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51. High-resolution observations of bright boulders on asteroid Ryugu: 1. Size frequency distribution and morphology

Author

Sugimoto, Chiho, primary, Tatsumi, Eri, additional, Cho, Yuichiro, additional, Morota, Tomokatsu, additional, Honda, Rie, additional, Kameda, Shingo, additional, Yokota, Yosuhiro, additional, Yumoto, Koki, additional, Aoki, Minami, additional, DellaGiustina, Daniella N., additional, Michikami, Tatsuhiro, additional, Hiroi, Takahiro, additional, Domingue, Deborah L., additional, Michel, Patrick, additional, Schröder, Stefan E., additional, Nakamura, Tomoki, additional, Yamada, Manabu, additional, Sakatani, Naoya, additional, Kouyama, Toru, additional, Honda, Chikatoshi, additional, Hayakawa, Masahiko, additional, Matsuoka, Moe, additional, Suzuki, Hidehiko, additional, Yoshioka, Kazuo, additional, Ogawa, Kazunori, additional, Sawada, Hirotaka, additional, Arakawa, Masahiko, additional, Saiki, Takanao, additional, Imamura, Hiroshi, additional, Takagi, Yasuhiko, additional, Yano, Hajime, additional, Shirai, Kei, additional, Okamoto, Chisato, additional, Tsuda, Yuichi, additional, Nakazawa, Satoru, additional, Iijima, Yuichi, additional, and Sugita, Seiji, additional

Published
2021
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52. Opposition Observations of 162173 Ryugu: Normal Albedo Map Highlights Variations in Regolith Characteristics

Author

Yokota, Yasuhiro, primary, Honda, Rie, additional, Tatsumi, Eri, additional, Domingue, Deborah, additional, Schröder, Stefan, additional, Matsuoka, Moe, additional, Morota, Tomokatsu, additional, Sakatani, Naoya, additional, Kameda, Shingo, additional, Kouyama, Toru, additional, Yamada, Manabu, additional, Honda, Chikatoshi, additional, Hayakawa, Masahiko, additional, Cho, Yuichiro, additional, Michikami, Tatsuhiro, additional, Suzuki, Hidehiko, additional, Yoshioka, Kazuo, additional, Sawada, Hirotaka, additional, Ogawa, Kazunori, additional, Yumoto, Kouki, additional, and Sugita, Seiji, additional

Published
2021
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53. Boulder size and shape distributions on asteroid Ryugu

Author

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

Subjects
Number density, 010504 meteorology & atmospheric sciences, Impact processes, Equator, Astronomy and Astrophysics, 01 natural sciences, Regolith, Parent body, Asteroids, Latitude, Optical navigation, Surfaces, Impact crater, Space and Planetary Science, Asteroid, 0103 physical sciences, Geological processes, Asteroid Ryugu, Regoliths, 010303 astronomy & astrophysics, Geomorphology, Geology, 0105 earth and related environmental sciences
Abstract

著者人数: 36名, Accepted: 2019-05-17, 資料番号: SA1190100000

Published
2019

54. Remote Boulder counting and thermal IR temperature curves constrain strength, microporosity, thermal conductivity and grain density of rubble pile Ryugu's rock

Author

Biele, Jens, Grott, Matthias, Hamm, Maximilian, Michel, Patrick, Sugita, Seiji, Sakatani, Naoya, Neumann, Wladimir, Kameda, Shingo, Michikami, Tatsuhiro, and Honda, Chikatoshi

Subjects
Planetenphysik, Ryugu, microporosity, IR temperature, Nutzerzentrum für Weltraumexperimente (MUSC)
Abstract

In this paper, we summarize the findings and deductions for small asteroid Ryugu from Hayabusa2 remote sensing as well as from MASCOT radiometer (MARA) data. Observations cover the VIS (broadband) and MIR (broadband) wavelength ranges. For a typical rock on Ryugu's surface, we find a thermal inertia of 295±18 Jm-2K-1s-1/2 (Hamm+ 2020), a microporosity of 50 ± 3% (Grott+ 2020, Hamm+, 2020), and assuming a CM composition and thus an inferred specific heat capacity of cp = 890 Jkg-1K-1 (± 10%, at an average temperature of 277 K), we estimate a thermal conductivity of 0.069 ± 0.012 Jm-1K-1 at ~277 K. These estimates are based on MARA surface brightness temperature measurements of an arguably (Biele+ 2019) dust-free boulder at MASCOT's landing site obtained over a full diurnal cycle. Those values are consistent with the TIR instrument's global findings (Okada+ 2020). The main source of uncertainty in the thermal inertia estimate is due to the uncertain surface orientation of the boulder top that determines the insolation power. Including a Digital Terrain Model (DTM) of the observed boulder, embedded in the MASCOT landing site (Scholten+, 2019), into the thermal model could reduce this uncertainty significantly. The very high deduced microporosity lets us reasonably estimate the tensile strength of those abundant "cauliflower rocks" (Jaumann+, 2019), ~200-280 kPa (Grott+, 2019).

Published
2021

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

Author

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

Published
2021
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56. The shape distribution of boulders on Asteroid 25143 Itokawa: Comparison with fragments from impact experiments

Author

Michikami, Tatsuhiro, Nakamura, Akiko M., and Hirata, Naru

Subjects
Universities and colleges -- Analysis, Astronomy, Earth sciences
Abstract

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2009.10.008 Byline: Tatsuhiro Michikami (a)(b), Akiko M. Nakamura (c), Naru Hirata (d) Keywords: Asteroids; Asteroid Itokawa; Asteroid Eros; Asteroids, Surfaces; Regoliths Abstract: Laboratory impact experiments have found that the shape of fragments over a broad size range is distributed around the mean value of the axial ratio 2:a2:1, which is independent of a wide range of experimental conditions. We report the shape statistics of boulders with size of 0.1-30m on the surface of Asteroid 25143 Itokawa based on high-resolution images obtained by the Hayabusa spacecraft in order to investigate whether their shape distribution is similar to the distribution obtained for fragments (smaller than 0.1m) in laboratory impact experiments. We also investigated the shapes of boulders with size of 0.1-150m on Asteroid 433 Eros using a few arbitrary selected images by the NEAR spacecraft, in order to compare those with the shapes on Asteroid Itokawa. In addition, the shapes of small- and fast-rotating asteroids (diameter Author Affiliation: (a) Fukushima National College of Technology, Iwaki, Fukushima 970-8034, Japan (b) Planetary and Space Sciences Research Institute, The Open University, Walton Hall, Milton Keynes, MK7 6AA, United Kingdom (c) Graduate School of Science/Center for Planetary Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan (d) Department of Computer Science and Engineering/ARC-Space, CAIST, The University of Aizu, Ikki-machi, Aizu-Wakamatsu, Fukushima 965-8580, Japan Article History: Received 10 June 2009; Revised 30 September 2009; Accepted 4 October 2009

Published
2010

57. Geologic History and Crater Morphology of Asteroid (162173) Ryugu

Author

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

Published
2021
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63. Oblique impact cratering experiments in brittle targets: Implications for elliptical craters on the Moon

Author

Hagermann, Axel, Michikami, Tatsuhiro, Morota, Tomokatsu, Haruyama, Junichi, and Hasegawa, Sunao

Subjects
010504 meteorology & atmospheric sciences, Meteoroid, Projectile, Oblique case, Laboratory experiments, Geometry, Pit crater, Astronomy and Astrophysics, 01 natural sciences, Astrobiology, Elliptical crater, Brittleness, Compressive strength, Impact crater, Angle of incidence (optics), Space and Planetary Science, 0103 physical sciences, Oblique impact cratering process, Moon, 010303 astronomy & astrophysics, Geology, 0105 earth and related environmental sciences
Abstract

Accepted: 2016-11-20, 資料番号: SA1160315000

Published
2017
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64. Macro-Porosity and Grain Density of C-Type Asteroid (162173) Ryugu

Author

Grott, Matthias, Biele, Jens, Michel, P., Sugita, S., Schröder, Stefan, Sakatani, N., Neumann, Wladimir, Kameda, S., Michikami, Tatsuhiro, and Honda, C.

Subjects
Planetengeologie, MASCOT MARA Hayabusa2 Asteroids Ryugu Regolith, Planetenphysik, Institut für Planetenforschung, Nutzerzentrum für Weltraumexperimente (MUSC)
Abstract

The Macroporosity of (162173) Ryugu is estimated based on the observed boulder size-frequency distribution.

Published
2019

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

Author

Scheeres, Daniel J., Barnouin, Olivier S., Michel, Patrick, Schwartz, Stephen R., Hirabayashi, Masatoshi, Tatsumi, Eri, Miyamoto, Hideaki, Komatsu, Goro, Sugita, Seiji, Watanabe, Sei-ichiro, Honda, Chikatoshi, Michikami, Tatsuhiro, Cho, Yuichiro, Morota, Tomokatsu, Hirata, Naru, Hirata, Naoyuki, Sakatani, Naoya, Honda, Rie, Yokota, Yasuhiro, Kameda, Shingo, Suzuki, Hidehiko, Kouyama, Toru, Hayakawa, Masahiko, Matsuoka, Moe, Yoshioka, Kazuo, Ogawa, Kazunori, Sawada, Hirotaka, Yoshikawa, Makoto, Tsuda, Yuichi, Department of Earth and Planetary Sciences [TITECH Tokyo], Tokyo Institute of Technology [Tokyo] (TITECH), Dept of Complex Science and Engineering, Graduate School of Frontier Science, The University of Tokyo (UTokyo), Flight Dynamics and Control (University of Michigan), University of Michigan [Ann Arbor], University of Michigan System-University of Michigan System, Johns Hopkins University Applied Physics Laboratory [Laurel, MD] (APL), Joseph Louis LAGRANGE (LAGRANGE), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Graduate School of Science [Sendai], Tohoku University [Sendai], Department of Earth and Planetary Science [Tokyo], ANR-15-IDEX-0001,UCA JEDI,Idex UCA JEDI(2015), Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency [Sagamihara] (JAXA), Graduate School of Science [Tokyo], and The University of Tokyo (UTokyo)-The University of Tokyo (UTokyo)

Subjects
Earth and Planetary Astrophysics (astro-ph.EP), Centrifugal force, Physics, 010504 meteorology & atmospheric sciences, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], FOS: Physical sciences, Astronomy and Astrophysics, Geometry, Deformation (meteorology), Ridge (differential geometry), 01 natural sciences, Finite element method, Space and Planetary Science, Asteroid, Bulge, 0103 physical sciences, minor planets, asteroids: individual (162173 Ryugu), 010303 astronomy & astrophysics, Spin (aerodynamics), Spinning, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Astrophysics - Earth and Planetary Astrophysics
Abstract

著者人数: 29名, Accepted: 2019-03-11, 資料番号: SA1180406000

Published
2019

67. Lコンドライト隕石に対する衝突実験～コンドリュール中のクラック分布

Author

Michikami, Tatsuhiro, Hagermann, Axel, Tsuchiyama, Akira, Yamaguchi, Hirotaka, Irie, Terunori, Nomura, Keita, Nakamura, Michihiko, Okumura, Satoshi, and Hasegawa, Sunao

Abstract

平成30年度宇宙科学に関する室内実験シンポジウム (2019年2月28日-3月1日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, 2019 Symposium on Laboratory Experiment for Space Science (February 28 - March 1, 2019. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 資料番号: SA6000139021

Published
2019

70. Fragment shapes in impact experiments ranging from cratering to catastrophic disruption

Author

Hagermann, Axel, Michikami, Tatsuhiro, Kadokawa, Tokiyuki, Yoshida, Akifumi, Shimada, Akira, Hasegawa, Sunao, and Tsuchiyama, Akira

Subjects
Rotation period, Physics, 010504 meteorology & atmospheric sciences, Target surface, Projectile, Impact processes, Collisional physics, Mean value, Asteroid Itokawa, mpact processes, Geometry, Astronomy and Astrophysics, 01 natural sciences, Parent body, Asteroids, Astrobiology, Impact crater, 13. Climate action, Asteroid, Space and Planetary Science, 0103 physical sciences, Impact energy, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract

Accepted: 2015-09-23, 資料番号: SA1150217000

Published
2016
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71. 微小衝突破片とイトカワ粒子の形状分布の比較

Author

Michikami, Tatsuhiro, Kadokawa, Tokiyuki, Tsuchiyama, Akira, Hagermann, Axel, Nakano, Tsukasa, Uesugi, Kentaro, and Hasegawa, Sunao

Abstract

平成29年度宇宙科学に関する室内実験シンポジウム (2018年2月26日-27日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, 2018 Symposium on Laboratory Experiment for Space Science (February 26-27, 2018. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 資料番号: SA6000123032

Published
2018

72. Shape and Rotational Motion Models for Tumbling and Monolithic Asteroid 2012 TC4: High Time Resolution Light Curve with the Tomo-e Gozen Camera

Author

Urakawa, Seitaro, primary, Ohsawa, Ryou, additional, Sako, Shigeyuki, additional, Okumura, Shin-ichiro, additional, Sakurai, Yuri, additional, Takahashi, Jun, additional, Imamura, Kazuyoshi, additional, Naito, Hiroyuki, additional, Watanabe, Fumitake, additional, Nagayoshi, Ryoma, additional, Murakami, Yasuhiko, additional, Okazaki, Ryo, additional, Sekiguchi, Tomohiko, additional, Ishiguro, Masateru, additional, Michikami, Tatsuhiro, additional, and Yoshikawa, Makoto, additional

Published
2019
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73. The Western Bulge of 162173 Ryugu Formed as a Result of a Rotationally Driven Deformation Process

Author

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

Published
2019
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74. Detection of Intact Lava Tubes at Marius Hills on the Moon by SELENE (Kaguya) Lunar Radar Sounder

Author

Kaku, Tetsuya, Haruyama, Junichi, Miyake, Wataru, Kumamoto, Atsushi, Ishiyama, Ken, Nishibori, Toshiyuki, Yamamoto, Keiko, Crites, Sarah T., Michikami, Tatsuhiro, Yokota, Yasuhiro, Sood, R., Melosh, H. J., Chappaz, L., Howell, K. C., 郭, 哲也, 春山, 純一, 三宅, 亙, 熊本, 篤志, 石山, 謙, 西堀, 俊幸, 山本, 圭香, 道上, 達広, 横田, 康弘, Kaku, Tetsuya, Haruyama, Junichi, Miyake, Wataru, Kumamoto, Atsushi, Ishiyama, Ken, Nishibori, Toshiyuki, Yamamoto, Keiko, Crites, Sarah T., Michikami, Tatsuhiro, Yokota, Yasuhiro, Sood, R., Melosh, H. J., Chappaz, L., Howell, K. C., 郭, 哲也, 春山, 純一, 三宅, 亙, 熊本, 篤志, 石山, 謙, 西堀, 俊幸, 山本, 圭香, 道上, 達広, and 横田, 康弘

Abstract

著者人数: 14名, Accepted: 2017-09-24

Published
2018

75. 脆性標的に対する斜め衝突クレーター形成実験 ～月の楕円クレーターへの応用

Author

Michikami, Tatsuhiro, Hagermann, Axel, Morota, Tomokatsu, Haruyama, Junichi, and Hasegawa, Sunao

Abstract

平成28年度宇宙科学に関する室内実験シンポジウム (2017年2月27日-28日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, 2017 Symposium on Laboratory Experiment for Space Science (February 27-28, 2017. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 資料番号: SA6000095032

Published
2017

76. Mission Concepts of Unprecedented Zipangu Underworld of the Moon Exploration (UZUME) Project

Author

Haruyama, Junichi, Kawano, Isao, Kubota, Takashi, Otsuki, Masatsugu, Kato, Hiroki, Nishibori, Toshihiko, Iwata, Takahiro, Yamamoto, Yukio, Ishihara, Yoshiaki, Nagamatsu, Aiko, Shimada, Kazuhito, Hasenaka, Toshiaki, Morota, Tomokatsu, Nishino, Masaki N., Hashizume, Ko, Saiki, Kazuto, Shirao, Motomaro, Komatsu, Goro, Hasebe, Nobuyuki, Shimizu, Hisayoshi, Miyamoto, Hideaki, Kobayashi, Kensei, Yokobori, Shinichi, Michikami, Tatsuhiro, Yamamoto, Satoru, Yokota, Yasuhiro, Arisumi, Hitoshi, Ishigami, Genya, Furutani, Katsushi, Michikawa, Yuichi, 春山, 純一, 河野, 功, 久保田, 孝, 大槻, 真嗣, 加藤, 裕基, 岩田, 隆浩, 山本, 幸生, 石原, 吉明, 永松, 愛子, 嶋田, 和人, 長谷中, 利昭, 諸田, 智克, 西野, 真木, 橋爪, 光, 佐伯, 和人, 白尾, 元理, 小松, 吾郎, 長谷部, 信行, 清水, 久芳, 宮本, 英昭, 小林, 憲正, 横堀, 伸一, 道上, 達広, 山本, 聡, 横田, 康弘, 有隅, 仁, 石上, 玄也, 古谷, 克司, Haruyama, Junichi, Kawano, Isao, Kubota, Takashi, Otsuki, Masatsugu, Kato, Hiroki, Nishibori, Toshihiko, Iwata, Takahiro, Yamamoto, Yukio, Ishihara, Yoshiaki, Nagamatsu, Aiko, Shimada, Kazuhito, Hasenaka, Toshiaki, Morota, Tomokatsu, Nishino, Masaki N., Hashizume, Ko, Saiki, Kazuto, Shirao, Motomaro, Komatsu, Goro, Hasebe, Nobuyuki, Shimizu, Hisayoshi, Miyamoto, Hideaki, Kobayashi, Kensei, Yokobori, Shinichi, Michikami, Tatsuhiro, Yamamoto, Satoru, Yokota, Yasuhiro, Arisumi, Hitoshi, Ishigami, Genya, Furutani, Katsushi, Michikawa, Yuichi, 春山, 純一, 河野, 功, 久保田, 孝, 大槻, 真嗣, 加藤, 裕基, 岩田, 隆浩, 山本, 幸生, 石原, 吉明, 永松, 愛子, 嶋田, 和人, 長谷中, 利昭, 諸田, 智克, 西野, 真木, 橋爪, 光, 佐伯, 和人, 白尾, 元理, 小松, 吾郎, 長谷部, 信行, 清水, 久芳, 宮本, 英昭, 小林, 憲正, 横堀, 伸一, 道上, 達広, 山本, 聡, 横田, 康弘, 有隅, 仁, 石上, 玄也, and 古谷, 克司

Abstract

著者人数: 30名

Published
2017

77. 衝突破片の形状分布と小惑星イトカワ母天体の天体衝突

Author

Michikami, Tatsuhiro, Hagermann, Axel, Kadokawa, Tokiyuki, Yoshida, Akifumi, Shimada, Akira, Hasegawa, Sunao, and Tsuchiyama, Akira

Abstract

平成27年度宇宙科学に関する室内実験シンポジウム (2016年2月23日-24日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, 2016 Symposium on Laboratory Experiment for Space Science (July 23-24, 2016. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 資料番号: SA6000055036

Published
2016

78. Three-Dimensional Structure of Hayabusa Samples: Origin and Evolution of Itokawa Regolith

Author

Sandford, Scott A., Ireland, Trevor R., Zolensky, Michael E., Tsuchiyama, Akira, Uesugi, Masayuki, Matsushima, Takashi, Michikami, Tatsuhiro, Kadono, Toshihiko, Nakamura, Tomoki, Uesugi, Kentaro, Nakano, Tsukasa, Noguchi, Ryo, Matsumoto, Toru, Matsuno, Junya, Nagano, Takashi, Imai, Yuta, Takeuchi, Akihisa, Suzuki, Yoshio, Ogami, Toshihiro, Katagiri, Jun, Ebihara, Mitsuru, Kitajima, Fumio, Nagao, Keisuke, Naraoka, Hiroshi, Noguchi, Takaaki, Okazaki, Ryuji, Yurimoto, Hisayoshi, Mukai, Toshifumi, Abe, Masanao, Yada, Toru, Fujimura, Akio, Yoshikawa, Makoto, and Kawaguchi, Junichiro

Subjects
Multidisciplinary, Materials science, Meteoroid, Asteroid, Chondrite, Particle, Mineralogy, Particle size, Impact structure, Regolith, Grain size, Astrobiology
Abstract

著者人数: 33名, Accepted: 2011-08-05, 資料番号: SA1003197000

Published
2011

81. 小惑星族形成の放出速度と衝突を模擬した予備実験

Author

Michikami, Tatsuhiro and Hasegawa, Sunao

Abstract

平成18年度スペースプラズマ研究会 (2007年3月22日-23日. 宇宙航空研究開発機構宇宙科学研究本部(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, Space Plasma Conference FY2006 (March 22-23, 2007. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 資料番号: SA6000114005

Published
2007

82. Regolith Migration and Sorting on Asteroid Itokawa

Author

Scheeres, Daniel J., Barnouin-Jha, Olivier, Cheng, Andrew F., Gaskell, Robert W., Miyamoto, Hideaki, Yano, Hajime, Abe, Shinsuke, Demura, Hirohide, Hirata, Naru, Ishiguro, Masateru, Michikami, Tatsuhiro, Nakamura, Akiko M., Nakamura, Ryosuke, Saito, Jun, and Sasaki, Sho

Subjects
Multidisciplinary, Granulometry, Asteroid, Sorting (sediment), High resolution, Granular convection, Particle sorting, Graded bedding, Regolith, Geology, Astrobiology
Abstract

著者人数: 15名, 資料番号: SA1003702000

Published
2007

83. 様々な厚さを持つ標的に対するクレーター形成実験～月、火星の縦穴への応用

Author

Michikami, Tatsuhiro, Hagermann, Axel, Miyamoto, Hideaki, Mura, Sei-ichiro, and Haruyama, Junichi

Abstract

平成26年度宇宙科学に関する室内実験シンポジウム (2015年2月23日-24日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, 2015 Symposium on Laboratory Experiment for Space Science (July 23-24, 2015. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 資料番号: SA6000076020

Published
2015

84. 玄武岩の衝突破片形状と最大破片

Author

Michikami, Tatsuhiro, Yoshida, Akifumi, Shimada, Akira, Tsuchiyama, Akira, and Hasegawa, Sunao

Abstract

平成25年度スペースプラズマ研究会 (2014年2月27日-28日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, Space Plasma Conference FY2013 (February 27-28, 2014. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)Sagamihara Campus), Sagamihara, Kanagawa Japan, 資料番号: SA6000077029

Published
2014

85. 月の縦孔・地下空洞探査 UZUME計画の科学的意義

Author

Haruyama, Junichi, Nishibori, Toshiyuki, Iwata, Takahiro, Nishino, Masaki N., Shimizu, Hisayoshi, Shirao, Motomaro, Saiki, Kazuto, Komatsu, Goro, Kobayashi, Kensei, Yamagishi, Akihiko, Yokobori, Shin-ichi, Oshigami, Shoko, Hashizume, Yoshimitsu, Yamamoto, Yukio, Nagamatsu, Aiko, Morota, Tomokatsu, Miyamoto, Hideaki, Hasenaka, Toshiaki, Hasebe, Nobuyuki, Imaeda, Ryunosuke, Michikami, Tatsuhiro, Yokota, Yasuhiro, and Yamamoto, Satoru

Abstract

第14回宇宙科学シンポジウム (2014年1月9日-10日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, 14ｔh Space Science Symposium (January 9-10, 2014. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)Sagamihara Campus), Sagamihara, Kanagawa Japan, 著者人数: 24名, 資料番号: SA6000058202, レポート番号: P2-170

Published
2014

86. Mission Concepts of Unprecedented Zipangu Underworld of the Moon Exploration (UZUME) Project

Author

HARUYAMA, Junichi, primary, KAWANO, Isao, additional, KUBOTA, Takashi, additional, OTSUKI, Masatsugu, additional, KATO, Hiroki, additional, NISHIBORI, Toshihiko, additional, IWATA, Takahiro, additional, YAMAMOTO, Yukio, additional, ISHIHARA, Yoshiaki, additional, NAGAMATSU, Aiko, additional, SHIMADA, Kazuhito, additional, HASENAKA, Toshiaki, additional, MOROTA, Tomokatsu, additional, NISHINO, Masaki N., additional, HASHIZUME, Ko, additional, SAIKI, Kazuto, additional, SHIRA, Motomaro, additional, KOMATSU, Goro, additional, HASEBE, Nobuyuki, additional, SHIMIZU, Hisayoshi, additional, MIYAMOTO, Hideaki, additional, KOBAYASHI, Kensei, additional, YOKOBORI, Shinichi, additional, MICHIKAMI, Tatsuhiro, additional, YAMAMOTO, Satoru, additional, YOKOTA, Yasuhiro, additional, ARISUMI, Hitoshi, additional, ISHIGAMI, Genya, additional, FURUTANI, Katsushi, additional, and MICHIKAWA, Yuichi, additional

Published
2016
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87. Three-Dimensional Structure of Hayabusa Samples: Origin and Evolution of Itokawa Regolith

Author

土山, 明, 上椙, 真之, 松島, 亘志, 道上, 達弘, 門野, 敏彦, 中村, 智樹, 上杉, 健太朗, 中野, 司, Sandford, Scott A., 野口, 遼, 松本, 徹, 松野, 淳也, 永野, 崇, 今井, 悠太, 竹内, 晃久, 鈴木, 芳生, 大神, 稔皓, 片桐, 淳, 海老原, 充, Ireland, Trevor R., 北島, 富美雄, 長尾, 敬介, 奈良岡, 浩, 野口, 高明, 岡崎, 隆司, 圦本, 尚義, Zolensky, Michael E., 向井, 利典, 安部, 正真, 矢田, 達, 藤村, 彰夫, 吉川, 真, 川口, 淳一郎, Tsuchiyama, Akira, Uesugi, Masayuki, Matsushima, Takashi, Michikami, Tatsuhiro, Kadono, Toshihiko, Nakamura, Tomoki, Uesugi, Kentaro, Nakano, Tsukasa, Noguchi, Ryo, Matsumoto, Toru, Matsuno, Junya, Nagano, Takashi, Imai, Yuta, Takeuchi, Akihisa, Suzuki, Yoshio, Ogami, Toshihiro, Katagiri, Jun, Ebihara, Mitsuru, Kitajima, Fumio, Nagao, Keisuke, Naraoka, Hiroshi, Noguchi, Takaaki, Okazaki, Ryuji, Yurimoto, Hisayoshi, Mukai, Toshifumi, Abe, Masanao, Yada, Toru, Fujimura, Akio, Yoshikawa, Makoto, Kawaguchi, Junichiro, 土山, 明, 上椙, 真之, 松島, 亘志, 道上, 達弘, 門野, 敏彦, 中村, 智樹, 上杉, 健太朗, 中野, 司, Sandford, Scott A., 野口, 遼, 松本, 徹, 松野, 淳也, 永野, 崇, 今井, 悠太, 竹内, 晃久, 鈴木, 芳生, 大神, 稔皓, 片桐, 淳, 海老原, 充, Ireland, Trevor R., 北島, 富美雄, 長尾, 敬介, 奈良岡, 浩, 野口, 高明, 岡崎, 隆司, 圦本, 尚義, Zolensky, Michael E., 向井, 利典, 安部, 正真, 矢田, 達, 藤村, 彰夫, 吉川, 真, 川口, 淳一郎, Tsuchiyama, Akira, Uesugi, Masayuki, Matsushima, Takashi, Michikami, Tatsuhiro, Kadono, Toshihiko, Nakamura, Tomoki, Uesugi, Kentaro, Nakano, Tsukasa, Noguchi, Ryo, Matsumoto, Toru, Matsuno, Junya, Nagano, Takashi, Imai, Yuta, Takeuchi, Akihisa, Suzuki, Yoshio, Ogami, Toshihiro, Katagiri, Jun, Ebihara, Mitsuru, Kitajima, Fumio, Nagao, Keisuke, Naraoka, Hiroshi, Noguchi, Takaaki, Okazaki, Ryuji, Yurimoto, Hisayoshi, Mukai, Toshifumi, Abe, Masanao, Yada, Toru, Fujimura, Akio, Yoshikawa, Makoto, and Kawaguchi, Junichiro

Abstract

著者人数: 33名, Accepted: 2011-08-05

Published
2015

88. Regolith Migration and Sorting on Asteroid Itokawa

Author

宮本, 英昭, 矢野, 創, Scheeres, Daniel J., 阿部, 新助, Barnouin-Jha, Olivier, Cheng, Andrew F., 出村, 裕英, Gaskell, Robert W., 平田, 成, 石黒, 正晃, 道上, 達広, 中村, 昭子, 中村, 良介, 斎藤, 潤, 佐々木, 晶, Miyamoto, Hideaki, Yano, Hajime, Abe, Shinsuke, Demura, Hirohide, Hirata, Naru, Ishiguro, Masateru, Michikami, Tatsuhiro, Nakamura, Akiko M., Nakamura, Ryosuke, Saito, Jun, Sasaki, Sho, 宮本, 英昭, 矢野, 創, Scheeres, Daniel J., 阿部, 新助, Barnouin-Jha, Olivier, Cheng, Andrew F., 出村, 裕英, Gaskell, Robert W., 平田, 成, 石黒, 正晃, 道上, 達広, 中村, 昭子, 中村, 良介, 斎藤, 潤, 佐々木, 晶, Miyamoto, Hideaki, Yano, Hajime, Abe, Shinsuke, Demura, Hirohide, Hirata, Naru, Ishiguro, Masateru, Michikami, Tatsuhiro, Nakamura, Akiko M., Nakamura, Ryosuke, Saito, Jun, and Sasaki, Sho

Abstract

著者人数: 15名

Published
2015

89. Impact Strength and Antipodal Velocity on the Catastrophic Disruption of Porous Targets

Author

Michikami, Tatsuhiro

Abstract

第45回月・惑星シンポジウム (2012年8月1日-3日. 宇宙航空研究開発機構宇宙科学研究所), 相模原市, 神奈川県, 45th ISAS Lunar and Planetary Symposium (August 1-3, 2012. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 形態: カラー図版あり, 形態: CD-ROM1枚, 資料番号: SA6000014022

Published
2012

90. 衝突破片の形状分布と天体表面の粒子の形状

Author

Michikami, Tatsuhiro

Abstract

平成23年度スペースプラズマ研究会(2012年2月27-28日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, Space Plasma Conference FY2011 (February 27-28, 2012. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)Sagamihara Campus), Sagamihara, Kanagawa Japan, 資料番号: SA6000079019

Published
2012

91. Shape of break-up fragment brittle bodies and its numerical model

Author

Michikami, Tatsuhiro and Shirono, Shinichi

Abstract

平成21年度スペースプラズマ研究会(2010年3月11-12日, 宇宙航空研究開発機構宇宙科学研究本部), Space Plasma Conference(March 11-12, 2010, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan), 形態: カラー図版あり, 形態: CD-ROM1枚, Physical characteristics: Original contains color illustrations, Note: One CD-ROM, 資料番号: AA0064740013

Published
2010

92. Studies of small body surface processes using microgravity environment: The creation of 'Microgravity Geology'

Author

Takagi, Yasuhiko, Yano, Hajime, Hasegawa, Sunao, Miyamoto, Hideaki, Sugita, Seiji, Demura, Hirohide, Hirata, Naru, and Michikami, Tatsuhiro

Subjects
microgravity geology, impact phenomena, regolith migration
Abstract

第25回宇宙利用シンポジウム(2009年1月14日-15日, 宇宙航空研究開発機構宇宙科学研究本部相模原キャンパス), The Twenty-fifth Space Utilization Symposium (January 14-15, 2009: ISAS/JAXA Sagamihara, Japan), Microgravity experiments are important for studies of surface phenomena (e.g., impact cratering, regolith migration and sorting) on the solar system small bodies. We are investigating the method, devices, and sample materials of these experiments. The creation of "Microgravity Geology" is expected., 資料番号: AA0064297094

Published
2009

93. A survey of possible impact structures on 25143 Itokawa

Author

Hirata, Naru, primary, Barnouin-Jha, Olivier S., additional, Honda, Chikatoshi, additional, Nakamura, Ryosuke, additional, Miyamoto, Hideaki, additional, Sasaki, Sho, additional, Demura, Hirohide, additional, Nakamura, Akiko M., additional, Michikami, Tatsuhiro, additional, Gaskell, Robert W., additional, and Saito, Jun, additional

Published
2009
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94. Shape and Distribution of Craters on the Asteroid Ryugu.

Author

Cho, Yuichiro, Morota, Tomokatsu, Kanamaru, Masanori, Ernst, Carolyn, Barnouin, Olivier, Otto, Katharina, Schmitz, Nicole, Wagner, Roland, Jaumann, Ralf, Hirabayashi, Masatoshi, Michikami, Tatsuhiro, Miyamoto, Hirdy, Kikuchi, Hiroshi, Hemmi, Ryodo, Hirata, Naru, Tatsumi, Eri, and Sugita, Seiji

Published
2019

95. Fragment shapes in impact experiments ranging from cratering to catastrophic disruption

Author

Michikami, Tatsuhiro, Hagermann, Axel, Kadokawa, Tokiyuki, Yoshida, Akifumi, Shimada, Akira, Hasegawa, Sunao, Tsuchiyama, Akira, Michikami, Tatsuhiro, Hagermann, Axel, Kadokawa, Tokiyuki, Yoshida, Akifumi, Shimada, Akira, Hasegawa, Sunao, and Tsuchiyama, Akira

Abstract

Laboratory impact experiments have found that impact fragments tend to be elongated. Their shapes, as defined by axes a, b and c, these being the maximum dimensions of the fragment in three mutually orthogonal planes (a ⩾ b ⩾ c), are distributed around mean values of the axial ratios b/a ∼ 0.7 and c/a ∼ 0.5. This corresponds to a:b:c in the simple proportion 2:√2:1. The shape distributions of some boulders on Asteroid Eros, the small- and fast-rotating asteroids (diameter <200 m and rotation period <1 h), and asteroids in young families, are similar to those of laboratory fragments created in catastrophic disruptions. Catastrophic disruption is, however, a process that is different from impact cratering. In order to systematically investigate the shapes of fragments in the range from impact cratering to catastrophic disruption, impact experiments for basalt targets 5–15 cm in size were performed. A total of 28 impact experiments were carried out by firing a spherical nylon projectile (diameter 7.14 mm) perpendicularly into the target surface at velocities of 1.60–7.13 km/s. More than 12,700 fragments with b ⩾ 4 mm generated in the impact experiments were measured. We found that the mean value of c/a in each impact decreases with decreasing impact energy per unit target mass. For instance, the mean value of c/a in an impact cratering event is nearly 0.2, which is considerably smaller than c/a in a catastrophic disruption (∼0.5). The data presented here can provide important evidence to interpret the shapes of asteroids and boulders on asteroid surfaces, and can constrain current interpretations of asteroid formation. As an example, by applying our experimental results to the boulder shapes on Asteroid Itokawa’s surface, we can infer that Itokawa’s parent body must have experienced a catastrophic disruption.

96. Influence of petrographic textures on the shapes of impact experiment fine fragments measuring several tens of microns: Comparison with Itokawa regolith particles

Author

Michikami, Tatsuhiro, Kadokawa, Tokiyuki, Tsuchiyama, Akira, Hagermann, Axel, Nakano, Tsukasa, Uesugi, Kentaro, Hasegawa, Sunao, Michikami, Tatsuhiro, Kadokawa, Tokiyuki, Tsuchiyama, Akira, Hagermann, Axel, Nakano, Tsukasa, Uesugi, Kentaro, and Hasegawa, Sunao

Abstract

In 2010, fine regolith particles on asteroid Itokawa were recovered by the Hayabusa mission. The three-dimensional microstructure of 48 Itokawa particles smaller than 120 µm was examined in previous studies. The shape distribution of Itokawa particles is distributed around the mean values of the axial ratio 2:√2:1, which is similar to laboratory impact fragments larger than several mm created in catastrophic disruptions. Thus, the Itokawa particles are considered to be impact fragments on the asteroid's surface. However, there have never been any laboratory impact experiments investigating the shapes of fine fragments smaller than 120 µm, and little is known about the relation between the shapes of fine fragments and the petrographic textures within those fragments. In this study, in order to investigate the relation between the petrographic textures and the shapes of fine fragments by impacts, the shapes of 2163 fine fragments smaller than 120 µm are examined by synchrotron radiation-based microtomography at SPring-8. Most samples are fine fragments from basalt targets, obtained in previous laboratory impact experiments by Michikami et al. (2016). Moreover, two impacts into L5 chondrite targets were carried out and the shapes of their fine fragments are examined for comparison. The results show that the shape distributions of fine fragments in basalt targets are similar regardless of impact energy per target mass (in contract to the shape distribution of relatively large fragments, which are affected by impact energy), and are similar to those in L5 chondrite targets and Itokawa regolith particles. The physical process producing these fine fragments would be due to multiple rarefaction waves in the target. Besides, the petrographic textures do not significantly affect the shapes of fine fragments in our experiments. On the other hand, according to Molaro et al. (2015), the shapes of the fragments produced by thermal fatigue by the day-night temperature cycles on th

97. Influence of petrographic textures on the shapes of impact experiment fine fragments measuring several tens of microns: Comparison with Itokawa regolith particles

Author

Michikami, Tatsuhiro, Kadokawa, Tokiyuki, Tsuchiyama, Akira, Hagermann, Axel, Nakano, Tsukasa, Uesugi, Kentaro, Hasegawa, Sunao, Michikami, Tatsuhiro, Kadokawa, Tokiyuki, Tsuchiyama, Akira, Hagermann, Axel, Nakano, Tsukasa, Uesugi, Kentaro, and Hasegawa, Sunao

Abstract

In 2010, fine regolith particles on asteroid Itokawa were recovered by the Hayabusa mission. The three-dimensional microstructure of 48 Itokawa particles smaller than 120 µm was examined in previous studies. The shape distribution of Itokawa particles is distributed around the mean values of the axial ratio 2:√2:1, which is similar to laboratory impact fragments larger than several mm created in catastrophic disruptions. Thus, the Itokawa particles are considered to be impact fragments on the asteroid's surface. However, there have never been any laboratory impact experiments investigating the shapes of fine fragments smaller than 120 µm, and little is known about the relation between the shapes of fine fragments and the petrographic textures within those fragments. In this study, in order to investigate the relation between the petrographic textures and the shapes of fine fragments by impacts, the shapes of 2163 fine fragments smaller than 120 µm are examined by synchrotron radiation-based microtomography at SPring-8. Most samples are fine fragments from basalt targets, obtained in previous laboratory impact experiments by Michikami et al. (2016). Moreover, two impacts into L5 chondrite targets were carried out and the shapes of their fine fragments are examined for comparison. The results show that the shape distributions of fine fragments in basalt targets are similar regardless of impact energy per target mass (in contract to the shape distribution of relatively large fragments, which are affected by impact energy), and are similar to those in L5 chondrite targets and Itokawa regolith particles. The physical process producing these fine fragments would be due to multiple rarefaction waves in the target. Besides, the petrographic textures do not significantly affect the shapes of fine fragments in our experiments. On the other hand, according to Molaro et al. (2015), the shapes of the fragments produced by thermal fatigue by the day-night temperature cycles on th

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

Author

Ito, Motoo, Tomioka, Naotaka, Uesugi, Masayuki, Yamaguchi, Akira, Shirai, Naoki, Ohigashi, Takuji, Liu, Ming-Chang, Greenwood, Richard C., Kimura, Makoto, Imae, Naoya, Uesugi, Kentaro, Nakato, Aiko, Yogata, Kasumi, Yuzawa, Hayato, Kodama, Yu, Tsuchiyama, Akira, Yasutake, Masahiro, Findlay, Ross, Franchi, Ian A., Malley, James A., McCain, Kaitlyn A., Matsuda, Nozomi, McKeegan, Kevin D., Hirahara, Kaori, Takeuchi, Akihisa, Sekimoto, Shun, Sakurai, Ikuya, Okada, Ikuo, Karouji, Yuzuru, Arakawa, Masahiko, Fujii, Atsushi, Fujimoto, Masaki, 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, Mori, Osamu, 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, Sawada, Hirotaka, 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, Fukai, Ryota, Furuya, Shizuho, Hatakeda, Kentaro, Hayashi, Tasuku, Hitomi, Yuya, Kumagai, Kazuya, Miyazaki, Akiko, Nishimura, Masahiro, Soejima, Hiromichi, Iwamae, Ayako, Yamamoto, Daiki, Yoshitake, Miwa, Yada, Toru, Abe, Masanao, Usui, Tomohiro, Watanabe, Sei-ichiro, Tsuda, Yuichi, Ito, Motoo, Tomioka, Naotaka, Uesugi, Masayuki, Yamaguchi, Akira, Shirai, Naoki, Ohigashi, Takuji, Liu, Ming-Chang, Greenwood, Richard C., Kimura, Makoto, Imae, Naoya, Uesugi, Kentaro, Nakato, Aiko, Yogata, Kasumi, Yuzawa, Hayato, Kodama, Yu, Tsuchiyama, Akira, Yasutake, Masahiro, Findlay, Ross, Franchi, Ian A., Malley, James A., McCain, Kaitlyn A., Matsuda, Nozomi, McKeegan, Kevin D., Hirahara, Kaori, Takeuchi, Akihisa, Sekimoto, Shun, Sakurai, Ikuya, Okada, Ikuo, Karouji, Yuzuru, Arakawa, Masahiko, Fujii, Atsushi, Fujimoto, Masaki, 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, Mori, Osamu, 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, Sawada, Hirotaka, 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, Fukai, Ryota, Furuya, Shizuho, Hatakeda, Kentaro, Hayashi, Tasuku, Hitomi, Yuya, Kumagai, Kazuya, Miyazaki, Akiko, Nishimura, Masahiro, Soejima, Hiromichi, Iwamae, Ayako, Yamamoto, Daiki, Yoshitake, Miwa, Yada, Toru, Abe, Masanao, Usui, Tomohiro, Watanabe, Sei-ichiro, and Tsuda, Yuichi

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.

99. Macroporosity and Grain Density of Rubble Pile Asteroid (162173) Ryugu

Author

Jens Biele, Chikatoshi Honda, Patrick Michel, Matthias Grott, Seiji Sugita, Shingo Kameda, Stefan Schröder, Tatsuhiro Michikami, Wladimir Neumann, Naoya Sakatani, Biele, Jens, 2 German Aerospace Center Cologne Germany, Michel, Patrick, 3 Laboratoire Lagrange Université Côte d'Azur Observatoire de la Côte d'Azur CNRS Nice France, Sugita, Seiji, 4 University of Tokyo Tokyo Japan, Schröder, Stefan, 1 German Aerospace Center Berlin Germany, Sakatani, Naoya, 5 ISAS/JAXA Sagamihara Japan, Neumann, Wladimir, Kameda, Shingo, 7 Rikkyo University Tokyo Japan, Michikami, Tatsuhiro, 8 Kindai University Hiroshima Japan, Honda, Chikatoshi, 9 University of Aizu Aizu‐Wakamatsu Japan, and Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS, Laboratoire Lagrange, Nice, France

Subjects
Void (astronomy), 010504 meteorology & atmospheric sciences, Density, engineering.material, 01 natural sciences, Planetenphysik, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), Geotechnical engineering, Ryugu, Porosity, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Rubble, Asteroids, Nutzerzentrum für Weltraumexperimente (MUSC), Planetengeologie, Geophysics, [SDU]Sciences of the Universe [physics], Space and Planetary Science, Asteroid, Asteroiden Ryugu Hayabusa2 MASCOT, engineering, Pile, Grain density, Geology
Abstract

Rubble pile asteroids such as (162173) Ryugu have large bulk porosities, which are believed to result from void spaces in between the constituent boulders (macroporosity) as well as void spaces within the boulders themselves (microporosity). In general, both macroporosity and microporosity are estimated based on comparisons between the asteroid bulk density and both the bulk and grain density of meteorite analogs, and relatively large macroporosities are usually obtained. Here we use semiempirical models for the macroporosity of multicomponent mixtures to determine Ryugu's macroporosity based on the observed size‐frequency distribution (SFD) of boulders on the surface. We find that Ryugu's macroporosity can be significantly smaller than usually assumed, as the observed SFD allows for an efficient packing of boulders, resulting in a macroporosity of 16% ± 3%. Therefore, we confirm that Ryugu's high bulk porosity is a direct consequence of a very large boulder microporosity. Furthermore, using estimates of boulder microporosity of around 50% as derived from in situ measurements, the average grain density in boulders is 2,848 ± 152 kg m–3, similar to values obtained for CM and the Tagish lake meteorites. Ryugu's bulk porosity corresponding to the above values is 58%. Thus, the macroporosity of rubble pile asteroids may have been systematically overestimated in the past., Plain Language Summary: The carbonaceous asteroid (162173) Ryugu formed from fragments which reaccreted after its parent body was disrupted by a catastrophic collision. Asteroids of this type are also known as rubble piles and the reaccumulation process is thought to be one of the causes for their large bulk porosity. We have applied mixing models to determine the amount of interboulder porosity taking the observed abundance of large and small boulders on the surface into account. We find that the relative abundances of differently sized boulders allow for a very efficient packing, such that interboulder porosity in Ryugu is rather small and only 16% ± 3%. This implies that a large part of Ryugu's total porosity must reside inside the boulders themselves. Using estimates of boulder intrinsic porosity, we furthermore constrain the average density of the boulder's constituent minerals to 2,848 ± 152 kg m−3, which is consistent with values measured for carbonaceous meteorites as collected on Earth. Thus, interboulder porosity of rubble pile asteroids may have been systematically overestimated in the past., Key Points: Ryugu's large bulk porosity is distributed between intrinsic boulder microporosity and macroporosity due to void spaces in‐between boulders. We use the boulder size‐frequency distribution as observed on the surface together with mixing models to estimate Ryugu's macroporosity. We find that macroporosity is 16% ± 3%, indicating that Ryugu's large bulk porosity of close to 50% is governed by microporosity.

Published
2020

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