Here we present the results of a detailed bulk and microanalytical study of pristine Ryugu particles, brought to Earth by the Hayabusa2 spacecraft. Ryugu particles display a close compositional match with the chemically unfractionated, but aqueously altered, CI (Ivuna-type) chondrites, which are widely used as a proxy for the bulk Solar System composition. The sample shows an intricate spatial relationship between aliphatic-rich organics and phyllosilicates and indicates maximum temperatures of ~30 °C during aqueous alteration. We find that heavy hydrogen and nitrogen abundances are consistent with an outer Solar System origin. Ryugu particles are the most uncontaminated and unfractionated extraterrestrial materials studied so far, and provide the best available match to the bulk Solar System composition.

DOI： 10.1038/s41550-022-01745-5

Other Link： https://www.nature.com/articles/s41550-022-01745-5

Formation and evolution of carbonaceous asteroid Ryugu: Direct evidence from returned samples Reviewed International coauthorship Open Access

T. Nakamura, M. Matsumoto, K. Amano, Y. Enokido, M. E. Zolensky, T. Mikouchi, H. Genda, S. Tanaka, M. Y. Zolotov, K. Kurosawa, S. Wakita, R. Hyodo, H. Nagano, D. Nakashima, Y. Takahashi, Y. Fujioka, M. Kikuiri, E. Kagawa, M. Matsuoka, A. J. Brearley, A. Tsuchiyama, M. Uesugi, J. Matsuno, Y. Kimura, M. Sato, R. E. Milliken, E. Tatsumi, S. Sugita, T. Hiroi, K. Kitazato, D. Brownlee, D. J. Joswiak, M. Takahashi, K. Ninomiya, T. Takahashi, T. Osawa, K. Terada, F. E. Brenker, B. J. Tkalcec, L. Vincze, R. Brunetto, A. Aléon-Toppani, Q. H. S. Chan, M. Roskosz, J.-C. Viennet, P. Beck, E. E. Alp, T. Michikami, Y. Nagaashi, T. Tsuji, Y. Ino, J. Martinez, J. Han, A. Dolocan, R. J. Bodnar, M. Tanaka, H. Yoshida, K. Sugiyama, A. J. King, K. Fukushi, H. Suga, S. Yamashita, T. Kawai, K. Inoue, A. Nakato, T. Noguchi, F. Vilas, A. R. Hendrix, C. Jaramillo-Correa, D. L. Domingue, G. Dominguez, Z. Gainsforth, C. Engrand, J. Duprat, S. S. Russell, E. Bonato, C. Ma, T. Kawamoto, T. Wada, S. Watanabe, R. Endo, S. Enju, L. Riu, S. Rubino, P. Tack, S. Takeshita, Y. Takeichi, A. Takeuchi, A. Takigawa, D. Takir, T. Tanigaki, A. Taniguchi, K. Tsukamoto, T. Yagi, S. Yamada, K. Yamamoto, Y. Yamashita, M. Yasutake, K. Uesugi, I. Umegaki, I. Chiu, T. Ishizaki, S. Okumura, E. Palomba, C. Pilorget, S. M. Potin, A. Alasli, S. Anada, Y. Araki, N. Sakatani, C. Schultz, O. Sekizawa, S. D. Sitzman, K. Sugiura, M. Sun, E. Dartois, E. De Pauw, Z. Dionnet, Z. Djouadi, G. Falkenberg, R. Fujita, T. Fukuma, I. R. Gearba, K. Hagiya, M. Y. Hu, T. Kato, T. Kawamura, M. Kimura, M. K. Kubo, F. Langenhorst, C. Lantz, B. Lavina, M. Lindner, J. Zhao, B. Vekemans, D. Baklouti, B. Bazi, F. Borondics, S. Nagasawa, G. Nishiyama, K. Nitta, J. Mathurin, T. Matsumoto, I. Mitsukawa, H. Miura, A. Miyake, Y. Miyake, H. Yurimoto, R. Okazaki, H. Yabuta, H. Naraoka, K. Sakamoto, S. Tachibana, H. C. Connolly, D. S. Lauretta, M. Yoshitake, M. Yoshikawa, K. Yoshikawa, K. Yoshihara, Y. Yokota, K. Yogata, H. Yano, Y. Yamamoto, D. Yamamoto, M. Yamada, T. Yamada, T. Yada, K. Wada, T. Usui, R. Tsukizaki, F. Terui, H. Takeuchi, Y. Takei, A. Iwamae, H. Soejima, K. Shirai, Y. Shimaki, H. Senshu, H. Sawada, T. Saiki, M. Ozaki, G. Ono, T. Okada, N. Ogawa, K. Ogawa, R. Noguchi, H. Noda, M. Nishimura, N. Namiki, S. Nakazawa, T. Morota, A. Miyazaki, A. Miura, Y. Mimasu, K. Matsumoto, K. Kumagai, T. Kouyama, S. Kikuchi, K. Kawahara, S. Kameda, T. Iwata, Y. Ishihara, M. Ishiguro, H. Ikeda, S. Hosoda, R. Honda, C. Honda, Y. Hitomi, N. Hirata, N. Hirata, T. Hayashi, M. Hayakawa, K. Hatakeda, S. Furuya, R. Fukai, A. Fujii, Y. Cho, M. Arakawa, M. Abe, S. Watanabe, Y. Tsuda

SCIENCE Vol. 379 ( 6634 ) 2022.9

Site selection for the Hayabusa2 artificial cratering and subsurface material sampling on Ryugu Reviewed Open Access

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

Planetary and Space Science Vol. 219 page： 105519 - 105519 2022.9

On the origin and evolution of the asteroid Ryugu: A comprehensive geochemical perspective Reviewed Open Access

Eizo NAKAMURA, Katsura KOBAYASHI, Ryoji TANAKA, Tak KUNIHIRO, Hiroshi KITAGAWA, Christian POTISZIL, Tsutomu OTA, Chie SAKAGUCHI, Masahiro YAMANAKA, Dilan M. RATNAYAKE, Havishk TRIPATHI, Rahul KUMAR, Maya-Liliana AVRAMESCU, Hidehisa TSUCHIDA, Yusuke YACHI, Hitoshi MIURA, Masanao ABE, Ryota FUKAI, Shizuho FURUYA, Kentaro HATAKEDA, Tasuku HAYASHI, Yuya HITOMI, Kazuya KUMAGAI, Akiko MIYAZAKI, Aiko NAKATO, Masahiro NISHIMURA, Tatsuaki OKADA, Hiromichi SOEJIMA, Seiji SUGITA, Ayako SUZUKI, Tomohiro USUI, Toru YADA, Daiki YAMAMOTO, Kasumi YOGATA, Miwa YOSHITAKE, Masahiko ARAKAWA, Atsushi FUJII, Masahiko HAYAKAWA, Naoyuki HIRATA, Naru HIRATA, Rie HONDA, Chikatoshi HONDA, Satoshi HOSODA, Yu-ichi IIJIMA, Hitoshi IKEDA, Masateru ISHIGURO, Yoshiaki ISHIHARA, Takahiro IWATA, Kosuke KAWAHARA, Shota KIKUCHI, Kohei KITAZATO, Koji MATSUMOTO, Moe MATSUOKA, Tatsuhiro MICHIKAMI, Yuya MIMASU, Akira MIURA, Tomokatsu MOROTA, Satoru NAKAZAWA, Noriyuki NAMIKI, Hirotomo NODA, Rina NOGUCHI, Naoko OGAWA, Kazunori OGAWA, Chisato OKAMOTO, Go ONO, Masanobu OZAKI, Takanao SAIKI, Naoya SAKATANI, Hirotaka SAWADA, Hiroki SENSHU, Yuri SHIMAKI, Kei SHIRAI, Yuto TAKEI, Hiroshi TAKEUCHI, Satoshi TANAKA, Eri TATSUMI, Fuyuto TERUI, Ryudo TSUKIZAKI, Koji WADA, Manabu YAMADA, Tetsuya YAMADA, Yukio YAMAMOTO, Hajime YANO, Yasuhiro YOKOTA, Keisuke YOSHIHARA, Makoto YOSHIKAWA, Kent YOSHIKAWA, Masaki FUJIMOTO, Sei-ichiro WATANABE, Yuichi TSUDA

Proceedings of the Japan Academy, Series B Vol. 98 ( 6 ) page： 227 - 282 2022.6

Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meteorites Reviewed International coauthorship Open Access

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 Jr., 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

SCIENCE 2022.6

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

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

Science Vol. 375 ( 6584 ) page： 1011 - + 2022.3

Language：English Publishing type：Research paper (scientific journal) Publisher：American Association for the Advancement of Science (AAAS)

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....

DOI： 10.1126/science.abj8624

First compositional analysis of Ryugu samples by the MicrOmega hyperspectral microscope Reviewed International coauthorship

C. Pilorget, T. Okada, V. Hamm, R. Brunetto, T. Yada, D. Loizeau, L. Riu, T. Usui, A. Moussi-Soffys, K. Hatakeda, A. Nakato, K. Yogata, M. Abe, A. Aléon-Toppani, J. Carter, M. Chaigneau, B. Crane, B. Gondet, K. Kumagai, Y. Langevin, C. Lantz, T. Le Pivert-Jolivet, G. Lequertier, L. Lourit, A. Miyazaki, M. Nishimura, F. Poulet, M. Arakawa, N. Hirata, K. Kitazato, S. Nakazawa, N. Namiki, T. Saiki, S. Sugita, S. Tachibana, S. Tanaka, M. Yoshikawa, Y. Tsuda, S. Watanabe, J.-P. Bibring

Nature Astronomy Vol. 6 ( 2 ) page： 221 - 225 2022.2

Preliminary analysis of the Hayabusa2 samples returned from C-type asteroid Ryugu Reviewed International coauthorship Open Access

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

Nature Astronomy Vol. 6 ( 2 ) page： 214 - + 2022.2

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

Abstract

C-type asteroids1 are considered to be primitive small Solar System bodies enriched in water and organics, providing clues to the origin and evolution of the Solar System and the building blocks of life. C-type asteroid 162173 Ryugu has been characterized by remote sensing2–7 and on-asteroid measurements8,9 with Hayabusa2 (ref. 10). However, the ground truth provided by laboratory analysis of returned samples is invaluable to determine the fine properties of asteroids and other planetary bodies. We report preliminary results of analyses on returned samples from Ryugu of the particle size distribution, density and porosity, spectral properties and textural properties, and the results of a search for Ca–Al-rich inclusions (CAIs) and chondrules. The bulk sample mainly consists of rugged and smooth particles of millimetre to submillimetre size, confirming that the physical and chemical properties were not altered during the return from the asteroid. The power index of its size distribution is shallower than that of the surface boulder observed on Ryugu11, indicating differences in the returned Ryugu samples. The average of the estimated bulk densities of Ryugu sample particles is 1,282 ± 231 kg m−3, which is lower than that of meteorites12, suggesting a high microporosity down to the millimetre scale, extending centimetre-scale estimates from thermal measurements5,9. The extremely dark optical to near-infrared reflectance and spectral profile with weak absorptions at 2.7 and 3.4 μm imply a carbonaceous composition with indigenous aqueous alteration, matching the global average of Ryugu3,4 and confirming that the sample is representative of the asteroid. Together with the absence of submillimetre CAIs and chondrules, these features indicate that Ryugu is most similar to CI chondrites but has lower albedo, higher porosity and more fragile characteristics.

DOI： 10.1038/s41550-021-01550-6

Other Link： https://www.nature.com/articles/s41550-021-01550-6

Deformation of a rotated granular pile governed by body-force-dependent friction Reviewed Open Access

Terunori Irie, Ryusei Yamaguchi, Sei-ichiro Watanabe, Hiroaki Katsuragi

Physical Review E Vol. 104 page： 064902 2021.12

YORP Effect on Asteroid 162173 Ryugu: Implications for the Dynamical History Reviewed

Masanori Kanamaru, Sho Sasaki, Tomokatsu Morota, Yuichiro Cho, Eri Tatsumi, Masatoshi Hirabayashi, Naru Hirata, Hiroki Senshu, Yuri Shimaki, Naoya Sakatani, Satoshi Tanaka, Tatsuaki Okada, Tomohiro Usui, Seiji Sugita, Sei-ichiro Watanabe

JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS Vol. 126 ( 12 ) 2021.12

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER GEOPHYSICAL UNION

Asteroid 162173 Ryugu is a carbonaceous asteroid that was visited by Japan's Hayabusa2 spacecraft in 2018. The formation mechanism of the "spinning-top" shape of Ryugu is a vital clue to the dynamical history of the near-Earth asteroid. In this study, we address the long-term evolution of its spin state induced by the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect, that is, the thermal recoil torque that changes the rotation period and spin-pole direction. Given the current orbit, spin state, and three-dimensional shape of Ryugu observed by Hayabusa2, we computed the YORP torque exerted on Ryugu using a simplified thermal model assuming zero thermal conductivity. Despite variations in the meter-scaled topography, all 20 shape models that we examined indicate that the spin velocity of Ryugu is currently decreasing at a rate of (-6.3 to -0.42) x 10(-6) deg/day(2). Our findings also suggest that the thermal torque is responsible for maintaining the spin pole upright with respect to the orbital plane. Therefore, the YORP effect may explain the significant spin-down from an earlier period of 3.5 hr to the present period of 7.6 hr. The corresponding time scale of the spin-down is estimated to be 0.58-8.7 million years, depending on the input shape models. This time scale is comparable to the formation period of the largest crater, Urashima (5-12 Ma), or the western bulge (2-9 Ma) as derived from previous studies on crater statistics in Ryugu. Thus, its rotation may have started to decelerate as a consequence of major resurfacing events.

DOI： 10.1029/2021JE006863

Hayabusa2 Pinpoint Touchdown near the Artificial Crater on Ryugu: Trajectory Design and Guidance Performance Reviewed International journal Open Access

Shota Kikuchi, Takanao Saiki, Yuto Takei, Fuyuto Terui, Naoko Ogawa, Yuya Mimasu, Go Ono, Kent Yoshikawa, Hirotaka Sawada, Hiroshi Takeuchi, Hitoshi Ikeda, Atsushi Fujii, eiji 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

Advances in Space Research Vol. 68 ( 8 ) page： 3093 - 3140 2021.10

SPH simulations for shape deformation of rubble-pile asteroids through spinup: The challenge for making top-shaped asteroids Ryugu and Bennu Reviewed Open Access

Keisuke Sugiura, Hiroshi Kobayashi, Sei-ichiro Watanabe, Hidenori Genda, Ryuki Hyodo, Shu-ichiro Inutsuka

ICARUS Vol. 365 page： 114505 2021.9

Language：English Publishing type：Research paper (scientific journal) Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE

Asteroid 162173 Ryugu and asteroid 101955 Bennu, which were recently visited by spacecraft Hayabusa2 and OSIRIS-REx, respectively, are spinning top-shaped rubble piles. Other axisymmetric top-shaped near-Earth asteroids have been observed with ground-based radar, most of which rotate near breakup rotation periods of similar to 3 h. This suggests that rotation-induced deformation of asteroids through rotational spinup produces top shapes. Although some previous simulations using the Discrete Element Method showed that spinup of rubble piles may produce oblate top shapes, it is still unclear what kinds of conditions such as friction angles of constituent materials and spinup timescales are required for top-shape formation. Here we show, through Smoothed Particle Hydrodynamics simulations of granular bodies spinning-up at different rates, that the rotation-induced deformation of spherical rubble piles before breakup can be classified into three modes according to the friction angle phi(d) : quasi-static and internal deformation for phi(d) <= 40 degrees, dynamical and internal deformation for 50 degrees <= phi(d) <= 60 degrees , and a set of surface landslides for phi(d) >= 70 degrees. Note that these apparent large values of friction angle can be acceptable if we consider the effect of cohesion among blocks of a rubble pile under weak gravity. Bodies with phi(d) <= 60 degrees evolve into oblate spheroids through internal deformation, but never form pronounced equators defining a top shape. In contrast, bodies with phi(d) >= 70 degrees deform into axisymmetric top shapes through an axisymmetric set of surface landslides if spinup timescales are less than or similar to a few days. In addition, through slow spinups with timescales greater than or similar to 1 month, bodies with phi(d) >= 70 degrees deform into non-axisymmetric shapes via localized sets of landslides. We suggest that rapid spinup mechanisms are preferable for the formation of axisymmetric top shapes.

DOI： 10.1016/j.icarus.2021.114505

Anomalously porous boulders on (162173) Ryugu as primordial materials from its parent body Reviewed International coauthorship

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

Nature Astronomy Vol. 5 ( 8 ) page： 766 - + 2021.8

Language：English Publishing type：Research paper (scientific journal)

Planetesimals—the initial stage of the planetary formation process—are considered to be initially very porous aggregates of dusts1,2, and subsequent thermal and compaction processes reduce their porosity3. The Hayabusa2 spacecraft found that boulders on the surface of asteroid (162173) Ryugu have an average porosity of 30–50% (refs. 4–6), higher than meteorites but lower than cometary nuclei7, which are considered to be remnants of the original planetesimals8. Here, using high-resolution thermal and optical imaging of Ryugu’s surface, we discovered, on the floor of fresh small craters (<20 m in diameter), boulders with reflectance (~0.015) lower than the Ryugu average6 and porosity >70%, which is as high as in cometary bodies. The artificial crater formed by Hayabusa2’s impact experiment9 is similar to these craters in size but does not have such high-porosity boulders. Thus, we argue that the observed high porosity is intrinsic and not created by subsequent impact comminution and/or cracking. We propose that these boulders are the least processed material on Ryugu and represent remnants of porous planetesimals that did not undergo a high degree of heating and compaction3. Our multi-instrumental analysis suggests that fragments of the highly porous boulders are mixed within the surface regolith globally, implying that they might be captured within collected samples by touch-down operations10,11.

DOI： 10.1038/s41550-021-01371-7

Thermally altered subsurface material of asteroid (162173) Ryugu Reviewed International coauthorship

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

Nature Astronomy Vol. 5 ( 3 ) page： 246 - + 2021.3

Alignment determination of the Hayabusa2 laser altimeter (LIDAR) Reviewed International journal Open Access

Noda, H; Senshu, H; Matsumoto, K; Namiki, N; Mizuno, T; Sugita, S; Abe, S; Araki, H; Asari, K; Cho, Y; Fujii, A; Hayakawa, M; Higuchi, A; Hirata, N; Hirata, N; Honda, C; Honda, R; Ishihara, Y; Kameda, S; Kikuchi, S; Kouyama, T; Matsuoka, M; Mimasu, Y; Morota, T; Nakazawa, S; Ogawa, K; Ogawa, N; Ono, G; Oshigami, S; Saiki, T; Sakatani, N; Sasaki, S; Sawada, H; Shizugami, M; Suzuki, H; Takahashi, T; Takei, Y; Tanaka, S; Tatsumi, E; Terui, F; Tsuda, Y; Tsuruta, S; Watanabe, S; Yamada, M; Yamada, R; Yamaguchi, T; Yamamoto, K; Yokota, Y; Yoshida, F; Yoshikawa, K; Yoshikawa, M; Yoshioka, K

EARTH PLANETS AND SPACE Vol. 73 ( 1 ) 2021.1

Characterization of D-Type Spectra Based on Hyperspectral Remote Sensing of the Lunar Surface Reviewed

Yamamoto Satoru, Watanabe Sei-ichiro

JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS Vol. 126 ( 1 ) 2021.1

Sample collection from asteroid (162173) Ryugu by Hayabusa2: Implications for surface evolution Reviewed International coauthorship Open Access

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

Science Vol. 368 ( 6491 ) page： 654 - + 2020.5

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal)

© 2020 American Association for the Advancement of Science. All rights reserved. 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.

DOI： 10.1126/science.aaz6306

An artificial impact on the asteroid (162173) Ryugu formed a crater in the gravity-dominated regime Reviewed International journal Open Access

Arakawa M, Saiki T, Wada K, Ogawa K, Kadono T, Shirai K, Sawada H, Ishibashi K, Honda R, Sakatani N, Iijima Y, Okamoto C, Yano H, Takagi Y, Hayakawa M, Michel P, Jutzi M, Shimaki Y, Kimura S, Mimasu Y, Toda T, Imamura H, Nakazawa S, Hayakawa H, Sugita S, Morota T, Kameda S, Tatsumi E, Cho Y, Yoshioka K, Yokota Y, Matsuoka M, Yamada M, Kouyama T, Honda C, Tsuda Y, Watanabe S, Yoshikawa M, Tanaka S, Terui F, Kikuchi S, Yamaguchi T, Ogawa N, Ono G, Yoshik

SCIENCE Vol. 368 ( 6486 ) page： 67 - + 2020.4

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：American Association for the Advancement of Science (AAAS)

Blowing a crater in asteroid Ryugu

The Hayabusa2 spacecraft was designed to collect samples from the nearby asteroid (162173) Ryugu and return them to Earth for laboratory analysis. Arakawa et al. describe how the spacecraft's Small Carry-on Impactor was fired into the asteroid's surface, producing an artificial impact crater. Analysis of the resulting plume of ejecta, recorded by a remote camera, sets an upper limit on the strength of the rubble-pile surface. The crater has a semicircular shape, probably due to a large boulder buried close to the impact location. The crater exposed material from Ryugu's subsurface, which has not been subjected to space weathering, that is suitable for collection by Hayabusa2.

Science , this issue p. 67

DOI： 10.1126/science.aaz1701

Highly porous nature of a primitive asteroid revealed by thermal imaging Reviewed International coauthorship Open Access

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

NATURE Vol. 579 ( 7800 ) page： 518 - 522 2020.3

Authorship：Corresponding author Language：Japanese Publishing type：Research paper (scientific journal) Publisher：NATURE PUBLISHING GROUP

Carbonaceous (C-type) asteroids(1) are relics of the early Solar System that have preserved primitive materials since their formation approximately 4.6 billion years ago. They are probably analogues of carbonaceous chondrites(2,3) and are essential for understanding planetary formation processes. However, their physical properties remain poorly known because carbonaceous chondrite meteoroids tend not to survive entry to Earth's atmosphere. Here we report on global one-rotation thermographic images of the C-type asteroid 162173 Ryugu, taken by the thermal infrared imager (TIR)(4) onboard the spacecraft Hayabusa2(5), indicating that the asteroid's boulders and their surroundings have similar temperatures, with a derived thermal inertia of about 300 J m(-2) s(-0.5) K-1 (300 tiu). Contrary to predictions that the surface consists of regolith and dense boulders, this low thermal inertia suggests that the boulders are more porous than typical carbonaceous chondrites(6) and that their surroundings are covered with porous fragments more than 10 centimetres in diameter. Close-up thermal images confirm the presence of such porous fragments and the flat diurnal temperature profiles suggest a strong surface roughness effect(7,8). We also observed in the close-up thermal images boulders that are colder during the day, with thermal inertia exceeding 600 tiu, corresponding to dense boulders similar to typical carbonaceous chondrites(6). These results constrain the formation history of Ryugu: the asteroid must be a rubble pile formed from impact fragments of a parent body with microporosity(9) of approximately 30 to 50 per cent that experienced a low degree of consolidation. The dense boulders might have originated from the consolidated innermost region or they may have an exogenic origin. This high-porosity asteroid may link cosmic fluffy dust to dense celestial bodies(10).Thermal imaging data obtained from the spacecraft Hayabusa2 reveal that the carbonaceous asteroid 162173 Ryugu is an object of unusually high porosity.

DOI： 10.1038/s41586-020-2102-6

Hayabusa2 arrives at the carbonaceous asteroid 162173 Ryugu-A spinning top-shaped rubble pile. Reviewed International coauthorship International journal Open Access

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

Science (New York, N.Y.) Vol. 364 ( 6437 ) page： 268 - 272 2019.4

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal)

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.

DOI： 10.1126/science.aav8032

The surface composition of asteroid 162173 Ryugu from Hayabusa2 near-infrared spectroscopy Reviewed International coauthorship Open Access

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

Science Vol. 364 ( 6437 ) page： 272 - + 2019.4

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：American Association for the Advancement of Science (AAAS)

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.

DOI： 10.1126/science.aav7432

The geomorphology, color, and thermal properties of Ryugu: Implications for parent-body processes Reviewed International coauthorship Open Access

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

Science Vol. 364 ( 6437 ) page： 252 - + 2019.4

Space-weathered anorthosite as spectral D-type material on the Martian satellites Reviewed

S. Yamamoto, S. Watanabe, T. Matsunaga

Geophysical Research Letters Vol. 45 ( 3 ) page： 1305-1312 2018.2

Hayabusa2 Mission Overview Reviewed Open Access

S. Watanabe, Y. Tsuda, M. Yoshikawa, S. Tanaka, T. Saiki, S. Nakazawa

Space Science Reviews Vol. 208 page： 3-16 2017.7

Thermal waves in irradiated protoplanetary disks Reviewed International coauthorship Open Access

Sei-ichiro Watanabe, D. N. C. Lin

The Astrophysical Journal Vol. 672 ( 2 ) page： 1183 - 1195 2008.1

Phyllosilicates with embedded Fe-based nanophases in Ryugu and Orgueil Reviewed International coauthorship International journal Open Access

Leroux, H; Le Guillou, C; Marinova, M; Laforet, S; Viennet, JC; Mouloud, BE; Teurtrie, A; de la Peña, F; Jacob, D; Hallatt, D; Fernandez, MP; Troadec, D; Noguchi, T; Matsumoto, T; Miyake, A; Igami, Y; Haruta, M; Saito, H; Hata, S; Seto, Y; Miyahara, M; Tomioka, N; Ishii, HA; Bradley, JP; Ohtaki, KK; Dobrica, E; Langenhorst, F; Harries, D; Beck, P; Phan, THV; Rebois, R; Abreu, NM; Gray, J; Zega, T; Zanetta, PM; Thompson, MS; Stroud, R; Burgess, K; Cymes, BA; Bridges, JC; Hicks, L; Lee, MR; Daly, L; Bland, PA; Zolensky, ME; Frank, DR; Martinez, J; Tsuchiyama, A; Yasutake, M; Matsuno, J; Okumura, S; Mitsukawa, I; Uesugi, K; Uesugi, M; Takeuchi, A; Sun, MQ; Enju, S; Takigawa, A; Michikami, T; Nakamura, T; Matsumoto, M; Nakauchi, Y; Abe, M; Nakazawa, S; Okada, T; Saiki, T; Tanaka, S; Terui, F; Yoshikawa, M; Miyazaki, A; Nakato, A; Nishimura, M; Usui, T; Yada, T; Yurimoto, H; Nagashima, K; Kawasaki, N; Sakamotoa, N; Okazaki, R; Yabuta, H; Naraoka, H; Sakamoto, K; Tachibana, S; Watanabe, SI; Tsuda, Y

METEORITICS & PLANETARY SCIENCE Vol. 59 ( 8 ) page： 1947 - 1965 2024.8

Quantification of bulk elemental composition for C-type asteroid Ryugu samples with nondestructive elemental analysis using muon beam Reviewed International coauthorship International journal

Ninomiya, K; Osawa, T; Terada, K; Wada, T; Nagasawa, S; Chiu, IH; Nakamura, T; Takahashi, T; Miyake, Y; Kubo, MK; Takeshita, S; Taniguchi, A; Umegaki, I; Watanabe, S; Azuma, T; Katsuragawa, M; Minami, T; Mizumoto, K; Shimomura, K; Takeda, S; Morita, T; Kikuiri, M; Amano, K; Kagawa, E; Furukawa, Y; Yurimoto, H; Noguchi, T; Okazaki, R; Yabuta, H; Naraoka, H; Sakamoto, K; Tachibana, S; Yada, T; Nishimura, M; Nakato, A; Miyazaki, A; Yogata, K; Abe, M; Okada, T; Usui, T; Yoshikawa, M; Saiki, T; Tanaka, S; Terui, F; Nakazawa, S; Watanabe, S; Tsuda, Y

METEORITICS & PLANETARY SCIENCE Vol. 59 ( 8 ) page： 2044 - 2057 2024.8

IR SPECTRA OF RYUGU'S ANHYDROUS INGREDIENTS COMPARED WITH PRIMITIVE DUST FROM THE OUTER SOLAR SYSTEM Reviewed International coauthorship International journal

Brunetto, R; Nakamura, T; Lantz, C; Fukuda, Y; Aléon-Toppani, A; Dionnet, Z; Baklouti, D; Borondics, F; Djouadi, Z; Rubino, S; Amano, K; Matsumoto, M; Fujioka, Y; Morita, T; Kikuiri, M; Kagawa, E; Milliken, R; Matsuoka, M; Yurimoto, H; Noguchi, T; Okazaki, R; Yabuta, H; Naraoka, H; Sakamoto, K; Tachibana, S; Watanabe, S; Tsuda, Y

METEORITICS & PLANETARY SCIENCE Vol. 59 page： A46 - A46 2024.8

Soluble organic matter Molecular atlas of Ryugu reveals cold hydrothermalism on C-type asteroid parent body Reviewed International coauthorship International journal Open Access

Schmitt-Kopplin, P; Hertkorn, N; Harir, M; Moritz, F; Lucio, M; Bonal, L; Quirico, E; Takano, Y; Dworkin, JP; Naraoka, H; Tachibana, S; Nakamura, T; Noguchi, T; Okazaki, R; Yabuta, H; Yurimoto, H; Sakamoto, K; Yada, T; Nishimura, M; Nakato, A; Miyazaki, A; Yogata, K; Abe, M; Usui, T; Yoshikawa, M; Saiki, T; Tanaka, S; Terui, F; Nakazawa, S; Okada, T; Watanabe, SI; Tsuda, Y

NATURE COMMUNICATIONS Vol. 14 ( 1 ) 2023.10

Chemical evolution of primordial salts and organic sulfur molecules in the asteroid 162173 Ryugu. Reviewed International journal Open Access

Toshihiro Yoshimura, Yoshinori Takano, Hiroshi Naraoka, Toshiki Koga, Daisuke Araoka, Nanako O Ogawa, Philippe Schmitt-Kopplin, Norbert Hertkorn, Yasuhiro Oba, Jason P Dworkin, José C Aponte, Takaaki Yoshikawa, Satoru Tanaka, Naohiko Ohkouchi, Minako Hashiguchi, Hannah McLain, Eric T Parker, Saburo Sakai, Mihoko Yamaguchi, Takahiro Suzuki, Tetsuya Yokoyama, Hisayoshi Yurimoto, Tomoki Nakamura, Takaaki Noguchi, Ryuji Okazaki, Hikaru Yabuta, Kanako Sakamoto, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Satoru Nakazawa, Sei-Ichiro Watanabe, Yuichi Tsuda, Shogo Tachibana

Nature communications Vol. 14 ( 1 ) page： 5284 - 5284 2023.9

Language：English Publishing type：Research paper (scientific journal)

Samples from the carbonaceous asteroid (162173) Ryugu provide information on the chemical evolution of organic molecules in the early solar system. Here we show the element partitioning of the major component ions by sequential extractions of salts, carbonates, and phyllosilicate-bearing fractions to reveal primordial brine composition of the primitive asteroid. Sodium is the dominant electrolyte of the salt fraction extract. Anions and NH4+ are more abundant in the salt fraction than in the carbonate and phyllosilicate fractions, with molar concentrations in the order SO42- > Cl- > S2O32- > NO3- > NH4+. The salt fraction extracts contain anionic soluble sulfur-bearing species such as Sn-polythionic acids (n < 6), Cn-alkylsulfonates, alkylthiosulfonates, hydroxyalkylsulfonates, and hydroxyalkylthiosulfonates (n < 7). The sulfur-bearing soluble compounds may have driven the molecular evolution of prebiotic organic material transforming simple organic molecules into hydrophilic, amphiphilic, and refractory S allotropes.

DOI： 10.1038/s41467-023-40871-0

Visualization of nanoscale magnetic domain states in the asteroid Ryugu Reviewed International coauthorship International journal Open Access

Yuki Kimura, Takeharu Kato, Toshiaki Tanigaki, Tetsuya Akashi, Hiroto Kasai, Satoshi Anada, Ryuji Yoshida, Kazuo Yamamoto, Tomoki Nakamura, Masahiko Sato, Kana Amano, Mizuha Kikuiri, Tomoyo Morita, Eiichi Kagawa, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Satoru Nakazawa, Hisayoshi Yurimoto, Takaaki Noguchi, Ryuji Okazaki, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Sei-ichiro Watanabe, Yuichi Tsuda, Shogo Tachibana

Scientific Reports Vol. 13 ( 1 ) 2023.8

Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

Abstract

In the samples collected from the asteroid Ryugu, magnetite displays natural remanent magnetization due to nebular magnetic field, whereas contemporaneously grown iron sulfide does not display stable remanent magnetization. To clarify this counterintuitive feature, we observed their nanoscale magnetic domain structures using electron holography and found that framboidal magnetites have an external magnetic field of 300 A m−1, similar to the bulk value, and its magnetic stability was enhanced by interactions with neighboring magnetites, permitting a disk magnetic field to be recorded. Micrometer-sized pyrrhotite showed a multidomain magnetic structure that was unable to retain natural remanent magnetization over a long time due to short relaxation time of magnetic-domain-wall movement, whereas submicron-sized sulfides formed a nonmagnetic phase. These results show that both magnetite and sulfide could have formed simultaneously during the aqueous alteration in the parent body of the asteroid Ryugu.

DOI： 10.1038/s41598-023-41242-x

Other Link： https://www.nature.com/articles/s41598-023-41242-x

Abundant presolar grains and primordial organics preserved in carbon-rich exogenous clasts in asteroid Ryugu Reviewed International coauthorship International journal Open Access

Ann. N. Nguyen, Prajkta Mane, Lindsay P. Keller, Laurette Piani, 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, Shoichi Itoh, Noriyuki Kawasaki, Noriko T. Kita, Kouki Kitajima, Thorsten Kleine, Shintaro Komatani, Alexander N. Krot, Ming-Chang Liu, Yuki Masuda, Kevin D. McKeegan, Mayu Morita, Kazuko Motomura, Frédéric Moynier, Izumi Nakai, Kazuhide Nagashima, David Nesvorný, Larry Nittler, Morihiko Onose, Andreas Pack, Changkun Park, Liping Qin, Sara S. Russell, Naoya Sakamoto, Maria Schönbächler, Lauren Tafla, Haolan Tang, Kentaro Terada, Yasuko Terada, Tomohiro Usui, Sohei Wada, Meenakshi Wadhwa, Richard J. Walker, Katsuyuki Yamashita, Qing-Zhu Yin, Tetsuya Yokoyama, Shigekazu Yoneda, Edward D. Young, Hiroharu Yui, Ai-Cheng Zhang, Tomoki Nakamura, Hiroshi Naraoka, Takaaki Noguchi, Ryuji Okazaki, Kanako Sakamoto, Hikaru Yabuta, Masanao Abe, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Tatsuaki Okada, Toru Yada, Kasumi Yogata, Satoru Nakazawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Yuichi Tsuda, Sei-ichiro Watanabe, Makoto Yoshikawa, Shogo Tachibana, Hisayoshi Yurimoto

Science Advances Vol. 9 ( 28 ) 2023.7

Language：English Publishing type：Research paper (scientific journal) Publisher：American Association for the Advancement of Science (AAAS)

Preliminary analyses of asteroid Ryugu samples show kinship to aqueously altered CI (Ivuna-type) chondrites, suggesting similar origins. We report identification of C-rich, particularly primitive clasts in Ryugu samples that contain preserved presolar silicate grains and exceptional abundances of presolar SiC and isotopically anomalous organic matter. The high presolar silicate abundance (104 ppm) indicates that the clast escaped extensive alteration. The 5 to 10 times higher abundances of presolar SiC (~235 ppm), N-rich organic matter, organics with N isotopic anomalies (1.2%), and organics with C isotopic anomalies (0.2%) in the primitive clasts compared to bulk Ryugu suggest that the clasts formed in a unique part of the protoplanetary disk enriched in presolar materials. These clasts likely represent previously unsampled outer solar system material that accreted onto Ryugu after aqueous alteration ceased, consistent with Ryugu’s rubble pile origin.

DOI： 10.1126/sciadv.adh1003

Preliminary design of the Hayabusa2 extended mission to the fast-rotating Asteroid 1998 KY26 Reviewed International coauthorship International journal Open Access

Shota Kikuchi, Yuya Mimasu, Yuto Takei, Takanao Saiki, Daniel J. Scheeres, Masatoshi Hirabayashi, Koji Wada, Makoto Yoshikawa, Sei-ichiro Watanabe, Satoshi Tanaka, Yuichi Tsuda

Acta Astronautica 2023.6

Hydrogen Isotopic Composition of Hydrous Minerals in Asteroid Ryugu Reviewed International coauthorship International journal Open Access

Laurette Piani, Kazuhide Nagashima, Noriyuki Kawasaki, Naoya Sakamoto, Ken-ichi Bajo, Yoshinari Abe, Jérôme Aléon, Conel M. O’D. Alexander, Sachiko Amari, Yuri Amelin, Martin Bizzarro, Audrey Bouvier, Richard W. Carlson, Marc Chaussidon, Byeon-Gak Choi, Nicolas Dauphas, Andrew M. Davis, Tommaso Di Rocco, Wataru Fujiya, Ryota Fukai, Ikshu Gautam, Makiko K. Haba, Yuki Hibiya, Hiroshi Hidaka, Hisashi Homma, Peter Hoppe, Gary R. Huss, Kiyohiro Ichida, Tsuyoshi Iizuka, Trevor R. Ireland, Akira Ishikawa, Shoichi Itoh, Noriko T. Kita, Kouki Kitajima, Thorsten Kleine, Shintaro Komatani, Alexander N. Krot, Ming-Chang Liu, Yuki Masuda, Kevin D. McKeegan, Mayu Morita, Kazuko Motomura, Frédéric Moynier, Izumi Nakai, Ann Nguyen, Larry Nittler, Morihiko Onose, Andreas Pack, Changkun Park, Liping Qin, Sara S. Russell, Maria Schönbächler, Lauren Tafla, Haolan Tang, Kentaro Terada, Yasuko Terada, Tomohiro Usui, Sohei Wada, Meenakshi Wadhwa, Richard J. Walker, Katsuyuki Yamashita, Qing-Zhu Yin, Tetsuya Yokoyama, Shigekazu Yoneda, Edward D. Young, Hiroharu Yui, Ai-Cheng Zhang, Tomoki Nakamura, Hiroshi Naraoka, Ryuji Okazaki, Kanako Sakamoto, Hikaru Yabuta, Masanao Abe, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Tatsuaki Okada, Toru Yada, Kasumi Yogata, Satoru Nakazawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Yuichi Tsuda, Sei-ichiro Watanabe, Makoto Yoshikawa, Shogo Tachibana, Hisayoshi Yurimoto

The Astrophysical Journal Letters Vol. 946 ( 2 ) page： L43 - L43 2023.4

Language：English Publishing type：Research paper (scientific journal) Publisher：American Astronomical Society

Abstract

Rock fragments of the Cb-type asteroid Ryugu returned to Earth by the JAXA Hayabusa2 mission share mineralogical, chemical, and isotopic properties with the Ivuna-type (CI) carbonaceous chondrites. Similar to CI chondrites, these fragments underwent extensive aqueous alteration and consist predominantly of hydrous minerals likely formed in the presence of liquid water on the Ryugu parent asteroid. Here we present an in situ analytical survey performed by secondary ion mass spectrometry from which we have estimated the D/H ratio of Ryugu’s hydrous minerals, D/HRyugu, to be [165 ± 19] × 10−6, which corresponds to δDRyugu = +59 ± 121‰ (2σ). The hydrous mineral D/HRyugu’s values for the two sampling sites on Ryugu are similar; they are also similar to the estimated D/H ratio of hydrous minerals in the CI chondrites Orgueil and Alais. This result reinforces a link between Ryugu and CI chondrites and an inference that Ryugu’s samples, which avoided terrestrial contamination, are our best proxy to estimate the composition of water at the origin of hydrous minerals in CI-like material. Based on this data and recent literature studies, the contribution of CI chondrites to the hydrogen of Earth’s surficial reservoirs is evaluated to be ∼3%. We conclude that the water responsible for the alteration of Ryugu’s rocks was derived from water ice precursors inherited from the interstellar medium; the ice partially re-equilibrated its hydrogen with the nebular H2 before being accreted on the Ryugu’s parent asteroid.

DOI： 10.3847/2041-8213/acc393

Other Link： https://iopscience.iop.org/article/10.3847/2041-8213/acc393/pdf

Extraterrestrial amino acids and amines identified in asteroid Ryugu samples returned by the Hayabusa2 mission Reviewed International coauthorship Open Access

Eric T. Parker, Hannah L. McLain, Daniel P. Glavin, Jason P. Dworkin, Jamie E. Elsila, José C. Aponte, Hiroshi Naraoka, Yoshinori Takano, Shogo Tachibana, Hikaru Yabuta, Hisayoshi Yurimoto, Kanako Sakamoto, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Satoru Nakazawa, Yuichi Tsuda, Fuyuto Terui, Takaaki Noguchi, Ryuji Okazaki, Sei-ichiro Watanabe, Tomoki Nakamura

Geochimica et Cosmochimica Acta Vol. 347 page： 42 - 57 2023.4

Measurement of Microscopic Thermal Diffusivity Distribution for Ryugu Sample by Infrared Lock-in Periodic Heating Method Reviewed International coauthorship International journal Open Access

Takuya Ishizaki, Hosei Nagano, Satoshi Tanaka, Naoya Sakatani, Tomoki Nakamura, Tatsuaki Okada, Ryohei Fujita, Abdulkareem Alasli, Tomoyo Morita, Mizuha Kikuiri, Kana Amano, Eiichi Kagawa, Hisayoshi Yurimoto, Takaaki Noguchi, Ryuji Okazaki, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Shogo Tachibana, Sei-ichiro Watanabe, Yuichi Tsuda

International Journal of Thermophysics Vol. 44 ( 4 ) 2023.4

Insights into the formation and evolution of extraterrestrial amino acids from the asteroid Ryugu Reviewed Open Access

Christian Potiszil, Tsutomu Ota, Masahiro Yamanaka, Chie Sakaguchi, Katsura Kobayashi, Ryoji Tanaka, Tak Kunihiro, Hiroshi Kitagawa, Masanao Abe, Akiko Miyazaki, Aiko Nakato, Satoru Nakazawa, Masahiro Nishimura, Tatsuaki Okada, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Yuichi Tsuda, Tomohiro Usui, Sei-ichiro Watanabe, Toru Yada, Kasumi Yogata, Makoto Yoshikawa, Eizo Nakamura

Nature Communications Vol. 14 ( 1 ) page： 1482 2023.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

Abstract

All life on Earth contains amino acids and carbonaceous chondrite meteorites have been suggested as their source at the origin of life on Earth. While many meteoritic amino acids are considered indigenous, deciphering the extent of terrestrial contamination remains an issue. The Ryugu asteroid fragments (JAXA Hayabusa2 mission), represent the most uncontaminated primitive extraterrestrial material available. Here, the concentrations of amino acids from two particles from different touchdown sites (TD1 and TD2) are reported. The concentrations show that N,N-dimethylglycine (DMG) is the most abundant amino acid in the TD1 particle, but below detection limit in the other. The TD1 particle mineral components indicate it experienced more aqueous alteration. Furthermore, the relationships between the amino acids and the geochemistry suggest that DMG formed on the Ryugu progenitor body during aqueous alteration. The findings highlight the importance of aqueous chemistry for defining the ultimate concentrations of amino acids in primitive extraterrestrial samples.

DOI： 10.1038/s41467-023-37107-6

Other Link： https://www.nature.com/articles/s41467-023-37107-6

The noble gas and nitrogen relationship between Ryugu and carbonaceous chondrites Reviewed International coauthorship Open Access

Broadley M. W., Byrne D. J., Furi E., Zimmermann L., Marty B., Okazaki R., Yada T., Kitajima F., Tachibana S., Yogata K., Sakamoto K., Yurimoto H., Nakamura T., Noguchi T., Naraoka H., Yabuta H., Watanabe S., Tsuda Y., Nishimura M., Nakato A., Miyazaki A., Abe M., Okada T., Usui T., Yoshikawa M., Saiki T., Tanaka S., Terui F., Nakazawa S., Busemann H., Hashizume K., Gilmour J. D., Meshik A., Riebe M. E. I., Krietsch D., Maden C., Ishida A., Clay P., Crowther S. A., Fawcett L., Lawton T., Pravdivtseva O., Miura Y. N., Park J., Bajo K., Takano Y., Yamada K., Kawagucci S., Matsui Y., Yamamoto M., Righter K., Sakai S., Iwata N., Shirai N., Sekimoto S., Inagaki M., Ebihara M., Yokochi R., Nishiizumi K., Nagao K., Lee J. I, Kano A., Caffee M. W., Uemura R.

GEOCHIMICA ET COSMOCHIMICA ACTA Vol. 345 page： 62 - 74 2023.3

Interaction between clay minerals and organics in asteroid Ryugu Reviewed International coauthorship Open Access

J.-C. Viennet, M. Roskosz, T. Nakamura, P. Beck, B. Baptiste, B. Lavina, E.E. Alp, M.Y. Hu, J. Zhao, M. Gounelle, R. Brunetto, H. Yurimoto, T. Noguchi, R. Okazaki, H. Yabuta, H. Naraoka, K. Sakamoto, S. Tachibana, T. Yada, M. Nishimura, A. Nakato, A. Miyazaki, K. Yogata, M. Abe, T. Okada, T. Usui, M. Yoshikawa, T. Saiki, S. Tanaka, F. Terui, S. Nakazawa, S. Watanabe, Y. Tsuda

Geochemical Perspectives Letters Vol. 25 page： 8 - 12 2023.3

Chemical composition of carbonaceous asteroid Ryugu from synchrotron spectroscopy in the mid- to far-infrared of Hayabusa2-returned samples Reviewed International coauthorship Open Access

Emmanuel Dartois, Yoko Kebukawa, Hikaru Yabuta, Jérémie Mathurin, Cécile Engrand, Jean Duprat, Laure Bejach, Alexandre Dazzi, Ariane Deniset-Besseau, Lydie Bonal, Eric Quirico, Christophe Sandt, Ferenc Borondics, Jens Barosch, George D. Cody, Brad T. De Gregorio, Minako Hashiguchi, David A. L. Kilcoyne, Mutsumi Komatsu, Zita Martins, Megumi Matsumoto, Gilles Montagnac, Smail Mostefaoui, Larry R. Nittler, Takuji Ohigashi, Taiga Okumura, Laurent Remusat, Scott Sandford, Miho Shigenaka, Rhonda Stroud, Hiroki Suga, Yoshio Takahashi, Yasuo Takeichi, Yusuke Tamenori, Maximilien Verdier-Paoletti, Shohei Yamashita, Tomoki Nakamura, Tomoyo Morita, Mizuha Kikuiri, Kana Amano, Eiichi Kagawa, Takaaki Noguchi, Hiroshi Naraoka, Ryuji Okazaki, Kanako Sakamoto, Hisayoshi Yurimoto, Masanao Abe, Kanami Kamide, Akiko Miyazaki, Aiko Nakato, Satoru Nakazawa, Masahiro Nishimura, Tatsuaki Okada, Takanao Saiki, Shogo Tachibana, Satoshi Tanaka, Fuyuto Terui, Yuichi Tsuda, Tomohiro Usui, Sei-ichiro Watanabe, Toru Yada, Kasumi Yogata, Makoto Yoshikawa

Astronomy & Astrophysics Vol. 671 page： A2 - A2 2023.2

Language：English Publishing type：Research paper (scientific journal) Publisher：EDP Sciences

Context. The current period is conducive to exploring our Solar System's origins with recent and future space sample return missions, which provide invaluable information from known Solar System asteroids and comets The Hayabusa2 mission of the Japan Aerospace Exploration Agency (JAXA) recently brought back samples from the surface of the Ryugu carbonaceous asteroid.

Aims. We aim to identify the different forms of chemical composition of organic matter and minerals that constitute these Solar System primitive objects, to shed light on the Solar System's origins.

Methods. In this work, we recorded infrared (IR) hyper-spectral maps of whole-rock Ryugu asteroid samples at the highest achievable spatial resolution with a synchrotron in the mid-IR (MIR). Additional global far-IR (FIR) spectra of each sample were also acquired.

Results. The hyper-spectral maps reveal the variability of the functional groups at small scales and the intimate association of phyl-losilicates with the aliphatic components of the organic matter present in Ryugu. The relative proportion of column densities of the identified IR functional groups (aliphatics, hydroxyl + interlayer and/or physisorbed water, carbonyl, carbonates, and silicates) giving access to the composition of the Ryugu samples is estimated from these IR hyper-spectral maps. Phyllosilicate spectra reveal the presence of mixtures of serpentine and saponite. We do not detect anhydrous silicates in the samples analysed, at the scales probed. The carbonates are dominated by dolomite. Aliphatics organics are distributed over the whole samples at the micron scale probed with the synchrotron, and intimately mixed with the phyllosilicates. The aromatic C=C contribution could not be safely deconvolved from OH in most spectra, due to the ubiquitous presence of hydrated minerals. The peak intensity ratios of the organics methylene to methyl (CH2/CH3) of the Ryugu samples vary between about 1.5 and 2.5, and are compared to the ratios in chondrites from types 1 to 3. Overall, the mineralogical and organic characteristics of the Ryugu samples show similarities with those of CI chondrites, although with a noticeably higher CH2/CH3 in Ryugu than generally measured in C1 chondrites collected on Earth, and possibly a higher carbonate content.

DOI： 10.1051/0004-6361/202244702

Small grains from Ryugu: handling and analysis pipeline for infrared synchrotron microspectroscopy Reviewed International coauthorship Open Access

Stefano Rubino, Zélia Dionnet, Alice Aléon-Toppani, Rosario Brunetto, Tomoki Nakamura, Donia Baklouti, Zahia Djouadi, Cateline Lantz, Obadias Mivumbi, Ferenc Borondics, Stephane Lefrançois, Christophe Sandt, Francesco Capitani, Eva Héripré, David Troadec, Megumi Matsumoto, Kana Amano, Tomoyo Morita, Hisayoshi Yurimoto, Takaaki Noguchi, Ryuji Okazaki, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Shogo Tachibana, Seiichiro Watanabe, Yuichi Tsuda

Earth, Planets and Space Vol. 75 ( 1 ) 2023.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

Abstract

Sample-return missions allow the study of materials collected directly from celestial bodies, unbiased by atmospheric entry effects and/or terrestrial alteration and contamination phenomena, using state-of-the-art techniques which are available only in a laboratory environment—but only if the collected material stays pristine. The scarcity of outer-space unaltered material recovered until now makes this material extremely precious for the potential scientific insight it can bring. To maximize the scientific output of current and future sample-return missions, the scientific community needs to plan for ways of storing, handling, and measuring this precious material while preserving their pristine state for as long as the ‘invasiveness’ of measurements allows. In July 2021, as part of the Hayabusa2 (JAXA) “Stone” preliminary examination team, we received several microscopic particles from the asteroid Ryugu, with the goal of performing IR hyper-spectral imaging and IR micro-tomography studies. Here, we describe the sample transfer, handling methods and analytical pipeline we implemented to study this very precious material while minimizing and surveilling their alteration history on Earth.

Graphical Abstract

DOI： 10.1186/s40623-022-01762-8

Other Link： https://link.springer.com/article/10.1186/s40623-022-01762-8/fulltext.html

Trace-element analysis of mineral grains in Ryugu rock fragment sections by synchrotron-based confocal X-ray fluorescence Reviewed International coauthorship International journal Open Access

Benjamin Bazi, Pieter Tack, Miles Lindner, Bart Vekemans, Ella De Pauw, Beverley Tkalcec, Frank E. Brenker, Jan Garrevoet, Gerald Falkenberg, Hikaru Yabuta, Hisayoshi Yurimoto, Tomoki Nakamura, Kana Amano, Megumi Matsumoto, Yuri Fujioka, Yuma Enokido, Daisuke Nakashima, Masayuki Uesugi, Hiroshi Naraoka, Takaaki Noguchi, Ryuji Okazaki, Kanako Sakamoto, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Satoru Nakazawa, Shogo Tachibana, Sei-ichiro Watanabe, Yuichi Tsuda, Laszlo Vincze

Earth, Planets and Space Vol. 74 ( 1 ) 2022.11

Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

Abstract

A fundamental parameter-based quantification scheme for confocal XRF was applied to sub-micron synchrotron radiation X-ray fluorescence (SR-XRF) data obtained at the beamline P06 of the Deutsches Elektronen-Synchrotron (DESY, Hamburg, Germany) from two sections C0033-01 and C0033-04 that were wet cut from rock fragment C0033 collected from Cb-type asteroid (162173) Ryugu by JAXA’s Hayabusa2 mission. Trace-element quantifications show that C0033 bulk matrix is CI-like, whereas individual mineral grains (i.e., magnetite, pyrrhotite, dolomite, apatite and breunnerite) show, depending on the respective phase, minor to strong deviations. The non-destructive nature of SR-XRF coupled with a new PyMca (a Python toolkit for XRF data analysis)-based quantification approach, performed in parallel with the synchrotron experiments, proves to be an attractive tool for the initial analysis of samples from return missions, such as Hayabusa2 and OSIRIS-REx, the latter returning material from a B-type asteroid (101955) Bennu in 2023.

Graphical Abstract

DOI： 10.1186/s40623-022-01726-y

Other Link： https://link.springer.com/article/10.1186/s40623-022-01726-y/fulltext.html

Rock Magnetic Characterization of Returned Samples From Asteroid (162173) Ryugu: Implications for Paleomagnetic Interpretation and Paleointensity Estimation Reviewed International journal

Masahiko Sato, Yuki Kimura, Satoshi Tanaka, Tadahiro Hatakeyama, Seiji Sugita, Tomoki Nakamuna, Shogo Tachibana, Hisayoshi Yurimoto, Takaaki Noguchi, Ryuji Okazaki, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Makoto Yoshikawa, Takanao Saiki, Fuyuto Terui, Satoru Nakazawa, Sei-ichiro Watanabe, Yuichi Tsuda

JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS Vol. 127 ( 11 ) 2022.11

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER GEOPHYSICAL UNION

In this study, systematic rock magnetic measurements and saturation isothermal remanent magnetization (SIRM) paleointensity calibration experiments were conducted for the returned samples from C-type asteroid (162173) Ryugu and two carbonaceous chondrites (Orgueil and Tagish Lake) to evaluate the remanence carriers of the Ryugu sample and its ability as a paleomagnetic recorder. Our magnetic measurements show that Ryugu samples exhibit signatures for framboidal magnetite, coarse-grained magnetite, and pyrrhotite, and that framboidal magnetite is the dominant remanence carrier of Ryugu samples in the middle-coercivity range. The SIRM paleointensity constant was obtained for two Ryugu samples, and the median value was 3,318 +/- 1,038 mu T, which is close to the literature's value based on the average among magnetite, titanomagnetite, pyrrhotite, and FeNi alloys and is widely used for SIRM paleointensity experiments. The paleointensity values estimated using the obtained SIRM paleointensity constant indicate a strong magnetic field of the protoplanetary disk, suggesting that Sun's protoplanetary disk existed at the disk location of Ryugu's parent planetesimal when framboidal magnetite precipitated from the aqueous fluid.

DOI： 10.1029/2022JE007405

The Solar System calcium isotopic composition inferred from Ryugu samples Reviewed International coauthorship Open Access

Moynier F., Dai W., Yokoyama T., Hu Y., Paquet M., Abe Y., Aleon J., Alexander C. M. O'D., Amari S., Amelin Y., Bajo K. -I., Bizzarro M., Bouvier A., Carlson R. W., Chaussidon M., Choi B. -G., Dauphas N., Davis A. M., Di Rocco T., Fujiya W., Fukai R., Gautam I., Haba M. K., Hibiya Y., Hidaka H., Homma H., Hoppe P., Huss G. R., Ichida K., Iizuka T., Ireland T. R., Ishikawa A., Ito M., Itoh S., Kawasaki N., Kita N. T., Kitajima K., Kleine T., Komatani S., Krot A. N., Liu M. -C., Masuda Y., McKeegan K. D., Morita M., Motomura K., Nakai I., Nagashima K., Nesvorny D., Nguyen A., Nittler L., Onose M., Pack A., Park C., Piani L., Qin L., Russell S. S., Sakamoto N., Schoenbaechler M., Tafla L., Tang H., Terada K., Terada Y., Usui T., Wada S., Wadhwa M., Walker R. J., Yamashita K., Yin Q. -Z., Yoneda S., Young E. D., Yui H., Zhang A. -c., Nakamura T., Naraoka H., Noguchi T., Okazaki R., Sakamoto K., Yabuta H., Abe M., Miyazaki A., Nakato A., Nishimura M., Okada T., Yada T., Yogata K., Nakazawa S., Saiki T., Tanaka S., Terui F., Tsuda Y., Watanabe S. -I., Yoshikawa M., Tachibana S., Yurimoto H.

GEOCHEMICAL PERSPECTIVES LETTERS Vol. 24 2022.10

Rare earth element identification and quantification in millimetre-sized Ryugu rock fragments from the Hayabusa2 space mission Reviewed International coauthorship International journal Open Access

Pieter Tack, Ella De Pauw, Beverley Tkalcec, Miles Lindner, Benjamin Bazi, Bart Vekemans, Frank Brenker, Marco Di Michiel, Masayuki Uesugi, Hisayoshi Yurimoto, Tomoki Nakamura, Kana Amano, Megumi Matsumoto, Yuri Fujioka, Yuma Enokido, Daisuke Nakashima, Takaaki Noguchi, Ryuji Okazaki, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Shogo Tachibana, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Satoru Nakazawa, Sei-Ichiro Watanabe, Yuichi Tsuda, Laszlo Vincze

Earth, Planets and Space Vol. 74 ( 1 ) 2022.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

Abstract

Millimetre-sized primordial rock fragments originating from asteroid Ryugu were investigated using high energy X-ray fluorescence spectroscopy, providing 2D and 3D elemental distribution and quantitative composition information on the microscopic level. Samples were collected in two phases from two sites on asteroid Ryugu and safely returned to Earth by JAXA’s asteroid explorer Hayabusa2, during which time the collected material was stored and maintained free from terrestrial influences, including exposure to Earth’s atmosphere. Several grains of interest were identified and further characterised to obtain quantitative information on the rare earth element (REE) content within said grains, following a reference-based and computed-tomography-assisted fundamental parameters quantification approach. Several orders of magnitude REE enrichments compared to the mean CI chondrite composition were found within grains that could be identified as apatite phase. Small enrichment of LREE was found for dolomite grains and slight enrichment or depletion for the general matrices within the Ryugu rock fragments A0055 and C0076, respectively.

Graphical Abstract

DOI： 10.1186/s40623-022-01705-3

Other Link： https://link.springer.com/article/10.1186/s40623-022-01705-3/fulltext.html

Presolar Stardust in Asteroid Ryugu Reviewed International coauthorship Open Access

Barosch Jens, Nittler Larry R., Wang Jianhua, Alexander Conel M. O'D, De Gregorio Bradley T., Engrand Cecile, Kebukawa Yoko, Nagashima Kazuhide, Stroud Rhonda M., Yabuta Hikaru, Abe Yoshinari, Aleon Jerome, Amari Sachiko, Amelin Yuri, Bajo Ken-ichi, Bejach Laure, Bizzarro Martin, Bonal Lydie, Bouvier Audrey, Carlson Richard W., Chaussidon Marc, Choi Byeon-Gak, Cody George D., Dartois Emmanuel, Dauphas Nicolas, Davis Andrew M., Dazzi Alexandre, Deniset-Besseau Ariane, Di Rocco Tommaso, Duprat Jean, Fujiya Wataru, Fukai Ryota, Gautam Ikshu, Haba Makiko K., Hashiguchi Minako, Hibiya Yuki, Hidaka Hiroshi, Homma Hisashi, Hoppe Peter, Huss Gary R., Ichida Kiyohiro, Iizuka Tsuyoshi, Ireland Trevor R., Ishikawa Akira, Ito Motoo, Itoh Shoichi, Kamide Kanami, Kawasaki Noriyuki, Kilcoyne A. L. David, Kita Noriko T., Kitajima Kouki, Kleine Thorsten, Komatani Shintaro, Komatsu Mutsumi, Krot Alexander N., Liu Ming-Chang, Martins Zita, Masuda Yuki, Mathurin Jeremie, McKeegan Kevin D., Montagnac Gilles, Morita Mayu, Mostefaoui Smail, Motomura Kazuko, Moynier Frederic, Nakai Izumi, Nguyen Ann N., Ohigashi Takuji, Okumura Taiga, Onose Morihiko, Pack Andreas, Park Changkun, Piani Laurette, Qin Liping, Quirico Eric, Remusat Laurent, Russell Sara S., Sakamoto Naoya, Sandford Scott A., Schonbachler Maria, Shigenaka Miho, Suga Hiroki, Tafla Lauren, Takahashi Yoshio, Takeichi Yasuo, Tamenori Yusuke, Tang Haolan, Terada Kentaro, Terada Yasuko, Usui Tomohiro, Verdier-Paoletti Maximilien, Wada Sohei, Wadhwa Meenakshi, Wakabayashi Daisuke, Walker Richard J., Yamashita Katsuyuki, Yamashita Shohei, Yin Qing-Zhu, Yokoyama Tetsuya, Yoneda Shigekazu, Young Edward D., Yui Hiroharu, Zhang Ai-Cheng, Abe Masanao, Miyazaki Akiko, Nakato Aiko, Nakazawa Satoru, Nishimura Masahiro, Okada Tatsuaki, Saiki Takanao, Tanaka Satoshi, Terui Fuyuto, Tsuda Yuichi, Watanabe Sei-ichiro, Yada Toru, Yogata Kasumi, Yoshikawa Makoto, Nakamura Tomoki, Naraoka Hiroshi, Noguchi Takaaki, Okazaki Ryuji, Sakamoto Kanako, Tachibana Shogo, Yurimoto Hisayoshi

ASTROPHYSICAL JOURNAL LETTERS Vol. 935 ( 1 ) 2022.8

History-dependent deformation of a rotated granular pile governed by granular friction Reviewed Open Access

Irie Terunori, Yamaguchi Ryusei, Watanabe Sei-ichiro, Katsuragi Hiroaki

ADVANCED POWDER TECHNOLOGY Vol. 33 ( 8 ) 2022.8

Three-axial shape distributions of pebbles, cobbles and boulders smaller than a few meters on asteroid Ryugu Reviewed International coauthorship International journal Open Access

Tatsuhiro Michikami, Axel Hagermann, Tomokatsu Morota, Yasuhiro Yokota, Seitaro Urakawa, Hiroyuki Okamura, Naoya Tanabe, Koki Yumoto, Tatsuki Ebihara, Yuichiro Cho, Carolyn M. Ernst, Masahiko Hayakawa, Masatoshi Hirabayashi, Naru Hirata, Chikatoshi Honda, Rie Honda, Shingo Kameda, Masanori Kanamaru, Hiroshi Kikuchi, Shota Kikuchi, Toru Kouyama, Moe Matsuoka, Hideaki Miyamoto, Takaaki Noguchi, Rina Noguchi, Kazunori Ogawa, Tatsuaki Okada, Naoya Sakatani, Sho Sasaki, Hirotaka Sawada, Chiho Sugimoto, Hidehiko Suzuki, Satoshi Tanaka, Eri Tatsumi, Akira Tsuchiyama, Yuichi Tsuda, Sei-ichiro Watanabe, Manabu Yamada, Makoto Yoshikawa, Kazuo Yoshioka, Seiji Sugita

Icarus Vol. 381 page： 115007 - 115007 2022.7

NIRS3 spectral analysis of the artificial Omusubi-Kororin crater on Ryugu Reviewed International coauthorship International journal Open Access

A. Galiano, E. Palomba, F. Dirri, A. Longobardo, K. Kitazato, T. Iwata, M. Matsuoka, T. Hiroi, D. Takir, T. Nakamura, M. Abe, M. Ohtake, S. Matsuura, S. Watanabe, M. Yoshikawa, T. Saiki, S. Tanaka, T. Okada, Y. Yamamoto, Y. Takei, K. Shirai, N. Hirata, K. Matsumoto, Y. Tsuda

Monthly Notices of the Royal Astronomical Society Vol. 514 ( 4 ) page： 6173 - 6182 2022.7

Language：English Publishing type：Research paper (scientific journal)

The JAXA Hayabusa2 mission accomplished the formation of an artificial crater on the asteroid Ryugu. The aim of this work is to analyse the area surrounding the artificial crater and reveal spectral variability compared to the same region before the crater formation, to mineralogically and physically characterize the subsurface exposed material. The crater's investigation focused on the analysis of two regions corresponding to the inner part of crater (the pit and the crater wall/floor), two areas related to ejecta deposited close to the crater, two areas of ejecta moved far from the crater, and two external areas. Each area was investigated both before and after the crater formation, by the study of the photometrically corrected spectral parameters: the 1.9 μm reflectance, the near-infrared spectral slope, and the depth of the bands at 2.7 and 2.8 μm. The subsurface material of the post-crater areas shows deeper absorption bands, a decrease in reflectance, and a reddening in spectral slope with respect to the surface material of pre-crater areas. The subsurface regolith could have experienced a lower OH devolatilization due to space weathering and/or could be composed of finer dark grains than the surface layer. The ejecta reached distances of ~20 m from the impact point, mainly moving in the northern direction; nevertheless, a few ejecta also reached the south-eastern part of crater.

DOI： 10.1093/mnras/stac1547

Mission objectives, planning, and achievements of Hayabusa2 Reviewed

Yuichi Tsuda, Satoru Nakazawa, Makoto Yoshikawa, Takanao Saiki, Fuyuto Terui, Masahiko Arakawa, Masanao Abe, Kohei Kitazato, Seiji Sugita, Shogo Tachibana, Noriyuki Namiki, Satoshi Tanaka, Tatsuaki Okada, Hitoshi Ikeda, Sei-ichiro Watanabe

Hayabusa2 Asteroid Sample Return Mission page： 5 - 23 2022.4

Extended mission of Hayabusa2 Reviewed International coauthorship

Yuya Mimasu, Shota Kikuchi, Yuto Takei, Takanao Saiki, Sei-ichiro Watanabe, Satoshi Tanaka, Masatoshi Hirabayashi, Naoya Sakatani, Toru Kouyama, Makoto Yoshikawa, Satoru Nakazawa, Yuichi Tsuda

Hayabusa2 Asteroid Sample Return Mission page： 557 - 571 2022.4

Landing site selection for the Hayabusa2 mission: Pre-arrival training and post-arrival analyses Reviewed

Shota Kikuchi, Tomohiro Yamaguchi, Sei-ichiro Watanabe, Hikaru Yabuta, Koji Wada, Takanao Saiki, Yuto Takei, Satoshi Tanaka, Yuichi Tsuda

Hayabusa2 Asteroid Sample Return Mission page： 189 - 208 2022.4

MASCOT—A Mobile Lander On-board the Hayabusa2 Spacecraft—Operations on Ryugu Reviewed International coauthorship

C. Krause, U. Auster, J. P. Bibring, J. Biele, C. Cenac-Morthe, F. Cordero, B. Cozzoni, C. Dudal, D. Embacher, C. Fantinati, H. H. Fischer, K. H. Glassmeier, D. Granena, M. Grott, J. T. Grundmann, V. Hamm, D. Hercik, T. M. Ho, R. Jaumann, K. Kayal, J. Knollenberg, O. Küchemann, C. Lange, L. Lorda, M. Maibaum, D. May, Y. Mimasu, A. Moussi, T. Okada, J. Reill, T. Saiki, K. Sasaki, M. Schlotterer, N. Schmitz, N. Toth, Y. Tsuda, S. Ulamec, T. Yoshimitsu, S. Watanabe, F. Wolff

Hayabusa2 Asteroid Sample Return Mission page： 559 - 575 2022.4

Language：English Publishing type：Part of collection (book)

MASCOT (‘Mobile Asteroid Surface Scout’) is a 10 kg mobile surface science package part of JAXA’s Hayabusa2 sample return mission. The mission was launched in December 2014 from Tanegashima Space Center, Japan. The Hayabusa2 spacecraft reached the target asteroid in summer 2018. After a mapping phase of the asteroid and a landing site selection process the MASCOT lander was deployed to the surface on the 3rd of October 2018. MASCOT operated successfully for about 17 h on the surface of Ryugu. It performed three relocation manoeuvres and one “Mini-Move” and returned 128 MBytes of data. MASCOT has been developed by the German Aerospace Center (DLR) in cooperation with the Centre National d’Etudes Spatiales (CNES). The main objectives were to perform in-situ investigations of the asteroid surface and to support the sampling site selection for the mother spacecraft. These objectives could be reached successfully. On 6th December 2020 Hayabusa2 successfully returned asteroid samples to the Earth.

DOI： 10.1007/978-3-030-94628-9_25

Martian moons exploration MMX: sample return mission to Phobos elucidating formation processes of habitable planets Invited Reviewed International coauthorship Open Access

Kiyoshi Kuramoto, Yasuhiro Kawakatsu, Masaki Fujimoto, Akito Araya, Maria Antonietta Barucci, Hidenori Genda, Naru Hirata, Hitoshi Ikeda, Takeshi Imamura, Jörn Helbert, Shingo Kameda, Masanori Kobayashi, Hiroki Kusano, David J. Lawrence, Koji Matsumoto, Patrick Michel, Hideaki Miyamoto, Tomokatsu Morota, Hiromu Nakagawa, Tomoki Nakamura, Kazunori Ogawa, Hisashi Otake, Masanobu Ozaki, Sara Russell, Sho Sasaki, Hirotaka Sawada, Hiroki Senshu, Shogo Tachibana, Naoki Terada, Stephan Ulamec, Tomohiro Usui, Koji Wada, Sei-ichiro Watanabe, Shoichiro Yokota

Earth, Planets and Space Vol. 74 ( 1 ) 2022.1

Language：English Publishing type：Research paper (scientific journal) Publisher：SPRINGER

Martian moons exploration, MMX, is the new sample return mission planned by the Japan Aerospace Exploration Agency (JAXA) targeting the two Martian moons with the scheduled launch in 2024 and return to the Earth in 2029. The major scientific objectives of this mission are to determine the origin of Phobos and Deimos, to elucidate the early Solar System evolution in terms of volatile delivery across the snow line to the terrestrial planets having habitable surface environments, and to explore the evolutionary processes of both moons and Mars surface environment. To achieve these objectives, during a stay in circum-Martian space over about 3 years MMX will collect samples from Phobos along with close-up observations of this inner moon and carry out multiple flybys of Deimos to make comparative observations of this outer moon. Simultaneously, successive observations of the Martian atmosphere will also be made by utilizing the advantage of quasi-equatorial spacecraft orbits along the moons' orbits.

DOI： 10.1186/s40623-021-01545-7

Measurement of surface deformation and cohesion of a granular pile under the effect of centrifugal force Reviewed Open Access

Irie Terunori, Yamaguchi Ryusei, Watanabe Sei-ichiro, Katsuragi Hiroaki

MEASUREMENT SCIENCE AND TECHNOLOGY Vol. 32 ( 12 ) 2021.12

Spectrally blue hydrated parent body of asteroid (162173) Ryugu Reviewed International coauthorship Open Access

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

Nature Communications Vol. 12 ( 1 ) 2021.10

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

<title>Abstract</title>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.

DOI： 10.1038/s41467-021-26071-8

Other Link： https://www.nature.com/articles/s41467-021-26071-8

Magma source transition of lunar mare volcanism at 2.3 Ga Reviewed Open Access

S. Kato, T. Morota, Y. Yamaguchi, S. Watanabe, H. Otake, M. Ohtake

Meteoritics & Planetary Science 2017.6

Dust ring formation due to sublimation of dust grains: An analytical model Reviewed

H. Kobayashi, S. Watanabe, H. Kimura, T. Yamamoto

Icarus Vol. 201 ( 1 ) page： 395-405 2009.5

Dust ring formation due to ice sublimation of radially drifting dust particles under the Poynting-Robertson effect in debris disks Reviewed

Kobayashi, H., Watanabe S., Kimura, H., and Yamamoto T.

Icarus Vol. 195 ( 2 ) page： 871-881 2008.6

Analytic Model of Upper Tropospheric Clouds in Tropical Hadley Cell Reviewed

Kyoko K. Tanaka, Tetsuo Yamamoto, Sei-ichiro Watanabe, and Kensuke Nakajima

Earth Planets Space Vol. 60 ( 3 ) page： 219-228 2008.3

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal)

We develop a two-dimensional analytic model that describes the behavior of upper tropospheric clouds in the tropical Hadley cell. The behavior of model is characterized by two dimensionless parameters: one is proportional to the temperature lapse rate, and the other is relevant to the initial altitude of the cloud particles. We derive analytic expressions for the motion and evaporation of the cloud particles and calculate various cloud properties such as the cloudiness and the column water content. We find the outflow from the convective regions spreads out and generates a cirrus layer whose converge has a maximum at the tropopause: the cloudiness is as large as 0.5 to 1 in the vicinity of the tropopause for small cloud particles of their radii less than 5 micron.

Co-accretion of the Earth-Moon system after the giant impact Reviewed

Icarus Vol. 168 page： 60 - 79 2004

Gas accretion flows onto giant protoplanets: High-resolution two-dimensional simulations Reviewed

The Astrophysical Journal Vol. 580 page： 506 - 518 2002

Hugoniot equation of state of basalt Reviewed

Planetary Space Science Vol. 45 ( 11 ) page： 1489 1997

Collision and Tidal Interaction between Planetesimals. Reviewed

Watanabe, S., Miyama, S. M.

The Astrophysical Journal Vol. 391 page： 318-335 1992.5

Cooling and Quasi-Static Contraction of the Primitive Solar Nebula after Gas Accretion Reviewed

Watanabe, S., Nakagawa, Y., Nakazawa, K.

The Astrophysical Journal Vol. 358 page： 282 - 292 1990.7

Cooling of the Solar Nebula Reviewed

Watanabe S. Nakagawa, Y.

Progress of Theoretical Physics Supplement Vol. 96 page： 130-140 1988.12

Methylene‐to‐methyl ratio variability in Ryugu samples: Clues to a heterogeneous aqueous alteration Reviewed International coauthorship International journal

Zélia Dionnet, Zahia Djouadi, Lukas Delaye, Lucas Caron, Rosario Brunetto, Alice Aléon‐Toppani, Cateline Lantz, Stefano Rubino, Donia Baklouti, Tomoki Nakamura, Ferenc Borondics, Christophe Sandt, Megumi Matsumoto, Kana Amano, Tomoyo Morita, Hisayoshi Yurimoto, Takaaki Noguchi, Ryuji Okazaki, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Shogo Tachibana, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Satoru Nakazawa, Seiichiro Watanabe, Yuichi Tsuda

Meteoritics & Planetary Science Vol. 60 ( 2 ) page： 273 - 285 2024.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Wiley

Abstract

Understanding the processes of aqueous alteration within primitive bodies is crucial for unraveling the complex history of early planetesimals. To better identify the signs of this process and its consequences, we have studied the heterogeneity at a micrometric scale of the structure of the aliphatic organic compounds and its relationship to its mineralogical environment. Here, we report an analysis performed on two micrometric grains of Ryugu (C0002‐FC027 and C0002‐FC028). The samples were crushed in a diamond compression cell and analyzed using high‐spatial resolution Fourier Transform InfraRed (FT‐IR) hyperspectral imaging measurements conducted in transmission mode. We showed here the spatial distributions of the main components and the structural heterogeneity of the aliphatic organic matter highlighting a micrometer‐scale variability in the methylene‐to‐methyl ratio. Moreover, we connected this heterogeneity to the one of the phyllosilicate band positions. Our findings indicate that the organic matter within Ryugu's micrometric grains underwent varying degrees of aqueous alteration in distinct microenvironments resulting in an elongation of the length of their aliphatic chains, and/or a reduction in their branching and/or cross‐linking.

DOI： 10.1111/maps.14304

Microscopic slickenside as a record of weak shock metamorphism in the surface layer of asteroid Ryugu Reviewed International coauthorship International journal

Miyahara, M; Noguchi, T; Matsumoto, T; Tomioka, N; Miyake, A; Igami, Y; Seto, Y; Haruta, M; Saito, H; Hata, S; Ishii, HA; Bradley, JP; Ohtaki, KK; Dobrica, E; Leroux, H; Le Guillou, C; Jacob, D; de la Peña, F; Laforet, S; Mouloud, BE; Marinova, M; Langenhorst, F; Harries, D; Beck, P; Phan, THV; Rebois, R; Abreu, NM; Gray, J; Zega, T; Zanetta, PM; Thompson, MS; Stroud, R; Burgess, K; Cymes, BA; Bridges, JC; Hicks, L; Lee, MR; Daly, L; Bland, PA; Zolensky, ME; Frank, DR; Martinez, J; Tsuchiyama, A; Yasutake, M; Matsuno, J; Okumura, S; Mitsukawa, I; Uesugi, K; Uesugi, M; Takeuchi, A; Sun, M; Enju, S; Takigawa, A; Michikami, T; Nakamura, T; Matsumoto, M; Nakauchi, Y; Abe, M; Nakazawa, S; Okada, T; Saiki, T; Tanaka, S; Terui, F; Yoshikawa, M; Miyazaki, A; Nakato, A; Nishimura, M; Usui, T; Yada, T; Yurimoto, H; Nagashima, K; Kawasaki, N; Sakamotoa, N; Okazaki, R; Yabuta, H; Naraoka, H; Sakamoto, K; Tachibana, S; Watanabe, S; Tsuda, Y

METEORITICS & PLANETARY SCIENCE Vol. 59 ( 12 ) page： 3181 - 3192 2024.12

Correlated IR-SEM-TEM studies of three different grains from Ryugu: from the initial material to post-accretional processes. Reviewed International coauthorship International journal Open Access

Aléon-Toppani, A; Brunetto, R; Dionnet, Z; Rubino, S; Baklouti, D; Brisset, F; Vallet, M; Heripre, E; Nakamura, T; Lantz, C; Djouadi, Z; Borondics, F; Sandt, C; Troadec, D; Mivumbi, O; Matsumoto, M; Amano, K; Morita, T; Yurimoto, H; Noguchi, T; Okazaki, R; Yabuta, H; Naraoka, H; Sakamoto, K; Tachibana, S; Yada, T; Nishimura, M; Nakato, A; Miyazaki, A; Yogata, K; Abe, M; Okada, T; Usui, T; Yoshikawa, M; Saiki, T; Tanaka, S; Terui, F; Nakazawa, S; Watanabe, S; Tsuda, Y

METEORITICS & PLANETARY SCIENCE Vol. 59 page： A5 - A5 2024.8

SPATIAL HETEROGENEITY OF ALIPHATIC COMPOUNDS AND THEIR LINK WITH PHYLLOSILICATES AS A RESULT OF AQUEOUS ALTERATION OF RYUGU SAMPLES. International coauthorship International journal

Dionnet, Z; Djouadi, Z; Brunetto, R; Aléon-Toppani, A; Nakamura, T; Rubino, S; Delaye, L; Caron, L; Baklouti, D; Lantz, C; Mivumbi, O; Borondics, F; Héripré, E; Troadec, D; Tsuchiyama, A; Matsuno, J; Matsumoto, M; Morita, T; Kikuiri, M; Amano, K; Kagawa, E; Yurimoto, H; Noguchi, T; Okazaki, R; Yabuta, H; Naraoka, H; Sakamoto, K; Tachibana, S; Watanabe, S; Tsuda, Y

METEORITICS & PLANETARY SCIENCE Vol. 59 page： A99 - A99 2024.8

Simultaneous geometric calibration and orbit-attitude determination of Hayabusa2’s deployable camera (DCAM3) Reviewed International coauthorship International journal Open Access

Shota Kikuchi, Kei Shirai, Ko Ishibashi, Koji Wada, Yasuhiro Yokota, Rie Honda, Toshihiko Kadono, Yuri Shimaki, Naoya Sakatani, Kazunori Ogawa, Hirotaka Sawada, Takanao Saiki, Yuya Mimasu, Yuto Takei, Seiji Sugita, Toru Kouyama, Naru Hirata, Satoru Nakazawa, Makoto Yoshikawa, Satoshi Tanaka, Sei-ichiro Watanabe, Yuichi Tsuda, Masahiko Arakawa

Advances in Space Research Vol. 74 ( 2 ) page： 899 - 936 2024.7

Raman spectroscopy of Ryugu particles and their extracted residues: Fluorescence background characteristics and similarities to CI chondrites Reviewed International coauthorship International journal

Komatsu, M; Yabuta, H; Kebukawa, Y; Bonal, L; Quirico, E; Fagan, TJ; Cody, GD; Barosch, J; Bejach, L; Dartois, E; Dazzi, A; De Gregorio, B; Deniset-Besseau, A; Duprat, J; Engrand, C; Hashiguchi, M; Martins, Z; Mathurin, J; Montagnac, G; Mostefaoui, S; Nittler, LR; Ohigashi, T; Okumura, T; Rémusat, L; Sandford, S; Stroud, R; Suga, H; Takahashi, Y; Takeichi, Y; Tamenori, Y; Verdier-Paoletti, M; Yamashita, S; Yurimoto, H; Nakamura, T; Noguchi, T; Okazaki, R; Naraoka, H; Sakamoto, K; Yoshikawa, M; Saiki, T; Tanaka, S; Terui, F; Nakazawa, S; Usui, T; Abe, M; Okada, T; Yada, T; Nishimura, M; Nakato, A; Miyazaki, A; Yogata, K; Tachibana, S; Watanabe, S; Tsuda, Y

METEORITICS & PLANETARY SCIENCE 2024.7

Incipient space weathering on asteroid 162173 Ryugu recorded by pyrrhotite Reviewed International coauthorship International journal Open Access

Harries, D; Matsumoto, T; Langenhorst, F; Noguchi, T; Miyake, A; Igami, Y; Haruta, M; Seto, Y; Miyahara, M; Tomioka, N; Saito, H; Hata, S; Takigawa, A; Nakauchi, Y; Tachibana, S; Nakamura, T; Matsumoto, M; Ishii, HA; Bradley, JP; Ohtaki, K; Dobrica, E; Leroux, H; Le Guillou, C; Jacob, D; de la Pena, F; Laforet, S; Mouloud, BE; Marinova, M; Beck, P; Phan, VH; Rebois, R; Abreu, NM; Gray, J; Zega, T; Zanetta, PM; Thompson, MS; Stroud, R; Burgess, K; Cymes, BA; Bridges, JC; Hicks, L; Lee, MR; Daly, L; Bland, PA; Zolensky, ME; Frank, DR; Martinez, J; Tsuchiyama, A; Yasutake, M; Matsuno, J; Okumura, S; Mitsukawa, I; Uesugi, K; Uesugi, M; Takeuchi, A; Sun, MQ; Enju, S; Michikami, T; Yurimoto, H; Okazaki, R; Yabuta, H; Naraoka, H; Sakamoto, K; Yada, T; Nishimura, M; Nakato, A; Miyazaki, A; Yogata, K; Abe, M; Okada, T; Usui, T; Yoshikawa, M; Saiki, T; Tanaka, S; Terui, F; Nakazawa, S; Watanabe, SI; Tsuda, Y

METEORITICS & PLANETARY SCIENCE 2024.5

A comprehensive study of apatite grains in Ryugu rock fragments Reviewed International coauthorship International journal Open Access

Tkalcec, BJ; Tack, P; De Pauw, E; Bazi, B; Vekemans, B; Lindner, M; Vincze, L; Di Michiel, M; Garrevoet, J; Falkenberg, G; Nakamura, T; Morita, T; Amano, K; Nakashima, D; Langenhorst, F; Pollok, K; Yurimoto, H; Noguchi, T; Okazaki, R; Yabuta, H; Naraoka, H; Sakamoto, K; Tachibana, S; Yada, T; Nishimura, M; Nakato, A; Miyazaki, A; Yogata, K; Abe, M; Okada, T; Usui, T; Yoshikawa, M; Saiki, T; Tanaka, S; Terui, F; Nakazawa, S; Watanabe, S; Tsuda, Y; Brenker, FE

METEORITICS & PLANETARY SCIENCE 2024.5

Enantioselective three-dimensional high-performance liquid chromatographic determination of amino acids in the Hayabusa2 returned samples from the asteroid Ryugu Reviewed International coauthorship International journal Open Access

Aogu Furusho, Chiharu Ishii, Takeyuki Akita, Mai Oyaide, Masashi Mita, Hiroshi Naraoka, Yoshinori Takano, Jason P. Dworkin, Yasuhiro Oba, Toshiki Koga, Kazuhiko Fukushima, Dan Aoki, Minako Hashiguchi, Hajime Mita, Yoshito Chikaraishi, Naohiko Ohkouchi, Nanako O. Ogawa, Saburo Sakai, Daniel P. Glavin, Jamie E. Elsila, Eric T. Parker, José C. Aponte, Hannah L. McLain, Francois-Regis Orthous-Daunay, Véronique Vuitton, Roland Thissen, Cédric Wolters, Philippe Schmitt-Kopplin, Alexander Ruf, Junko Isa, Norbert Hertkorn, John M. Eiler, Toshihiro Yoshimura, Haruna Sugahara, Heather V. Graham, Yoshihiro Furukawa, Daisuke Araoka, Satoru Tanaka, Takaaki Yoshikawa, Fumie Kabashima, Kazunori Sasaki, Hajime Sato, Tomoya Yamazaki, Morihiko Onose, Mayu Morita, Yuki Kimura, Kuniyuki Kano, Junken Aoki, Kosuke Fujishima, Shin-ichiro Nomura, Shogo Tachibana, Tomoki Nakamura, Takaaki Noguchi, Ryuji Okazaki, Hikaru Yabuta, Hisayoshi Yurimoto, Kanako Sakamoto, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tomohiro Usui, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Satoru Nakazawa, Tatsuaki Okada, Sei-ichiro Watanabe, Yuichi Tsuda, Kenji Hamase

Journal of Chromatography Open page： 100134 - 100134 2024.5

The Earth atmosphere-like bulk nitrogen isotope composition obtained by stepwise combustion analyses of Ryugu return samples Reviewed International coauthorship International journal Open Access

Hashizume, K; Ishida, A; Chiba, A; Okazaki, R; Yogata, K; Yada, T; Kitajima, F; Yurimoto, H; Nakamura, T; Noguchi, T; Yabuta, H; Naraoka, H; Takano, Y; Sakamoto, K; Tachibana, S; Nishimura, M; Nakato, A; Miyazaki, A; Abe, M; Okada, T; Usui, T; Yoshikawa, M; Saiki, T; Terui, F; Tanaka, S; Nakazawa, S; Watanabe, SI; Tsuda, Y; Broadley, MW; Busemann, H

METEORITICS & PLANETARY SCIENCE 2024.4

Coevolution of phyllosilicate, carbon, sulfide, and apatite in Ryugu's parent body Reviewed International coauthorship International journal Open Access

Gainsforth, Z; Dominguez, G; Amano, K; Matsumoto, M; Fujioka, Y; Kagawa, E; Nakamura, T; Tachibana, S; Morita, T; Kikuiri, M; Yurimoto, H; Noguchi, T; Okazaki, R; Yabuta, H; Naraoka, H; Sakamoto, K; Yada, T; Nishimura, M; Nakato, A; Miyazaki, A; Yogata, K; Abe, M; Okada, T; Usui, T; Yoshikawa, M; Saiki, T; Tanaka, S; Terui, F; Nakazawa, S; Watanabe, S; Tsuda, Y

METEORITICS & PLANETARY SCIENCE 2024.4

Disequilibrium oxygen isotope distribution among aqueously altered minerals in Ryugu asteroid returned samples Reviewed International coauthorship International journal Open Access

Kita, NT; Kitajima, K; Nagashima, K; Kawasaki, N; Sakamoto, N; Fujiya, W; Abe, Y; Aleon, J; Alexander, CMO; Amari, S; Amelin, Y; Bajo, KI; Bizzarro, M; Bouvier, A; Carlson, RW; Chaussidon, M; Choi, BG; Dauphas, N; Davis, AM; Di Rocco, T; Fukai, R; Gautam, I; Haba, MK; Hibiya, Y; Hidaka, H; Homma, H; Hoppe, P; Huss, GR; Ichida, K; Iizuka, T; Ireland, TR; Ishikawa, A; Itoh, S; Kleine, T; Komatani, S; Krot, AN; Liu, MC; Masuda, Y; Mckeegan, KD; Morita, M; Motomura, K; Moynier, F; Nakai, I; Nguyen, A; Nittler, L; Onose, M; Pack, A; Park, C; Piani, L; Qin, LP; Russell, SS; Schoenbaechler, M; Tafla, L; Tang, HL; Terada, K; Terada, Y; Usui, T; Wada, S; Wadhwa, M; Walker, RJ; Yamashita, K; Yin, QZ; Yokoyama, T; Yoneda, S; Young, ED; Yui, H; Zhang, AC; Nakamura, T; Naraoka, H; Noguchi, T; Okazaki, R; Sakamoto, K; Yabuta, H; Abe, M; Miyazaki, A; Nakato, A; Nishimura, M; Okada, T; Yada, T; Yogata, K; Nakazawa, S; Saiki, T; Tanaka, S; Terui, F; Tsuda, Y; Watanabe, SI; Yoshikawa, M; Tachibana, S; Yurimoto, H

METEORITICS & PLANETARY SCIENCE 2024.4

Hydrogen in magnetite from asteroid Ryugu Reviewed International coauthorship International journal Open Access

Aléon, J; Mostefaoui, S; Bureau, H; Vangu, D; Khodja, H; Nagashima, K; Kawasaki, N; Abe, Y; Alexander, CMO; Amari, S; Amelin, Y; Bajo, K; Bizzarro, M; Bouvier, A; Carlson, RW; Chaussidon, M; Choi, BG; Dauphas, N; Davis, AM; Di Rocco, T; Fujiya, W; Fukai, R; Gautam, I; Haba, MK; Hibiya, Y; Hidaka, H; Homma, H; Hoppe, P; Huss, GR; Ichida, K; Iizuka, T; Ireland, TR; Ishikawa, A; Itoh, S; Kita, NT; Kitajima, K; Kleine, T; Komatani, S; Krot, AN; Liu, MC; Masuda, Y; Morita, M; Motomura, K; Moynier, F; Nakai, I; Nguyen, A; Nittler, LR; Onose, M; Pack, A; Park, C; Piani, L; Qin, L; Russell, SS; Sakamoto, N; Schönbächler, M; Tafla, L; Tang, H; Terada, K; Terada, Y; Usui, T; Wada, S; Wadhwa, M; Walker, RJ; Yamashita, K; Yin, QZ; Yokoyama, T; Yoneda, S; Young, ED; Yui, H; Zhang, AC; Nakamura, T; Naraoka, H; Noguchi, T; Okazaki, R; Sakamoto, K; Yabuta, H; Abe, M; Miyazaki, A; Nakato, A; Nishimura, M; Okada, T; Yada, T; Yogata, K; Nakazawa, S; Saiki, T; Tanaka, S; Terui, F; Tsuda, Y; Watanabe, S; Yoshikawa, M; Tachibana, S; Yurimoto, H

METEORITICS & PLANETARY SCIENCE 2024.1

In situ investigation of an organic micro-globule and its mineralogical context within a Ryugu "sand" grain Reviewed International coauthorship International journal Open Access

Phan, VH; Beck, P; Rebois, R; Quirico, E; Noguchi, T; Matsumoto, T; Miyake, A; Igami, Y; Haruta, M; Saito, H; Hata, S; Seto, Y; Miyahara, M; Tomioka, N; Ishii, HA; Bradley, JP; Ohtaki, KK; Dobrica, E; Leroux, H; Le Guillou, C; Jacob, D; de la Pena, F; Laforet, S; Marinova, M; Langenhorst, F; Harries, D; Abreu, NM; Gray, J; Zega, T; Zanetta, PM; Thompson, MS; Stroud, R; Mathurin, J; Dazzi, A; Dartois, E; Engrand, C; Burgess, K; Cymes, BA; Bridges, JC; Hicks, L; Lee, MR; Daly, L; Bland, PA; Zolensky, ME; Frank, DR; Martinez, J; Tsuchiyama, A; Yasutake, M; Matsuno, J; Okumura, S; Mitsukawa, I; Uesugi, K; Uesugi, M; Takeuchi, A; Sun, MQ; Enju, S; Takigawa, A; Michikami, T; Nakamura, T; Matsumoto, M; Nakauchi, Y; Abe, M; Nakazawa, S; Okada, T; Saiki, T; Tanaka, S; Terui, F; Yoshikawa, M; Miyazaki, A; Nakato, A; Nishimura, M; Usui, T; Yada, T; Yurimoto, H; Nagashima, K; Kawasaki, N; Sakamotoa, N; Hoppe, P; Okazaki, R; Yabuta, H; Naraoka, H; Sakamoto, K; Tachibana, S; Watanabe, SI; Tsuda, Y

METEORITICS & PLANETARY SCIENCE 2024.1

Four-dimensional-STEM analysis of the phyllosilicate-rich matrix of Ryugu samples Reviewed International coauthorship International journal Open Access

Mouloud, BE; Jacob, D; de la Peña, F; Marinova, M; Le Guillou, C; Viennet, JC; Laforet, S; Leroux, H; Teurtrie, A; Noguchi, T; Matsumoto, T; Miyake, A; Igami, Y; Haruta, M; Saito, H; Hata, S; Seto, Y; Miyahara, M; Tomioka, N; Ishii, HA; Bradley, JP; Ohtaki, KK; Dobrica, E; Langenhorst, F; Harries, D; Beck, P; Phan, THV; Rebois, R; Abreu, NM; Gray, J; Zega, T; Zanetta, PM; Thompson, MS; Stroud, R; Burgess, K; Cymes, BA; Bridges, JC; Hicks, L; Lee, MR; Daly, L; Bland, PA; Zolensky, ME; Frank, DR; Martinez, J; Tsuchiyama, A; Yasutake, M; Matsuno, J; Okumura, S; Mitsukawa, I; Uesugi, K; Uesugi, M; Takeuchi, A; Sun, MQ; Enju, S; Takigawa, A; Michikami, T; Nakamura, T; Matsumoto, M; Nakauchi, Y; Abe, M; Nakazawa, S; Okada, T; Saiki, T; Tanaka, S; Terui, F; Yoshikawa, M; Miyazaki, A; Nakato, A; Nishimura, M; Usui, T; Yada, T; Yurimoto, H; Nagashima, K; Kawasaki, N; Sakamotoa, N; Okazaki, R; Yabuta, H; Naraoka, H; Sakamoto, K; Tachibana, S; Watanabe, S; Tsuda, Y

METEORITICS & PLANETARY SCIENCE 2024.1

Analysis of Cation Composition in Dolomites on the Intact Particles Sampled from Asteroid Ryugu Reviewed International coauthorship International journal Open Access

Mayu Morita, Hiroharu Yui, Shu-hei Urashima, Morihiko Onose, Shintaro Komatani, Izumi Nakai, Yoshinari Abe, Yasuko Terada, Hisashi Homma, Kazuko Motomura, Kiyohiro Ichida, Tetsuya Yokoyama, Kazuhide Nagashima, 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, Wataru Fujiya, Ryota Fukai, Ikshu Gautam, Makiko K. Haba, Yuki Hibiya, Hiroshi Hidaka, Peter Hoppe, Gary R. Huss, Tsuyoshi Iizuka, Trevor R. Ireland, Akira Ishikawa, Shoichi Itoh, Noriyuki Kawasaki, Noriko T. Kita, Kouki Kitajima, Thorsten Kleine, Sasha Krot, Ming-Chang Liu, Yuki Masuda, Frédéric Moynier, Ann Nguyen, Larry Nittler, Andreas Pack, Changkun Park, Laurette Piani, Liping Qin, Tommaso Di Rocco, Sara S. Russell, Naoya Sakamoto, Maria Schönbächler, Lauren Tafla, Haolan Tang, Kentaro Terada, Tomohiro Usui, Sohei Wada, Meenakshi Wadhwa, Richard J. Walker, Katsuyuki Yamashita, Qing-Zhu Yin, Shigekazu Yoneda, Edward D. Young, Ai-Cheng Zhang, Tomoki Nakamura, Hiroshi Naraoka, Takaaki Noguchi, Ryuji Okazaki, Kanako Sakamoto, Hikaru Yabuta, Masanao Abe, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Tatsuaki Okada, Toru Yada, Kasumi Yogata, Satoru Nakazawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Yuichi Tsuda, Sei-ichiro Watanabe, Makoto Yoshikawa, Shogo Tachibana, Hisayoshi Yurimoto

Analytical Chemistry Vol. 96 ( 1 ) page： 170 - 178 2023.12

Neodymium-142 deficits and samarium neutron stratigraphy of C-type asteroid (162173) Ryugu Reviewed International coauthorship International journal Open Access

Torrano, ZA; Jordan, MK; Mock, TD; Carlson, RW; Gautam, I; Haba, MK; Yokoyama, T; Abe, Y; Aléon, J; Alexander, C; Amari, S; Amelin, Y; Bajo, K; Bizzarro, M; Bouvier, A; Chaussidon, M; Choi, BG; Dauphas, N; Davis, AM; Di Rocco, T; Fujiya, W; Fukai, R; Hibiya, Y; Hidaka, H; Homma, H; Hoppe, P; Huss, GR; Ichida, K; Iizuka, T; Ireland, T; Ishikawa, A; Itoh, S; Kawasaki, N; Kita, NT; Kitajima, K; Kleine, T; Komatani, S; Krot, AN; Liu, MC; Masuda, Y; Mckeegan, KD; Morita, M; Motomura, K; Moynier, F; Nakai, I; Nagashima, K; Nguyen, A; Nittler, L; Onose, M; Pack, A; Park, C; Piani, L; Qin, LP; Russell, S; Sakamoto, N; Schönbächler, M; Tafla, L; Tang, HL; Terada, K; Terada, Y; Usui, T; Wada, S; Wadhwa, M; Walker, RJ; Yamashita, K; Yin, QZ; Yoneda, S; Young, ED; Yui, H; Zhang, AC; Nakamura, T; Naraoka, H; Noguchi, T; Okazaki, R; Sakamoto, K; Yabuta, H; Abe, M; Miyazaki, A; Nakato, A; Nishimura, M; Okada, T; Yada, T; Yogata, K; Nakazawa, S; Saiki, T; Tanaka, S; Terui, F; Tsuda, Y; Watanabe, S; Yoshikawa, M; Tachibana, S; Yurimoto, H

METEORITICS & PLANETARY SCIENCE 2023.12

A new primordial noble gas component in the solar system discovered in Ryugu asteroid

Alexander Verchovsky, Feargus Abernethy, Mahesh Anand, Ian Franchi, Monica Grady, Richard Greenwood, Simeon Barber, Martin Suttle, Motoo Ito, Naotaka Tomioka, Masayuki Uesugi, Akira Yamaguchi, Makoto Kimura, Naoya Imae, Naoki Shirai, Takuji Ohigashi, Ming-Chang Liu, Kentaro Uesugi, Aiko Nakato, Kasumi Yogata, Hayato Yuzawa, Yuzuru Karouji, Satoru Nakazawa, Tatsuaki Okada, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Makoto Yoshikawa, Akiko Miyazaki, Masahiro Nishimura, Toru Yada, Masanao Abe, Tomohiro Usui, Sei-ichiro Watanabe, Yuichi Tsuda

2023.12

The Magnesium Isotope Composition of Samples Returned from Asteroid Ryugu Reviewed International coauthorship International journal Open Access

Martin Bizzarro, Martin Schiller, Tetsuya Yokoyama, Yoshinari Abe, Jérôme Aléon, Conel M. O’D. Alexander, Sachiko Amari, Yuri Amelin, Ken-ichi Bajo, Audrey Bouvier, Richard W. Carlson, Marc Chaussidon, Byeon-Gak Choi, Nicolas Dauphas, Andrew M. Davis, Tommaso Di Rocco, Wataru Fujiya, Ryota Fukai, Ikshu Gautam, Makiko K. Haba, Yuki Hibiya, Hiroshi Hidaka, Hisashi Homma, Peter Hoppe, Gary R. Huss, Kiyohiro Ichida, Tsuyoshi Iizuka, Trevor R. Ireland, Akira Ishikawa, Shoichi Itoh, Noriyuki Kawasaki, Noriko T. Kita, Kouki Kitajima, Thorsten Kleine, Shintaro Komatani, Alexander N. Krot, Ming-Chang Liu, Yuki Masuda, Mayu Morita, Fréderic Moynier, Kazuko Motomura, Izumi Nakai, Kazuhide Nagashima, David Nesvorný, Ann Nguyen, Larry Nittler, Morihiko Onose, Andreas Pack, Changkun Park, Laurette Piani, Liping Qin, Sara S. Russell, Naoya Sakamoto, Maria Schönbächler, Lauren Tafla, Haolan Tang, Kentaro Terada, Yasuko Terada, Tomohiro Usui, Sohei Wada, Meenakshi Wadhwa, Richard J. Walker, Katsuyuki Yamashita, Qing-Zhu Yin, Shigekazu Yoneda, Edward D. Young, Hiroharu Yui, Ai-Cheng Zhang, Tomoki Nakamura, Hiroshi Naraoka, Takaaki Noguchi, Ryuji Okazaki, Kanako Sakamoto, Hikaru Yabuta, Masanao Abe, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Tatsuaki Okada, Toru Yada, Kasumi Yogata, Satoru Nakazawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Yuichi Tsuda, Sei-ichiro Watanabe, Makoto Yoshikawa, Shogo Tachibana, Hisayoshi Yurimoto

The Astrophysical Journal Letters Vol. 958 ( 2 ) page： L25 - L25 2023.12

Language：English Publishing type：Research paper (scientific journal) Publisher：American Astronomical Society

Abstract

The nucleosynthetic isotope composition of planetary materials provides a record of the heterogeneous distribution of stardust within the early solar system. In 2020 December, the Japan Aerospace Exploration Agency Hayabusa2 spacecraft returned to Earth the first samples of a primitive asteroid, namely, the Cb-type asteroid Ryugu. This provides a unique opportunity to explore the kinship between primitive asteroids and carbonaceous chondrites. We report high-precision μ26Mg* and μ25Mg values of Ryugu samples together with those of CI, CM, CV, and ungrouped carbonaceous chondrites. The stable Mg isotope composition of Ryugu aliquots defines μ25Mg values ranging from –160 ± 20 ppm to –272 ± 30 ppm, which extends to lighter compositions relative to Ivuna-type (CI) and other carbonaceous chondrite groups. We interpret the μ25Mg variability as reflecting heterogeneous sampling of a carbonate phase hosting isotopically light Mg (μ25Mg ∼ –1400 ppm) formed by low temperature equilibrium processes. After correcting for this effect, Ryugu samples return homogeneous μ26Mg* values corresponding to a weighted mean of 7.1 ± 0.8 ppm. Thus, Ryugu defines a μ26Mg* excess relative to the CI and CR chondrite reservoirs corresponding to 3.8 ± 1.1 and 11.9 ± 0.8 ppm, respectively. These variations cannot be accounted for by in situ decay of 26Al given their respective 27Al/24Mg ratios. Instead, it requires that Ryugu and the CI and CR parent bodies formed from material with a different initial 26Al/27Al ratio or that they are sourced from material with distinct Mg isotope compositions. Thus, our new Mg isotope data challenge the notion that Ryugu and CI chondrites share a common nucleosynthetic heritage.

DOI： 10.3847/2041-8213/ad09d9

Other Link： https://iopscience.iop.org/article/10.3847/2041-8213/ad09d9/pdf

Evidence of global space weathering by solar wind on asteroid 162173 Ryugu Reviewed International coauthorship International journal Open Access

T. Hiroi, R.E. Milliken, K.M. Robertson, C.D. Schultz, K. Amano, T. Nakamura, H. Yurimoto, T. Noguchi, R. Okazaki, H. Naraoka, H. Yabuta, K. Sakamoto, T. Yada, M. Nishimura, A. Nakato, A. Miyazaki, K. Yogata, M. Abe, T. Okada, T. Usui, M. Yoshikawa, T. Saiki, S. Tanaka, S. Nakazawa, Y. Yokota, E. Tatsumi, Y. Tsuda, S. Tachibana, T. Fuyuto, S. Watanabe, S. Sasaki, H. Kaiden, K. Kitazato, M. Matsuoka

Icarus Vol. 406 page： 115755 - 115755 2023.12

Mineralogy and petrology of fine-grained samples recovered from the asteroid (162173) Ryugu Reviewed International coauthorship International journal Open Access

Noguchi, T; Matsumoto, T; Miyake, A; Igami, Y; Haruta, M; Saito, H; Hata, S; Seto, Y; Miyahara, M; Tomioka, N; Ishii, HA; Bradley, JP; Ohtaki, KK; Dobrica, E; Leroux, H; Le Guillou, C; Jacob, D; de la Peña, F; Laforet, S; Mouloud, BE; Marinova, M; Langenhorst, F; Harries, D; Beck, P; Phan, THV; Rebois, R; Abreu, NM; Gray, J; Zega, T; Zanetta, PM; Thompson, MS; Stroud, R; Burgess, K; Cymes, BA; Bridges, JC; Hicks, L; Lee, MR; Daly, L; Bland, PA; Smith, WA; Mcfadzean, S; Martin, PE; Bagot, PAJ; Fougerouse, D; Saxey, DW; Reddy, S; Rickard, WDA; Zolensky, ME; Frank, DR; Martinez, J; Tsuchiyama, A; Yasutake, M; Matsuno, J; Okumura, S; Mitsukawa, I; Uesugi, K; Uesugi, M; Takeuchi, A; Sun, MQ; Enju, S; Takigawa, A; Michikami, T; Nakamura, T; Matsumoto, M; Nakauchi, Y; Abe, M; Nakazawa, S; Okada, T; Saiki, T; Tanaka, S; Terui, F; Yoshikawa, M; Miyazaki, A; Nakato, A; Nishimura, M; Usui, T; Yada, T; Yurimoto, H; Nagashima, K; Kawasaki, N; Sakamotoa, N; Hoppe, P; Okazaki, R; Yabuta, H; Naraoka, H; Sakamoto, K; Tachibana, S; Watanabe, S; Tsuda, Y

METEORITICS & PLANETARY SCIENCE 2023.11

The iron oxidation state of Ryugu samples Reviewed International coauthorship International journal Open Access

Roskosz, M; Beck, P; Viennet, JC; Nakamura, T; Lavina, B; Hu, MY; Zhao, JY; Alp, EE; Takahashi, Y; Morita, T; Amano, K; Yurimoto, H; Noguchi, T; Okazaki, R; Yabuta, H; Naraoka, H; Sakamoto, K; Tachibana, S; Yada, T; Nishimura, M; Nakato, A; Miyazaki, A; Yogata, K; Abe, M; Okada, T; Usui, T; Yoshikawa, M; Saiki, T; Tanaka, S; Terui, F; Nakazawa, S; Watanabe, SI; Tsuda, Y

METEORITICS & PLANETARY SCIENCE 2023.11

Compositional heterogeneity of insoluble organic matter extracted from asteroid Ryugu samples Reviewed International coauthorship International journal Open Access

Quirico, E; Bonal, L; Kebukawa, Y; Amano, K; Yabuta, H; Phan, VH; Beck, P; Remusat, L; Dartois, E; Engrand, C; Martins, Z; Bejach, L; Dazzi, A; Deniset-Besseau, A; Duprat, J; Mathurin, J; Montagnac, G; Barosch, J; Cody, GD; De Gregorio, B; Enokido, Y; Hashiguchi, M; Kamide, K; Kilcoyne, D; Komatsu, M; Matsumoto, M; Mostefaoui, S; Nittler, L; Ohigashi, T; Okumura, T; Sandford, S; Shigenaka, M; Stroud, R; Suga, H; Takahashi, Y; Takeichi, Y; Tamenori, Y; Verdier-Paoletti, M; Wakabayashi, D; Yamashita, S; Nakamura, T; Naraoka, H; Noguchi, T; Okazaki, R; Yurimoto, H; Sakamoto, K; Tachibana, S; Watanabe, SI; Tsuda, Y; Yada, T; Nishimura, M; Nakato, A; Miyazaki, A; Yogata, K; Abe, M; Okada, T; Usui, T; Yoshikawa, M; Saiki, T; Tanaka, S; Terui, F; Nakazawa, S

METEORITICS & PLANETARY SCIENCE 2023.11

<scp>Three‐dimensional</scp> multiscale assembly of phyllosilicates, organics, and carbonates in small Ryugu fragments Reviewed International coauthorship International journal Open Access

Zelia Dionnet, Stefano Rubino, Alice Aléon‐Toppani, Rosario Brunetto, Akira Tsuchiyama, Cateline Lantz, Zahia Djouadi, Donia Baklouti, Tomoki Nakamura, Ferenc Borondics, Christophe Sandt, Eva Heripre, David Troadec, Obadias Mivumbi, Jérome Aléon, Theo Ternier, Megumi Matsumoto, Kana Amano, Tomoyo Morita, Hisayoshi Yurimoto, Takaaki Noguchi, Ryuji Okazaki, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Shogo Tachibana, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Satoru Nakazawa, Seiichiro Watanabe, Yuichi Tsuda

Meteoritics & Planetary Science 2023.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Wiley

Abstract

We report μm‐scale nondestructive infrared (IR) hyperspectral results (IR computed tomography, IR‐CT) in 3‐D and IR surface imaging, IR‐S) in 2‐D, at SOLEIL) combined with X‐ray nano‐computed tomography analyses (at SPring‐8) performed on eight small Ryugu fragments extracted from mm‐sized grains coming both from touchdown first and second sites. We describe the multiscale assembly of phyllosilicates, carbonates, sulfides, oxides, and organics. Two types of silicates, as well as diverse kinds of organic matter, were detected inside Ryugu material. Their spatial correlations are described to discuss the role of the mineralogical microenvironments in the formation/evolution of organic matter. In particular, we have shown that there is a redistribution of the organic matter diffuse component during aqueous alteration on the parent body, with a preferential circulation among fine‐grained phyllosilicates.

DOI： 10.1111/maps.14068

Infrared absorption spectra from organic matter in the asteroid Ryugu samples: Some unique properties compared to unheated carbonaceous chondrites Reviewed International coauthorship International journal

Kebukawa, Y; Quirico, E; Dartois, E; Yabuta, H; Bejach, L; Bonal, L; Dazzi, A; Deniset-Besseau, A; Duprat, J; Engrand, C; Mathurin, J; Barosch, J; Cody, GD; De Gregorio, B; Hashiguchi, M; Kamide, K; Kilcoyne, D; Komatsu, M; Martins, Z; Montagnac, G; Mostefaoui, S; Nittler, LR; Ohigashi, T; Okumura, T; Remusat, L; Sandford, S; Shigenaka, M; Stroud, R; Suga, H; Takahashi, Y; Takeichi, Y; Tamenori, Y; Verdier-Paoletti, M; Wakabayashi, D; Yamashita, S; Yurimoto, H; Nakamura, T; Noguchi, T; Okazaki, R; Naraoka, H; Sakamoto, K; Tachibana, S; Yada, T; Nishimura, M; Nakato, A; Miyazaki, A; Yogata, K; Abe, M; Okada, T; Usui, T; Yoshikawa, M; Saiki, T; Tanaka, S; Terui, F; Nakazawa, S; Watanabe, S; Tsuda, Y

METEORITICS & PLANETARY SCIENCE 2023.8

The Oxygen Isotopic Composition of Samples Returned from Asteroid Ryugu with Implications for the Nature of the Parent Planetesimal Reviewed International coauthorship International journal Open Access

Haolan Tang, Edward D. Young, Lauren Tafla, Andreas Pack, Tommaso Di Rocco, 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, 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, Kazuhide Nagashima, Izumi Nakai, Ann Nguyen, Larry Nittler, Morihiko Onose, Changkun Park, Laurette Piani, Liping Qin, Sara S. Russell, Naoya Sakamoto, Maria Schönbächler, Kentaro Terada, Yasuko Terada, Tomohiro Usui, Sohei Wada, Meenakshi Wadhwa, Richard J. Walker, Katsuyuki Yamashita, Qing-Zhu Yin, Tetsuya Yokoyama, Shigekazu Yoneda, Hiroharu Yui, Ai-Cheng Zhang, Tomoki Nakamura, Hiroshi Naraoka, Takaaki Noguchi, Ryuji Okazaki, Kanako Sakamoto, Hikaru Yabuta, Masanao Abe, Akiko Miyazaki, Aiko Nakato, Masahiro Nishimura, Tatsuaki Okada, Toru Yada, Kasumi Yogata, Satoru Nakazawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Yuichi Tsuda, Sei-ichiro Watanabe, Makoto Yoshikawa, Shogo Tachibana, Hisayoshi Yurimoto

The Planetary Science Journal Vol. 4 ( 8 ) page： 144 - 144 2023.8

Language：English Publishing type：Research paper (scientific journal) Publisher：American Astronomical Society

Abstract

We present oxygen isotopic analyses of fragments of the near-Earth Cb-type asteroid Ryugu returned by the Hayabusa2 spacecraft that reinforce the close correspondence between Ryugu and CI chondrites. Small differences between Ryugu samples and CI chondrites in ${ { \rm{\Delta } } }^{ { \prime} 17}{\rm{O } }$ can be explained at least in part by contamination of the latter by terrestrial water. The discovery that a randomly sampled C-complex asteroid is composed of CI-chondrite-like rock, combined with thermal models for formation prior to significant decay of the short-lived radioisotope 26Al, suggests that if lithified at the time of alteration, the parent body was small (≪50 km radius). If the parent planetesimal was large (>50 km in radius), it was likely composed of high-permeability, poorly lithified sediment rather than consolidated rock.

DOI： 10.3847/PSJ/acea62

Other Link： https://iopscience.iop.org/article/10.3847/PSJ/acea62/pdf

Noble gas mass-spectrometry for extraterrestrial micro-samples: analyses of asteroid matter returned by Hayabusa2 JAXA mission Reviewed International coauthorship International journal Open Access

Alexander Meshik, Olga Pravdivtseva, Ryuji Okazaki, Kasumi Yogata, Toru Yada, Fumio Kitajima, Hisayoshi Yurimoto, Tomoki Nakamura, Takaaki Noguchi, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Shogo Tachibana, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Makoto Yoshikawa, Takanao Sakai, Satoshi Tanaka, Fuyuto Terui, Satoru Nakazawa, Seiichiro Watanabe, Yuichi Tsuda, Hayabusa2 Initial Analysis Volatile Team

Journal of Analytical Atomic Spectrometry 2023.7

Language：English Publishing type：Research paper (scientific journal) Publisher：Royal Society of Chemistry (RSC)

Mass spectrometry of noble gas isotopes from the asteroid materials delivered by robotic space missions requires high sensitivity, high ion transmission, low detection limit, and other characteristics not readily available in commercial instruments.

DOI： 10.1039/d3ja00125c

Ryugu: A brand-new planetary sample returned from a C-type asteroid

Elastic Property of Returned Samples From Asteroid (162173) Ryugu

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

ESS Open Archive 2023.5

Language：English Publishing type：Research paper (other academic) Publisher：Authorea, Inc.

The elastic property of asteroids is one of the paramount parameters forunderstanding their physical nature. For example, the rigidity enablesus to discuss the asteroid’s shape and surface features such as cratersand boulders, leading to a better understanding of geomorphological andgeological features on small celestial bodies. The sound velocity allowsus to construct an equation of state that is the most fundamental stepto simulate the formation of small bodies numerically. Moreover, seismicwave velocities and attenuation factors are useful to account forresurfacing caused by impact-induced seismic shaking. The elasticproperty of asteroids thus plays an important role in elucidating theasteroid’s evolution and current geological processes. The Hayabusa2spacecraft brought back the rock samples from C-type asteroid (162173)Ryugu in December 2020. As a part of the initial analysis of returnedsamples, we measured the seismic wave velocity of the Ryugu samplesusing the pulse transmission method. We found that P- and S-wavevelocities of the Ryugu samples were about 2.1 km/s and 1.2 km/s,respectively. We also estimated Young’s modulus of 6.0 – 8.0 GPa. Acomparison of the derived parameters with those of carbonaceouschondrites showed that the Ryugu samples have a similar elastic propertyto the Tagish Lake meteorite, which may have come from a D-typeasteroid. Both Ryugu and Tagish Lake show a high degree of aqueousalteration and few high-temperature components such as chondrules,indicating that they formed in the outer region of the solar system.

DOI： 10.22541/essoar.168500248.80647094/v1

Re-distribution of volatiles on the airless surface of the C-type carbonaceous asteroid Ryugu. International coauthorship International journal

Toru Matsumoto, Takaaki Noguchi, Akira Miyake, Yohei Igami, Mitsutaka Haruta, Yusuke Seto, Masaaki Miyahara, Naotaka Tomioka, Hikaru Saito, Satoshi Hata, Dennis Harries, Aki Takigawa, Yuusuke Nakauchi, Shogo Tachibana, Tomoki Nakamura, Megumi Matsumoto, Hope Ishii, John Bradley, Kenta Ohtaki, Elena Dobrică, Hugues Leroux, Corentin Le Guillou, Damien Jacob, Francisco de la Peña, Sylvain Laforet, Maya Marinova, Falko Langenhorst, Pierre Beck, Thi Phan, Rolando Rebois, Neyda Abreu, Jennifer Gray, Thomas Zega, Pierre-Marie Zanetta, Michelle Thompson, Rhonda Stroud, Katherine Burgess, Brittany Cymes, John Bridges, Leon Hicks, Martin Lee, Luke Daly, Phil Bland, Michael Zolensky, David Frank, James Martinez, Akira Tsuchiyama, Masahiro Yasutake, Junya Matsuno, Shota Okumura, Itaru Mitsukawa, Kentaro Uesugi, Masayuki Uesugi, Akihisa Takeuchi, Mingqi Sun, Satomi Enju, Tatsuhiro Michikami, Hisayoshi Yurimoto, Ryuji Okazaki, Hikaru Yabuta, Hiroshi Naraoka, Kanako Sakamoto, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Satoru Nakazawa, Sei-ichiro Watanabe, Yuichi Tsuda

2023.3

Crack Orientation of Boulders on Ryugu: Meridional Preference and Exfoliation

Sho SASAKI, Shiho KANDA, Hiroshi KIKUCHI, Tatsuhiro MICHIKAMI, Tomokatsu MOROTA, Chikatoshi HONDA, Hideaki MIYAMOTO, Ryodo HEMMI, Seiji SUGITA, Eri TATSUMI, Masanori KANAMARU, Sei-ichiro WATANABE, Noriyuki NAMIKI, Patrick MICHEL, Masatoshi HIRABAYASHI, Naru HIRATA, Tomoki NAKAMURA, Takaaki NOGUCHI, Takahiro HIROI, Naoya SAKATANI, Koji MATSUMOTO, Hirotomo NODA, Shingo KAMEDA, Tohru KOUYAMA, Hidehiko SUZUKI, Manabu YAMADA, Rie HONDA, Yuichiro CHO, Kazuo YOSHIOKA, Masahiko HAYAKAWA, Moe MATSUOKA, Rina NOGUCHI, Hirotaka SAWADA, Yasuhiro YOKOTA, Makoto YOSHIKAWA

Journal of Evolving Space Activities 2023

Early fluid activity on Ryugu: perspectives from oxygen, carbon, and 53Mn-53Cr isotopes Reviewed International coauthorship International journal

Kaitlyn McCain, Nozomi Matsuda, Ming-Chang Liu, Kevin McKeegan, Akira Yamaguchi, Makoto Kimura, Naotaka Tomioka, Motoo Ito, Naoya Imae, Masayuki Uesugi, Naoki Shirai, Takuji Ohigashi, Richard Greenwood, Kentaro Uesugi, Aiko Nakato, Kasumi Yogata, Hayato Yuzawa, Yu Kodama, Kaori Hirahara, Ikuya Sakurai, Ikuo Okada, Yuzuru Karouji, Satoru Nakazawa, Tatsuaki Okada, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Makoto Yoshikawa, Akiko Miyazaki, Masahiro Nishimura, Toru Yada, Masanao Abe, Tomohiro Usui, Sei-ichiro Watanabe, Yuichi Tsuda

2022.6

EARLY FLUID ACTIVITY ON THE RYUGU PARENT ASTEROID INFERRED FROM (MN)-M-53-(CR)-C-53 AGES OF RYUGU CARBONATE Reviewed International coauthorship International journal

McCain, K. A., Matsuda, N., Liu, M. -C., McKeegan, K. D., Yamaguchi, A., Kimura, M., Tomioka, N., Ito, M., Imae, N., Uesugi, M., Shirai, N., Ohigashi, T., Greenwood, R. C., Uesugi, K., Nakato, A., Yogata, K., Yu-Zawa, H., Kodama, Y., Hirahara, K., Sakurai, I., Okada, I., Karouji, Y., Nakazawa, S., Okada, T., Saiki, T., Tanaka, S., Terui, F., Yoshikawa, M., Miyazaki, A., Nishimura, M., Yada, T., Abe, M., Usui, T., Watanabe, S., Tsuda, Y.

Meteoritics & Planetary Science 2022

Rotational states and shapes of Ryugu and Bennu: Implications for interior structure and strength Reviewed Open Access

PLANETARY AND SPACE SCIENCE Vol. 204 2021.9

Hayabusa2 extended mission: New voyage to rendezvous with a small asteroid rotating with a short period Reviewed International coauthorship Open Access

M. Hirabayashi, Y. Mimasu, N. Sakatani, S. Watanabe, Y. Tsuda, T. Saiki, S. Kikuchi, T. Kouyama, M. Yoshikawa, S. Tanaka, S. Nakazawa, Y. Takei, F. Terui, H. Takeuchi, A. Fujii, T. Iwata, K. Tsumura, S. Matsuura, Y. Shimaki, S. Urakawa, Y. Ishibashi, S. Hasegawa, M. Ishiguro, D. Kuroda, S. Okumura, S. Sugita, T. Okada, S. Kameda, S. Kamata, A. Higuchi, H. Senshu, H. Noda, K. Matsumoto, R. Suetsugu, T. Hirai, K. Kitazato, D. Farnocchia, S.P. Naidu, D.J. Tholen, C.W. Hergenrother, R.J. Whiteley, N.A. Moskovitz, P.A. Abell

Advances in Space Research Vol. 68 ( 3 ) page： 1533 - 1555 2021.8

FIRST NIR HYPER-SPECTRAL IMAGING OF HAYABUSA2 RETURNED SAMPLES BY THE MICROMEGA MICROSCOPE WITHIN THE ISAS CURATION FACILITY Reviewed International coauthorship

Bibring J. P., Pilorget C., Okada T., Hamm V., Brunetto R., Yada T., Loizeau D., Riu L., Usui T., Moussi-Soffys A., Hatakeda K., Nakato A., Yogata K., Abe M., Aleon-Toppani A., Carter J., Chaigneau M., Crane B., Gondet B., Kumagai K., Langevin Y., Lantz C., Le Pivert-Jolivet T., Lequertier G., Lourit L., Miyazaki A., Nishimura M., Poulet F., Arakawa M., Hirata N., Kitazato K., Nakazawa S., Namiki N., Saiki T., Sugita S., Tachibana S., Tanaka S., Yoshikawa M., Tsuda Y., Watanabe S.

METEORITICS & PLANETARY SCIENCE Vol. 56 2021.8

INITIAL DESCRIPTIONS OF ASTEROID RYUGU SAMPLES RETURNED BY HAYABUSA2. Reviewed International coauthorship

Yada T., Abe M., Nakato A., Yogata K., Miyazaki A., Kumagai K., Hatakeda K., Okada T., Nishimura M., Furuya S., Yoshitake M., Iwamae A., Soejima H., Hitomi Y., Riu L., Lourit L., Pilorget C., Hamm V., Brunetto R., Bibring J. -P., Cho Y., Yumoto K., Yabe Y., Sugita S., Tachibana S., Sawada H., Sakamoto K., Hayashi T., Yamamoto D., Fukai R., Sugahara H., Yurimoto H., Usui T., Watanabe S., Tsuda Y.

METEORITICS & PLANETARY SCIENCE Vol. 56 2021.8

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 Miura, Hajime Yano, Trevor 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, Kazunori Ogawa, Kei Shirai, 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

2021.6

Publisher：Research Square Platform LLC

<title>Abstract</title>
C-type asteroids are considered to be primitive small Solar-System bodies enriched in water and organics, providing clues for understanding the origin and evolution of the Solar System and the building blocks of life. C-type asteroid 162173 Ryugu has been characterized by remote sensing and on-asteroid measurements with Hayabusa2, but further studies are expected by direct analyses of returned samples. Here we describe the bulk sample mainly consisting of rugged and smooth particles of millimeter to submillimeter size, preserving physical and chemical properties as they were on the asteroid. The particle size distribution is found steeper than that of surface boulders11. Estimated grain densities of the samples have a peak around 1350 kg m-3, which is lower than that of meteorites suggests a high micro-porosity down to millimeter-scale, as estimated at centimeter-scale by thermal measurements. The extremely dark optical to near-infrared reflectance and the spectral profile with weak absorptions at 2.7 and 3.4 microns implying carbonaceous composition with indigenous aqueous alteration, respectively, match the global average of Ryugu, confirming the sample’s representativeness. Together with the absence of chondrule and Ca-Al-rich inclusion of larger than sub-mm, these features indicate Ryugu is most similar to CI chondrites but with darker, more porous and fragile characteristics.

DOI： 10.21203/rs.3.rs-608561/v1

Other Link： https://www.researchsquare.com/article/rs-608561/v1.html

Ballistic deployment of the Hayabusa2 artificial landmarks in the microgravity environment of Ryugu Reviewed International coauthorship Open Access

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

Icarus Vol. 358 page： 114220 - 114220 2021.4

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

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

Icarus Vol. 354 ( 15 ) page： 114016 - 114016 2021.1

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

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

Icarus Vol. 354 page： 114073 - 114073 2021.1

Collisional history of Ryugu’s parent body from bright surface boulders Reviewed International coauthorship Open Access

E. Tatsumi, C. Sugimoto, L. Riu, S. Sugita, T. Nakamura, T. Hiroi, T. Morota, M. Popescu, T. Michikami, K. Kitazato, M. Matsuoka, S. Kameda, R. Honda, M. Yamada, N. Sakatani, T. Kouyama, Y. Yokota, C. Honda, H. Suzuki, Y. Cho, K. Ogawa, M. Hayakawa, H. Sawada, K. Yoshioka, C. Pilorget, M. Ishida, D. Domingue, N. Hirata, S. Sasaki, J. de León, M. A. Barucci, P. Michel, M. Suemitsu, T. Saiki, S. Tanaka, F. Terui, S. Nakazawa, S. Kikuchi, T. Yamaguchi, N. Ogawa, G. Ono, Y. Mimasu, K. Yoshikawa, T. Takahashi, Y. Takei, A. Fujii, Y. Yamamoto, T. Okada, C. Hirose, S. Hosoda, O. Mori, T. Shimada, S. Soldini, R. Tsukizaki, T. Mizuno, T. Iwata, H. Yano, M. Ozaki, M. Abe, M. Ohtake, N. Namiki, S. Tachibana, M. Arakawa, H. Ikeda, M. Ishiguro, K. Wada, H. Yabuta, H. Takeuchi, Y. Shimaki, K. Shirai, N. Hirata, Y. Iijima, Y. Tsuda, S. Watanabe, M. Yoshikawa

Nature Astronomy Vol. 5 ( 1 ) page： 39 - 45 2021.1

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

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN Vol. 19 ( 5 ) page： 654 - 659 2021

Sample Return Accomplished: Flight Result of Asteroid Explorer Hayabusa2 International coauthorship International journal

Y. Tsuda, T. Saiki, F. Terui, S. Nakazawa, M. Yoshikawa, S. Watanabe

Proceedings of the International Astronautical Congress, IAC Vol. A3 2021

Language：English Publishing type：Research paper (international conference proceedings)

Hayabusa2 is an asteroid sample return mission developed and operated by the Japan Aerospace Exploration Agency (JAXA). Hayabusa2 visited the C-Type asteroid Ryugu in 2018, stayed in the proximity of the asteroid for 1.5 years, and returned to Earth in 2020. Hayabusa2 succeeded in delivering three surface exploration robots to the asteroid surface, performing two landing and sample collection activities, generating one artificial crater impact, and deploying three small objects into orbit around the asteroid. The terrain of Ryugu was found to be unexpectedly harsh through the in-situ observations, and the operation strategy was obliged to be changed and aligned to the Ryugu environment. The project team overcame all the difficulties through tight and collaborative works between the team s scientists and engineers, and completed the planned missions perfectly. The total of 5.4 g of Ryugu sample was confirmed to contain in the returned capsule, which is now being analysed by specifically organized initial analysis teams, and will be delivered to international researchers through AO in 2022. This paper describes the entire flight result of the Hayabusa2 mission, and summarizes the engineering and scientific accomplishments of the mission.

Spin-driven evolution of asteroids' top-shapes at fast and slow spins seen from (101955) Bennu and (162173) Ryugu Reviewed International coauthorship International journal Open Access

Hirabayashi Masatoshi, Nakano Ryota, Tatsumi Eri, Walsh Kevin J, Barnouin Olivier S, Michel Patrick, Hartzell Christine M, Britt Daniel T, Sugita Seiji, Watanabe Sei-ichiro, Bottke William F, Scheeres Daniel J, Ballouz Ronald-Louis, Cho Yuichiro, Morota Tomokatsu, Howell Ellen S, Lauretta Dante S

ICARUS Vol. 352 page： 113946 - 113946 2020.12

Motion reconstruction of the small carry-on impactor aboard Hayabusa2 Reviewed International journal

Takanao Saiki, Yuya Mimasu, Yuto Takei, Manabu Yamada, Hirotaka Sawada, Kazunori Ogawa, Naoko Ogawa, Hiroshi Takeuchi, Akira Miura, Yuri Shimaki, Koji Wada, Rie Honda, Yasuhiro Yokota, Kei Shirai, Naruhisa Sano, Hirohito Ohtsuka, Go Ono, Kent Yoshikawa, Shota Kikuchi, Chikako Hirose, Yukio Yamamoto, Takahiro Iwata, Masahiko Arakawa, Seiji Sugita, Satoshi Tanaka, Fuyuto Terui, Makoto Yoshikawa, Satoru Nakazawa, Sei-ichiro Watanabe, Yuichi Tsuda

Astrodynamics Vol. 4 ( 4 ) page： 289 - 308 2020.12

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

Galiano A, Palomba E, D'Amore M, Zinzi A, Dirri F, Longobardo A, Kitazato K, Iwata T, Matsuoka M, Hiroi T, Takir D, Nakamura T, Abe M, Ohtake M, Matsuura S, Watanabe S, Yoshikawa M, Saiki T, Tanaka S, Okada T, Yamamoto Y, Takei Y, Shirai K, Hirata N, Matsumoto K, Tsuda Y

ICARUS Vol. 351 page： 113959 - 113959 2020.11

Author Correction: Shape of (101955) Bennu indicative of a rubble pile with internal stiffness (Nature Geoscience, (2019), 12, 4, (247-252), 10.1038/s41561-019-0330-x) Reviewed International coauthorship International journal Open Access

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, N. Hirata, N. Hirata, S. I. Watanabe, K. N. Burke, D. N. DellaGiustina, C. A. Bennett, D. S. Lauretta, D. E. Highsmith, J. Small, D. Vokrouhlický, N. E. Bowles, E. Brown, K. L. Donaldson Hanna, T. Warren, C. Brunet, R. A. Chicoine, S. Desjardins, D. Gaudreau, T. Haltigin, S. Millington-Veloza, A. Rubi, J. Aponte, N. Gorius, A. Lunsford, B. Allen, J. Grindlay, D. Guevel, D. Hoak, J. Hong, D. L. Schrader, J. Bayron, O. Golubov, P. Sánchez, J. Stromberg, M. Hirabayashi, C. M. Hartzell, S. Oliver, M. Rascon, A. Harch, J. Joseph, S. Squyres, D. Richardson, J. P. Emery, L. McGraw, R. Ghent, R. P. Binzel, M. M.Al Asad, C. L. Johnson, L. Philpott, H. C.M. Susorney, E. A. Cloutis, R. D. Hanna, H. C. Connolly, F. Ciceri, A. R. Hildebrand, E. M. Ibrahim, L. Breitenfeld, T. Glotch, A. D. Rogers, B. E. Clark, S. Ferrone, C. A. Thomas, H. Campins, Y. Fernandez, W. Chang, A. Cheuvront

Nature Geoscience Vol. 13 ( 11 ) page： 764 2020.11

Hayabusa2 Landing Site Selection: Surface Topography of Ryugu and Touchdown Safety Reviewed International coauthorship

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

Space Science Reviews Vol. 216 ( 7 ) page： 116 2020.10

Mission Status of Hayabusa2, Science Highlights, and Outlook for Sample Analyses

Seiji Sugita, Rie Honda, Tomokatsu Morota, Shingo Kameda, Eri Tatsumi, Shogo Tachibana, Kohei Kitazato, Tatsuaki Okada, Noriyuki Namiki, Masahiko Arakawa, Patrick Michel, Deborah Domingue, Satoshi Tanaka, Makoto Yoshikawa, Sei-ichiro Watanabe, Yuichi Tsuda

2020.10

Publisher：Copernicus GmbH

&lt;p&gt;JAXA&amp;#8217;s Hayabusa2 is a sample-return mission was launched on Dec. 3, 2014 for bringing back first samples from a C-complex asteroid [1,2]. It arrived at asteroid Ryugu on June 27, 2018 and left for Earth on Nov. 13, 2019 after conducting global remote-sensing observations, two touchdown sampling operations, rover deployments, and an artificial impact experiment. We review our science results and update the mission status of Hayabusa2 in this presentation.&amp;#160;&lt;/p&gt;
&lt;p&gt;The global observations revealed that Ryugu has a top-shaped body with very low density (1.19&amp;#177;0.02 g/cc) [3], spatially uniform Cb-type spectra without strong Fe-rich serpentine absorption at 0.7-um [4], and a weak but significant OH absorption at 2.7 um [5]. Based on these observations, we proposed that Ryugu materials may have experienced aqueous alteration and subsequent thermal metamorphism due to radiogenic heating [4]. However, other scenarios, such as impact-induced thermal metamorphism and extremely primitive carbonaceous materials before extensive alteration, were also considered because there were many new properties of Ryugu whose origins are unclear. Also, numerical calculations show that impact heating can raise the temperatures high enough to dehydrate serpentine at typical collision speed in the asteroid main belt [6]. &amp;#160;&lt;/p&gt;
&lt;p&gt;Further analysis using high-resolution data obtained at low-altitude descents for both rehearsal and actual touchdown operations as well as the artificial impact experiment by small carryon impactor (SCI) and landers observations the Ryugu surface on allowed us to find out what caused the properties of Ryugu. For example, subtle but distinct latitudinal variation of spectral slope in optical wavelengths found in the initial observations [4] turned out be caused by solar heating or space weathering during orbital excursion toward the Sun and subsequent erosion of the equatorial ridge owing to slowdown in Ryugu&amp;#8217;s spin rate [7]. The SCI impact created a very large (~17 m in crest diameter) crater consistent with gravity-controlled scaling showing that Ryugu surface has very low intra-boulder cohesion and the Ryugu surface is very young and well mixed [8].&lt;/p&gt;
&lt;p&gt;Furthermore, the MASCOT lander also showed that typical boulders on Ryugu is not covered with a layer of fine regolith [9] and yet possess very low thermal inertia (282+93/-35 MKS) consistent with highly porous structure [10]. This value is consistent with the global values or Ryugu [4, 11], suggesting that the vast majority of boulders on Ryugu are very porous. However, thermal infrared imager (TIR) also found that Ryugu has a number of &amp;#8220;dense boulders&amp;#8221; with high thermal inertia (&gt;600 MKS) consistent with typical carbonaceous chondrites, showing that Ryugu&amp;#8217;s parent body must have had a large enough gravity and pressure to compress the constituent materials [11]. This observation supports that Ryugu originated from a large parent body, such as proto-Polana and proto-Eulalia, which are estimated to be ~100 km in diameter.&lt;/p&gt;
&lt;p&gt;Some of the dense boulders were also covered by multi-band images of optical navigation camera (ONC-T) and turned out to have C-type spectra with albedos much higher than the Ryugu average [12]. These spectra and albedos are similar to carbonaceous chondrites heated at low temperatures. Although the total mass of these high-albedo boulders on Ryugu is estimated to be very small (&lt; 1%), the spectral and albedo varieties are much greater than the bulk Ryugu surface and approximately follow the dehydration track of carbonaceous chondrites [12]. These spectral match supports that Ryugu materials experienced aqueous alteration and subsequent thermal metamorphism. The dominance of a high-temperature component and scarcity of lower temperature components are consistent with radiogenic heating in a relatively large parent body because large bodies would have only thin low-temperature thermal skin and large volume of high-temperature interior.&amp;#160;&lt;/p&gt;
&lt;p&gt;If radiogenic heating is really responsible for Ryugu&amp;#8217;s moderate dehydration, this may place a very important constraint on the timing of the formation of Ryugu&amp;#8217;s parent body. Because the radiogenic heat source for most meteorite parent bodies are likely extinct species, such as 26Al, the peak temperature is chiefly controlled by the timing of accretion [13]. Thus, high metamorphism temperatures (several hundred degrees in Celsius) of Ryugu&amp;#8217;s bulk materials inferred from spectral comparison with laboratory heated CM and CI meteorites [4, 12] require Ryugu&amp;#8217;s parent body formed early in the Solar System. Because Ryugu&amp;#8217;s parent body contained substantial amount of water at the time of formation, it must have been formed outside the snowline. Thus, the birth place of Ryugu&amp;#8217;s parent body would be a high-accretion-rate location outside the snowline.&lt;/p&gt;
&lt;p&gt;Recent high-precision measurements of stable isotopes of meteorites have found that there is a major dichotomy between carbonaceous chondrites (CCs) and some iron meteorites, which formed outside Jupiter&amp;#8217;s orbit, and non-carbonaceous meteorites (NCs), which formed inside Jupiter&amp;#8217;s orbit [e.g., 14]. If Ryugu belongs to CCs, then Ryugu materials could be form near Jupiter, where accretion could occur early. Thus, measurements of stable isotopes of elements, such as Cr, Ti and Mo, of Ryugu samples to be returned to Earth by the end of 2020 would be highly valuable for constraining the original locations of Polana or Eulalia, among the largest C-complex asteroids in the inner main belt.&amp;#160;&lt;/p&gt;
&lt;p&gt;&lt;strong&gt;Acknowledgements:&lt;/strong&gt; This study was supported by JSPS Core-to-Core program &amp;#8220;International Network of Planetary Sciences&amp;#8221;, CNES, and Univ. Co?te d&amp;#8217;Azur.&amp;#160;&lt;/p&gt;
&lt;p&gt;&lt;strong&gt;References:&lt;/strong&gt;&amp;#160; [1] Watanabe et al., SSR, 208, 3-16, 2017. [2] Tsuda et at., Acta Astronaut. 91, 356-363, 2013. [3] Watanabe et al., Science, 364, 268-272, 2019. [4] Sugita et al., Science, 364, eaaw0422, 2019. [5] Kitazato et al., Science, 364, 272-275, 2019. [6] Michel et al., Nature Comm., 11, 5184, 2020. [7] Morota et al., Science, 368, 654-659, 2020. [8] Akarawa et al. Science, 368, 67-671, 2020. [9] Jaumann et al. Science, 365, 817-820, 2019.&amp;#160; [10] Grott et al., Nature Astron. 3, 971-976, 2019.&amp;#160; [11] Okada et al., Nature, 579, 518-522, 2020. [12] Sugimoto et al. 51st LPSC, #1770, 2020.&amp;#160; [13] Grimm and McSween, Science, 259, 653-655, 1993.&amp;#160; [14] Kruijer et al., PNAS, 114, 6712-6716, 2017.&amp;#160;&lt;/p&gt;

DOI： 10.5194/epsc2020-995

Hayabusa2's kinetic impact experiment: Operational planning and results Reviewed

Saiki Takanao, Takei Yuto, Mimasu Yuya, Sawada Hirotaka, Ogawa Naoko, Ono Go, Yoshikawa Kent, Terui Fuyuto, Arakawa Masahiko, Sugita Seiji, Watanabe Sei-ichiro, Yoshikawa Makoto, Nakazawa Satoru, Tsuda Yuichi

ACTA ASTRONAUTICA Vol. 175 page： 362 - 374 2020.10

Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD

Hayabusa2 is a Japanese interplanetary probe launched on December 3, 2014, which arrived at asteroid Ryugu on June 27, 2018. During its stay around Ryugu, it completed several challenging operations, including deploying two rovers and a lander, conducing two sample collections, and performing a kinetic impact experiment. The kinetic impact experiment was one of the biggest challenges of the Hayabusa2 mission. Investigating the physical and chemical properties of asteroid internal materials and structures is an important scientific objective for small body exploration. We developed a small kinetic impactor called the SCI (Small Carry-on Impactor) to achieve this objective. The SCI is a compact kinetic impactor designed to remove a small region of Ryugu's uppermost surface regolith layer and create an artificial crater. The spacecraft deployed the SCI on April 5, 2019, successfully creating an artificial crater with a diameter of 15 m. This paper describes the operational planning of the kinetic impact experiment and summarizes the operation results.

DOI： 10.1016/j.actaastro.2020.05.064

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

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

ICARUS Vol. 348 2020.9

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE

TIR, the thermal infrared imager on Hayabusa2, acquired high-resolution thermal images of the asteroid 162173 Ryugu for one asteroid rotation period on August 1, 2018 to investigate the thermophysical properties of the asteroid. The surface temperatures of Ryugu suggest that the surface has a low thermal inertia, indicating the presence of porous materials. Thermophysical models that neglect or oversimplify surface roughness cannot reproduce the flat diurnal temperature profiles observed during daytime. We performed numerical simulations of a thermophysical model, including the effects of roughness on the diurnal brightness temperature, the predictions of which successfully reproduced the observed diurnal variation of temperature. The global thermal inertia was obtained with a standard deviation of 225 +/- 45 J m(-2) S-0.5 K-1 which is relatively low but still within the range of the value estimated in our previous study (Okada et al., Nature 579, 518-522, 2020), confirming that the boulders on Ryugu are more porous in nature than typical carbonaceous chondrites. The global surface roughness (the ratio of the variance of the height relative to a local horizontal surface length) was determined as 0.41 +/- 0.08, corresponding to a RMS surface slope of 47 +/- 5 degrees. We identified a slightly lower roughness distributed along the equatorial ridge, implying a mass movement of boulders from the equatorial ridge to the mid-latitudes.

DOI： 10.1016/j.icarus.2020.113835

Dynamic precise orbit determination of Hayabusa2 using laser altimeter (LIDAR) and image tracking data sets Reviewed Open Access

Yamamoto Keiko, Otsubo Toshimichi, Matsumoto Koji, Noda Hirotomo, Namiki Noriyuki, Takeuchi Hiroshi, Ikeda Hitoshi, Yoshikawa Makoto, Yamamoto Yukio, Senshu Hiroki, Mizuno Takahide, Hirata Naru, Yamada Ryuhei, Ishihara Yoshiaki, Araki Hiroshi, Abe Shinsuke, Yoshida Fumi, Higuchi Arika, Sasaki Sho, Oshigami Shoko, Tsuruta Seiitsu, Asari Kazuyoshi, Shizugami Makoto, Ogawa Naoko, Ono Go, Mimasu Yuya, Yoshikawa Kent, Takahashi Tadateru, Takei Yuto, Fujii Atsushi, Yamaguchi Tomohiro, Kikuchi Shota

EARTH PLANETS AND SPACE Vol. 72 ( 1 ) 2020.6

Language：English Publishing type：Research paper (scientific journal) Publisher：SPRINGER

The precise orbit of the Hayabusa2 spacecraft with respect to asteroid Ryugu is dynamically determined using the data sets collected by the spacecraft's onboard laser altimeter (LIght Detection And Ranging, LIDAR) and automated image tracking (AIT). The LIDAR range data and the AIT angular data play complementary roles because LIDAR is sensitive to the line-of-sight direction from Hayabusa2 to Ryugu, while the AIT is sensitive to the directions perpendicular to it. Using LIDAR and AIT, all six components of the initial state vector can be derived stably, which is difficult to achieve using only LIDAR or AIT. The coefficient of solar radiation pressure (SRP) of the Hayabusa2 spacecraft and standard gravitational parameter (GM) of Ryugu can also be estimated in the orbit determination process, by combining multiple orbit arcs at various altitudes. In the process of orbit determination, the Ryugu-fixed coordinate of the center of the LIDAR spot is determined by fitting the range data geometrically to the topography of Ryugu using the Markov Chain Monte Carlo method. Such an approach is effective for realizing the rapid convergence of the solution. The root mean squares of the residuals of the observed minus computed values of the range and brightness-centroid direction of the image are 1.36 m and 0.0270 degrees, respectively. The estimated values of the GM of Ryugu and a correction factor to our initial SRP model are 29.8 +/- 0.3 m(3)/s(2) and 1.13 +/- 0.16, respectively.

DOI： 10.1186/s40623-020-01213-2

Hayabusa2 mission status: Landing, roving and cratering on asteroid Ryugu Reviewed

Tsuda Yuichi, Saiki Takanao, Terui Fuyuto, Nakazawa Satoru, Yoshikawa Makoto, Watanabe Sei-ichiro

ACTA ASTRONAUTICA Vol. 171 page： 42 - 54 2020.6

Collisional formation of top-shaped asteroids and implications for the origins of Ryugu and Bennu Reviewed International coauthorship Open Access

Michel P, Ballouz R-L, Barnouin O. S, Jutzi M, Walsh K. J, May B. H, Manzoni C, Richardson D. C, Schwartz S. R, Sugita S, Watanabe S, Miyamoto H, Hirabayashi M, Bottke W. F, Connolly H. C, Yoshikawa M, Lauretta D. S

NATURE COMMUNICATIONS Vol. 11 ( 1 ) 2020.5

Language：English Publishing type：Research paper (scientific journal)

Asteroid shapes and hydration levels can serve as tracers of their history and origin. For instance, the asteroids (162173) Ryugu and (101955) Bennu have an oblate spheroidal shape with a pronounced equator, but contain different surface hydration levels. Here we show, through numerical simulations of large asteroid disruptions, that oblate spheroids, some of which have a pronounced equator defining a spinning top shape, can form directly through gravitational reaccumulation. We further show that rubble piles formed in a single disruption can have similar porosities but variable degrees of hydration. The direct formation of top shapes from single disruption alone can explain the relatively old crater-retention ages of the equatorial features of Ryugu and Bennu. Two separate parent-body disruptions are not necessarily required to explain their different hydration levels.

DOI： 10.1038/s41467-020-16433-z

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

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

ICARUS Vol. 338 2020.3

The spatial distribution of impact craters on Ryugu Reviewed Open Access

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

ICARUS Vol. 338 2020.3

Initial Achievements of Hayabusa2 in Asteroid Proximity Phase Reviewed Open Access

Yuichi TSUDA, Takanao SAIKI, Fuyuto TERUI, Satoru NAKAZAWA, Makoto YOSHIKAWA, Seiichiro WATANABE

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES Vol. 63 ( 4 ) page： 115 - 123 2020

Design and Reconstruction of the Hayabusa2 Precision Landing on Ryugu Reviewed International coauthorship

Shota Kikuchi, Fuyuto Terui, Naoko Ogawa, Takanao Saiki, Go Ono, Kent Yoshikawa, Yuto Takei, Yuya Mimasu, Hitoshi Ikeda, Hirotaka Sawada, Stefaan Van Wal, Seiji Sugita, Sei-ichiro Watanabe, Yuichi Tsuda

Journal of Spacecraft and Rockets Vol. 57 ( 5 ) page： 1033 - 1060 2020

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

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

Icarus Vol. Accepted 2019.11

Boulder size and shape distributions on asteroid Ryugu Reviewed International coauthorship Open Access

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 Kikuchi, Kazunori Ogawa, Sei-ichiro Watanabe, Satoshi Tanaka, Makoto Yoshikawa, Yuichi Tsuda, Seiji Sugita

Icarus Vol. 331 page： 179 - 191 2019.10

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal)

© 2019 The Authors In 2018, the Japanese spacecraft Hayabusa2, arrived at the small asteroid Ryugu. The surface of this C-type asteroid is covered with numerous boulders whose size and shape distributions are investigated in this study. Using a few hundred Optical Navigation Camera (ONC) images with a pixel scale of approximately 0.65 m, we focus on boulders greater than 5 m in diameter. Smaller boulders are also considered using five arbitrarily chosen ONC close-up images with pixel scales ranging from 0.7 to 6 cm. Across the entire surface area (~2.7 km2) of Ryugu, nearly 4400 boulders larger than 5 m were identified. Boulders appear to be uniformly distributed across the entire surface, with some slight differences in latitude and longitude. At ~50 km−2, the number density of boulders larger than 20 m is twice as large as on asteroid Itokawa (or Bennu). The apparent shapes of Ryugu's boulders resemble laboratory impact fragments, with larger boulders being more elongated. The ratio of the total volume of boulders larger than 5 m to the total excavated volume of craters larger than 20 m on Ryugu can be estimated to be ~94%, which is comparatively high. These observations strongly support the hypothesis that most boulders found on Ryugu resulted from the catastrophic disruption of Ryugu's larger parent body, as described in previous papers (Watanabe et al., 2019; Sugita et al., 2019). The cumulative size distribution of boulders larger than 5 m has a power-index of −2.65 ± 0.05, which is comparatively shallow compared with other asteroids visited by spacecraft. For boulders smaller than 4 m, the power-index is even shallower and ranges from −1.65 ± 0.05 to −2.01 ± 0.06. This particularly shallow power-index implies that some boulders are buried in Ryugu's regolith. Based on our observations, we suggest that boulders near the equator might have been buried by the migration of finer material and, as a result, the number density of boulders larger than 5 m in the equatorial region is lower than at higher latitudes.

DOI： 10.1016/j.icarus.2019.05.019

Images from the surface of asteroid Ryugu show rocks similar to carbonaceous chondrite meteorites Reviewed International coauthorship Open Access

R. Jaumann, N. Schmitz, T. M. Ho, S. E. Schröder, K. A. Otto, K. Stephan, S. Elgner, K. Krohn, F. Preusker, F. Scholten, J. Biele, S. Ulamec, C. Krause, S. Sugita, K. D. Matz, T. Roatsch, R. Parekh, S. Mottola, M. Grott, P. Michel, F. Trauthan, A. Koncz, H. Michaelis, C. Lange, J. T. Grundmann, M. Maibaum, K. Sasaki, F. Wolff, J. Reill, A. Moussi-Soffys, L. Lorda, W. Neumann, J. B. Vincent, R. Wagner, J. P. Bibring, S. Kameda, H. Yano, S. Watanabe, M. Yoshikawa, Y. Tsuda, T. Okada, T. Yoshimitsu, Y. Mimasu, T. Saiki, H. Yabuta, H. Rauer, R. Honda, T. Morota, Y. Yokota, T. Kouyama

Science Vol. 365 ( 6455 ) page： 817 - + 2019.8

Language：English Publishing type：Research paper (scientific journal)

© 2017 The Authors. The near-Earth asteroid (162173) Ryugu is a 900-m-diameter dark object expected to contain primordial material from the solar nebula. The Mobile Asteroid Surface Scout (MASCOT) landed on Ryugu’s surface on 3 October 2018. We present images from the MASCOT camera (MASCam) taken during the descent and while on the surface. The surface is covered by decimeter- to meter-sized rocks, with no deposits of fine-grained material. Rocks appear either bright, with smooth faces and sharp edges, or dark, with a cauliflower-like, crumbly surface. Close-up images of a rock of the latter type reveal a dark matrix with small, bright, spectrally different inclusions, implying that it did not experience extensive aqueous alteration. The inclusions appear similar to those in carbonaceous chondrite meteorites.

DOI： 10.1126/science.aaw8627

Multivariable statistical analysis of spectrophotometry and spectra of (162173) Ryugu as observed by JAXA Hayabusa2 mission Reviewed International coauthorship Open Access

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

ASTRONOMY & ASTROPHYSICS Vol. 629 page： A13 - A13 2019.8

Language：English Publishing type：Research paper (scientific journal) Publisher：EDP Sciences

<italic>Context.</italic> 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.

<italic>Aims.</italic> 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.

<italic>Methods.</italic> In order to isolate and interpret the difference in the asteroid surface spectral behavior, we applied the <italic>G</italic>-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.

<italic>Results.</italic> The analysis of both ONC-T and NIRS3 data allows us to highlight small spectral variations on the Ryugu surface. At a 3<italic>σ</italic> confidence level, only two groups are evident, while going down to 2<italic>σ</italic> more groups are obtained with differences in spectral slope and band depth.

<italic>Conclusions.</italic> 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.

DOI： 10.1051/0004-6361/201935851

HAYABUSA2: CURRENT SUMMARY. Reviewed International coauthorship

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.

METEORITICS & PLANETARY SCIENCE Vol. 54 page： . 2019.8

SPECTRAL CHARACTERISTICS OF ASTEROID (162173) RYUGU WITH HAYABUSA2 NIRS3 Reviewed International coauthorship

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

METEORITICS & PLANETARY SCIENCE Vol. 54 page： . 2019.8

RYUGU'S PARENT-BODY PROCESSES ESTIMATED FROM HAYABUSA2 MULTI-BAND OPTICAL OBSERVATIONS Reviewed International coauthorship

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

METEORITICS & PLANETARY SCIENCE Vol. 54 page： . 2019.8

The unexpected surface of asteroid (101955) Bennu Reviewed International coauthorship Open Access

Lauretta D. S, DellaGiustina D. N, Bennett C. A, Golish D. R, Becker K. J, Balram-Knutson S. S, Barnouin O. S, Becker T. L, Bottke W. F, Boynton W. V, Campins H, Clark B. E, Connolly H. C. Jr, d'Aubigny C, Y. Drouet, Dworkin J. P, Emery J. P, Enos H. L, Hamilton V. E, Hergenrother C. W, Howell E. S, Izawa M. R. M, Kaplan H. H, Nolan M. C, Rizk B, Roper H. L, Scheeres D. J, Smith P. H, Walsh K. J, Wolner C. W. V, Highsmith D. E, Small J, Vokrouhlicky D, Bowles N. E, Brown E, Hanna K, L. Donaldson, Warren T, Brunet C, Chicoine R. A, Desjardins S, Gaudreau D, Haltigin T, Millington-Veloza S, Rubi A, Aponte J, Gorius N, Lunsford A, Allen B, Grindlay J, Guevel D, Hoak D, Hong J, Schrader D. L, Bayron J, Golubov O, Sanchez P, Stromberg J, Hirabayashi M, Hartzell C. M, Oliver S, Rascon M, Harch A, Joseph J, Squyres S, Richardson D, McGraw L, Ghent R, Binzel R. P, Al Asad M. M, Johnson C. L, Philpott L, Susorney H. C. M, Cloutis E. A, Hanna R. D, Ciceri F, Hildebrand A. R, Ibrahim E. -M, Breitenfeld L, Glotch T, Rogers A. D, Ferrone S, Thomas C. A, Fernandez Y, Chang W, Cheuvront A, Trang D, Tachibana S, Yurimoto H, Brucato J. R, Poggiali G, Pajola M, Dotto E, Epifani E. Mazzotta, Crombie M. K, Lantz C, de Leon J, Licandro J, Rizos Garcia J. L, Clemett S, Thomas-Keprta K, Van Wal S, Yoshikawa M, Bellerose J, Bhaskaran S, Boyles C, Chesley S. R, Elder C. M, Farnocchia D, Harbison A, Kennedy B, Knight A, Martinez-Vlasoff N, Mastrodemos N, McElrath T, Owen W, Park R, Rush B, Swanson L, Takahashi Y, Velez D, Yetter K, Thayer C, Adam C, Antreasian P, Bauman J, Bryan C, Carcich B, Corvin M, Geeraert J, Hoffman J, Leonard J. M, Lessac-Chenen E, Levine A, McAdams J, McCarthy L, Nelson D, Page B, Pelgrift J, Sahr E, Stakkestad K, Stanbridge D, Wibben D, Williams B, Williams K, Wolff P, Hayne P, Kubitschek D, Barucci M. A, Deshapriya J. D. P, Fornasier S, Fulchignoni M, Hasselmann P, Merlin F, Praet A, Bierhaus E. B, Billett O, Boggs A, Buck B, Carlson-Kelly S, Cerna J, Chaffin K, Church E, Coltrin M, Daly J, Deguzman A, Dubisher R, Eckart D, Ellis D, Falkenstern P, Fisher A, Fisher M. E, Fleming P, Fortney K, Francis S, Freund S, Gonzales S, Haas P, Hasten A, Hauf D, Hilbert A, Howell D, Jaen F, Jayakody N, Jenkins M, Johnson K, Lefevre M, Ma H, Mario C, Martin K, May C, Mcgee M, Miller B, Miller C, Miller G, Mirfakhrai A, Muhle E, Norman C, Olds R, Parish C, Ryle M, Schmitzer M, Sherman P, Skeen M, Susak M, Sutter B, Tran Q, Welch C, Witherspoon R, Wood J, Zareski J, Arvizu-Jakubicki M, Asphaug E, Audi E, Ballouz R. -L, Bandrowski R, Bendall S, Bloomenthal H, Blum D, Brodbeck J, Burke K. N, Chojnacki M, Colpo A, Contreras J, Cutts J, Dean D, Diallo B, Drinnon D, Drozd K, Enos R, Fellows C, Ferro T, Fisher M. R, Fitzgibbon G, Fitzgibbon M

NATURE Vol. 568 ( 7750 ) page： 55 - + 2019.4

The dynamic geophysical environment of (101955) Bennu based on OSIRIS-REx measurements Reviewed Open Access

Scheeres D. J, McMahon J. W, French A. S, Brack D. N, Chesley S. R, Farnocchia D, Takahashi Y, Leonard J. M, Geeraert J, Page B, Antreasian P, Getzandanner K, Rowlands D, Mazarico E. M, Small J, Highsmith D. E, Moreau M, Emery J. P, Rozitis B, Hirabayashi M, Sanchez P, Van Wal S, Tricarico P, Ballouz R-L, Johnson C. L, Al Asad M. M, Susorney H. C. M, Barnouin O. S, Daly M. G, Seabrook J. A, Gaskell R. W, Palmer E. E, Weirich J. R, Walsh K. J, Jawin E. R, Bierhaus E. B, Michel P, Bottke W. F, Nolan M. C, Connolly H. C. Jr, Lauretta D. S, Vokrouhlicky D, Bowles N. E, Brown E, Hanna K, L. Donaldson, Warren T, Brunet C, Chicoine R. A, Desjardins S, Gaudreau D, Haltigin T, Millington-Veloza S, Rubi A, Aponte J, Gorius N, Lunsford A, Allen B, Grindlay J, Guevel D, Hoak D, Hong J, Schrader D. L, Bayron J, Golubov O, Stromberg J, Hirabayashi M, Hartzell C. M, Oliver S, Rascon M, Harch A, Joseph J, Squyres S, Richardson D, Emery J. P, McGraw L, Ghent R, Binzel R. P, Philpott L, Cloutis E. A, Hanna R. D, Connolly H. C. Jr, Ciceri F, Hildebrand A. R, Ibrahim E-M, Breitenfeld L, Glotch T, Rogers A. D, Clark B. E, Ferrone S, Thomas C. A, Campins H, Fernandez Y, Chang W, Cheuvront A, Trang D, Tachibana S, Yurimoto H, Brucato J. R, Poggiali G, Pajola M, Dotto E, Epifani E. Mazzotta, Crombie M. K, Lantz C, Izawa M. R. M, de Leon J, Licandro J, Rizos Garcia J. L, Clemett S, Thomas-Keprta K, Yoshikawa M, Bellerose J, Bhaskaran S, Boyles C, Elder C. M, Harbison A, Kennedy B, Knight A, Martinez-Vlasoff N, Mastrodemos N, McElrath T, Owen W, Park R, Rush B, Swanson L, Velez D, Yetter K, Thayer C, Adam C, Bauman J, Bryan C, Carcich B, Corvin M, Hoffman J, Lessac-Chenen E, Levine A, McAdams J, McCarthy L, Nelson D, Pelgrift J, Sahr E, Stakkestad K, Stanbridge D, Wibben D, Williams B, Williams K, Wolff P, Hayne P, Kubitschek D, Barucci M. A, Deshapriya J. D. P, Fornasier S, Fulchignoni M, Hasselmann P, Merlin F, Praet A, Bierhaus E. B, Billett O, Boggs A, Buck B, Carlson-Kelly S, Cerna J, Chaffin K, Church E, Coltrin M, Daly J, Deguzman A, Dubisher R, Eckart D, Ellis D, Falkenstern P, Fisher A, Fisher M. E, Fleming P, Fortney K, Francis S, Freund S, Gonzales S, Haas P, Hasten A, Hauf D, Hilbert A, Howell D, Jaen F, Jayakody N, Jenkins M, Johnson K, Lefevre M, Ma H, Mario C, Martin K, May C, McGee M, Miller B, Miller C, Miller G, Mirfakhrai A, Muhle E, Norman C, Olds R, Parish C, Ryle M, Schmitzer M, Sherman P, Skeen M, Susak M, Sutter B, Tran Q, Welch C, Witherspoon R, Wood J, Zareski J, Arvizu-Jakubicki M, Asphaug E, Audi E, Bandrowski R, Becker K. J, Becker T. L, Bendall S, Bennett C. A, Bloomenthal H, Blum D, Boynton W. V, Brodbeck J, Burke K. N, Chojnacki M, Colpo A, Contreras J, Cutts J, d'Aubigny C, Y. Drouet, Dean D, DellaGiustina D. N, Diall

NATURE ASTRONOMY Vol. 3 ( 4 ) page： 352 - 361 2019.4

Shape of (101955) Bennu indicative of a rubble pile with internal stiffness Reviewed International coauthorship Open Access

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, N. Hirata, S. Watanabe, K. N. Burke, D. N. DellaGiustina, C. A. Bennett, D. S. Lauretta, D. E. Highsmith, J. Small, D. Vokrouhlický, N. E. Bowles, E. Brown, K. L. Donaldson Hanna, T. Warren, C. Brunet, R. A. Chicoine, S. Desjardins, D. Gaudreau, T. Haltigin, S. Millington-Veloza, A. Rubi, J. Aponte, N. Gorius, A. Lunsford, B. Allen, J. Grindlay, D. Guevel, D. Hoak, J. Hong, D. L. Schrader, J. Bayron, O. Golubov, P. Sánchez, J. Stromberg, M. Hirabayashi, C. M. Hartzell, S. Oliver, M. Rascon, A. Harch, J. Joseph, S. Squyres, D. Richardson, J. P. Emery, L. McGraw, R. Ghent, R. P. Binzel, M. M.Al Asad, L. Philpott, E. A. Cloutis, R. D. Hanna, H. C. Connolly, F. Ciceri, A. R. Hildebrand, E. M. Ibrahim, L. Breitenfeld, T. Glotch, A. D. Rogers, B. E. Clark, S. Ferrone, C. A. Thomas, H. Campins, Y. Fernandez, W. Chang, A. Cheuvront, D. Trang, S. Tachibana, H. Yurimoto

Nature Geoscience Vol. 12 ( 4 ) page： 247 - + 2019.4

Language：English Publishing type：Research paper (scientific journal)

© 2019, The Author(s), under exclusive licence to Springer Nature Limited. The shapes of asteroids reflect interplay between their interior properties and the processes responsible for their formation and evolution as they journey through the Solar System. Prior to the OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer) mission, Earth-based radar imaging gave an overview of (101955) Bennu’s shape. Here we construct a high-resolution shape model from OSIRIS-REx images. We find that Bennu’s top-like shape, considerable macroporosity and prominent surface boulders suggest that it is a rubble pile. High-standing, north–south ridges that extend from pole to pole, many long grooves and surface mass wasting indicate some low levels of internal friction and/or cohesion. Our shape model indicates that, similar to other top-shaped asteroids, Bennu formed by reaccumulation and underwent past periods of fast spin, which led to its current shape. Today, Bennu might follow a different evolutionary pathway, with an interior stiffness that permits surface cracking and mass wasting.

DOI： 10.1038/s41561-019-0330-x

Properties of rubble-pile asteroid (101955) Bennu from OSIRIS-REx imaging and thermal analysis Reviewed

DellaGiustina D. N, Emery J. P, Golish D. R, Rozitis B, Bennett C. A, Burke K. N, Ballouz R-L, Becker K. J, Christensen P. R, d'Aubigny C, Y. Drouet, Hamilton V. E, Reuter D. C, Rizk B, Simon A. A, Asphaug E, Bandfield J. L, Barnouin O. S, Barucci M. A, Bierhaus E. B, Binzel R. P, Bottke W. F, Bowles N. E, Campins H, Clark B. C, Clark B. E, Connolly H. C. Jr, Daly M. G, de Leon J, Delbo' M, Deshapriya J. D. P, Elder C. M, Fornasier S, Hergenrother C. W, Howell E. S, Jawin E. R, Kaplan H. H, Kareta T. R, Le Corre L, Li J-Y, Licandro J, Lim L. F, Michel P, Molaro J, Nolan M. C, Pajola M, Popescu M, Rizos Garcia J. L, Ryan A, Schwartz S. R, Shultz N, Siegler M. A, Smith P. H, Tatsumi E, Thomas C. A, Walsh K. J, Wolner C. W. V, Zou X-D, Lauretta D. S, Highsmith D. E, Small J, Vokrouhlicky D, Brown E, Hanna K, L. Donaldson, Warren T, Brunet C, Chicoine R. A, Desjardins S, Gaudreau D, Haltigin T, Millington-Veloza S, Rubi A, Aponte J, Gorius N, Lunsford A, Allen B, Grindlay J, Guevel D, Hoak D, Hong J, Schrader D. L, Bayron J, Golubov O, Sanchez P, Stromberg J, Hirabayashi M, Hartzell C. M, Oliver S, Rascon M, Harch A, Joseph J, Squyres S, Richardson D, McGraw L, Ghent R, Al Asad M. M, Johnson C. L, Philpott L, Susorney H. C. M, Cloutis E. A, Hanna R. D, Ciceri F, Hildebrand A. R, Ibrahim E-M, Breitenfeld L, Glotch T, Rogers A. D, Ferrone S, Fernandez Y, Chang W, Cheuvront A, Trang D, Tachibana S, Yurimoto H, Brucato J. R, Poggiali G, Dotto E, Epifani E. Mazzotta, Crombie M. K, Lantz C, Izawa M. R. M, Clemett S, Thomas-Keprta K, Van Wal S, Yoshikawa M, Bellerose J, Bhaskaran S, Boyles C, Chesley S. R, Farnocchia D, Harbison A, Kennedy B, Knight A, Martinez-Vlasoff N, Mastrodemos N, McElrath T, Owen W, Park R, Rush B, Swanson L, Takahashi Y, Velez D, Yetter K, Thayer C, Adam C, Antreasian P, Bauman J, Bryan C, Carcich B, Corvin M, Geeraert J, Hoffman J, Leonard J. M, Lessac-Chenen E, Levine A, McAdams J, McCarthy L, Nelson D, Page B, Pelgrift J, Sahr E, Stakkestad K, Stanbridge D, Wibben D, Williams B, Williams K, Wolff P, Hayne P, Kubitschek D, Fulchignoni M, Hasselmann P, Merlin F, Praet A, Billett O, Boggs A, Buck B, Carlson-Kelly S, Cerna J, Chaffin K, Church E, Coltrin M, Daly J, Deguzman A, Dubisher R, Eckart D, Ellis D, Falkenstern P, Fisher A, Fisher M. E, Fleming P, Fortney K, Francis S, Freund S, Gonzales S, Haas P, Hasten A, Hauf D, Hilbert A, Howell D, Jaen F, Jayakody N, Jenkins M, Johnson K, Lefevre M, Ma H, Mario C, Martin K, May C, McGee M, Miller B, Miller C, Miller G, Mirfakhrai A, Muhle E, Norman C, Olds R, Parish C, Ryle M, Schmitzer M, Sherman P, Skeen M, Susak M, Sutter B, Tran Q, Welch C, Witherspoon R, Wood J, Zareski J, Arvizu-Jakubicki M, Audi E, Bandrowski R, Becker T. L, Bendall S, Bloomenthal H, Blum D

NATURE ASTRONOMY Vol. 3 ( 4 ) page： 341 - 351 2019.4

Evidence for widespread hydrated minerals on asteroid (101955) Bennu Reviewed Open Access

Hamilton V. E, Simon A. A, Christensen P. R, Reuter D. C, Clark B. E, Barucci M. A, Bowles N. E, Boynton W. V, Brucato J. R, Cloutis E. A, Connolly H. C. Jr, Hannah K, L. Donaldson, Emery J. P, Enos H. L, Fornasier S, Haberle C. W, Hanna R. D, Howell E. S, Kaplan H. H, Keller L. P, Lantz C, Li J-Y, Lim L. F, McCoy T. J, Merlins F, Nolan M. C, Praet A, Rozitis B, Sandford S. A, Schrader D. L, Thomas C. A, Zou X-D, Lauretta D. S, Highsmith D. E, Small J, Vokrouhlicky D, Brown E, Warren T, Brunet C, Chicoine R. A, Desjardins S, Gaudreau D, Haltigin T, Millington-Veloza S, Rubi A, Aponte J, Gorius N, Lunsford A, Allen B, Grindlay J, Guevel D, Hoak D, Hong J, Bayron J, Golubov O, Sanchez P, Stromberg J, Hirabayashi M, Hartzell C. M, Oliver S, Rascon M, Harch A, Joseph J, Squyres S, Richardson D, McGraw L, Ghent R, Binzel R. P, Al Asad M. M, Johnson C. L, Philpott L, Susorney H. C. M, Ciceri F, Hildebrand A. R, Ibrahim E-M, Breitenfeld L, Glotch T, Rogers A. D, Ferrone S, Campins H, Fernandez Y, Chang W, Cheuvront A, Trang D, Tachibana S, Yurimoto H, Poggiali G, Pajola M, Dotto E, Epifani E. Mazzotta, Crombie M. K, Izawa M. R. M, de Leon J, Licandro J, Garcia J, L. Rizos, Clemett S, Thomas-Keprta K, Van Wal S, Yoshikawa M, Bellerose J, Bhaskaran S, Boyles C, Chesley S. R, Elder C. M, Farnocchia D, Harbison A, Kennedy B, Knight A, Martinez-Vlasoff N, Mastrodemos N, McElrath T, Owen W, Park R, Rush B, Swanson L, Takahashi Y, Velez D, Yetter K, Thayer C, Adam C, Antreasian P, Bauman J, Bryan C, Carcich B, Corvin M, Geeraert J, Hoffman J, Leonard J. M, Lessac-Chenen E, Levine A, McAdams J, McCarthy L, Nelson D, Page B, Pelgrift J, Sahr E, Stakkestad K, Stanbridge D, Wibben D, Williams B, Williams K, Wolff P, Hayne P, Kubitschek D, Deshapriya J. D. P, Fulchignoni M, Hasselmann P, Merlin F, Bierhaus E. B, Billett O, Boggs A, Buck B, Carlson-Kelly S, Cerna J, Chaffin K, Church E, Coltrin M, Daly J, Deguzman A, Dubisher R, Eckart D, Ellis D, Falkenstern P, Fisher A, Fisher M. E, Fleming P, Fortney K, Francis S, Freund S, Gonzales S, Haas P, Hasten A, Hauf D, Hilbert A, Howell D, Jaen F, Jayakody N, Jenkins M, Johnson K, Lefevre M, Ma H, Mario C, Martin K, May C, McGee M, Miller B, Miller C, Miller G, Mirfakhrai A, Muhle E, Norman C, Olds R, Parish C, Ryle M, Schmitzer M, Sherman P, Skeen M, Susak M, Sutter B, Tran Q, Welch C, Witherspoon R, Wood J, Zareski J, Arvizu-Jakubicki M, Asphaug E, Audi E, Ballouz R-L, Bandrowski R, Becker K. J, Becker T. L, Bendall S, Bennett C. A, Bloomenthal H, Blum D, Brodbeck J, Burke K. N, Chojnacki M, Colpo A, Contreras J, Cutts J, d'Aubigny C, Y. Drouet, Dean D, DellaGiustina D. N, Diallo B, Drinnon D, Drozd K, Enos R, Fellows C, Ferro T, Fisher M. R, Fitzgibbon G, Fitzgibbon M, Forelli J, Forrester T, Gal

NATURE ASTRONOMY Vol. 3 ( 4 ) page： 332 - 340 2019.4

Craters, boulders and regolith of (101955) Bennu indicative of an old and dynamic surface Reviewed International coauthorship

Walsh, K.J., Jawin, E.R., Ballouz, R.-L., Barnouin, O.S., Bierhaus, E.B., Connolly, H.C., Molaro, J.L., McCoy, T.J., Delbo’, M., Hartzell, C.M., Pajola, M., Schwartz, S.R., Trang, D., Asphaug, E., Becker, K.J., Beddingfield, C.B., Bennett, C.A., Bottke, W.F., Burke, K.N., Clark, B.C., Daly, M.G., DellaGiustina, D.N., Dworkin, J.P., Elder, C.M., Golish, D.R., Hildebrand, A.R., Malhotra, R., Marshall, J., Michel, P., Nolan, M.C., Perry, M.E., Rizk, B., Ryan, A., Sandford, S.A., Scheeres, D.J., Susorney, H.C.M., Thuillet, F., Lauretta, D.S., Highsmith, D.E., Small, J., Vokrouhlický, D., Bowles, N.E., Brown, E., Donaldson Hanna, K.L., Warren, T., Brunet, C., Chicoine, R.A., Desjardins, S., Gaudreau, D., Haltigin, T., Millington-Veloza, S., Rubi, A., Aponte, J., Gorius, N., Lunsford, A., Allen, B., Grindlay, J., Guevel, D., Hoak, D., Hong, J., Schrader, D.L., Bayron, J., Golubov, O., Sánchez, P., Stromberg, J., Hirabayashi, M., Hartzell, C.M., Oliver, S., Rascon, M., Harch, A., Joseph, J., Squyres, S., Richardson, D., Emery, J.P., McGraw, L., Ghent, R., Binzel, R.P., Al Asad, M.M., Johnson, C.L., Philpott, L., Susorney, H.C.M., Cloutis, E.A., Hanna, R.D., Connolly, H.C., Ciceri, F., Hildebrand, A.R., Ibrahim, E.-M., Breitenfeld, L., Glotch, T., Rogers, A.D., Clark, B.E., Ferrone, S., Thomas, C.A., Campins, H., Fernandez, Y., Chang, W., Cheuvront, A., Trang, D., Tachibana, S., Yurimoto, H., Brucato, J.R., Poggiali, G., Pajola, M., Dotto, E., Epifani, E.M., Crombie, M.K., Lantz, C., Izawa, M.R.M., de Leon, J., Licandro, J., Garcia, J.L.R., Clemett, S., Thomas-Keprta, K., Van wal, S., Yoshikawa, M., Bellerose, J., Bhaskaran, S., Boyles, C., Chesley, S.R., Elder, C.M., Farnocchia, D., Harbison, A., Kennedy, B., Knight, A., Martinez-Vlasoff, N., Mastrodemos, N., McElrath, T., Owen, W., Park, R., Rush, B., Swanson, L., Takahashi, Y., Velez, D., Yetter, K., Thayer, C., Adam, C., Antreasian, P., Bauman, J., Bryan, C., Carcich, B., Corvin, M., Geeraert, J., Hoffman, J., Leonard, J.M., Lessac-Chenen, E., Levine, A., McAdams, J., McCarthy, L., Nelson, D., Page, B., Pelgrift, J., Sahr, E., Stakkestad, K., Stanbridge, D., Wibben, D., Williams, B., Williams, K., Wolff, P., Hayne, P., Kubitschek, D., Barucci, M.A., Deshapriya, J.D.P., Fornasier, S., Fulchignoni, M., Hasselmann, P., Merlin, F., Praet, A., Bierhaus, E.B., Billett, O., Boggs, A., Buck, B., Carlson-Kelly, S., Cerna, J., Chaffin, K., Church, E., Coltrin, M., Daly, J., Deguzman, A., Dubisher, R., Eckart, D., Ellis, D., Falkenstern, P., Fisher, A., Fisher, M.E., Fleming, P., Fortney, K., Francis, S., Freund, S., Gonzales, S., Haas, P., Hasten, A., Hauf, D., Hilbert, A., Howell, D., Jaen, F., Jayakody, N., Jenkins, M., Johnson, K., Lefevre, M., Ma, H., Mario, C., Martin, K., May, C., McGee, M., Miller, B., Miller, C., Miller, G., Mirfakhrai, A., Muhle, E., Norman, C., Olds, R., Parish, C., Ryle, M., Schmitzer, M., Sherman, P., Skeen, M., Susak, M., Sutter, B., Tran, Q., Welch, C., Witherspoon, R., Wood, J., Zareski, J., Arvizu-Jakubicki, M., Asphaug, E., Audi, E., Ballouz, R.-L., Bandrowski, R., Becker, K.J., Becker, T.L., Bendall, S., Bennett, C.A., Bloomenthal, H., Blum, D., Boynton, W.V., Brodbeck, J., Burke, K.N., Chojnacki, M., Colpo, A., Contreras, J., Cutts, J., Drouet d’Aubigny, C.Y., Dean, D., DellaGiustina, D.N., Diallo, B., Drinnon, D., Drozd, K., Enos, H.L., Enos, R., Fellows, C., Ferro, T., Fisher, M.R., Fitzgibbon, G., Fitzgibbon, M., Forelli, J., Forrester, T., Galinsky, I., Garcia, R., Gardner, A., Golish, D.R., Habib, N., Hamara, D., Hammond, D., Hanley, K., Harshman, K., Hergenrother, C.W., Herzog, K., Hill, D., Hoekenga, C., Hooven, S., Howell, E.S., Huettner, E., Janakus, A., Jones, J., Kareta, T.R., Kidd, J., Kingsbury, K., Balram-Knutson, S.S., Koelbel, L., Kreiner, J., Lambert, D., Lauretta, D.S., Lewin, C., Lovelace, B., Loveridge, M., Lujan, M., Maleszewski, C.K., Malhotra, R., Marchese, K., McDonough, E., Mogk, N., Morrison, V., Morton, E., Munoz, R., Nelson, J., Nolan, M.C., Padilla, J., Pennington, R., Polit, A., Ramos, N., Reddy, V., Riehl, M., Rizk, B., Roper, H.L., Salazar, S., Schwartz, S.R., Selznick, S., Shultz, N., Smith, P.H., Stewart, S., Sutton, S., Swindle, T., Tang, Y.H., Westermann, M., Wolner, C.W.V., Worden, D., Zega, T., Zeszut, Z., Bjurstrom, A., Bloomquist, L., Dickinson, C., Keates, E., Liang, J., Nifo, V., Taylor, A., Teti, F., Caplinger, M., Bowles, H., Carter, S., Dickenshied, S., Doerres, D., Fisher, T., Hagee, W., Hill, J., Miner, M., Noss, D., Piacentine, N., Smith, M., Toland, A., Wren, P., Bernacki, M., Munoz, D.P., Watanabe, S., Sandford, S.A., Aqueche, A., Ashman, B., Barker, M., Bartels, A., Berry, K., Bos, B., Burns, R., Calloway, A., Carpenter, R., Castro, N., Cosentino, R., Donaldson, J., Dworkin, J.P., Cook, J.E., Emr, C., Everett, D., Fennell, D., Fleshman, K., Folta, D., Gallagher, D., Garvin, J., Getzandanner, K., Glavin, D., Hull, S., Hyde, K., Ido, H., Ingegneri, A., Jones, N., Kaotira, P., Lim, L.F., Liounis, A., Lorentson, C., Lorenz, D., Lyzhoft, J., Mazarico, E.M., Mink, R., Moore, W., Moreau, M., Mullen, S., Nagy, J., Neumann, G., Nuth, J., Poland, D., Reuter, D.C., Rhoads, L., Rieger, S., Rowlands, D., Sallitt, D., Scroggins, A., Shaw, G., Simon, A.A., Swenson, J., Vasudeva, P., Wasser, M., Zellar, R., Grossman, J., Johnston, G., Morris, M., Wendel, J., Burton, A., Keller, L.P., McNamara, L., Messenger, S., Nakamura-Messenger, K., Nguyen, A., Righter, K., Queen, E., Bellamy, K., Dill, K., Gardner, S., Giuntini, M., Key, B., Kissell, J., Patterson, D., Vaughan, D., Wright, B., Gaskell, R.W., Le Corre, L., Li, J.-Y., Molaro, J.L., Palmer, E.E., Siegler, M.A., Tricarico, P., Weirich, J.R., Zou, X.-D., Ireland, T., Tait, K., Bland, P., Anwar, S., Bojorquez-Murphy, N., Christensen, P.R., Haberle, C.W., Mehall, G., Rios, K., Franchi, I., Rozitis, B., Beddingfield, C.B., Marshall, J., Brack, D.N., French, A.S., McMahon, J.W., Scheeres, D.J., Jawin, E.R., McCoy, T.J., Russell, S., Killgore, M., Bottke, W.F., Hamilton, V.E., Kaplan, H.H., Walsh, K.J., Bandfield, J.L., Clark, B.C., Chodas, M., Lambert, M., Masterson, R.A., Daly, M.G., Freemantle, J., Seabrook, J.A., Barnouin, O.S., Craft, K., Daly, R.T., Ernst, C., Espiritu, R.C., Holdridge, M., Jones, M., Nair, A.H., Nguyen, L., Peachey, J., Perry, M.E., Plescia, J., Roberts, J.H., Steele, R., Turner, R., Backer, J., Edmundson, K., Mapel, J., Milazzo, M., Sides, S., Manzoni, C., May, B., Delbó, M., Libourel, G., Michel, P., Ryan, A., Thuillet, F., Marty, B.

Nature Geoscience Vol. 12 ( 4 ) page： 242 - + 2019.4

The Western Bulge of 162173 Ryugu Formed as a Result of a Rotationally Driven Deformation Process Reviewed International coauthorship Open Access

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

Astrophysical Journal Letters Vol. 874 ( 1 ) 2019.3

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal)

© 2019. The American Astronomical Society. All rights reserved.. 162173 Ryugu, the target of Hayabusa2, has a round shape with an equatorial ridge, which is known as a spinning top shape. A strong centrifugal force is a likely contributor to Ryugu's top-shaped features. Observations by the Optical Navigation Camera on board Hayabusa2 show a unique longitudinal variation in geomorphology; the western side of this asteroid, later called the western bulge, has a smooth surface and a sharp equatorial ridge, compared to the other side. Here, we propose a structural deformation process that generated the western bulge. Applying the mission-derived shape model, we employ a finite element model technique to analyze the locations that experience structural failure within the present shape. Assuming that materials are uniformly distributed, our model shows the longitudinal variation in structurally failed regions when the spin period is shorter than ∼3.75 hr. Ryugu is structurally intact in the subsurface region of the western bulge while other regions are sensitive to structural failure. We infer that this variation is indicative of the deformation process that occurred in the past, and the western bulge is more relaxed structurally than the other region. Our analysis also shows that this deformation process might occur at a spin period between ∼3.5 and ∼3.0 hr, providing the cohesive strength ranging between ∼4 and ∼10 Pa.

DOI： 10.3847/2041-8213/ab0e8b

The operational environment and rotational acceleration of asteroid (101955) Bennu from OSIRIS-REx observations Reviewed International coauthorship Open Access

Hergenrother C. W, Maleszewski C. K, Nolan M. C, Li J-Y, d'Aubigny C, Y. Drouet, Shelly F. C, Howell E. S, Kareta T. R, Izawa M. R. M, Barucci M. A, Bierhaus E. B, Campins H, Chesley S. R, Clark B. E, Christensen E. J, DellaGiustina D. N, Fornasier S, Golish D. R, Hartzell C. M, Rizk B, Scheeres D. J, Smith P. H, Zou X-D, Lauretta D. S, Highsmith D. E, Small J, Vokrouhlicky D, Bowles N. E, Brown E, Hanna K, L. Donaldson, Warren T, Brunet C, Chicoine R. A, Desjardins S, Gaudreau D, Haltigin T, Millington-Veloza S, Rubi A, Aponte J, Gorius N, Lunsford A, Allen B, Grindlay J, Guevel D, Hoak D, Hong J, Schrader D. L, Bayron J, Golubov O, Sanchez P, Stromberg J, Hirabayashi M, Oliver S, Rascon M, Harch A, Joseph J, Squyres S, Richardson D, Emery J. P, McGraw L, Ghent R, Binzel R. P, Al Asad M. M, Johnson C. L, Philpott L, Susorney H. C. M, Cloutis E. A, Hanna R. D, Connolly H. C. Jr, Ciceri F, Hildebrand A. R, Ibrahim E-M, Breitenfeld L, Glotch T, Rogers A. D, Ferrone S, Thomas C. A, Fernandez Y, Chang W, Cheuvront A, Trang D, Tachibana S, Yurimoto H, Brucato J. R, Poggiali G, Pajola M, Dotto E, Epifani E. Mazzotta, Crombie M. K, Lantz C, de Leon J, Licandro J, Rizos Garcia J. L, Clemett S, Thomas-Keprta K, Van Wal S, Yoshikawa M, Bellerose J, Bhaskaran S, Boyles C, Elder C. M, Farnocchia D, Harbison A, Kennedy B, Knight A, Martinez-Vlasoff N, Mastrodemos N, McElrath T, Owen W, Park R, Rush B, Swanson L, Takahashi Y, Velez D, Yetter K, Thayer C, Adam C, Antreasian P, Bauman J, Bryan C, Carcich B, Corvin M, Geeraert J, Hoffman J, Leonard J. M, Lessac-Chenen E, Levine A, McAdams J, McCarthy L, Nelson D, Page B, Pelgrift J, Sahr E, Stakkestad K, Stanbridge D, Wibben D, Williams B, Williams K, Wolff P, Hayne P, Kubitschek D, Deshapriya J. D. P, Fulchignoni M, Hasselmann P, Merlin F, Praet A, Billett O, Boggs A, Buck B, Carlson-Kelly S, Cerna J, Chaffin K, Church E, Coltrin M, Daly J, Deguzman A, Dubisher R, Eckart D, Ellis D, Falkenstern P, Fisher A, Fisher M. E, Fleming P, Fortney K, Francis S, Freund S, Gonzales S, Haas P, Hasten A, Hauf D, Hilbert A, Howell D, Jaen F, Jayakody N, Jenkins M, Johnson K, Lefevre M, Ma H, Mario C, Martin K, May C, McGee M, Miller B, Miller C, Miller G, Mirfakhrai A, Muhle E, Norman C, Olds R, Parish C, Ryle M, Schmitzer M, Sherman P, Skeen M, Susak M, Sutter B, Tran Q, Welch C, Witherspoon R, Wood J, Zareski J, Arvizu-Jakubicki M, Asphaug E, Audi E, Ballouz R-L, Bandrowski R, Becker K. J, Becker T. L, Bendall S, Bennett C. A, Bloomenthal H, Blum D, Boynton W. V, Brodbeck J, Burke K. N, Chojnacki M, Colpo A, Contreras J, Cutts J, Dean D, Diallo B, Drinnon D, Drozd K, Enos H. L, Enos R, Fellows C, Ferro T, Fisher M. R, Fitzgibbon G, Fitzgibbon M, Forelli J, Forrester T, Galinsky I, Garcia R, Gardner A

NATURE COMMUNICATIONS Vol. 10 2019.3

Hayabusa2-Sample return and kinetic impact mission to near-earth asteroid Ryugu Reviewed

Tsuda Yuichi, Yoshikawa Makoto, Saiki Takanao, Nakazawa Satoru, Watanabe Sei-ichiro

ACTA ASTRONAUTICA Vol. 156 page： 387 - 393 2019.3

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

S. Watanabe, M. Hirabayashi, Naru 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. 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

Proceedings of Lunar and Planetary Science Conference Vol. 50 page： 1265 2019.3

Thermal Imaging of C-Type Near Earth Asteroid 162173 Ryugu by Thermal Imfrared Imager TIR on Hayabusa2

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

50th Lunar and Planetary Science Conference Vol. 2132 page： 1325 - 1326 2019.3

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, N. Hirata, N. 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

Proceedings of Lunar and Planetary Science Conference 2019.3

Landing site selection and landing dispersion analysis for the Hayabusa2 mission Reviewed

S. Kikuchi, T. Saiki, F. Terui, Y. Takei, K. Yoshikawa, N. Ogawa, G. Ono, Y. Mimasu, H. Sawada, N. Shibata, T. Morota, N. Hirata, N. Hirata, T. Michikami, C. Honda, Y. Yokota, H. Yabuta, M. Yoshikawa, S. Watanabe, Y. Tsuda

Proceedings of the International Astronautical Congress, IAC Vol. 2019-October 2019

Language：English Publishing type：Research paper (international conference proceedings)

One of the primary operations in the Hayabusa2 mission is touchdown on the asteroid Ryugu, which was successfully performed on February 21st, 2019. Because of the abundance of boulders on the asteroid surface, it was challenging to guarantee a safe and secure landing. To identify a promising landing site and design a feasible landing trajectory even under such a situation, this research develops detailed site selection and dispersion analysis strategies. The dispersion of the landing points is computed by a Monte Carlo simulation. Moreover, the distributions of landing conditions, such as a surface contact angle and a clearance distance, are analyzed, validating the feasibility of the touchdown operation. Consequently, a circular area with a radius of 3 m was selected as a safe landing site, leading to the successful landing.

Publisher Correction: Craters, boulders and regolith of (101955) Bennu indicative of an old and dynamic surface (Nature Geoscience, (2019), 10.1038/s41561-019-0326-6) Reviewed International coauthorship Open Access

Walsh, K.J., Jawin, E.R., Ballouz, R.-L., Barnouin, O.S., Bierhaus, E.B., Connolly, H.C., Molaro, J.L., McCoy, T.J., Delbo’, M., Hartzell, C.M., Pajola, M., Schwartz, S.R., Trang, D., Asphaug, E., Becker, K.J., Beddingfield, C.B., Bennett, C.A., Bottke, W.F., Burke, K.N., Clark, B.C., Daly, M.G., DellaGiustina, D.N., Dworkin, J.P., Elder, C.M., Golish, D.R., Hildebrand, A.R., Malhotra, R., Marshall, J., Michel, P., Nolan, M.C., Perry, M.E., Rizk, B., Ryan, A., Sandford, S.A., Scheeres, D.J., Susorney, H.C.M., Thuillet, F., Lauretta, D.S., Highsmith, D.E., Small, J., Vokrouhlický, D., Bowles, N.E., Brown, E., Hanna, K.L.D., Warren, T., Brunet, C., Chicoine, R.A., Desjardins, S., Gaudreau, D., Haltigin, T., Millington-Veloza, S., Rubi, A., Aponte, J., Gorius, N., Lunsford, A., Allen, B., Grindlay, J., Guevel, D., Hoak, D., Hong, J., Schrader, D.L., Bayron, J., Golubov, O., Sánchez, P., Stromberg, J., Hirabayashi, M., Hartzell, C.M., Oliver, S., Rascon, M., Harch, A., Joseph, J., Squyres, S., Richardson, D., Emery, J.P., McGraw, L., Ghent, R., Binzel, R.P., Asad, M.M.A., Johnson, C.L., Philpott, L., Susorney, H.C.M., Cloutis, E.A., Hanna, R.D., Connolly, H.C., Ciceri, F., Hildebrand, A.R., Ibrahim, E.-M., Breitenfeld, L., Glotch, T., Rogers, A.D., Clark, B.E., Ferrone, S., Thomas, C.A., Campins, H., Fernandez, Y., Chang, W., Cheuvront, A., Trang, D., Tachibana, S., Yurimoto, H., Brucato, J.R., Poggiali, G., Pajola, M., Dotto, E., Epifani, E.M., Crombie, M.K., Lantz, C., Izawa, M.R.M., de Leon, J., Licandro, J., Garcia, J.L.R., Clemett, S., Thomas-Keprta, K., Van wal, S., Yoshikawa, M., Bellerose, J., Bhaskaran, S., Boyles, C., Chesley, S.R., Elder, C.M., Farnocchia, D., Harbison, A., Kennedy, B., Knight, A., Martinez-Vlasoff, N., Mastrodemos, N., McElrath, T., Owen, W., Park, R., Rush, B., Swanson, L., Takahashi, Y., Velez, D., Yetter, K., Thayer, C., Adam, C., Antreasian, P., Bauman, J., Bryan, C., Carcich, B., Corvin, M., Geeraert, J., Hoffman, J., Leonard, J.M., Lessac-Chenen, E., Levine, A., McAdams, J., McCarthy, L., Nelson, D., Page, B., Pelgrift, J., Sahr, E., Stakkestad, K., Stanbridge, D., Wibben, D., Williams, B., Williams, K., Wolff, P., Hayne, P., Kubitschek, D., Barucci, M.A., Deshapriya, J.D.P., Fornasier, S., Fulchignoni, M., Hasselmann, P., Merlin, F., Praet, A., Bierhaus, E.B., Billett, O., Boggs, A., Buck, B., Carlson-Kelly, S., Cerna, J., Chaffin, K., Church, E., Coltrin, M., Daly, J., Deguzman, A., Dubisher, R., Eckart, D., Ellis, D., Falkenstern, P., Fisher, A., Fisher, M.E., Fleming, P., Fortney, K., Francis, S., Freund, S., Gonzales, S., Haas, P., Hasten, A., Hauf, D., Hilbert, A., Howell, D., Jaen, F., Jayakody, N., Jenkins, M., Johnson, K., Lefevre, M., Ma, H., Mario, C., Martin, K., May, C., McGee, M., Miller, B., Miller, C., Miller, G., Mirfakhrai, A., Muhle, E., Norman, C., Olds, R., Parish, C., Ryle, M., Schmitzer, M., Sherman, P., Skeen, M., Susak, M., Sutter, B., Tran, Q., Welch, C., Witherspoon, R., Wood, J., Zareski, J., Arvizu-Jakubicki, M., Asphaug, E., Audi, E., Ballouz, R.-L., Bandrowski, R., Becker, K.J., Becker, T.L., Bendall, S., Bennett, C.A., Bloomenthal, H., Blum, D., Boynton, W.V., Brodbeck, J., Burke, K.N., Chojnacki, M., Colpo, A., Contreras, J., Cutts, J., Drouet d’Aubigny, C.Y., Dean, D., DellaGiustina, D.N., Diallo, B., Drinnon, D., Drozd, K., Enos, H.L., Enos, R., Fellows, C., Ferro, T., Fisher, M.R., Fitzgibbon, G., Fitzgibbon, M., Forelli, J., Forrester, T., Galinsky, I., Garcia, R., Gardner, A., Golish, D.R., Habib, N., Hamara, D., Hammond, D., Hanley, K., Harshman, K., Hergenrother, C.W., Herzog, K., Hill, D., Hoekenga, C., Hooven, S., Howell, E.S., Huettner, E., Janakus, A., Jones, J., Kareta, T.R., Kidd, J., Kingsbury, K., Balram-Knutson, S.S., Koelbel, L., Kreiner, J., Lambert, D., Lauretta, D.S., Lewin, C., Lovelace, B., Loveridge, M., Lujan, M., Maleszewski, C.K., Malhotra, R., Marchese, K., McDonough, E., Mogk, N., Morrison, V., Morton, E., Munoz, R., Nelson, J., 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Nature Geoscience Vol. 12 ( 5 ) page： 399 - 399 2019

Language：English Publishing type：Research paper (scientific journal)

© 2019, Springer Nature Limited. In the version of this Article originally published, in the sentence “There are three identified boulders with long axes exceeding 40 m and more than 200 boulders larger than 10 m2”, the term “10 m2” should have been “10 m (ref.2)”. This has now been corrected.

DOI： 10.1038/s41561-019-0360-4

Hayabuas2 mission status: Landing, roving and cratering on asteroid Ryugu Reviewed International journal

Yuichi Tsuda, Takanao Saiki, Fuyuto Terui, Satoru Nakazawa, Makoto Yoshikawa, Sei-Ichiro Watanabe

Proceedings of the International Astronautical Congress, IAC Vol. 2019- 2019

Language：English Publishing type：Research paper (international conference proceedings) Publisher：International Astronautical Federation, IAF

Hayabusa2 arrived at the C-type asteroid Ryugu in June 2018. During one and a half year of the Ryugu-proximity operation, we succeeded in two rovers landing, one lander landing, two spacecraft touchdown/sample collection, one kinetic impact operation and two tiny reflective balls and one rover orbiting. Among the two successful touchdowns, the second one succeeded in collecting subsurface material exposed by the kinetic impact operation. This paper describes the asteroid proximity operation activity of the Hayabuas2 mission, and gives an overview of the achievements done so far. Some important engineering and scientific activities, which have been done in synchronous with the spacecraft operations to tackle with unexpected Ryugu environment, are also described.

Cruise status of Hayabusa2: Round trip mission to asteroid 162173 Ryugu Reviewed

Yuichi Tsuda, Sei-ichiro Watanabe, Takanao Saiki, Makoto Yoshikawa, Satoru Nakazawa

ACTA ASTRONAUTICA Vol. 136 page： 176 - 181 2017.7

Language：English Publishing type：Research paper (scientific journal) Publisher：PERGAMON-ELSEVIER SCIENCE LTD

The Japan Aerospace Exploration Agency launched an asteroid sample return spacecraft "Hayabusa2" on December 3, 2014 by the Japanese H2A launch vehicle. Hayabusa2 aims at the round trip mission to the asteroid 162173 Ryugu. Hayabusa2 successfully conducted the Earth gravity assist on December 3, 2015, and now the spacecraft is flying toward Ryugu with the microwave discharge ion engine as the means of propulsion. As of September 2016, 1346 h of the ion engine operation has been achieved as planned. Three touch downs/sample collections, one kinetic impact/crater generation, four surface rovers deployment and many other in-situ observations are planned in the asteroid proximity phase. The operation team will perform extensive operation practice/rehearsal using a hardware-in-the-loop simulator in the year 2017 to be ready for the asteroid arrival in the summer 2018.

DOI： 10.1016/j.actaastro.2017.03.015

The Camera of the MASCOT Asteroid Lander on Board Hayabusa 2 Reviewed International coauthorship International journal

R. Jaumann, N. Schmitz, A. Koncz, H. Michaelis, S. E. Schroeder, S. Mottola, F. Trauthan, H. Hoffmann, T. Roatsch, D. Jobs, J. Kachlicki, B. Pforte, R. Terzer, M. Tschentscher, S. Weisse, U. Mueller, L. Perez-Prieto, B. Broll, A. Kruselburger, T. -M. Ho, J. Biele, S. Ulamec, C. Krause, M. Grott, J. -P. Bibring, S. Watanabe, S. Sugita, T. Okada, M. Yoshikawa, H. Yabuta

SPACE SCIENCE REVIEWS Vol. 208 ( 1-4 ) page： 375 - 400 2017.7

Language：English Publishing type：Research paper (scientific journal) Publisher：SPRINGER

The MASCOT Camera (MasCam) is part of the Mobile Asteroid Surface Scout (MASCOT) lander's science payload. MASCOT has been launched to asteroid (162173) Ryugu onboard JAXA's Hayabusa 2 asteroid sample return mission on Dec 3rd, 2014. It is scheduled to arrive at Ryugu in 2018, and return samples to Earth by 2020. MasCam was designed and built by DLR's Institute of Planetary Research, together with Airbus-DS Germany. The scientific goals of the MasCam investigation are to provide ground truth for the orbiter's remote sensing observations, provide context for measurements by the other lander instruments (radiometer, spectrometer and magnetometer), the orbiter sampling experiment, and characterize the geological context, compositional variations and physical properties of the surface (e.g. rock and regolith particle size distributions). During daytime, clear filter images will be acquired. During night, illumination of the dark surface is performed by an LED array, equipped with 4 x 36 monochromatic light-emitting diodes (LEDs) working in four spectral bands. Color imaging will allow the identification of spectrally distinct surface units. Continued imaging during the surface mission phase and the acquisition of image series at different sun angles over the course of an asteroid day will contribute to the physical characterization of the surface and also allow the investigation of time-dependent processes and to determine the photometric properties of the regolith. The MasCam observations, combined with the MASCOT hyperspectral microscope (MMEGA) and radiometer (MARA) thermal observations, will cover a wide range of observational scales and serve as a strong tie point between Hayabusa 2's remote-sensing scales (10(3)-10(-3) m) and sample scales (10(-3)-10(-6) m). The descent sequence and the close-up images will reveal the surface features over a broad range of scales, allowing an assessment of the surface's diversity and close the gap between the orbital observations and those made by the in-situ measurements. The MasCam is mounted inside the lander slightly tilted, such that the center of its 54.8 degrees square field-of-view is directed towards the surface at an angle of 22 degrees with respect to the surface plane. This is to ensure that both the surface close to the lander and the horizon are observable. The camera optics is designed according to the Scheimpflug principle, thus that the entire scene along the camera's depth of field (150 mm to infinity) is in focus. The camera utilizes a 1024 x 1024 pixel CMOS sensor sensitive in the 400-1000 nm wavelength range, peaking at 600-700 nm. Together with the f-16 optics, this yields a nominal ground resolution of 150 micron/px at 150 mm distance (diffraction limited). The camera flight model has undergone standard radiometric and geometric calibration both at the component and system (lander) level. MasCam relies on the use of wavelet compression to maximize data return within stringent mission downlink limits. All calibration and flight data products will be generated and archived in the Planetary Data System in PDS image format.

DOI： 10.1007/s11214-016-0263-2

NIRS3: The Near Infrared Spectrometer on Hayabusa2 Reviewed International coauthorship

Iwata Takahiro, Kitazato Kohei, Abe Masanao, Ohtake Makiko, Arai Takehiko, Arai Tomoko, Hirata Naru, Hiroi Takahiro, Honda Chikatoshi, Imae Naoya, Komatsu Mutsumi, Matsunaga Tsuneo, Matsuoka Moe, Matsuura Shuji, Nakamura Tomoki, Nakato Aiko, Nakauchi Yusuke, Osawa Takahito, Senshu Hiroki, Takagi Yasuhiko, Tsumura Kohji, Takato Naruhisa, Watanabe Sei-ichiro, Barucci Maria Antonietta, Palomba Ernesto, Ozaki Masanobu

SPACE SCIENCE REVIEWS Vol. 208 ( 1-4 ) page： 317 - 337 2017.7

Language：English Publishing type：Research paper (scientific journal) Publisher：SPRINGER

NIRS3: The Near Infrared Spectrometer is installed on the Hayabusa2 spacecraft to observe the target C-type asteroid 162173 Ryugu at near infrared wavelengths of 1.8 to 3.2 mu m. It aims to obtain reflectance spectra in order to detect absorption bands of hydrated and hydroxide minerals in the 3 mu m-band. We adopted a linear-image sensor with indium arsenide (InAs) photo diodes and a cooling system with a passive radiator to achieve an optics temperature of 188 K (-85 degrees C), which enables to retaining sufficient sensitivity and noise level in the 3 mu m wavelength region. We conducted ground performance tests for the NIRS3 flight model (FM) to confirm its baseline specifications. The results imply that the properties such as the signal-to-noise ratio (SNR) conform to scientific requirements to determine the degree of aqueous alteration, such as CM or CI chondrite, and the stage of thermal metamorphism on the asteroid surface.

DOI： 10.1007/s11214-017-0341-0

Mascot - Preparations for its landing in 2018: A status update from ground and space one year ahead of the landing on ryugu

Christian Ziach, Volodymyr Baturkin, Christian Grimm, Jan Thimo Grundmann, Tra Mi Ho, Caroline Lange, Kaname Sasaki, Nawarat Termtanasombat, Norbert Toth, Elisabet Wejmo, Maximilian Maier, Josef Reill, Hans Jürgen Sedlmayr, Friederike Wolff, Michael Lange, Olaf Mierheim, Jens Biele, Barbara Cozzoni, Cinzia Fantinati, Koen Geurts, Kagan Kayal, Christian Krause, Oliver Küchemann, Michael Maibaum, Stephan Ulamec, Matthias Grott, Ralf Jaumann, Céline Cénac-Morthe, Muriel Deleuze, Clément Dudal, David Granena, Laurence Lorda, Aurélie Moussi, Jean Pierre Bibring, David Hercik, Hans Ulrich Auster, Yuya Mimasu, Tatsuaki Okada, Takanao Saiki, Sathoshi Tanaka, Fuyuto Terui, Yuichi Tsuda, Tomohiro Yamaguchi, Tetsuo Yoshimitsu, Seiichiro Watanabe

Proceedings of the International Astronautical Congress, IAC Vol. 5 page： 2897 - 2904 2017

Language：English Publishing type：Research paper (international conference proceedings)

© Copyright 2017 by the International Astronautical Federation (IAF). All rights reserved. Launched in December 2014 the Japanese spacecraft Hayabusa2 (HY2) and its small passenger MASCOT (Mobile Asteroid surface SCOuT) have meanwhile successfully performed more than half of their 4-year-long voyage to reach their target body, asteroid (162173) Ryugu, formerly referred to as 1999 JU3. While Hayabusa2 is aiming to characterize Ryugu on a global scale and to return samples to Earth, MASCOT's mission is to land on the surface, perform in-situ investigations and thus provide ground truth and context information for the overall Hayabusa2 science activities. The lander was jointly developed by the German Aerospace Centre (DLR) and the Centre National d'Etudes Spatiales (CNES). It is equipped with a sensor suite of four scientific instruments: a hyperspectral IR spectrometer (MicrOmega, IAS Paris), a camera (MasCam, DLR Berlin), a radiometer (MARA, DLR Berlin) and a magnetometer (MasMag, TU Braunschweig) to investigate Ryugu's surface structure, composition and physical properties including its thermal behaviour and magnetization. The planned on surface sequence of measurements will be repeated in a different site after MASCOT's relocation on the asteroid surface. Therefore a mobility subsystem was developed to make MASCOT jump due to applied angular momentum of an eccentric rotating mass inside the system. Since the characteristics of Ryugu such as the exact orientation of the rotation axis, the thermal conditions, shape and surface structure will be known only after arrival of Hayabusa2 in July 2018 there will be only a few weeks available to select a landing site and refine the specific MASCOT mission parameters according to the conditions found, before the landing can take place, in October 2018. MASCOT's on-asteroid lifetime is limited by the capacity of its primary battery which is the main driver to make maximum use of the given time. In order to prepare MASCOT's operation within these constraints, both, space and ground systems have to be well prepared and descent and on-asteroid phases need to be rigorously planned and tested. This paper will summarize the already performed and planned in-flight activities such as health checks, calibration activities, data transfer tests, and will report on MASCOTs overall health state. Beyond that, all on-ground activities such as the landing site selection process, the verification of operational timelines, planning and training aspects will be outlined.