2022/10/03 更新

写真b

カメダ シンゴ
亀田 真吾
KAMEDA Shingo
*大学が定期的に情報更新している項目(その他は、researchmapの登録情報を転載)
所属*
理学部 物理学科
理学研究科 物理学専攻博士課程後期課程
理学研究科 物理学専攻博士課程前期課程
職名*
教授
学位
博士(理学) ( 東京大学 )
研究テーマ*
  • 惑星探査機・宇宙望遠鏡に観測機器を搭載し、新たなデータを得るための技術開発を中心に研究を進めている。また、地上望遠鏡を使った惑星大気光の観測にも取り組んでいる。はやぶさ2、火星衛星探査計画MMXに参加して、データ解析、設計検討を進めながら、系外惑星大気観測装置、月惑星着陸機搭載用元素分析器の開発に力を入れている。

  • 研究キーワード
  • 惑星科学

  • 学内職務経歴*
    • 2018年4月 - 現在 
      理学部   物理学科   教授
    • 2018年4月 - 現在 
      理学研究科   物理学専攻博士課程前期課程   教授
    • 2018年4月 - 現在 
      理学研究科   物理学専攻博士課程後期課程   教授
    • 2011年4月 - 2018年3月 
      理学部   物理学科   准教授
     

    研究分野

    • 自然科学一般 / 宇宙惑星科学

    経歴

    • 2022年8月 - 現在 
      国立研究開発法人宇宙航空研究開発機構   宇宙科学研究所 WSO-UVプロジェクト   特任教授

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    • 2020年11月 - 現在 
      国立研究開発法人宇宙航空研究開発機構   宇宙科学研究所   特任教授

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    • 2018年4月 - 現在 
      立教大学   理学部 物理学科   教授

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    • 2018年4月 - 現在 
      立教大学   理学研究科 物理学専攻博士課程前期課程   教授

      詳細を見る

    • 2018年4月 - 現在 
      立教大学   理学研究科 物理学専攻博士課程後期課程   教授

      詳細を見る

    • 2011年4月 - 2018年3月 
      立教大学   理学部 物理学科   准教授

      詳細を見る

    ▼全件表示

    学歴

    • 2004年4月 - 2007年3月 
      東京大学   理学系研究科   地球惑星科学専攻

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      国名: 日本国

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    • 2004年4月 - 2007年3月 
      東京大学   理学系研究科   地球惑星科学専攻

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      国名: 日本国

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    • 2002年4月 - 2004年3月 
      東京大学   理学系研究科   地球惑星科学専攻

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      国名: 日本国

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    • 2002年4月 - 2004年3月 
      東京大学   理学系研究科   地球惑星科学専攻

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      国名: 日本国

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    • 1997年4月 - 2002年3月 
      東京大学   理学部   地球惑星物理学科

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      国名: 日本国

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    論文

    • The Mars system revealed by the Martian Moons eXploration mission

      Kazunori Ogohara, Hiromu Nakagawa, Shohei Aoki, Toru Kouyama, Tomohiro Usui, Naoki Terada, Takeshi Imamura, Franck Montmessin, David Brain, Alain Doressoundiram, Thomas Gautier, Takuya Hara, Yuki Harada, Hitoshi Ikeda, Mizuho Koike, François Leblanc, Ramses Ramirez, Eric Sawyer, Kanako Seki, Aymeric Spiga, Ann Carine Vandaele, Shoichiro Yokota, Antonella Barucci, Shingo Kameda

      Earth, Planets and Space74 ( 1 )   2022年12月

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      掲載種別:研究論文(学術雑誌)   出版者・発行元:Springer Science and Business Media LLC  

      Abstract

      Japan Aerospace Exploration Agency (JAXA) plans a Phobos sample return mission (MMX: Martian Moons eXploration). In this study, we review the related works on the past climate of Mars, its evolution, and the present climate and weather to describe the scientific goals and strategies of the MMX mission regarding the evolution of the Martian surface environment. The MMX spacecraft will retrieve and return a sample of Phobos regolith back to Earth in 2029. Mars ejecta are expected to be accumulated on the surface of Phobos without being much shocked. Samples from Phobos probably contain all types of Martian rock from sedimentary to igneous covering all geological eras if ejecta from Mars could be accumulated on the Phobos surface. Therefore, the history of the surface environment of Mars can be restored by analyzing the returned samples. Remote sensing of the Martian atmosphere and monitoring ions escaping to space while the spacecraft is orbiting Mars in the equatorial orbit are also planned. The camera with multi-wavelength filters and the infrared spectrometer onboard the spacecraft can monitor rapid transport processes of water vapor, dust, ice clouds, and other species, which could not be traced by the previous satellites on the sun-synchronous polar orbit. Such time-resolved pictures of the atmospheric phenomena should be an important clue to understand both the processes of water exchange between the surface/underground reservoirs and the atmosphere and the drivers of efficient material transport to the upper atmosphere. The mass spectrometer with unprecedented mass resolution can observe ions escaping to space and monitor the atmospheric escape which has made the past Mars to evolve towards the cold and dry surface environment we know today. Together with the above two instruments, it can potentially reveal what kinds of atmospheric events can transport tracers (e.g., H<sub>2</sub>O) upward and enhance the atmospheric escape.

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      DOI: 10.1186/s40623-021-01417-0

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      その他リンク: https://link.springer.com/article/10.1186/s40623-021-01417-0/fulltext.html

    • Resurfacing processes constrained by crater distribution on Ryugu

      Naofumi Takaki, Yuichiro Cho, Tomokatsu Morota, Eri Tatsumi, Rie Honda, Shingo Kameda, Yasuhiro Yokota, Naoya Sakatani, Toru Kouyama, Masahiko Hayakawa, Moe Matsuoka, Manabu Yamada, Chikatoshi Honda, Hidehiko Suzuki, Kazuo Yoshioka, Kazunori Ogawa, Hirotaka Sawada, Patrick Michel, Seiji Sugita

      Icarus377   114911 - 114911   2022年5月

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      掲載種別:研究論文(学術雑誌)   出版者・発行元:Elsevier BV  

      DOI: 10.1016/j.icarus.2022.114911

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

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

      Science375 ( 6584 ) 1011 - 1016   2022年3月4日

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      掲載種別:研究論文(学術雑誌)  

      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

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    • Comparative Na and K Mercury and Moon Exospheres

      F. Leblanc, C. Schmidt, V. Mangano, A. Mura, G. Cremonese, J. M. Raines, J. M. Jasinski, M. Sarantos, A. Milillo, R. M. Killen, S. Massetti, T. Cassidy, R. J. Vervack, S. Kameda, M. T. Capria, M. Horanyi, D. Janches, A. Berezhnoy, A. Christou, T. Hirai, P. Lierle, J. Morgenthaler

      Space Science Reviews218 ( 1 )   2022年2月

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      掲載種別:研究論文(学術雑誌)   出版者・発行元:Springer Science and Business Media LLC  

      Abstract

      Sodium and, in a lesser way, potassium atomic components of surface-bounded exospheres are among the brightest elements that can be observed from the Earth in our Solar System. Both species have been intensively observed around Mercury, the Moon and the Galilean Moons. During the last decade, new observations have been obtained thanks to space missions carrying remote and in situ instrumentation that provide a completely original view of these species in the exospheres of Mercury and the Moon. They challenged our understanding and modelling of these exospheres and opened new directions of research by suggesting the need to better take into account the relationship between the surface-exosphere and the magnetosphere. In this paper, we first review the large set of observations of Mercury and the Moon Sodium and Potassium exospheres. In the second part, we list what it tells us on the sources and sinks of these exospheres focusing in particular on the role of their magnetospheres of these objects and then discuss, in a third section, how these observations help us to understand and identify the key drivers of these exospheres.

      DOI: 10.1007/s11214-022-00871-w

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      その他リンク: https://link.springer.com/article/10.1007/s11214-022-00871-w/fulltext.html

    • Orbiting experiment of artificial objects deployed from Hayabusa2

      Yusuke Oki, Kent Yoshikawa, Yuto Takei, Hiroshi Takeuchi, Hitoshi Ikeda, Shota Kikuchi, Naoko Ogawa, Takanao Saiki, Yuichi Tsuda, Manabu Yamada, Toru Kouyama, Shingo Kameda

      Hayabusa2 Asteroid Sample Return Mission   313 - 340   2022年

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      掲載種別:論文集(書籍)内論文   出版者・発行元:Elsevier  

      DOI: 10.1016/b978-0-323-99731-7.00016-7

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    • Hayabusa2 radio science investigation

      Hitoshi Ikeda, Hiroshi Takeuchi, Shota Kikuchi, Yuya Mimasu, Naoko Ogawa, Kent Yoshikawa, Yuto Takei, Go Ono, Manabu Yamada, Toru Kouyama, Shingo Kameda, Yuichi Tsuda

      Hayabusa2 Asteroid Sample Return Mission   387 - 399   2022年

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      掲載種別:論文集(書籍)内論文   出版者・発行元:Elsevier  

      DOI: 10.1016/b978-0-323-99731-7.00019-2

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    • Martian moons exploration MMX: sample return mission to Phobos elucidating formation processes of habitable planets 招待有り 査読有り

      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 Space74 ( 1 )   2022年1月

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元: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

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    • Stray light analysis by ray tracing simulation for the wide-angle multiband camera OROCHI onboard the Martian Moons eXploration (MMX) spacecraft

      Ryota Fuse, Keigo Enya, Shingo Kameda, Hiroki Kato, Naoya Osada, Ko Ishibashi, Masanobu Ozaki, Naoya Sakatani, Toru Kouyama, Hidehiko Suzuki, Tomoki Nakamura, Hideaki Miyamoto, Shinsuke Abe, Yuya Goda, Hajime Murao

      Advances in Space Research69 ( 2 ) 1236 - 1248   2022年1月

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Elsevier BV  

      The Martian Moons eXploration (MMX) spacecraft is equipped with two cameras, i.e., the TElescopic Nadir imager for GeOmOrphology (TENGOO) and the Optical Radiometer composed Of CHromatic Imagers (OROCHI), for the scientific observation of the Martian moon Phobos. OROCHI is a wide-angle multiband camera system comprising seven cameras with different bandpass filters and one monochromatic camera in the visible and near-infrared range. Thus, OROCHI can simultaneously obtain multiband images. Previous space observations have revealed that the reflection spectra of Phobos exhibit regional differences, including a red unit and a blue unit with weak redness. Moreover, Phobos shows an absorption band near 650 nm, attributed to the red unit of Phobos. Global observations using OROCHI require the determination of such regional variations with high precision; therefore, we must reduce noise in the optical system design. In this study, to meet this requirement, we focus on stray light reduction. Stray light is a source of noise generated by reflections at surfaces of optical components (e.g., sensors, filters, lenses, and lens barrels). We design simulation models of the OROCHI optical system, measure the reflectance of its charge-coupled device (CCD) image sensor, and conduct stray light analysis via ray tracing. We estimate the ratio of the stray light intensity to the target signal intensity by deriving both the reflected (constituting stray light) and unreflected rays. We show that placing the filter away from the sensor and reducing the reflectances of the filter and lenses effectively reduce stray light. Such approaches are incorporated into the preliminary design of OROCHI. (C) 2021 COSPAR. Published by Elsevier B.V.

      DOI: 10.1016/j.asr.2021.11.011

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    • Alignment determination of the Hayabusa2 laser altimeter (LIDAR)

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

      Earth, Planets and Space73 ( 1 )   2021年12月

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      掲載種別:研究論文(学術雑誌)   出版者・発行元:Springer Science and Business Media LLC  

      Abstract

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

      DOI: 10.1186/s40623-020-01342-8

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      その他リンク: http://link.springer.com/article/10.1186/s40623-020-01342-8/fulltext.html

    • MIRS: an imaging spectrometer for the MMX mission

      Maria Antonietta Barucci, Jean-Michel Reess, Pernelle Bernardi, Alain Doressoundiram, Sonia Fornasier, Michel Le Du, Takahiro Iwata, Hiromu Nakagawa, Tomoki Nakamura, Yves André, Shohei Aoki, Takehiko Arai, Elisa Baldit, Pierre Beck, Jean-Tristan Buey, Elisabet Canalias, Matthieu Castelnau, Sebastien Charnoz, Marc Chaussidon, Fréderic Chapron, Valerie Ciarletti, Marco Delbo, Bruno Dubois, Stephane Gauffre, Thomas Gautier, Hidenori Genda, Rafik Hassen-Khodja, Gilles Hervet, Ryuki Hyodo, Christian Imbert, Takeshi Imamura, Laurent Jorda, Shingo Kameda, Driss Kouach, Toru Kouyama, Takeshi Kuroda, Hiroyuki Kurokawa, Laurent Lapaw, Jeremie Lasue, Laetitia Le Deit, Aurélien Ledot, Cedric Leyrat, Bertrand Le Ruyet, Moe Matsuoka, Frederic Merlin, Hideaki Miyamoto, Frederic Moynier, Napoleon Nguyen Tuong, Kazunori Ogohara, Takahito Osawa, Jérôme Parisot, Laurie Pistre, Benjamin Quertier, Sean N. Raymond, Francis Rocard, Takeshi Sakanoi, Takao M. Sato, Eric Sawyer, Fériel Tache, Sylvain Trémolières, Fuminori Tsuchiya, Pierre Vernazza, Didier Zeganadin

      Earth, Planets and Space73 ( 1 )   2021年12月

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      掲載種別:研究論文(学術雑誌)   出版者・発行元:Springer Science and Business Media LLC  

      Abstract

      The MMX infrared spectrometer (MIRS) is an imaging spectrometer onboard MMX JAXA mission. MMX (Martian Moon eXploration) is scheduled to be launched in 2024 with sample return to Earth in 2029. MIRS is built at LESIA-Paris Observatory in collaboration with four other French laboratories, collaboration and financial support of CNES and close collaboration with JAXA and MELCO. The instrument is designed to fully accomplish MMX’s scientific and measurement objectives. MIRS will remotely provide near-infrared spectral maps of Phobos and Deimos containing compositional diagnostic spectral features that will be used to analyze the surface composition and to support the sampling site selection. MIRS will also study Mars atmosphere, in particular spatial and temporal changes such as clouds, dust and water vapor.

      Graphical Abstract

      DOI: 10.1186/s40623-021-01423-2

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      その他リンク: https://link.springer.com/article/10.1186/s40623-021-01423-2/fulltext.html

    • Surface environment of Phobos and Phobos simulant UTPS

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

      Earth, Planets and Space73 ( 1 )   2021年12月

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      掲載種別:研究論文(学術雑誌)   出版者・発行元:Springer Science and Business Media LLC  

      Abstract

      The Martian Moons eXploration (MMX) mission will study the Martian moons Phobos and Deimos, Mars, and their environments. The mission scenario includes both landing on the surface of Phobos to collect samples and deploying a small rover for in situ observations. Engineering safeties and scientific planning for these operations require appropriate evaluations of the surface environment of Phobos. Thus, the mission team organized the Landing Operation Working Team (LOWT) and Surface Science and Geology Sub-Science Team (SSG-SST), whose view of the Phobos environment is summarized in this paper. While orbital and large-scale characteristics of Phobos are relatively well known, characteristics of the surface regolith, including the particle size-distributions, the packing density, and the mechanical properties, are difficult to constrain. Therefore, we developed several types of simulated soil materials (simulant), such as UTPS-TB (University of Tokyo Phobos Simulant, Tagish Lake based), UTPS-IB (Impact-hypothesis based), and UTPS-S (Simpler version) for engineering and scientific evaluation experiments.

      DOI: 10.1186/s40623-021-01406-3

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      その他リンク: https://link.springer.com/article/10.1186/s40623-021-01406-3/fulltext.html

    • Design of telescopic nadir imager for geomorphology (TENGOO) and observation of surface reflectance by optical chromatic imager (OROCHI) for the Martian Moons Exploration (MMX)

      Shingo Kameda, Masanobu Ozaki, Keigo Enya, Ryota Fuse, Toru Kouyama, Naoya Sakatani, Hidehiko Suzuki, Naoya Osada, Hiroki Kato, Hideaki Miyamoto, Atsushi Yamazaki, Tomoki Nakamura, Takaya Okamoto, Takahiro Ishimaru, Peng Hong, Ko Ishibashi, Takeshi Takashima, Ryoya Ishigami, Cheng-Ling Kuo, Shinsuke Abe, Yuya Goda, Hajime Murao, Saori Fujishima, Tsubasa Aoyama, Keiji Hagiwara, Satoko Mizumoto, Noriko Tanaka, Kousuke Murakami, Miho Matsumoto, Kenji Tanaka, Hironobu Sakuta

      Earth, Planets and Space73 ( 1 )   2021年12月

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Springer Science and Business Media LLC  

      Abstract

      The JAXA’s Martian Moons Exploration (MMX) mission is planned to reveal the origin of Phobos and Deimos. It will remotely observe both moons and return a sample from Phobos. The nominal instruments include the TElescopic Nadir imager for GeOmOrphology (TENGOO) and Optical RadiOmeter composed of CHromatic Imagers (OROCHI). The scientific objective of TENGOO is to obtain the geomorphological features of Phobos and Deimos. The spatial resolution of TENGOO is 0.3 m at an altitude of 25 km in the quasi-satellite orbit. The scientific objective of OROCHI is to obtain material distribution using spectral mapping. OROCHI possesses seven wide-angle bandpass imagers without a filter wheel and one monochromatic imager dedicated to the observation during the landing phase. Using these two instruments, we plan to select landing sites and obtain information that supports the analysis of return samples.

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      DOI: 10.1186/s40623-021-01462-9

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      その他リンク: https://link.springer.com/article/10.1186/s40623-021-01462-9/fulltext.html

    • Science operation plan of Phobos and Deimos from the MMX spacecraft

      Tomoki Nakamura, Hitoshi Ikeda, Toru Kouyama, Hiromu Nakagawa, Hiroki Kusano, Hiroki Senshu, Shingo Kameda, Koji Matsumoto, Ferran Gonzalez-Franquesa, Naoya Ozaki, Yosuke Takeo, Nicola Baresi, Yusuke Oki, David J. Lawrence, Nancy L. Chabot, Patrick N. Peplowski, Maria Antonietta Barucci, Eric Sawyer, Shoichiro Yokota, Naoki Terada, Stephan Ulamec, Patrick Michel, Masanori Kobayashi, Sho Sasaki, Naru Hirata, Koji Wada, Hideaki Miyamoto, Takeshi Imamura, Naoko Ogawa, Kazunori Ogawa, Takahiro Iwata, Takane Imada, Hisashi Otake, Elisabet Canalias, Laurence Lorda, Simon Tardivel, Stéphane Mary, Makoto Kunugi, Seiji Mitsuhashi, Alain Doressoundiram, Frédéric Merlin, Sonia Fornasier, Jean-Michel Reess, Pernelle Bernardi, Shigeru Imai, Yasuyuki Ito, Hatsumi Ishida, Kiyoshi Kuramoto, Yasuhiro Kawakatsu

      Earth, Planets and Space73 ( 1 )   2021年12月

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      掲載種別:研究論文(学術雑誌)   出版者・発行元:Springer Science and Business Media LLC  

      Abstract

      The science operations of the spacecraft and remote sensing instruments for the Martian Moon eXploration (MMX) mission are discussed by the mission operation working team. In this paper, we describe the Phobos observations during the first 1.5 years of the spacecraft’s stay around Mars, and the Deimos observations before leaving the Martian system. In the Phobos observation, the spacecraft will be placed in low-altitude quasi-satellite orbits on the equatorial plane of Phobos and will make high-resolution topographic and spectroscopic observations of the Phobos surface from five different altitudes orbits. The spacecraft will also attempt to observe polar regions of Phobos from a three-dimensional quasi-satellite orbit moving out of the equatorial plane of Phobos. From these observations, we will constrain the origin of Phobos and Deimos and select places for landing site candidates for sample collection. For the Deimos observations, the spacecraft will be injected into two resonant orbits and will perform many flybys to observe the surface of Deimos over as large an area as possible.

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      DOI: 10.1186/s40623-021-01546-6

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      その他リンク: https://link.springer.com/article/10.1186/s40623-021-01546-6/fulltext.html

    • In situ science on Phobos with the Raman spectrometer for MMX (RAX): preliminary design and feasibility of Raman measurements

      Yuichiro Cho, Ute Böttger, Fernando Rull, Heinz-Wilhelm Hübers, Tomàs Belenguer, Anko Börner, Maximilian Buder, Yuri Bunduki, Enrico Dietz, Till Hagelschuer, Shingo Kameda, Emanuel Kopp, Matthias Lieder, Guillermo Lopez-Reyes, Andoni Gaizka Moral Inza, Shoki Mori, Jo Akino Ogura, Carsten Paproth, Carlos Perez Canora, Martin Pertenais, Gisbert Peter, Olga Prieto-Ballesteros, Steve Rockstein, Selene Rodd-Routley, Pablo Rodriguez Perez, Conor Ryan, Pilar Santamaria, Thomas Säuberlich, Friedrich Schrandt, Susanne Schröder, Claudia Stangarone, Stephan Ulamec, Tomohiro Usui, Iris Weber, Karsten Westerdorff, Koki Yumoto

      Earth, Planets and Space73 ( 1 )   2021年12月

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      掲載種別:研究論文(学術雑誌)   出版者・発行元:Springer Science and Business Media LLC  

      Abstract

      Mineralogy is the key to understanding the origin of Phobos and its position in the evolution of the Solar System. In situ Raman spectroscopy on Phobos is an important tool to achieve the scientific objectives of the Martian Moons eXploration (MMX) mission, and maximize the scientific merit of the sample return by characterizing the mineral composition and heterogeneity of the surface of Phobos. Conducting in situ Raman spectroscopy in the harsh environment of Phobos requires a very sensitive, compact, lightweight, and robust instrument that can be carried by the compact MMX rover. In this context, the Raman spectrometer for MMX (i.e., RAX) is currently under development via international collaboration between teams from Japan, Germany, and Spain. To demonstrate the capability of a compact Raman system such as RAX, we built an instrument that reproduces the optical performance of the flight model using commercial off-the-shelf parts. Using this performance model, we measured mineral samples relevant to Phobos and Mars, such as anhydrous silicates, carbonates, and hydrous minerals. Our measurements indicate that such minerals can be accurately identified using a RAX-like Raman spectrometer. We demonstrated a spectral resolution of approximately 10 cm<sup>−1</sup>, high enough to resolve the strongest olivine Raman bands at ~ 820 and ~ 850 cm<sup>−1</sup>, with highly sensitive Raman peak measurements (e.g., signal-to-noise ratios up to 100). These results strongly suggest that the RAX instrument will be capable of determining the minerals expected on the surface of Phobos, adding valuable information to address the question of the moon’s origin, heterogeneity, and circum-Mars material transport.

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      DOI: 10.1186/s40623-021-01496-z

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      その他リンク: https://link.springer.com/article/10.1186/s40623-021-01496-z/fulltext.html

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

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

      Nature Communications12 ( 1 )   2021年12月

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      掲載種別:研究論文(学術雑誌)   出版者・発行元: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

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      その他リンク: https://www.nature.com/articles/s41467-021-26071-8

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

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

      Advances in Space Research68 ( 8 ) 3093 - 3140   2021年10月

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Elsevier BV  

      One of the major challenges in the Hayabusa2 sample-return mission was the second touchdown on the asteroid Ryugu, which was designed to collect subsurface materials near the artificial crater formed by a small carry-on impactor. Due to engineering and scientific requirements, a narrow area with a radius as small as 3.5 m was selected as the target landing site. To achieve pinpoint touchdown at the selected site, an artificial landmark called a target marker (TM) was used for optical navigation. The key to a successful touchdown was precise deployment of the TM in the microgravity environment of the asteroid. This study therefore investigates a viable trajectory for TM deployment, incorporating the uncertainty in the impact and rebound motions of the TM. Following the TM deployment operation, a detailed survey of the landing site around the TM settlement point is performed to assess the terrain conditions. To guarantee the observation quality and spacecraft safety, multi-impulse low-altitude trajectories are introduced in this paper, along with covariance analyses based on the high-fidelity polyhedral gravity model of Ryugu. Subsequently, a pinpoint touchdown trajectory that satisfies various engineering requirements, such as landing accuracy and velocity, is designed, taking advantage of optical TM tracking. The feasibility of the touchdown sequence is further validated by a Monte Carlo dispersion analysis. Consequently, Hayabusa2 successfully touched down within the target site on 11 July 2019. The current research also conducts a post-operation trajectory reconstruction based on the flight data to demonstrate the actual guidance performance in the TM deployment, landing site observations, and pinpoint touchdown. (C) 2021 COSPAR. Published by Elsevier B.V.

      DOI: 10.1016/j.asr.2021.07.031

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    • Opposition Observations of 162173 Ryugu: Normal Albedo Map Highlights Variations in Regolith Characteristics

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

      The Planetary Science Journal2 ( 5 ) 177 - 177   2021年10月1日

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      掲載種別:研究論文(学術雑誌)   出版者・発行元:American Astronomical Society  

      Abstract

      On 2019 January 8, the Telescopic Optical Navigation Camera (ONC-T) on board the Hayabusa2 spacecraft observed the Cb-type asteroid 162173 Ryugu under near-opposition illumination and viewing conditions from approximately 20 km in distance. Although opposition observations have never been used for mapping purposes of a planetary body, we found three advantages for mapping under these conditions: (1) images are free of topographic shadows, (2) the reflectance is nearly independent of the orientation of the surface, and (3) spurious color artifacts that may appear near shadowed terrain are avoided. We present normal albedo maps, one for each of the seven filters (0.40–0.95 μm), using an empirical photometric correction. Global coverage of Ryugu is 99.4%. The 0.55 μm band average normal albedo is 4.06% ± 0.10%. Various spectral variations are derived from these maps. Spectral features of regions and boulders are quantified by examining the normal albedo-derived spectral slope and UV index (spectral slope from visible to ultraviolet wavelength) value. In terms of space weathering, three spectral characteristics are observed over the majority of Ryugu: (1) reddening, (2) increases in reflectance at ultraviolet wavelengths compared to visible, and (3) darkening. By contrast, the bright boulders (“type 3”) show a different trend, with wide variations in the 0.95 μm albedo and UV index. Finally, principal component analysis (PCA) comparisons with other asteroids strongly suggest that the main components of Ryugu belong to the B-Cb-type populations. The PCA feature of the fresh material on Ryugu is close to the Eulalia family.

      DOI: 10.3847/psj/ac14ba

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      その他リンク: https://iopscience.iop.org/article/10.3847/PSJ/ac14ba/pdf

    • Development of image texture analysis technique for boulder distribution measurements: Applications to asteroids Ryugu and Itokawa

      Naoya Tanabe, Yuichiro Cho, Eri Tatsumi, Tatsuki Ebihara, Koki Yumoto, Tatsuhiro Michikami, Hideaki Miyamoto, Tomokatsu Morota, Chikatoshi Honda, Patrick Michel, Katharina Otto, Olivier Barnouin, Kazuo Yoshioka, Hirotaka Sawada, Yasuhiro Yokota, Naoya Sakatani, Masahiro Hayakawa, Rie Honda, Shingo Kameda, Moe Matsuoka, Manabu Yamada, Toru Kouyama, Hidehiko Suzuki, Kazunori Ogawa, Seiji Sugita

      Planetary and Space Science204   105249 - 105249   2021年9月

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      掲載種別:研究論文(学術雑誌)   出版者・発行元:Elsevier BV  

      Recent asteroid missions have revealed that many sub-kilometer asteroids are rubble piles. Large parts of their surfaces are covered with boulders larger than tens of centimeters. An evaluation of the abundance and size distribution of boulders provides clues to understand surface processes on boulder-covered asteroids. Here we report a new method that automatically measures the abundance of small boulders (sub-pixel to a few pixels), whose boundaries cannot be recognized with visual inspection, by quantifying the surface radiance variation that occurs during the spinning of the asteroid. After validating our approach with previous boulder counting data, we apply this method to images of the asteroids Ryugu and Itokawa, which were visited by JAXA's Hayabusa and Hayabusa2, and obtain a global distribution of the boulders larger than 0.75–3 ​m, which corresponds to 1.5–6 pixels. We find that the boulder number density of this size range is smaller (1) on the western bulge than on the eastern hemisphere and (2) on the equatorial ridge than on the higher latitudes, both of which exceed the number density of boulders ​> ​5 ​m by an order of magnitude. The boulder size distribution at 1.25–20 ​m shows that the boulders smaller than 1 ​m are more abundant at the equator than at mid-latitudes, while those larger than 1 ​m in diameter are more abundant at mid-latitudes than at the equator. This contrast suggests size-dependent migration of boulders in the latitudinal direction. We also find that the typical boulder size (the size reaching the cumulative areal coverage of 50%) is 1.9 ​m at the equatorial region (10°S-10°N) while it is 2.6 ​m at mid-latitudes (40°S-50°S, 40°N-50°N). The typical boulder size is also smaller in the western bulge (2.0–2.2 ​m). We construct global maps of the power-law index of the size frequency distribution of boulders and find minor variations over the entire surface of Ryugu (−2.53 ​± ​0.03) for boulders larger than 1.25 ​m. This small variation suggests homogeneous size sorting processes on Ryugu. Surface roughness does not show a significant correlation with the v-band albedo but shows a high anti-correlation (R ​= ​−0.73) with the current geological slope on the eastern hemisphere. Our method is useful enhancement of smooth area detection and boulder distribution characterization that will be applicable to other planetary explorations in the future, including those of Phobos and other asteroids.

      DOI: 10.1016/j.pss.2021.105249

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

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

      ICARUS366   2021年9月

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACADEMIC PRESS INC ELSEVIER SCIENCE  

      The resurfacing process on Ryugu accompanying the artificial impact crater formation by Hayabusa2's Small Carry-on Impactor (SCI) was studied by comparing pre- and post-impact images of this region captured by an optical navigation camera. Three different aspects of the resurfacing process were examined: the crater rim profiles, the motion of boulders and the appearance of new boulders, and the motion vectors of Ryugu's surface around the SCI crater. The averaged crater rim height, h, was derived as follows: h = h(r) exp [-(r/R-rim 1)/lambda(rim)], where R-rim is the SCI crater rim radius of 8.8 m, the fitted parameter, h(r), is 0.475 m, and the lambda(rim) is 0.245. The ejecta blanket thickness of the SCI crater was thinner than that estimated from both the observation of natural craters and the crater formation theory. However, this discrepancy of the ejecta blanket thickness was resolved by taking into account the new boulders appearing in the post-impact images in the volume. The motion of the discovered boulders could be classified by its mechanisms as follows: a dragging motion created by excavation flow during the crater formation, a pushing motion created by falling-back ejecta, a dragging motion created by the slight motion of the Okamoto boulder, and a motion caused by seismic shaking induced by the SCI impact itself. The seismic shaking caused boulders to move farther than 3 cm from the original site in most of the region within 15 m distance from the SCI crater center, where the maximum acceleration of the impact induced seismic waves 7 times larger than the surface gravity of Ryugu based on the laboratory experiments (Matsue et al. [2020] Icarus, 338, 113520), and the evidence of the seismic shaking for boulders with a movement of >3 cm was detected in about 10% of the boulders in the region between 15 m and 30 m from the crater center, which region was inferred to experience acceleration larger than the Ryugu's surface gravity based on previous laboratory experiments (Matsue et al. [2020] Icarus, 338, 113520).

      DOI: 10.1016/j.icarus.2021.114530

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    • Hayabusa2 extended mission: New voyage to rendezvous with a small asteroid rotating with a short period

      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 Research68 ( 3 ) 1533 - 1555   2021年8月

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      掲載種別:研究論文(学術雑誌)   出版者・発行元:Elsevier BV  

      Hayabusa2 is the Japanese Asteroid Return Mission and targeted the carbonaceous asteroid Ryugu, conducted by the Japan Aerospace Exploration Agency (JAXA). The goal of this mission was to conduct proximity operations including remote sensing observations, material sampling, and a Small Carry-On Impact experiment, as well as sample analyses. As of September 2020, the spacecraft is on the way back to Earth with samples from Ryugu with no critical issues after the successful departure in November 2019. Here, we propose an extended mission in which the spacecraft will rendezvous with a small asteroid with ~30 m - ~40 m in diameter that is rotating at a spin period of ~10 min after an additional ~10-year cruise phase. We introduce that two scenarios are suitable for the extended mission. In the first scenario, the spacecraft will perform swing-by maneuvers at Venus once and Earth twice to arrive at asteroid 2001 AV43. In the second scenario, it will perform swing-by maneuvers at Earth twice to reach asteroid 1998 KY26. In both scenarios, the mission will continue until the early 2030s. JAXA recently released the decision that the spacecraft will rendezvous with 1998 KY26. This paper focuses on our scientific assessments of the two scenarios but leaves the decision process to go to 1998 KY26 for future reports. Rendezvous operations will be planned to detail the physical properties and surrounding environments of the target, one of the smallest elements of small planetary bodies. By achieving the planned operations, the mission will provide critical hints on the violent histories of collisions and accumulations of small bodies in the solar system. Furthermore, the established scientific knowledge and techniques will advance key technologies for planetary defense.

      DOI: 10.1016/j.asr.2021.03.030

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

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

      Nature Astronomy5 ( 8 ) 766 - 774   2021年8月

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      掲載種別:研究論文(学術雑誌)  

      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

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    • 火の鳥「はやぶさ」未来編 その24 〜可視光でみたリュウグウ〜

      巽 瑛理, 杉田 精司, 本田 理恵, 諸田 智克, 亀田 真吾, 長 勇一郎, 澤田 弘崇, 横田 康弘, 坂谷 尚哉, 早川 雅彦, 松岡 萌, 山田 学, 神山 徹, 鈴木 秀彦, 本田 親寿, 吉岡 和夫, 小川 和律, 湯本 航生

      日本惑星科学会誌遊星人30 ( 2 ) 64 - 71   2021年6月25日

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      記述言語:日本語   出版者・発行元:日本惑星科学会  

      ONC (Optical Navigation Camera; 光学航法カメラ) は探査機はやぶさ2の目であり, リュウグウを訪れた際には科学的にも工学的にも広報的にも幅広く活⽤された.ONCは広域撮像⽤のONC-W1,ONC-W2,望遠カメラ且つ7色のバンドパスフィルターをもつONC-Tで構成されている.ONC-Tは科学観測において特に重要で,フィルターを活⽤し⼩惑星表⾯の色の変化を記載することや解像度の高い画像から詳細な地形の観測を目的としている.試料採取地点の選定にも,粒径や風化作⽤の推定といった核となる情報を得て貢献してきた.本稿では,今後のサンプル分析を見据えて,主にONCチームのONC-Tを⽤いた分光観測における活動とその結果として得られた“仮説”を振り返りたいと思う.

      DOI: 10.14909/yuseijin.30.2_64

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    • Correction to: Orbit insertion strategy of Hayabusa2’s rover with large release uncertainty around the asteroid Ryugu (Astrodynamics, (2020), 4, 4, (309-329), 10.1007/s42064-020-0080-y)

      Yusuke Oki, Kent Yoshikawa, Hiroshi Takeuchi, Shota Kikuchi, Hitosi Ikeda, Daniel J. Scheeres, Jay W. McMahon, Junichiro Kawaguchi, Yuto Takei, Yuya Mimasu, Naoko Ogawa, Go Ono, Fuyuto Terui, Manabu Yamada, Toru Kouyama, Shingo Kameda, Kazuya Yoshida, Kenji Nagaoka, Tetsuo Yoshimitsu, Takanao Saiki, Yuichi Tsuda

      Astrodynamics5 ( 2 ) 183   2021年6月

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      掲載種別:研究論文(学術雑誌)  

      The article “Orbit insertion strategy of Hayabusa2’s rover with large release uncertainty around the asteroid Ryugu” written by Yusuke Oki, Kent Yoshikawa, Hiroshi Takeuchi et al., was originally published electronically on the publisher’s internet portal (currently SpringerLink) on 05 November 2020 without open access. After publication in Volume 4, Issue 4, page 309–329, the author(s) decided to opt for Open Choice and to make the article an open access publication. Therefore, the copyright of the article has been changed to © The Author(s) 2020 and the article is forthwith distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits use, duplication, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

      DOI: 10.1007/s42064-021-0100-6

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    • High-resolution observations of bright boulders on asteroid Ryugu: 2. Spectral properties

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

      Icarus   114591 - 114591   2021年6月

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      掲載種別:研究論文(学術雑誌)   出版者・発行元:Elsevier BV  

      DOI: 10.1016/j.icarus.2021.114591

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    • Improved method of hydrous mineral detection by latitudinal distribution of 0.7-μm surface reflectance absorption on the asteroid Ryugu

      Shingo Kameda, Yasuhiro Yokota, Toru Kouyama, Eri Tatsumi, Marika Ishida, Tomokatsu Morota, Rie Honda, Naoya Sakatani, Manabu Yamada, Moe Matsuoka, Hidehiko Suzuki, Yuichiro Cho, Masahiko Hayakawa, Chikatoshi Honda, Hirotaka Sawada, Kazuo Yoshioka, Kazunori Ogawa, Seiji Sugita

      Icarus360   2021年5月15日

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      掲載種別:研究論文(学術雑誌)  

      © 2021 Elsevier Inc. Global multiband images of the C-type asteroid (162173) Ryugu were obtained by the optical navigation camera telescope (ONC-T) onboard Hayabusa2. The 0.7-μm absorption depth of the surface reflectance spectrum, which indicates the presence of hydrous minerals, was not clearly seen on Ryugu using flat field correction data obtained in the preflight measurement. The flat field correction data were obtained in the preflight calibration test only at room temperatures (24‐–28 °C), whereas most observations around Ryugu were performed at a charge-coupled device (CCD) temperature of approximately ‐−30 °C. To obtain higher accuracy measurements, we used a new flat field correction method using the Ryugu surface reflection data. We confirmed that the flat-field patterns are different in high and low temperature conditions. The 0.7-μm absorption map generated by the new method shows that the 0.7-μm absorption near the equator (5°N–5°S) is stronger than that from 30°N to 30°S. We found that the excess of the absorption depth at low latitudes was 0.072%, corresponding to 2.7σ. The spectral analysis also shows that the Ryugu surface at low latitudes is bluer than that at high latitudes and bluer materials tend to show stronger 0.7-μm absorption than redder materials, suggesting that this region has been subjected to less space weathering and less solar heating.

      DOI: 10.1016/j.icarus.2021.114348

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    • Post-arrival calibration of Hayabusa2's optical navigation cameras (ONCs): Severe effects from touchdown events

      Toru Kouyama, Eri Tatsumi, Yasuhiro Yokota, Koki Yumoto, Manabu Yamada, Rie Honda, Shingo Kameda, Hidehiko Suzuki, Naoya Sakatani, Masahiko Hayakawa, Tomokatsu Morota, Moe Matsuoka, Yuichiro Cho, Chikatoshi Honda, Hirotaka Sawada, Kazuo Yoshioka, Seiji Sugita

      Icarus360   2021年5月15日

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      掲載種別:研究論文(学術雑誌)  

      © 2021 Elsevier Inc. Accurate measurements of the surface brightness and its spectrophotometric properties are essential for obtaining reliable observations of the physical and material properties of planetary bodies. To measure the surface brightness of Ryugu accurately, we calibrated the optical navigation cameras (ONCs) of Hayabusa2 using both standard stars and Ryugu itself during the rendezvous phase including two touchdown operations for sampling. These calibration results showed that the nadir-viewing telescopic camera (ONC-T) and nadir-viewing wide-angle camera (ONC-W1) experienced substantial variation in sensitivity. In particular, ONC-W1 showed significant sensitivity degradation (~60%) after the first touchdown operation. We estimated the degradations to be caused by front lens contamination by fine-grain materials lifted from the Ryugu surface due to thruster gas for ascent back maneuver and sampler projectile impact upon touchdown. While ONC-T is located very close to W1 on the spacecraft, its degradation in sensitivity was only ~15% over the entire rendezvous phase. If in fact dust is really the main cause for the degradation, this lighter damage likely resulted from dust protection by the long hood attached to ONC-T. However, because large variations in the absolute sensitivity occurred after the touchdown events, which should be due to dust effect, uncertainty for the absolute sensitivity was rather large (3–4%). On the other hand, the change in relative spectral responsivity (i.e., 0.55-μm-band normalized responsivity) of ONC-T was small (1%). The variation in relative responsivity during the proximity phase has been well calibrated to have only a small uncertainty (< 1%). Furthermore, the degradation (i.e., increase) in the full width at half maximum of the point spread function of ONC-T and W1 was almost negligible, although the blurring effect due to dust scattering was confirmed in W1. These optical degradations due to the touchdown events were carefully monitored as a function of time along with other time-related deteriorations, such as the dark current level and hot pixels. We also conducted a new calibration of the flat-field change as a function of the detector temperature by observing the onboard flat-field lamp and validating with Ryugu's disk images. The results of these calibrations showed that ONC-T and W1 maintained their scientific performance by updating the calibration parameters.

      DOI: 10.1016/j.icarus.2021.114353

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

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

      Icarus369   114529 - 114529   2021年5月

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      掲載種別:研究論文(学術雑誌)   出版者・発行元:Elsevier BV  

      DOI: 10.1016/j.icarus.2021.114529

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    • Geologic History and Crater Morphology of Asteroid (162173) Ryugu

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

          2021年4月19日

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      出版者・発行元:Wiley  

      DOI: 10.1002/essoar.10506689.2

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    • Numerical modeling of lander interaction with a low-gravity asteroid regolith surface

      Florian Thuillet, Yun Zhang, Patrick Michel, Jens Biele, Shingo Kameda, Seiji Sugita, Eri Tatsumi, Stephen R. Schwartz, Ronald-Louis Ballouz

      Astronomy &amp; Astrophysics648   A56 - A56   2021年4月

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      掲載種別:研究論文(学術雑誌)   出版者・発行元:EDP Sciences  

      Context. The JAXA asteroid sample return mission Hayabusa2 reached its target (162173) Ryugu in June 2018 and released the European (CNES-DLR) lander MASCOT in October 2018. MASCOT successfully landed on the surface, and the Hayabusa2 Optical Navigation Camera system has been able to image parts of the MASCOT trajectory.

      Aims. This work builds on our previous study of interactions between a landing package and a granular material in the context of MASCOT on Ryugu. The purpose is to expand our knowledge on this topic and to help constrain physical properties of surfaces by considering the actual trajectory of MASCOT and observations of Ryugu from Hayabusa2.

      Methods. We ran a new campaign of numerical simulations using the N-body code pkdgrav with the soft-sphere discrete element method by expanding the parameter space to characterize the actual landing scenario of MASCOT on Ryugu. The surface was modeled as a granular medium, but we also considered a large boulder in the bed at various depths and a rigid wall representing a cliff. MASCOT was faithfully modeled as the actual lander, and we considered different impact angles, speeds, and surface slopes. We were particularly interested in the outgoing-to-incoming speed ratio of MASCOT during the landing process.

      Results. We found that a boulder in the bed generally increases both the stochasticity of the outcomes and the speed ratio, with larger increases when the boulder sits closer to the surface. We also found that the surface slope does not affect our previous results and that the impact speed does not affect the speed ratio for moderate-friction granular material. Finally, we found that a speed ratio as low as 0.3, as estimated in the actual scenario, can occur with a solid-rock surface, not only with a soft surface, because the geometry of the lander is nonspherical. This means that we must infer the physical properties of the surface from outcomes such as the speed ratio with caution: it depends on the lander geometry.

      DOI: 10.1051/0004-6361/201936128

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

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

      Icarus358   114220 - 114220   2021年4月

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      掲載種別:研究論文(学術雑誌)   出版者・発行元:Elsevier BV  

      DOI: 10.1016/j.icarus.2020.114220

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    • Spectral characterization of the craters of Ryugu as observed by the NIRS3 instrument on-board Hayabusa2

      Lucie Riu, Cédric Pilorget, Ralph Milliken, Kohei Kitazato, Tomoki Nakamura, Yuichiro Cho, Moe Matsuoka, Seiji Sugita, Masanao Abe, Shuji Matsuura, Makiko Ohtake, Shingo Kameda, Naoya Sakatani, Eri Tatsumi, Yasuhiro Yokota, Takahiro Iwata

      Icarus357   2021年3月15日

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      掲載種別:研究論文(学術雑誌)  

      © 2020 Elsevier Inc. C-type rubble pile asteroid (162173) Ryugu was observed and characterized up close for a year and a half by the instruments on-board the Japanese Aerospace eXploration Agency (JAXA) Hayabusa2 spacecraft. The asteroid exhibits relatively homogeneous spectral characteristics at near-infrared wavelengths (~1.8–3.2 μm), including a very low reflectance factor, a slight positive (“red”) slope towards longer wavelengths, and a narrow absorption feature centered at 2.72 μm that is attributed to the presence of OH− in phyllosilicate minerals. Numerous craters have been identified at the surface that provide good candidates for identifying and studying younger and/or more recently exposed near-surface material to further assess potential spectral/compositional heterogeneities. We present here the results of a spectral survey of all previously identified and referenced craters (Hirata et al. 2020) based on reflectance data acquired by the NIRS3 spectrometer, with an emphasis on the spectral characteristics between different craters as well as with their surrounding terrain. At a global scale, the spectral properties inside and outside of craters are found to be very similar, indicating that subsurface material is either compositionally similar to material at the surface that has a longer exposure age or that material at Ryugu's optical surface is spectrally altered over relatively short timescales by external factors such as space weathering. Although, the imaging data from ONC camera suites show more morphological and color diversity in craters at a smaller scale than the resolution provided by the NIRS3 instrument, which could indicate a wider compositional diversity on Ryugu than that observed in the near-infrared and discussed in this paper. The 2.72 μm band depth exhibit a slight anti-correlation with the reflectance factor selected at 2 μm, which could indicate different surface properties (e.g., grain size and/or porosity) or different alteration processes (e.g., space weathering, shock metamorphism and/or solar heating). Four different spectral classes were identified based on their reflectance factor at 2 μm and 2.72 μm absorption strength. The most commonly spectral behavior associated with crater floors, is defined by a slightly lower reflectance at 2 μm and deeper band depth. These spectral characteristics are similar to those of subsurface material excavated by the Hayabusa2 small carry-on impactor (SCI) experiment, suggesting these spectral characteristics may represent materials with a younger surface exposure age. Alternatively, these materials may have experienced significant solar heating and desiccation to form finer grains that subsequently migrated towards and preferentially accumulated in areas of low geopotential, such as craters floors. It is believed that the Hayabusa2 mission successfully collected typical surface material as well as darker material excavated by the SCI experiment, and detailed analyses of those samples upon their return will allow for further testing of these formation and alteration hypotheses.

      DOI: 10.1016/j.icarus.2020.114253

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    • Crater depth-to-diameter ratios on asteroid 162173 Ryugu d/D of craters on Ryugu

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

      Icarus354   2021年1月15日

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      掲載種別:研究論文(学術雑誌)  

      © 2020 Elsevier Inc. The near-Earth asteroid 162173 Ryugu, the target of the Hayabusa2 mission, is noted to be a spinning top-shaped rubble-pile. Craters are among the most prominent surface features on Ryugu. Their shapes, particularly their depth-to-diameter ratio (d/D), can provide an important proxy for probing both the internal structure and surface processes of planetary bodies. Here, we report d/D of every impact crater on Ryugu using a shape model derived from stereo-photoclinometry. We found that the average, standard deviation, and observed range of d/D for the entire set of craters are 0.09, 0.02, and 0.03–0.15, respectively. Except for possible pit craters, the maximum d/D of large craters on Ryugu (D > 50 m) is close to 0.13, which is comparable with those of fresh simple craters on rocky asteroids, such as Gaspra and Ida. Conversely, the d/D of small craters (D < 50 m) increases with the crater diameter. This behavior implies that a smaller crater on Ryugu is formed as a shallower crater. As on Itokawa, the surface environment on Ryugu likely inhibits craters becoming deep. This especially affects smaller craters, as their normal small depth decreases in the Ryugu environment and they become still more shallow. As a result, small craters rapidly degrade beyond the point where they can be identified as candidate craters. This is likely responsible for the apparent lack of small craters. The d/D has no reliable relationship with the types of crater classification in Hirata et al. (2020). Examination of latitudinal and longitudinal variation in d/D of craters on Ryugu revealed no statistically significant trends.

      DOI: 10.1016/j.icarus.2020.114016

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

      Matthias Grott, Jens Biele, Patrick Michel, Seiji Sugita, Stefan Schroeder, Naoya Sakatani, Wladimir Neumann, Shingo Kameda, Tatsuhiro Michikami, Chikatoshi Honda

      JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS125 ( 12 )   2020年12月

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER GEOPHYSICAL UNION  

      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.

      DOI: 10.1029/2020JE006519

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    • Orbit insertion strategy of Hayabusa2’s rover with large release uncertainty around the asteroid Ryugu

      Yusuke Oki, Kent Yoshikawa, Hiroshi Takeuchi, Shota Kikuchi, Hitosi Ikeda, Daniel J. Scheeres, Jay W. McMahon, Junichiro Kawaguchi, Yuto Takei, Yuya Mimasu, Naoko Ogawa, Go Ono, Fuyuto Terui, Manabu Yamada, Toru Kouyama, Shingo Kameda, Kazuya Yoshida, Kenji Nagaoka, Tetsuo Yoshimitsu, Takanao Saiki, Yuichi Tsuda

      Astrodynamics4 ( 4 ) 309 - 329   2020年12月

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      掲載種別:研究論文(学術雑誌)  

      This paper describes the orbit design of the deployable payload Rover 2 of MINERVA-II, installed on the Hayabusa2 spacecraft. Because Rover 2 did not have surface exploration capabilities, the operation team decided to experiment with a new strategy for its deployment to the surface. The rover was ejected at a high altitude and made a semi-hard landing on the surface of the asteroid Ryugu after several orbits. Based on the orbital analysis around Ryugu, the expected collision speed was tolerable for the rover to function post-impact. Because the rover could not control its position, its motion was entirely governed by the initial conditions. Thus, the largest challenge was to insert the rover into a stable orbit (despite its large release uncertainty), and avoid its escape from Ryugu due to an environment strongly perturbed by solar radiation pressure and gravitational irregularities. This study investigates the solution space of the orbit around Ryugu and evaluates the orbit’s robustness by utilizing Monte Carlo simulations to determine the orbit insertion policy. Upon analyzing the flight data of the rover operation, we verified that the rover orbited Ryugu for more than one period and established the possibility of a novel method for estimating the gravity of an asteroid.

      DOI: 10.1007/s42064-020-0080-y

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    • The deep-space multi-object orbit determination system and its application to Hayabusa2’s asteroid proximity operations

      Hiroshi Takeuchi, Kent Yoshikawa, Yuto Takei, Yusuke Oki, Shota Kikuchi, Hitoshi Ikeda, Stefania Soldini, Naoko Ogawa, Yuya Mimasu, Go Ono, Fuyuto Terui, Naoya Sakatani, Manabu Yamada, Toru Kouyama, Shingo Kameda, Takanao Saiki, Yuichi Tsuda

      Astrodynamics4 ( 4 ) 377 - 392   2020年12月

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      掲載種別:研究論文(学術雑誌)   出版者・発行元:Springer Science and Business Media LLC  

      DOI: 10.1007/s42064-020-0084-7

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      その他リンク: http://link.springer.com/article/10.1007/s42064-020-0084-7/fulltext.html

    • Surface roughness of asteroid (162173) Ryugu and comet 67P/Churyumov-Gerasimenko inferred from in-situ observations 査読有り

      K A Otto, K-D Matz, S E Schröder, R Parekh, K Krohn, R Honda, S Kameda, R Jaumann, N Schmitz, K Stephan, S Sugita, E Tatsumi, T-M Ho, A Koncz, F Trauthan, Y Cho, M Hayakawa, C Honda, T Kouyama, M Matsuoka, T Morota, S Mottola, K Ogawa, F Preusker, N Sakatani, H Sawada, F Scholten, H Suzuki, M Yamada, Y Yokota, K Yoshioka

      Monthly Notices of the Royal Astronomical Society500 ( 3 ) 3178 - 3193   2020年10月27日

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      掲載種別:研究論文(学術雑誌)   出版者・発行元:Oxford University Press (OUP)  

      <title>Abstract</title>
      Alteration processes on asteroid and comet surfaces, such as thermal fracturing, (micrometeorite) impacts or volatile outgassing, are complex mechanisms that form diverse surface morphologies and roughness on various scales. These mechanisms and their interaction may differ on the surfaces of different bodies. Asteroid Ryugu and comet 67P/Churyumov-Gerasimenko, both, have been visited by landers which imaged the surfaces in high spatial resolution. We investigate the surface morphology and roughness of Ryugu and 67P/Churyumov-Gerasimenko based on high resolution in situ images of 0.2 mm and 0.8 mm pixel resolution over an approximately 25 cm and 80 cm wide scene, respectively. To maintain comparability and reproducibility, we introduce a method to extract surface roughness descriptors (fractal dimension, Hurst exponent, joint roughness coefficient, root mean square slope, hemispherical crater density, small scale roughness parameter and Hapke mean slope angle) from in situ planetary images illuminated by LEDs. We validate our method and choose adequate parameters for an analysis of the roughness of the surfaces. We also derive the roughness descriptors from 3-dimensional shape models of Ryugu and orbiter camera images and show that the higher spatially resolved images results in a higher roughness. We find that 67P/Churyumov-Gerasimenko is up to 6% rougher than Ryugu depending on the descriptor used and attribute this difference to the different intrinsic properties of the materials imaged and the erosive processes altering them. On 67P/Churyumov-Gerasimenko sublimation appears to be the main cause for roughness, while on Ryugu micrometeoroid bombardment as well as thermal fatigue and solar weathering may play a significant role in shaping the surface.

      DOI: 10.1093/mnras/staa3314

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    • 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年10月8日

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      出版者・発行元:Copernicus GmbH  

      &amp;lt;p&amp;gt;JAXA&amp;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;amp;#160;&amp;lt;/p&amp;gt;
      &amp;lt;p&amp;gt;The global observations revealed that Ryugu has a top-shaped body with very low density (1.19&amp;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;amp;#160;&amp;lt;/p&amp;gt;
      &amp;lt;p&amp;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;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].&amp;lt;/p&amp;gt;
      &amp;lt;p&amp;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;amp;#8220;dense boulders&amp;amp;#8221; with high thermal inertia (&amp;gt;600 MKS) consistent with typical carbonaceous chondrites, showing that Ryugu&amp;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.&amp;lt;/p&amp;gt;
      &amp;lt;p&amp;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 (&amp;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;amp;#160;&amp;lt;/p&amp;gt;
      &amp;lt;p&amp;gt;If radiogenic heating is really responsible for Ryugu&amp;amp;#8217;s moderate dehydration, this may place a very important constraint on the timing of the formation of Ryugu&amp;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;amp;#8217;s bulk materials inferred from spectral comparison with laboratory heated CM and CI meteorites [4, 12] require Ryugu&amp;amp;#8217;s parent body formed early in the Solar System. Because Ryugu&amp;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;amp;#8217;s parent body would be a high-accretion-rate location outside the snowline.&amp;lt;/p&amp;gt;
      &amp;lt;p&amp;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;amp;#8217;s orbit, and non-carbonaceous meteorites (NCs), which formed inside Jupiter&amp;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;amp;#160;&amp;lt;/p&amp;gt;
      &amp;lt;p&amp;gt;&amp;lt;strong&amp;gt;Acknowledgements:&amp;lt;/strong&amp;gt; This study was supported by JSPS Core-to-Core program &amp;amp;#8220;International Network of Planetary Sciences&amp;amp;#8221;, CNES, and Univ. Co?te d&amp;amp;#8217;Azur.&amp;amp;#160;&amp;lt;/p&amp;gt;
      &amp;lt;p&amp;gt;&amp;lt;strong&amp;gt;References:&amp;lt;/strong&amp;gt;&amp;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;amp;#160; [10] Grott et al., Nature Astron. 3, 971-976, 2019.&amp;amp;#160; [11] Okada et al., Nature, 579, 518-522, 2020. [12] Sugimoto et al. 51st LPSC, #1770, 2020.&amp;amp;#160; [13] Grimm and McSween, Science, 259, 653-655, 1993.&amp;amp;#160; [14] Kruijer et al., PNAS, 114, 6712-6716, 2017.&amp;amp;#160;&amp;lt;/p&amp;gt;

      DOI: 10.5194/epsc2020-995

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

      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 Reviews216 ( 7 )   2020年10月

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      掲載種別:研究論文(学術雑誌)   出版者・発行元:Springer Science and Business Media LLC  

      DOI: 10.1007/s11214-020-00737-z

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      その他リンク: http://link.springer.com/article/10.1007/s11214-020-00737-z/fulltext.html

    • Collisional history of Ryugu’s parent body from bright surface boulders 査読有り

      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 Astronomy5 ( 1 ) 39 - 45   2020年9月21日

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      掲載種別:研究論文(学術雑誌)   出版者・発行元:Springer Science and Business Media LLC  

      DOI: 10.1038/s41550-020-1179-z

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      その他リンク: http://www.nature.com/articles/s41550-020-1179-z

    • Global photometric properties of (162173) Ryugu 査読有り

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

      Astronomy & Astrophysics639   A83 - A83   2020年7月

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      掲載種別:研究論文(学術雑誌)   出版者・発行元:EDP Sciences  

      <italic>Context.</italic> The Hayabusa2 spacecraft launched by Japan Aerospace Exploration Agency has been conducting observations of the asteroid (162173) Ryugu since June 2018. The Telescopic Optical Navigation Camera (ONC-T) onboard Hayabusa2 has obtained thousands of images under a variety of illumination and viewing conditions.


      <italic>Aims.</italic> Our objective is to examine and validate the camera calibration, derive a photometric correction for creating global albedo maps, and to interpret the photometric modeling results to characterize the surface of Ryugu.


      <italic>Methods.</italic> We observed (162173) Ryugu with the Gemini-South telescope, and combined these measurements with other published ground-based observations of the asteroid. The ground-based observations were compared with the data obtained by ONC-T in order to validate the radiometric calibration mutually. We used a combination of the Hapke disk-integrated and disk-resolved model equations to simultaneously analyze the combined ground- and spacecraft-based data.


      <italic>Results.</italic> The average spectrum of Ryugu was classified as Cb-type following the SMASSII taxonomy and C/F-type following the Tholen taxonomy based on spacecraft observations. We derived Hapke model parameters for all seven color filters, which allowed us to photometrically correct images to within an error of &lt;10% for ~80% of the image pixels used in the modeling effort. Using this model, we derived a geometric albedo of 4.0 ± 0.5% (<italic>v</italic> band) for Ryugu. The average reflectance factor at the standard illumination condition was 1.87 ± 0.14% in the <italic>v</italic> band. Moreover we measured a phase reddening of (2.0 ± 0.7) × 10<sup>−3</sup> <italic>μ</italic>m<sup>−1</sup> deg<sup>−1</sup> for Ryugu, similar to that observed for the asteroid (101955) Bennu.


      <italic>Conclusions.</italic> The global color map showed that the general trend was for darker regions to also be redder regions, however there were some distinct exceptions to this trend. For example, Otohime Saxum was bright and red while Kibidango crater was dark and blue. The darkness and flatness of Ryugu’s reflectance might be caused by a high abundance of organic materials.

      DOI: 10.1051/0004-6361/201937096

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

      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

      Science368 ( 6491 ) 654 - 659   2020年5月8日

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      掲載種別:研究論文(学術雑誌)   出版者・発行元:American Association for the Advancement of Science (AAAS)  

      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

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

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

      Science368 ( 6486 ) 67 - 71   2020年4月3日

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      掲載種別:研究論文(学術雑誌)   出版者・発行元:American Association for the Advancement of Science (AAAS)  

      The Hayabusa2 spacecraft investigated the small asteroid Ryugu, which has a rubble-pile structure. We describe an impact experiment on Ryugu using Hayabusa2’s Small Carry-on Impactor. The impact produced an artificial crater with a diameter &gt;10 meters, which has a semicircular shape, an elevated rim, and a central pit. Images of the impact and resulting ejecta were recorded by the Deployable CAMera 3 for &gt;8 minutes, showing the growth of an ejecta curtain (the outer edge of the ejecta) and deposition of ejecta onto the surface. The ejecta curtain was asymmetric and heterogeneous and it never fully detached from the surface. The crater formed in the gravity-dominated regime; in other words, crater growth was limited by gravity not surface strength. We discuss implications for Ryugu’s surface age.

      DOI: 10.1126/science.aaz1701

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    • The spatial distribution of impact craters on Ryugu 査読有り

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

      Icarus338   113527 - 113527   2020年3月

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Elsevier BV  

      Asteroid 162173 Ryugu has numerous craters. The initial measurement of impact craters on Ryugu, by Sugita et al. (2019), is based on Hayabusa2 ONC images obtained during the first month after the arrival of Hayabusa2 in June 2018. Utilizing new images taken until February 2019, we constructed a global impact crater catalogue of Ryugu, which includes all craters larger than 20 m in diameter on the surface of Ryugu. As a result, we identified 77 craters on the surface of Ryugu. Ryugu shows variation in crater density which cannot be explained by the randomness of cratering; there are more craters at lower latitudes and fewer at higher latitudes, and fewer craters in the western bulge (160 degrees E - 290 degrees E) than in the region around the meridian (300 degrees E - 30 degrees E). This variation implies a complicated geologic history for Ryugu. It seems that the variation in crater density indicates that the equatorial ridge located in the western hemisphere is relatively young, while that located in the eastern hemisphere is a fossil structure formed during the short rotational period in the distant past.

      DOI: 10.1016/j.icarus.2019.113527

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    • Scattering mechanism of surface material by thrusting near asteroid

      Maiko Yamakawa, Kentaro Watanabe, Hiroumi Tani, Yusuke Maru, Toshihiro Chujo, Jun Matsumoto, Hikaru Eguchi, Keisuke Michigami, Taro Kawano, Hajime Yano, Shingo Kameda, Shujiro Sawai, Osamu Mori, Yuichi Tsuda

      Proceedings of the International Astronautical Congress, IAC2020-October   2020年

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      掲載種別:研究論文(国際会議プロシーディングス)  

      During the touchdowns of the "Hayabusa2" spacecraft on the asteroid Ryugu, some of the ejected surface materials were scattered toward the spacecraft. Apart from impact sampling by firing a metallic projectile, another mechanism of this phenomenon is surface material ejecta from formation of a crater by RCS thrusts of the spacecraft during its ascent from the asteroid surface after the touchdown. We conducted ground experiments of gas injection into simulated soil under vacuum in order to investigate the interaction between thruster plume and asteroidal regolith.

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    • Design and reconstruction of the hayabusa2 precision landing on ryugu

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

      Advances in the Astronautical Sciences171   3101 - 3120   2020年

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      掲載種別:研究論文(国際会議プロシーディングス)  

      The Hayabusa2 spacecraft successfully landed on the asteroid Ryugu on February 22nd, 2019. Because of the abundance of boulders, the touchdown operation required high accuracy for spacecraft safety. This research, therefore, investigates a precision landing sequence using retroreflective marker tracking. The trajectory for the touchdown operation is computed based on a high-fidelity gravity model to minimize the landing error. This paper provides trajectory reconstruction results based on actual flight data. Consequently, it is demonstrated that a landing accuracy of 3 m can be achieved, resulting in the successful touchdown.

      DOI: 10.2514/1.A34683

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    • The Hayabusa2 lander MASCOT on the surface of asteroid (162173) Ryugu – Stereo-photogrammetric analysis of MASCam image data 査読有り

      F. Scholten, F. Preusker, S. Elgner, K.-D. Matz, R. Jaumann, M. Hamm, S. E. Schröder, A. Koncz, N. Schmitz, F. Trauthan, M. Grott, J. Biele, T.-M. Ho, S. Kameda, S. Sugita

      Astronomy & Astrophysics632   L5 - L5   2019年12月

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      掲載種別:研究論文(学術雑誌)   出版者・発行元:EDP Sciences  

      After its release and a descent and bouncing phase, the Hayabusa2 lander MASCOT came to a final rest and MASCOT’s camera MASCam acquired a set of images of the surface of Ryugu. With MASCam’s instantaneous field of view of about 1 mrad, the images provide pixel scales from 0.2 to 0.5 mm pixel<sup>−1</sup> in the foreground and up to 1 cm pixel<sup>−1</sup> for surface parts in the background. Using a stereo-photogrammetric analysis of the MASCam images taken from slightly different positions due to commanded and unintentional movements of the MASCOT lander, we were able to determine the orientation for the different measurement positions. Furthermore, we derived a 3D surface model of MASCOT’s vicinity. Although the conditions for 3D stereo processing were poor due to very small stereo angles, the derived 3D model has about 0.5 cm accuracy in the foreground at 20 cm distance and about 1.5 cm at a distance of 40–50 cm.

      DOI: 10.1051/0004-6361/201936760

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    • The MASCOT landing area on asteroid (162173) Ryugu: Stereo-photogrammetric analysis using images of the ONC onboard the Hayabusa2 spacecraft 査読有り

      F. Preusker, F. Scholten, S. Elgner, K.-D. Matz, S. Kameda, T. Roatsch, R. Jaumann, S. Sugita, R. Honda, T. Morota, E. Tatsumi, Y. Cho, K. Yoshioka, H. Sawada, Y. Yokota, N. Sakatani, M. Hayakawa, M. Matsuoka, M. Yamada, T. Kouyama, H. Suzuki, C. Honda, K. Ogawa

      Astronomy & Astrophysics632   L4 - L4   2019年12月

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      掲載種別:研究論文(学術雑誌)   出版者・発行元:EDP Sciences  

      A high-resolution 3D surface model, map-projected to a digital terrain model (DTM), and precisely ortho-rectified context images (orthoimages) of MASCOT landing site area are important data sets for the scientific analysis of relevant data that have been acquired with MASCOT’s image camera system MASCam and other instruments (e.g., the radiometer MARA and the magnetometer MASMag). We performed a stereo-photogrammetric (SPG) analysis of 1050 images acquired from the Hayabusa2 Optical Navigation Camera system (ONC) during the asteroid characterization phase and the MASCOT release phase in early October 2018 to construct a photogrammetric control point network of asteroid (162173) Ryugu. We validated existing rotational parameters for Ryugu and improved the camera orientation (position and pointing) of the ONC images to decimeter accuracy using SPG bundle block adjustment. We produced a high-resolution DTM of the entire MASCOT landing site area. Finally, based on this DTM, a set of orthoimages from the highest-resolution ONC images around MASCOT’s final rest position complements the results of this analysis.

      DOI: 10.1051/0004-6361/201936759

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    • The descent and bouncing path of the Hayabusa2 lander MASCOT at asteroid (162173) Ryugu 査読有り

      F. Scholten, F. Preusker, S. Elgner, K.-D. Matz, R. Jaumann, J. Biele, D. Hercik, H.-U. Auster, M. Hamm, M. Grott, C. Grimm, T.-M. Ho, A. Koncz, N. Schmitz, F. Trauthan, S. Kameda, S. Sugita, R. Honda, T. Morota, E. Tatsumi, Y. Cho, K. Yoshioka, H. Sawada, Y. Yokota, N. Sakatani, M. Hayakawa, M. Matsuoka, M. Yamada, T. Kouyama, H. Suzuki, C. Honda, K. Ogawa

      Astronomy & Astrophysics632   L3 - L3   2019年12月

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      掲載種別:研究論文(学術雑誌)   出版者・発行元:EDP Sciences  

      Images from the Optical Navigation Camera system (ONC) onboard the Hayabusa2 spacecraft show the MASCOT lander during its descent to the surface of asteroid (162173) Ryugu. We used results from a previous stereo-photogrammetric analysis that provided precise ONC image orientation data (camera position and pointing), ONC orthoimages, and an ONC-based 3D surface model to combine them with the visibilities of MASCOT itself and its shadow on-ground within the ONC images. We integrated additional information from instruments onboard MASCOT (MASMag, MARA, MASCam) and derived MASCOT’s release position and modeled its free-fall descent path and its velocity over 350 s from its release at ∼41 m altitude above ground until its first contact with the surface of Ryugu. After first contact, MASCOT bounced over the surface of Ryugu for 663 s and came to rest at its first settlement point after four intermediate surface contacts. We again used ONC images that show MASCOT and partly its shadow and reconstructed the bouncing path and the respective velocities of MASCOT. The achieved accuracy for the entire descent and bouncing path is ∼0.1 m (1<italic>σ</italic>).

      DOI: 10.1051/0004-6361/201936757

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    • Earth as an exoplanet mission concept for a lunar orbiting cubesat 査読有り

      Ana I. Gómez de Castro, Leire Beitia-Antero, Carlos E. Miravet-Fuster, Lorenzo Tarabini, Albert Tomás, Juan C. Vallejo, Ada Canet, Mikhail Sachkov, Shingo Kameda

      Journal of Astronomical Telescopes, Instruments, and Systems5 ( 04 ) 1 - 1   2019年10月23日

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      掲載種別:研究論文(学術雑誌)   出版者・発行元:SPIE-Intl Soc Optical Eng  

      DOI: 10.1117/1.jatis.5.4.044004

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    • Boulder size and shape distributions on asteroid Ryugu 査読有り

      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

      Icarus331   179 - 191   2019年10月

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      掲載種別:研究論文(学術雑誌)   出版者・発行元:Elsevier BV  

      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 km ) 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 , 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. 2 −2

      DOI: 10.1016/j.icarus.2019.05.019

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    • Development of high-efficiency reflective grating by holographic processing for UV exoplanet science 査読有り

      K. Enya, S. Kameda

      Proceedings of the SPIE   2019年9月9日

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      記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

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

      M. Barucci, S. Kameda他

      Astronomy & Astrophysics   2019年8月23日

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      記述言語:英語   掲載種別:研究論文(学術雑誌)  

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    • Images from the surface of asteroid Ryugu show rocks similar to carbonaceous chondrite meteorites 査読有り

      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

      Science365 ( 6455 ) 817 - 820   2019年8月23日

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      記述言語:英語   掲載種別:研究論文(学術雑誌)  

      © 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

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

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

      METEORITICS & PLANETARY SCIENCE54   .   2019年8月

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      記述言語:英語   掲載種別:研究論文(学術雑誌)  

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    • Updated inflight calibration of Hayabusa2's optical navigation camera (ONC) for scientific observations during the cruise phase 査読有り

      Eri Tatsumi, Toru Kouyama, Hidehiko Suzuki, Manabu Yamada, Naoya Sakatani, Shingo Kameda, Yasuhiro Yokota, Rie Honda, Tomokatsu Morota, Keiichi Moroi, Naoya Tanabe, Hiroaki Kamiyoshihara, Marika Ishida, Kazuo Yoshioka, Hiroyuki Sato, Chikatoshi Honda, Masahiko Hayakawa, Kohei Kitazato, Hirotaka Sawada, Seiji Sugita

      Icarus325   153 - 195   2019年6月

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Elsevier {BV}  

      DOI: 10.1016/j.icarus.2019.01.015

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    • Hayabusa2 arrives at the carbonaceous asteroid 162173 Ryugu─A spinning top—shaped rubble pile 査読有り 国際誌

      S. Watanabe, S. Kameda

      Science364 ( 6437 ) 268 - 272   2019年4月19日

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      記述言語:英語   掲載種別:研究論文(学術雑誌)  

      DOI: 10.1126/science.aav8032

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

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

      Astrophysical Journal Letters874 ( 1 )   2019年3月20日

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      記述言語:英語   掲載種別:研究論文(学術雑誌)  

      © 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

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    • Surface Physical Condition of Asteroid Ryugu Using Close-up Optical and Thermal Images

      Sakatani, N, Sugita, S, Honda, R, Morota, T, Yamada, M, Kameda, S, Tatsumi, E, Yokota, Y, Kouyama, T, Suzuki, H, Honda, C, Hayakawa, M, Yoshioka, K, Matsuoka, M, Cho, Y, Sawada, H, Ogawa, N, Miura, A, Okada, T, Tanaka, S, Senshu, H, Arai, T, Demura, H, Suko, K, Shimaki, Y, Sekiguchi, T, Takita, J, Fukuhara, T, Taguchi, M, Mueller, T, Hagermann, A, Biele, J, Grott, M, Delbo, M

      50th Lunar and Planetary Science Conference2132   1732 - 1733   2019年3月

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:The Lunar and Planetary Institute  

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

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

      Science364 ( 6437 )   2019年

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Association for the Advancement of Science  

      DOI: 10.1126/science.aaw0422

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

      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

      Science364 ( 6437 ) 272 - 275   2019年

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      記述言語:英語   掲載種別:研究論文(学術雑誌)  

      © 2019 American Association for the Advancement of Science. All rights reserved. The near-Earth asteroid 162173 Ryugu, the target of the 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 micrometers 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, which is 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

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    • Observability of hydrogen-rich exospheres in Earth-like exoplanets 査読有り

      Leonardo A. dos, Santos, Vincent Bourrier, David Ehrenreich, Shingo Kameda

      Astronomy & Astrophysics   2018年11月28日

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      記述言語:英語   掲載種別:研究論文(学術雑誌)  

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    • A chemical survey of exoplanets with ARIEL 査読有り

      Giovanna Tinetti, Pierre Drossart, Paul Eccleston, Paul Hartogh, Astrid Heske, Jeremy Leconte, Giusi Micela, Marc Ollivier, Goran Pilbratt, Ludovic Puig, Diego Turrini, Bart Vandenbussche, Paulina Wolkenberg, Jean-Philippe Beaulieu, Lars A. Buchave, Martin Ferus, Matt Griffin, Manuel Guedel, Kay Justtanont, Pierre-Olivier Lagage, Pedro Machado, Giuseppe Malaguti, Michiel Min, Hans Ulrik Norgaard-Nielsen, Mirek Rataj, Tom Ray, Ignasi Ribas, Mark Swain, Robert Szabo, Stephanie Werner, Joanna Barstow, Matt Burleigh, James Cho, Vincent Coude du Foresto, Athena Coustenis, Leen Decin, Therese Encrenaz, Marina Galand, Michael Gillon, Ravit Helled, Juan Carlos Morales, Antonio Garcia Munoz, Andrea Moneti, Isabella Pagano, Enzo Pascale, Giuseppe Piccioni, David Pinfield, Subhajit Sarkar, Franck Selsis, Jonathan Tennyson, Amaury Triaud, Olivia Venot, Ingo Waldmann, David Waltham, Gillian Wright, Jerome Amiaux, Jean-Louis Augueres, Michel Berthe, Naidu Bezawada, Georgia Bishop, Neil Bowles, Deirdre Coffey, Josep Colome, Martin Crook, Pierre-Elie Crouzet, Vania Da Peppo, Isabel Escudero Sanz, Mauro Focardi, Martin Frericks, Tom Hunt, Ralf Kohley, Kevin Middleton, Gianluca Morgante, Roland Ottensamer, Emanuele Pace, Chris Pearson, Richard Stamper, Kate Symonds, Miriam Rengel, Etienne Renotte, Peter Ade, Laura Affer, Christophe Alard, Nicole Allard, Francesca Altieri, Yves Andre, Claudio Arena, Ioannis Argyriou, Alan Aylward, Cristian Baccani, Gaspar Bakos, Marek Banaszkiewicz, Mike Barlow, Virginie Batista, Giancarlo Bellucci, Serena Benatti, Pernelle Bernardi, Bruno Bezard, Maria Blecka, Emeline Bolmont, Bertrand Bonfond, Rosaria Bonito, Aldo S. Bonomo, John Robert Brucato, Allan Sacha Brun, Ian Bryson, Waldemar Bujwan, Sarah Casewell, Bejamin Charnay, Cesare Cecchi Pestellini, Guo Chen, Angela Ciaravella, Riccardo Claudi, Rodolphe Cledassou, Mario Damasso, Mario Damiano, Camilla Danielski, Pieter Deroo, Anna Maria Di Giorgio, Carsten Dominik, Vanessa Doublier, Simon Doyle, Rene Doyon, Benjamin Drummond, Bastien Duong, Stephen Eales, Billy Edwards, Maria Farina, Ettore Flaccomio, Leigh Fletcher, Francois Forget, Steve Fossey, Markus Fraenz, Yuka Fujii, Alvaro Garcia-Piquer, Walter Gear, Herve Geoffray, Jean Claude Gerard, Lluis Gesa, H. Gomez, Rafal Graczyk, Caitlin Griffith, Denis Grodent, Mario Giuseppe Guarcello, Jacques Gustin, Keiko Hamano, Peter Hargrave, Yann Hello, Kevin Heng, Enrique Herrero, Allan Hornstrup, Benoit Hubert, Shigeru Ida, Masahiro Ikoma, Nicolas Iro, Patrick Irwin, Christopher Jarchow, Jean Jaubert, Hugh Jones, Queyrel Julien, Shingo Kameda, Franz Kerschbaum, Pierre Kervella, Tommi Koskinen, Matthijs Krijger, Norbert Krupp, Marina Lafarga, Federico Landini, Emanuel Lellouch, Giuseppe Leto, A. Luntzer, Theresa Rank-Luftinger, Antonio Maggio, Jesus Maldonado, Jean-Pierre Maillard, Urs Mall, Jean-Baptiste Marquette, Stephane Mathis, Pierre Maxted, Taro Matsuo, Alexander Medvedev, Yamila Miguel, Vincent Minier, Giuseppe Morello, Alessandro Mura, Norio Narita, Valerio Nascimbeni, N. Nguyen Tong, Vladimiro Noce, Fabrizio Oliva, Enric Palle, Paul Palmer, Maurizio Pancrazzi, Andreas Papageorgiou, Vivien Parmentier, Manuel Perger, Antonino Petralia, Stefano Pezzuto, Ray Pierrehumbert, Ignazio Pillitteri, Giampaolo Piotto, Giampaolo Pisano, Loredana Prisinzano, Aikaterini Radioti, Jean-Michel Reess, Ladislav Rezac, Marco Rocchetto, Albert Rosich, Nicoletta Sanna, Alexandre Santerne, Giorgio Savini, Gaetano Scandariato, Bruno Sicardy, Carles Sierra, Giuseppe Sindoni, Konrad Skup, Ignas Snellen, Mateusz Sobiecki, Lauriane Soret, Alessandro Sozzetti, A. Stiepen, Antoine Strugarek, Jake Taylor, William Taylor, Luca Terenzi, Marcell Tessenyi, Angelos Tsiaras, C. Tucker, Diana Valencia, Gautam Vasisht, Allona Vazan, Francesc Vilardell, Sabrine Vinatier, Serena Viti, Rens Waters, Piotr Wawer, Anna Wawrzaszek, Anthony Whitworth, Yuk L. Yung, Sergey N. Yurchenko, Maria Rosa Zapatero Osorio, Robert Zellem, Tiziano Zingales, Frans Zwart

      EXPERIMENTAL ASTRONOMY46 ( 1 ) 135 - 209   2018年11月

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

      Thousands of exoplanets have now been discovered with a huge range of masses, sizes and orbits: from rocky Earth-like planets to large gas giants grazing the surface of their host star. However, the essential nature of these exoplanets remains largely mysterious: there is no known, discernible pattern linking the presence, size, or orbital parameters of a planet to the nature of its parent star. We have little idea whether the chemistry of a planet is linked to its formation environment, or whether the type of host star drives the physics and chemistry of the planet's birth, and evolution. ARIEL was conceived to observe a large number (1000) of transiting planets for statistical understanding, including gas giants, Neptunes, super-Earths and Earth-size planets around a range of host star types using transit spectroscopy in the 1.25-7.8m spectral range and multiple narrow-band photometry in the optical. ARIEL will focus on warm and hot planets to take advantage of their well-mixed atmospheres which should show minimal condensation and sequestration of high-Z materials compared to their colder Solar System siblings. Said warm and hot atmospheres are expected to be more representative of the planetary bulk composition. Observations of these warm/hot exoplanets, and in particular of their elemental composition (especially C, O, N, S, Si), will allow the understanding of the early stages of planetary and atmospheric formation during the nebular phase and the following few million years. ARIEL will thus provide a representative picture of the chemical nature of the exoplanets and relate this directly to the type and chemical environment of the host star. ARIEL is designed as a dedicated survey mission for combined-light spectroscopy, capable of observing a large and well-defined planet sample within its 4-year mission lifetime. Transit, eclipse and phase-curve spectroscopy methods, whereby the signal from the star and planet are differentiated using knowledge of the planetary ephemerides, allow us to measure atmospheric signals from the planet at levels of 10-100 part per million (ppm) relative to the star and, given the bright nature of targets, also allows more sophisticated techniques, such as eclipse mapping, to give a deeper insight into the nature of the atmosphere. These types of observations require a stable payload and satellite platform with broad, instantaneous wavelength coverage to detect many molecular species, probe the thermal structure, identify clouds and monitor the stellar activity. The wavelength range proposed covers all the expected major atmospheric gases from e.g. H2O, CO2, CH4 NH3, HCN, H2S through to the more exotic metallic compounds, such as TiO, VO, and condensed species. Simulations of ARIEL performance in conducting exoplanet surveys have been performed - using conservative estimates of mission performance and a full model of all significant noise sources in the measurement - using a list of potential ARIEL targets that incorporates the latest available exoplanet statistics. The conclusion at the end of the Phase A study, is that ARIEL - in line with the stated mission objectives - will be able to observe about 1000 exoplanets depending on the details of the adopted survey strategy, thus confirming the feasibility of the main science objectives.

      DOI: 10.1007/s10686-018-9598-x

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    • Stellar imaging coronagraph and exoplanet coronal spectrometer: two additional instruments for exoplanet exploration onboard the WSO-UV 1.7-m orbital telescope 査読有り

      Alexander Tavrov, Shingo Kameda, Andrey Yudaev, Ilia Dzyuban, Alexander Kiselev, Inna Shashkova, Oleg Korablev, Mikhail Sachkov, Jun Nishikawa, Motohide Tamura, Go Murakami, Keigo Enya, Masahiro Ikoma, Norio Narita

      Journal of Astronomical Telescopes, Instruments, and Systems4 ( 4 )   2018年10月1日

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      記述言語:英語   掲載種別:研究論文(学術雑誌)  

      DOI: 10.1117/1.JATIS.4.4.044001

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    • Evaluation of hydrogen absorption cells for observations of the planetary coronas 査読有り

      M. Kuwabara, M. Taguchi, K. Yoshioka, T. Ishida, N. de Oliveira, K. Ito, S. Kameda, F. Suzuki, I. Yoshikawa

      Review of Scientific Instruments   2018年2月15日

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      記述言語:英語   掲載種別:研究論文(学術雑誌)  

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    • Initial products of Akatsuki 1-μm camera 査読有り

      Iwagami, Naomoto, Sakanoi, Takeshi, Hashimoto, George L, Kameda, Shingo他

      Earth, Planets and Space   2018年1月11日

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      記述言語:英語   掲載種別:研究論文(学術雑誌)  

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    • 太陽系ハビタブル惑星の成立を探る火星衛星探査計画MMX

      倉本 圭, 諸田 智克, 長岡 央, 中川 広務, 中村 智樹, 小川 和律, 大嶽 久志, 尾崎 正伸, 佐々木 晶, 千秋 博紀, 橘 省吾, 川勝 康弘, 寺田 直樹, 臼井 寛裕, 和田 浩二, 渡邊 誠一郎, MMX study team, 藤本 正樹, 玄田 英典, 平田 成, 今村 剛, 亀田 真吾, 松本 晃治, 宮本 英昭

      日本惑星科学会誌遊星人27 ( 3 ) 207 - 215   2018年

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      記述言語:日本語   出版者・発行元:日本惑星科学会  

      <p>火星衛星Phobosからのサンプルリターンに挑む火星衛星探査計画 (Martian Moons eXploration: MMX) は,現在,宇宙航空研究開発機構 (JAXA) プリプロジェクトとして,2024年の打ち上げと5年の往還期間を設定し,精力的な検討・初期開発が進められている.MMXは,サンプル分析,Deimosを加えた火星衛星の近接観測,そして火星大気および火星圏のモニタリング観測を組み合わせることにより,惑星に寄りそう衛星という切り口と視座から,太陽系における大気と水を湛えたハビタブル惑星の形成と進化の解明に迫ろうとしている.</p>

      DOI: 10.14909/yuseijin.27.3_207

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    • Initial inflight calibration for Hayabusa2 optical navigation camera (ONC) for science observations of asteroid Ryugu 査読有り

      H. Suzuki, M. Yamada, T. Kouyama, E. Tatsumi, S. Kameda, R. Honda, H. Sawada, N. Ogawa, T. Morota, C. Honda, N. Sakatani, M. Hayakawa, Y. Yokota, Y. Yamamoto, S. Sugita

      ICARUS300   341 - 359   2018年1月

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ACADEMIC PRESS INC ELSEVIER SCIENCE  

      Hayabusa2, the first sample return mission to a C-type asteroid was launched by the Japan Aerospace Exploration Agency (JAXA) on December 3, 2014 and will arrive at the asteroid in the middle of 2018 to collect samples from its surface, which may contain both hydrated minerals and organics. The optical navigation camera (ONC) system on board the Hayabusa2 consists of three individual framing CCD cameras, ONC-T for a telescopic nadir view, ONC-W1 for a wide-angle nadir view, and ONC-W2 for a wide-angle slant view will be used to observe the surface of Ryugu. The cameras will be used to measure the global asteroid shape, local morphologies, and visible spectroscopic properties. Thus, image data obtained by ONC will provide essential information to select landing (sampling) sites on the asteroid. This study reports the results of initial inflight calibration based on observations of Earth, Mars, Moon, and stars to verify and characterize the optical performance of the ONC, such as flat-field sensitivity, spectral sensitivity, point-spread function (PSF), distortion, and stray light of ONC-T, and distortion for ONC-W1 and W2. We found some potential problems that may influence our science observations. This includes changes in sensitivity of flat fields for all bands from those that were measured in the pre-flight calibration and existence of a stray light that arises under certain conditions of spacecraft attitude with respect to the sun. The countermeasures for these problems were evaluated by using data obtained during initial in-flight calibration. The results of our inflight calibration indicate that the error of spectroscopic measurements around 0.7 mu m using 0.55, 0.70, and 0.86 mu m bands of the ONC-T can be lower than 0.7% after these countermeasures and pixel binning. This result suggests that our ONC-T would be able to detect typical strength (similar to 3%) of the serpentine absorption band often found on CM chondrites and low albedo asteroids with &gt;= 4 sigma confidence. (C) 2017 Elsevier Inc. All rights reserved.

      DOI: 10.1016/j.icarus.2017.09.11

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    • Overview of Akatsuki data products: definition of data levels, method and accuracy of geometric correction 査読有り

      Kazunori Ogohara, Masahiro Takagi, Shin-ya Murakami, Takeshi Horinouchi, Manabu Yamada, Toru Kouyama, George L. Hashimoto, Takeshi Imamura, Yukio Yamamoto, Hiroki Kashimura, Naru Hirata, Naoki Sato, Atsushi Yamazaki, Takehiko Satoh, Naomoto Iwagami, Makoto Taguchi, Shigeto Watanabe, Takao M. Sato, Shoko Ohtsuki, Tetsuya Fukuhara, Masahiko Futaguchi, Takeshi Sakanoi, Shingo Kameda, Ko-ichiro Sugiyama, Hiroki Ando, Yeon Joo Lee, Masato Nakamura, Makoto Suzuki, Chikako Hirose, Nobuaki Ishii, Takumi Abe

      EARTH PLANETS AND SPACE69   2017年12月

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER HEIDELBERG  

      We provide an overview of data products from observations by the Japanese Venus Climate Orbiter, Akatsuki, and describe the definition and content of each data-processing level. Levels 1 and 2 consist of non-calibrated and calibrated radiance (or brightness temperature), respectively, as well as geometry information (e.g., illumination angles). Level 3 data are global-grid data in the regular longitude-latitude coordinate system, produced from the contents of Level 2. Non-negligible errors in navigational data and instrumental alignment can result in serious errors in the geometry calculations. Such errors cause mismapping of the data and lead to inconsistencies between radiances and illumination angles, along with errors in cloud-motion vectors. Thus, we carefully correct the boresight pointing of each camera by fitting an ellipse to the observed Venusian limb to provide improved longitude-latitude maps for Level 3 products, if possible. The accuracy of the pointing correction is also estimated statistically by simulating observed limb distributions. The results show that our algorithm successfully corrects instrumental pointing and will enable a variety of studies on the Venusian atmosphere using Akatsuki data.

      DOI: 10.1186/s40623-017-0749-5

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    • Ecliptic North-South Symmetry of Hydrogen Geocorona 査読有り

      Kameda, S, Ikezawa, S, Sato, M, Kuwabara, M, Osada, N, Murakami, G, Yoshioka, K, Yoshikawa, I, Taguchi, M, Funase, R, Sugita, S, Miyoshi, Y, Fujimoto, M

      Geophysical Research Letters   2017年11月9日

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      記述言語:英語   掲載種別:研究論文(学術雑誌)  

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    • Experimental characterization of elastomeric O-rings as reusable seals for mass spectrometric measurements: Application to in situ K-Ar dating on Mars 査読有り

      Yuichiro Cho, Shingo Kameda, Mamoru Okuno, Misa Horiuchi, Kazuo Shibasaki, Ryo Wagatsuma, Yusuke Aida, Yayoi N. Miura, Kazuo Yoshioka, Ryuji Okazaki, Seiji Sugita

      ADVANCES IN SPACE RESEARCH60 ( 7 ) 1453 - 1462   2017年10月

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCI LTD  

      Mass spectrometry has been widely used in lander missions to characterize the volatiles in rocks and soils on planetary surfaces. A good vacuum seal is very important for introducing such solid samples to a vacuum chamber and ejecting them. However, multiple measurements require many metal gaskets, leading to extra weight and complexity for the instruments. In this study, we investigate the capability of three kinds of elastomeric O-rings (Viton, Nexus-SLT, and Nexus-FV) as vacuum seals for mass spectrometric measurements, particularly for in situ K-Ar dating on Mars. First, thermal cycle tests revealed that low-temperature-resistant O-rings can maintain pressure &lt; 10(-5) Pa at -60 degrees C under 1 bar ambient pressure, whereas Viton O-rings leaked at -25 degrees C. Then, the amount of Ar-40 due to out gassing from the O-rings and permeation under the ambient pressure of 650 Pa or 3 Pa was measured and compared with the amounts of Ar-40 that a flight-equivalent laser would liberate from potential target Martian rocks. The measured amounts were &lt; 1% of that a target rock with 5000 ppm K2O and an age of 4.2 Ga would yield. These results suggest that a Viton O-ring can maintain the AT blank low under the Mars atmospheric pressure when temperatures are higher than -25 degrees C. A double O-ring seal using the low-temperature resistant elastomers would be an alternative approach at lower temperatures. The elastomeric O-rings would be useful for constructing a small and light-weighted mass spectrometric instrument for in situ K-Ar dating on Mars. (C) 2017 COSPAR. Published by Elsevier Ltd. All rights reserved.

      DOI: 10.1016/j.asr.2017.07.002

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    • Preflight Calibration Test Results for Optical Navigation Camera Telescope (ONC-T) Onboard the Hayabusa2 Spacecraft 査読有り

      S. Kameda, H. Suzuki, T. Takamatsu, Y. Cho, T. Yasuda, M. Yamada, H. Sawada, R. Honda, T. Morota, C. Honda, M. Sato, Y. Okumura, K. Shibasaki, S. Ikezawa, S. Sugita

      SPACE SCIENCE REVIEWS208 ( 1-4 ) 17 - 31   2017年7月

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:SPRINGER  

      The optical navigation camera telescope (ONC-T) is a telescopic framing camera with seven colors onboard the Hayabusa2 spacecraft launched on December 3, 2014. The main objectives of this instrument are to optically navigate the spacecraft to asteroid Ryugu and to conduct multi-band mapping the asteroid. We conducted performance tests of the instrument before its installation on the spacecraft. We evaluated the dark current and bias level, obtained data on the dependency of the dark current on the temperature of the charge-coupled device (CCD). The bias level depends strongly on the temperature of the electronics package but only weakly on the CCD temperature. The dark-reference data, which is obtained simultaneously with observation data, can be used for estimation of the dark current and bias level. A long front hood is used for ONC-T to reduce the stray light at the expense of flatness in the peripheral area of the field of view (FOV). The central area in FOV has a flat sensitivity, and the limb darkening has been measured with an integrating sphere. The ONC-T has a wheel with seven bandpass filters and a panchromatic glass window. We measured the spectral sensitivity using an integrating sphere and obtained the sensitivity of all the pixels. We also measured the point-spread function using a star simulator. Measurement results indicate that the full width at half maximum is less than two pixels for all the bandpass filters and in the temperature range expected in the mission phase except for short periods of time during touchdowns.

      DOI: 10.1007/s11214-015-0227-y

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    • IMAGING OBSERVATIONS OF THE HYDROGEN COMA OF COMET 67P/CHURYUMOV-GERASIMENKO IN 2015 SEPTEMBER BY THE PROCYON/LAICA 査読有り

      Yoshiharu Shinnaka, Nicolas Fougere, Hideyo Kawakita, Shingo Kameda, Michael R. Combi, Shota Ikezawa, Ayana Seki, Masaki Kuwabara, Masaki Sato, Makoto Taguchi, Ichiro Yoshikawa

      ASTRONOMICAL JOURNAL153 ( 2 )   2017年2月

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

      The water production rate of a comet is one of the. fundamental parameters necessary. to understand cometary activity when a comet approaches the Sun within 2.5 au, because water is the most abundant icy material in the cometary nucleus. Wide-field imaging observations of the hydrogen Ly alpha emission in comet 67P/Churyumov-Gerasimenko were performed by the Lyman Alpha Imaging Camera (LAICA) on. board the 50 kg class micro spacecraft, the Proximate Object Close Flyby with Optical Navigation (PROCYON), on UT 2015 September 7.40, 12.37, and 13.17 (corresponding to 25.31, 30.28, and 31.08 days after the perihelion passage of the comet, respectively). We derive the water production rates, QH(2)O, of the comet from Lya images of the comet by using a 2D axi-symmetric Direct Simulation Monte-Carlo model of the atomic hydrogen coma; (1.46. +/- 0.47) x 10(28), (1.24. +/- 0.40) x10(28), and (1.30. +/- 0.42) x 10(28) molecules s(-1) on 7.40, 12.37, and 13.17 September, respectively. These values are comparable to the values from in situ measurements by the Rosetta instruments in the 2015 apparition and the ground-based and space observations during the past apparitions. The comet did not show significant secular change in average water production rates just after the perihelion passage for the apparitions from 1982 to 2015. We emphasize that the measurements of absolute QH(2)O based on the wide field of view (e. g., by the LAICA/PROCYON) are so important to judge the soundness of the coma models used to infer QH(2)O based on in situ measurements by spacecraft, like the Rosetta.

      DOI: 10.3847/1538-3881/153/2/76

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    • An in-situ K-Ar isochron dating method for planetary landers using a spot-by-spot laser-ablation technique 査読有り

      Yuichiro Cho, Seiji Sugita, Yayoi N. Miura, Ryuji Okazaki, Naoyoshi Iwata, Tomokatsu Morota, Shingo Kameda

      PLANETARY AND SPACE SCIENCE128   14 - 29   2016年9月

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

      Age is essential information for interpreting the geologic record on planetary surfaces. Although crater counting has been widely used to estimate the planetary surface ages, crater chronology in the inner solar system is largely built on radiometric age data from limited sites on the Moon. This has resulted in major uncertainty in planetary chronology. Because opportunities for sample-return missions are limited, in-situ geochronology measurements from one-way lander/rover missions are extremely valuable. Here we developed an in-situ isochron-based dating method using the K-Ar system, with K and Ar in a single rock sample extracted locally by laser ablation and measured using laser-induced breakdown spectroscopy (LIBS) and a quadrupole mass spectrometer (QMS), respectively. We built an experimental system combining flight equivalent instruments and measured K-Ar ages for mineral samples with known ages (similar to 1.8 Ga) and K contents (1-8 wt%); we achieved precision of 20% except for a mineral with low mechanical strength. Furthermore, validation measurements with two natural rocks (gneiss slabs) obtained K-Ar isochron ages and initial Ar-40 consistent with known values for both cases. This result supports that our LIBS-MS approach can derive both isochron ages and contributions of non-in situ radiogenic Ar-40 from natural rocks. Error assessments suggest that the absolute ages of key geologic events including the Noachian/Hesperian- and the Hesperian/Amazonian-transition can be dated with 10-20% errors for a rock containing similar to 1 wt% K2O, greatly reducing the uncertainty of current crater chronology models on Mars. (C) 2016 Elsevier Ltd. All rights reserved.

      DOI: 10.1016/j.pss.2016.05.004

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    • Quantitative Potassium Measurements with Laser-Induced Breakdown Spectroscopy Using Low-Energy Lasers: Application to In Situ K-Ar Geochronology for Planetary Exploration 査読有り

      Cho Y, Horiuchi M, Shibasaki K, Kameda S, Sugita S

      Applied Spectroscopy   2016年8月

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      記述言語:英語   掲載種別:研究論文(学術雑誌)  

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    • Studies on Solar System Explorations using DESTINY: the Demonstration and Experiment of Space Technology for Interplanetary Voyage

      IWATA Takahiro, IMAMURA Takeshi, OGOHARA Kazunori, OYAMA Akira, IKENAGA Toshinori, KAWAKATSU Yasuhiro, MURAKAMI Go, EZOE Yuichiro, KAMEDA Shingo, KEIKA Kunihiro, ARAI Tomoko, MATSUURA Shuji, SAIKI Takanao

      TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN14 ( 30 ) Pk_111 - Pk_116   2016年

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      記述言語:英語   出版者・発行元:一般社団法人 日本航空宇宙学会  

      <p>DESTINY: the Demonstration and Experiment of Space Technology for Interplanetary Voyage, which is a candidate mission of Epsilon Launch Vehicle, plans to execute scientific observations using instruments with the mass of up to about 10 kg on the transfer and Halo orbit of the sun to earth Lagrangian point L1/L2 or on the fly-by orbit of near earth objects (NEO). Potential scientific objects include in-situ observation and remote sensing from these space are solar system explorations, such as, the observations of plasma and energetic particles around the terrestrial magnetosphere, inter-planetary and inter-stellar dust, and NEO. It is also considered to be useful for the pilot observations for future infrared, gamma-ray, and cosmic-ray space astronomical telescope in the deep space. Applied missions of DESTINY will be able to go to deep space with higher mass of payloads. Using the Epsilon Launch Vehicle, it will convey instruments of up to 50 kg to the space between Venus and Mars. DESTINY launched by the improved launch vehicle with the power of M-V rocket will carry payloads of up to 200 kg into the orbit of Venus and Mars. In these phases, Explorations for Venus, Mars, and multiple NEO, and astronomical observations from the deep space observatory will be realized by low cost deep space missions.</p>

      DOI: 10.2322/tastj.14.Pk_111

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    • Conceptual Design of an In Situ K-Ar Isochron Dating Instrument for Future Mars Rover Missions, Transactions of the Japan Society for Aeronautical and Space Sciences 査読有り

      Cho, Y, Kameda, S, Miura, Y, Saito, Y, Yokota, S, Kasahara, S, Okazaki, R, Yoshioka, K, Shibasaki, K, Oishi, T, Sugita, S

      Aerospace Technology Japan 2016.14 ( ists30 ) 89 - 94   2016年

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      記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

      DOI: 10.2322/tastj.14.pk_89

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    • Detectability of hydrous minerals using ONC-T camera onboard the Hayabusa2 spacecraft 査読有り

      S. Kameda, H. Suzuki, Y. Cho, S. Koga, M. Yamada, T. Nakamura, T. Hiroi, H. Sawada, R. Honda, T. Morota, C. Honda, A. Takei, T. Takamatsu, Y. Okumura, M. Sato, T. Yasuda, K. Shibasaki, S. Ikezawa, S. Sugita

      ADVANCES IN SPACE RESEARCH56 ( 7 ) 1519 - 1524   2015年10月

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCI LTD  

      The Hayabusa2 spacecraft has three framing cameras (ONC-T, ONC-W1, and ONC-W2) for optical navigation to asteroid 1999 JU(3). The ONC-T is a telescopic camera with seven band-pass filters in the visible and near-infrared range. These filters are placed on a wheel, which rotates to put a selected filter for different observations, enabling multiband imaging. Previous ground-based observations suggesting that hydrous materials may be present on the surface of 1999 JU(3) and distributed in relatively limited areas. The presence of hydrous minerals indicates that this asteroid experienced only low to moderate temperatures during its formation, suggesting that primordial materials are preserved. In order to find the best sampling sites, we will perform reflectance spectroscopic observations using the ONC-T near the asteroid after arrival. Finding regions rich in hydrous minerals is the key for this remote sensing observation. In preparation for this, we conducted ground-based experiments for the actual ONC-T flight model to confirm the detectability of the absorption band of Fe-rich serpentine. As a result, we detected the absorption band near 0.7 mu m by reflectance spectroscopy of CM2 chondrites, such as Murchison and Nogoya, which are known to contain the Fe-rich serpentine, and did not detect any 0.7 mu m absorption in Jbilet Winselwan CM2 chondrite with decomposed Fe-rich serpentine. (C) 2015 COSPAR. Published by Elsevier Ltd. All rights reserved.

      DOI: 10.1016/j.asr.2015.06.037

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    • High-precision potassium measurements using laser-induced breakdown spectroscopy under high vacuum conditions for in situ K-Ar dating of planetary surfaces 査読有り

      Cho Yuichiro, Sugita Seiji, Kameda Shingo, Miura Yayoi N, Ishibashi Ko, Ohno Sohsuke, Kamata Shunichi, Arai Tomoko, Morota Tomokatst, Namiki Noriyuki, Matsui Takafumi

      SPECTROCHIMICA ACTA PART B-ATOMIC SPECTROSCOPY106   28 - 35   2015年4月1日

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      掲載種別:研究論文(学術雑誌)  

      DOI: 10.1016/j.sab.2015.02.002

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    • 惑星探査での年代測定に向けた開発の動向

      長 勇一郎, 三浦 弥生, 亀田 真吾, 岡崎 隆司, 諸田 智克, 杉田 精司

      地球化学48 ( 4 ) 231 - 243   2014年

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      記述言語:日本語   出版者・発行元:The Geochemical Society of Japan  

      Age is one of the most important observables in planetary science. The ages of geologic events on planets including Mars, however, are estimated with the crater chronology approach, which is largely based on radiometric age data derived from very limited places on the Moon. Obtaining age data for the inner planets, asteroids, or the satellites of the outer planets is essential for accurate understanding of the history of our solar system. Although sample-return missions can achieve this goal, they are technically very challenging and extremely expensive. Thus, <i>in-situ</i> geochronology measurements with one-way lander/rover missions would be very important. This paper reviews (1) primary scientific issues on planetary chronology, such as uncertainties in the crater chronology models on Mars, (2) recent developments for <i>in-situ</i> dating instruments based on K–Ar, Rb–Sr, or Pb–Pb dating methods, (3) <i>in-situ</i> K–Ar age measurements conducted by NASAs Curiosity rover, and (4) the development status of our <i>in-situ</i> K–Ar isochron dating method based on a combination of laser-induced breakdown spectroscopy and quadrupole mass spectrometry for measurements of potassium and argon, respectively. We also discuss perspectives for a future Japanese <i>in-situ</i> geochronology mission to Mars.

      DOI: 10.14934/chikyukagaku.48.231

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      その他リンク: https://jlc.jst.go.jp/DN/JLC/20001008379?from=CiNii

    • Plasmaspheric filament: An isolated magnetic flux tube filled with dense plasmas 査読有り

      Go Murakami, Ichiro Yoshikawa, Kazuo Yoshioka, Atsushi Yamazaki, Masato Kagitani, Makoto Taguchi, Masayuki Kikuchi, Shingo Kameda, Masato Nakamura

      Geophysical Research Letters40 ( 2 ) 250 - 254   2013年1月28日

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      記述言語:英語   掲載種別:研究論文(学術雑誌)  

      The Telescope of Extreme Ultraviolet (TEX) onboard Japan's lunar orbiter KAGUYA provided the first sequential images of the Earth's plasmasphere from the "side" (meridian) view. The TEX instrument obtained the global distribution of the terrestrial helium ions (He+) by detecting resonantly scattered emission at 30.4 nm. One of the most striking features of the plasmasphere found by TEX is an arc-shaped structure of enhanced brightness, which we call a "plasmaspheric filament". In the TEX image on 2 June 2008, the filament structure was clearly aligned to the dipole magnetic field line of L = 3.7 at 7.3 magnetic local time. Our analysis suggests that the filament represents an isolated flux tube filled with four times higher He + density than its neighbors. We found four events of plasmaspheric filament in the images obtained between March and June 2008, and in all four events, the geomagnetic activity was quite low. The plasmaspheric filament in the TEX image is the first evidence that a "finger" structure seen in the IMAGE-EUV image is the projection of an isolated flux tube. © 2013. American Geophysical Union. All Rights Reserved.

      DOI: 10.1002/grl.50124

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    • Image of the Cold Plasmas around the Earth Observed by Telescope of Extreme Ultraviolet (TEX) onboard KAGUYA: Geoscience from the Moon 査読有り

      Murakami, Go, Yoshikawa, Ichiro, Yamazaki, Atsushi, Yoshioka, Kazuo, Kameda, Shingo, Miyake, Wataru, Taguchi, Makoto, Kikuchi, Masayuki, Nakamura, Masato, Okano, Shoichi

      Transactions of the Japanese Society for Artificial Intelligence8 ( 27 ) Tn_23 - Tn_28   2012年12月

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES  

      We have succeeded in imaging of the terrestrial plasmasphere by the Telescope of Extreme Ultraviolet (TEX) aboard Japan's lunar orbiter KAGUYA. The view afforded by the KAGUYA orbit encompasses the plasma distribution in a single exposure, enabling us to examine for the first time the globally-averaged properties of the plasmasphere from the "side" (meridian) perspective. This is the world first image of the plasmasphere from the moon.

      DOI: 10.2322/tastj.8.Tn_23

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    • はやぶさ2搭載の Optical Navigation Camera (ONC) による科学観測

      杉田 精司, 本田 理恵, 亀田 真吾, 諸田 智克, 澤田 弘崇, 本田 親寿, 鈴木 秀彦, 小川 和律, 飯島 祐一, 白井 慶, 中村 良介, 山田 学, ONC サイエンスチーム

      宇宙科学技術連合講演会講演集56   2012年

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      記述言語:日本語   掲載種別:研究論文(研究会,シンポジウム資料等)  

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    • Multi-element analysis technique for in-situ planetary exploration by laser-induced breakdown spectroscopy

      M. Kobayashi, K. Ishibashi, S. Ohno, S. Kameda, K. Wada, H. Senshu, T. Arai, N. Namiki, T. Matsui, Y. Cho, S. Sugita

      2nd International Conference on Space Technology, ICST 2011   2011年

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      記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

      Laser-induced breakdown spectroscopy (LIBS) is a very useful elemental analysis tool in planetary exploration. In this study we conduct LIBS measurements under low pressure (1×10-3 mbar) to investigate the feasibility of LIBS measurement under vacuum conditions. Although the optical emission intensity decreases remarkably under low ambient pressure, our preliminary experimental results indicate that the precision of elemental abundance measurements does not decrease drastically even under 1×10 -3 mbar. This paper suggests that LIBS can be used at the surface of airless bodies, such as the Moon and asteroids and also can be utilized for quantitative analysis of elemental abundance of minerals under lunar surface environment. © 2011 IEEE.

      DOI: 10.1109/ICSpT.2011.6064662

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    • The EXCEED mission 査読有り

      Yoshikawa I, Yoshioka K, Murakami G, Ogawa G, Ueno M, Yamazaki A, Uemizu K, Kameda S, Tsuchiya F, Kagitani M, Terada N, Kasaba Y

      Advances in Geosciences: Volume 25: Planetary Science (PS)   29 - 41   2011年

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      掲載種別:論文集(書籍)内論文  

      DOI: 10.1142/9789814355377_0003

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      その他リンク: http://orcid.org/0000-0002-8160-3553

    • Variation in lunar sodium exosphere measured from lunar orbiter SELENE (Kaguya) 査読有り

      M. Kagitani, M. Taguchi, A. Yamazaki, I. Yoshikawa, G. Murakami, K. Yoshioka, S. Kameda, S. Okano

      PLANETARY AND SPACE SCIENCE58 ( 12 ) 1660 - 1664   2010年10月

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

      Resonant scattering of the lunar sodium exosphere was measured from the lunar orbiter SELENE (Kaguya) from December 2008 to June 2009. Variations in line-of-sight integrated intensity measured on the night-side hemisphere of the Moon could be described as a spherical symmetric distribution of the sodium exosphere with a temperature of 2400-6000 K. Average surface density of sodium atoms in February is well above that in the other months by about 30%. A clear variation in surface density related to the Moon&apos;s passage across the Earth&apos;s magnetotail could not be seen, although sodium density gradually decreased (by 20 +/- 8%) during periods from the first through the last quarter of two lunar cycles. These results suggest that the supra-thermal components of the sodium exosphere are not mainly produced by classical sputtering of solar wind. The variation in sodium density (which depends on lunar-phase angle) is possibly explained by the presence of an inhomogeneous source distribution of photon-stimulated desorption (PSD) on the surface. (c) 2010 Elsevier Ltd. All rights reserved.

      DOI: 10.1016/j.pss.2010.07.025

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    • Plasmaspheric EUV images seen from lunar orbit: Initial results of the extreme ultraviolet telescope on board the Kaguya spacecraft 査読有り

      Yoshikawa, I, Murakami, G, Ogawa, G, Yoshioka, K, Obana, Y, Taguchi, M, Yamazaki, A, Kameda, S, Nakamura, M, Kikuchi, M, Kagitani, M, Okano, S, Miyake, W

      Journal of Geophysical Research   2010年8月27日

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      記述言語:英語   掲載種別:研究論文(学術雑誌)  

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    • Observation of the Near-Earth Plasmas by Telescope of Extreme Ultraviolet (TEX) Onboard SELENE: Science from the Moon 査読有り

      Yoshikawa, I, Yamazaki, A, Murakami, G, Ezawa, F, Yoshioka, K, Kameda, S, Miyake, W, Taguchi, M, Kikuchi, M, Nakamura, M, Sakanoi, T, Okano, T

      Transactions of the Japan society for aeronautical and space sciences, space technology Japan7 ( 26 ) 27 - 32   2010年

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES  

      The Upper Atmosphere and Plasma Imager (UPI) was launched in 2007, and went to the moon. From the lunar orbit, two telescopes direct toward the Earth. The moon has no atmosphere, which leads no active emission near the spacecraft, thus we have a high quality image of the near-Earth environment. Moreover the moon orbits the Earth once a month and the Earth is observed from many different directions. This is called a "science from the Moon". The two telescopes are mounted on 2-axis gimbal system, Telescope of Extreme ultraviolet (TEX) and Telescope of Visible light (TVIS). TEX detects the O II (83.4nm) and He II (30.4nm) emissions scattered by ionized oxygen and helium, respectively. The targets of EUV imaging are the polar ionosphere, the polar wind, and the plasmasphere and the inner magnetosphere. The maximum spatial and time resolutions are 0.09 Re and 1 minute, respectively.

      DOI: 10.2322/tstj.7.Tk_27

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    • Extreme ultraviolet spectroscope for exospheric dynamics explore (exceed) 査読有り

      Ichiro Yoshikawa, Kazuo Yoshioka, Go Murakami, Atsushi Yamazaki, Shingo Kameda, Munetaka Ueno, Naoki Terada, Fuminori Tsuchiya, Masato Kagitani, Yasumasa Kasaba

      Advances in Geosciences: Volume 19: Planetary Science (PS)   579 - 592   2010年1月

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      © 2010 by World Scientific Publishing Co. Pte. Ltd. All rights reserved. An earth-orbiting Extreme Ultraviolet spectroscopic mission, EXtreme ultraviolet spectrosCope for ExosphEric Dynamics explore (EXCEED) that will be launched in 2012 is now under development. The EXCEED mission will carry out observations of Extreme Ultraviolet (EUV) emissions from tenuous plasmas around the planets. It is essential for planetary EUV spectroscopy to avoid the Earth’s atmospheric absorption, therefore it should be mandatory to observe above the Earth’s atmosphere. In this paper, we will introduce the general mission overview, the instrument, and the scientific targets.

      DOI: 10.1142/9789812838162_0043

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    • Telescope of Extreme Ultraviolet boarded on KAGUYA: Science from the Moon 査読有り

      Yoshikawa, I, Murakami, G, Ezawa, F, Yoshioka, K, Obana, Y, Taguchi, M, Yamazaki, A, Kameda, S, Nakamura, M, Kikuchi, M, Kagitani, M, Okano, S, Shiokawa, K, Miyake, W

      Adv. Geosci.19   109 - 121   2010年

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      掲載種別:研究論文(学術雑誌)  

      DOI: 10.1142/9789812838162_0009

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    • The BepiColombo mission: An outstanding tool for investigating the Hermean environment 査読有り

      A. Milillo, M. Fujimoto, E. Kallio, S. Kameda, F. Leblanc, Y. Narita, G. Cremonese, H. Laakso, M. Laurenza, S. Massetti, S. McKenna-Lawlor, A. Mura, R. Nakamura, Y. Omura, D. A. Rothery, K. Seki, M. Storini, P. Wurz, W. Baumjohann, E. J. Bunce, Y. Kasaba, J. Helbert, A. Sprague

      PLANETARY AND SPACE SCIENCE58 ( 1-2 ) 40 - 60   2010年1月

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

      Mercury possesses a weak, internal, global magnetic field that supports a small magnetosphere populated by charged particles originating from the solar wind, the planet's exosphere and surface layers. Mercury's exosphere is continuously refilled and eroded through a variety of chemical and physical processes acting in the planet's surface and environment. Using simultaneous two-point measurements from two satellites, ESA's future mission BepiColombo will offer an unprecedented opportunity to investigate magnetospheric and exospheric dynamics at Mercury as well as their interactions with solar radiation and interplanetary dust. The expected data will provide important insights into the evolution of a planet in close proximity of a star. Many payload instruments aboard the two spacecraft making up the mission will be completely, or partially, devoted to studying the close environment of the planet as well as the complex processes that govern it. Coordinated measurements by different onboard instruments will permit a wider range of scientific questions to be addressed than those that could be achieved by the individual instruments acting alone. Thus, an important feature of the BepiColombo mission is that simultaneous two-point measurements can be implemented at a location in space other than the Earth. These joint observations are of key importance because many phenomena in Mercury's environment are temporarily and spatially varying. In the present paper, we focus on some of the exciting scientific goals achievable during the BepiColombo mission through making coordinated observations. (C) 2008 Elsevier Ltd. All rights reserved.

      DOI: 10.1016/j.pss.2008.06.005

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    • The Mercury sodium atmospheric spectral imager for the MMO spacecraft of Bepi-Colombo 査読有り

      I. Yoshikawa, O. Korablev, S. Kameda, D. Rees, H. Nozawa, S. Okano, V. Gnedykh, V. Kottsov, K. Yoshioka, G. Murakami, F. Ezawa, G. Cremonese

      PLANETARY AND SPACE SCIENCE58 ( 1-2 ) 224 - 237   2010年1月

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

      The Mercury Sodium Atmosphere Spectral Imager (MSASI) on the Mercury Magnetospheric Orbiter (MMO) of the JAXA/ESA Bepi-Colombo (BC) Mission will address a range of fundamental scientific questions pertaining to Mercury&apos;s exosphere. The measurements will provide new information on regolith-exosphere-magnetosphere coupling as well as new understanding of the dynamics governing the exosphere bounded by the planetary surface, the solar wind and interplanetary space. MSASI is a high-dispersion visible spectrometer working in the spectral region near the sodium D(2) emission (589 nm), a major constituent of the Mercury exosphere. A single high-resolution Fabry-Perot etalon is used in combination with a narrow-band interference filter to achieve a compact and efficient instrument design. The etalon and filter are extremely stable with respect to long-term aging and temperature variations. Full-disk images of the planet are obtained by means of a single-axis scanning mirror in combination with the spin of the MMO spacecraft. This paper presents an overview of the MSASI and the design of the Fabry-Perot interferometer used as its spectral analyser.
      It is concluded that:
      (1) The MSASI optical design is practical and can be implemented without new or critical technology developments.
      (2) The thermally stable etalon design is based on concepts, designs and materials that have a good space heritage.
      (3) The MSASI instrument will achieve a high signal-to-noise ratio (SNR) (&gt; 10) in the range of 2K-10M Rayleigh. (C) 2008 Elsevier Ltd. All rights reserved.

      DOI: 10.1016/j.pss.2008.07.008

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    • First sequential images of the plasmasphere from the meridian perspective observed by KAGUYA 査読有り

      Go Murakami, Ichiro Yoshikawa, Yuki Obana, Kazuo Yoshioka, Gentaro Ogawa, Atsushi Yamazaki, Masato Kagitani, Makoto Taguchi, Masayuki Kikuchi, Shingo Kameda, Masato Nakamura

      EARTH PLANETS AND SPACE62 ( 4 ) E9 - E12   2010年

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:TERRA SCIENTIFIC PUBL CO  

      Our understanding of plasmaspheric dynamics has increased in recent years largely due to the information generated during the IMAGE-EUV mission. Even though this successful mission has ended, we have succeeded in imaging the terrestrial helium ions (He(+)) by the Telescope of Extreme Ultraviolet (TEX) aboard the Japanese lunar orbiter KAGUYA by detecting resonantly scattered emission at 30.4 nm. The view afforded by the KAGUYA orbit encompasses the plasma (He(+)) distribution in a single exposure, enabling us to examine for the first time the globally averaged properties of the plasmasphere from the "side" (meridian) perspective. The TEX instrument observed a medium-scale density structure in the dawnside plasmasphere during a quiet period (1-2 June 2008). The meridian shape of the structure clearly agreed with the dipole magnetic field line. The TEX instrument also observed the structure in the plasmasphere co-rotating with a duration of 26 h, which is consistent with results from a number of recent studies derived from the IMAGE-EUV mission. These results confirm that the TEX instrument successfully obtained the spatial distribution and temporal variation of the plasmasphere.

      DOI: 10.5047/eps.2010.02.006

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    • Interplanetary dust distribution and temporal variability of Mercury&apos;s atmospheric Na 査読有り

      Shingo Kameda, Ichiro Yoshikawa, Masato Kagitani, Shoichi Okano

      GEOPHYSICAL RESEARCH LETTERS36   2009年8月

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER GEOPHYSICAL UNION  

      The interplanetary dust (IPD) distribution in the inner solar system is not yet well understood because of lack of direct dust measurements in the inner solar system and so one needs to rely on zodiacal light observations that are difficult to interpret. Mercury has an unstable atmosphere, and the source processes of Na in its atmosphere are unclear. Results of past observations have revealed that the atmospheric Na density has no or low correlation with the solar flux, sunspot number, heliocentric distance, or solar radiation pressure. We show that the variability of Mercury&apos;s atmospheric Na density depends strongly on the IPD distribution. That is, Na density is low (high) when Mercury is far away from (close to) the symmetry plane of IPD, and so one can infer the IPD distribution near Mercury orbit from the temporal variability of Na density in Mercury&apos;s atmosphere. Citation: Kameda, S., I. Yoshikawa, M. Kagitani, and S. Okano (2009), Interplanetary dust distribution and temporal variability of Mercury&apos;s atmospheric Na, Geophys. Res. Lett., 36, L15201, doi:10.1029/2009GL039036.

      DOI: 10.1029/2009GL039036

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    • Observation of the lunar sodium exposure using UPI-TVIS onboard SELENE (Kaguya) 査読有り

      M. Kagitani, M. Taguchi, A. Yamazaki, I. Yoshikawa, G. Murakami, K. Yoshioka, S. Kameda, F. Ezawa, T. Toyota, S. Okano

      Earth Planet. Space61 ( 1-5 )   2009年

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      記述言語:英語   掲載種別:研究論文(学術雑誌)  

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    • First optical observation of the Moon&apos;s sodium exosphere from the lunar orbiter SELENE (Kaguya) 査読有り

      M. Kagitani, M. Taguchi, A. Yamazaki, I. Yoshikawa, G. Murakami, K. Yoshioka, S. Kameda, F. Ezawa, T. Toyota, S. Okano

      EARTH PLANETS AND SPACE61 ( 8 ) 1025 - 1029   2009年

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:TERRA SCIENTIFIC PUBL CO  

      The first successful observations of resonant scattering emission from the lunar sodium exosphere were made from the lunar orbiter SELENE (Kaguya) using TVIS instruments during the period 17-19 December, 2008. The emission intensity of the NaD-line decreased by 12 +/- 6%, with an average value of 5.4 kR (kilorayleighs) in this period, which was preceded, by I day, by enhancement of the solar proton flux associated with a corotating interaction region. The results suggest that solar wind particles foster the diffusion of sodium atoms or ions in the lunar regolith up to the surface and that the time scale of the diffusion is a few tens of hours. The declining activity of the Geminid meteor shower is also one possible explanation for the decreasing sodium exosphere.

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    • The Upper Atmosphere and Plasma Imager/the Telescope of Visible Light (UPI/TVIS) onboard the Kaguya spacecraft 査読有り

      M. Taguchi, T. Sakanoi, S. Okano, M. Kagitani, M. Kikuchi, M. Ejiri, I. Yoshikawa, A. Yamazaki, G. Murakami, K. Yoshioka, S. Kameda, W. Miyake, M. Nakamura, K. Shiokawa

      EARTH PLANETS AND SPACE61 ( 12 ) XVII - XXIII   2009年

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:TERRA SCIENTIFIC PUBL CO  

      The Upper Atmosphere and Plasma Imager (UPI) was placed in a lunar orbit in order to Study both the Moon and Earth. The UPI consists of two telescopes: a Telescope of Extreme Ultraviolet (TEX) and a Telescope of Visible Light (TVIS), which are both mounted on a two-axis gimbals system. The TVIS is equipped with fast catadioptric optics and a high-sensitivity CCD to image swift aurora and dark airglow ill the terrestrial upper atmosphere. TVIS has a field-of-view equivalent to the Earth&apos;s disk as seen from the Moon. The spatial resolution is about 30 km x 70 km on the Earth&apos;s surface at auroral latitudes. The observation wavelengths can be changed by selecting different bandpass filters. Using the images of the northern and Southern auroral ovals taken by TVIS, the intensities and shapes of the conjugate auroras will be quantitatively compared. Using the an-low imaging, medium- and large-scale ionospheric disturbances will be Studied. In this paper, the instrumental design and performance of TVIS are presented.

      DOI: 10.1186/BF03352980

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    • Observation of Mercury's sodium exosphere during the transit on November 9, 2006 査読有り

      Ichiro Yoshikawa, Junya Ono, Kazuo Yoshioka, Go Murakami, Fukuhiro Ezawa, Shingo Kameda, Satoru Ueno

      PLANETARY AND SPACE SCIENCE56 ( 13 ) 1676 - 1680   2008年11月

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

      A rare, but normal, astronomical event occurred on November 9th 2006 (JST) as Mercury passed in front of the Sun from the perspective of the Earth. The abundance of the sodium vapor above the planet limb was observed by detecting an excess absorption in the solar sodium line D, during this event. The observation was performed with a 10-m spectrograph of Czerny-Turnar system at Domeless Solar Tower Telescope at the Hida Observatory in Japan. The excess absorption was red-shifted by 10 pm relative to the solar line, and was measured at the dawnside (eastside) and duskside (westside) of Mercury. Between the dawn and dusksides, an asymmetry of total sodium abundance was clearly identified. At the dawnside, the total sodium column density was 6.1 x 10(10) Na atoms/cm(2), while it was 4.1 x 10(10) Na atoms/cm(2) at the duskside. The investigation of dawn-dusk asymmetry of the sodium exosphere of Mercury is a clue to understand the release mechanism of sodium from the surface rock. Our result suggests that a thermal desorption is a main source process for sodium vapor in the vicinity of Mercury. (C) 2008 Elsevier Ltd. All rights reserved.

      DOI: 10.1016/j.pss.2008.07.026

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    • Attempt to identify a source mechanism of Mercury’s sodium exosphere by a spectrometer using Fabry Perot etalon 査読有り

      Yoshikawa, I, Kameda, S, Hikosaka, K, Murakami, G, Rees, D, Nozawa, H, Okano, S, Korablev, O

      Advances in Space Research42 ( 7 ) 1172 - 1179   2008年10月

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      記述言語:英語   掲載種別:研究論文(学術雑誌)  

      DOI: 10.1016/j.asr.2007.09.018

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    • Observation of Mercury’s sodium tail using Fabry Perot Interferometer 査読有り

      Kameda, S, Kagitani, M, Okano, S, Yoshikawa, I, Ono, J

      Advances in Space Research41 ( 9 ) 1381 - 1385   2008年

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      記述言語:英語   掲載種別:研究論文(学術雑誌)  

      DOI: 10.1016/j.asr.2007.09.039

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    • Mercury’s sodium exosphere explored by the BepiColombo mission 査読有り

      Yoshioka, K, Hikosaka, K, Kameda, S, Nozawa, H, Yamazaki, A, Yoshikawa, I

      Advances in Space Research41 ( 9 ) 1386 - 1391   2008年

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      記述言語:英語   掲載種別:研究論文(学術雑誌)  

      DOI: 10.1016/j.asr.2007.11.024

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    • Telescope of extreme ultraviolet (TEX) onboard SELENE: science from the Moon 査読有り

      I. Yoshikawa, A. Yamazaki, G. Murakami, K. Yoshioka, S. Kameda, F. Ezawa, T. Toyota, W. Miyake, M. Taguchi, M. Kikuchi, M. Nakamura

      EARTH PLANETS AND SPACE60 ( 4 ) 407 - 416   2008年

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:TERRA SCIENTIFIC PUBL CO  

      The Upper Atmosphere and Plasma Imager (UPI) is to be launched in 2007 and sent to the Moon. From the lunar orbit, two telescopes are to be directed towards the Earth. The Moon has no atmosphere, which results in there being no active emission near the spacecraft; consequently, we will have a high-quality image of the near-Earth environment. As the Moon orbits the Earth once a month, the Earth will also be observed from many different directions. This is called a "science from the Moon". The two telescopes are mounted on a two-axis gimbal system, the Telescope of Extreme ultraviolet (TEX) and Telescope of Visible light (TVIS). TEX detects the O II (83.4 nm) and He II (30.4 nm) emissions scattered by ionized oxygen and helium, respectively. The targets of extreme-ultraviolet (EUV) imaging are the polar ionosphere, the polar wind, and the plasmasphere and inner magnetosphere. The maximum spatial and time resolutions are 0.09 Re and 1 min, respectively.

      DOI: 10.1186/BF03352805

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    • Observation of Mercury's sodium exosphere by MSASI in the BepiColombo mission 査読有り

      I. Yoshikawa, S. Kameda, K. Matsuura, K. Hikosaka, G. Murakami, K. Yoshioka, H. Nozawa, D. Rees, S. Okano, H. Misawa, A. Yamazaki, O. Korablev

      PLANETARY AND SPACE SCIENCE55 ( 11 ) 1622 - 1633   2007年9月

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

      The Mercury's sodium atmosphere spectral imager (MSASI) on BepiColombo (BC) will address a range of fundamental scientific questions pertaining to Mercury's exosphere. The measurements will provide new information on regolith-exosphere-magnetosphere coupling as well as new understanding of the dynamics governing the exosphere bounded by the planetary surface, the solar wind and interplanetary space. MSASI is a high-dispersion visible spectrometer working in the spectral range around sodium D2 emission (589 nm). A tandem Fabry-Perot etalon is used to achieve a compact design. A one-degree-of-freedom scanning mirror is employed to obtain full-disk images of the planet. This paper presents an overview of the MSASI and the design of its spectral analyzer, which uses a Fabry-Perot interferometer. We conclude that: (1) The MSASI optical design is practical and can be implemented without new or critical technology developments. (2) The thermally tuned etalon design is based on concepts, designs and materials that have good space heritage. (3) The MSASI instrument achieves a high SNR (&gt; 10) in the range of 2k-10 MRayleigh. (C) 2007 Elsevier Ltd. All rights reserved.

      DOI: 10.1016/j.pss.2006.01.010

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    • Time variation in exospheric sodium density on Mercury 査読有り

      S. Kameda, I. Yoshikawa, J. Ono, H. Nozawa

      PLANETARY AND SPACE SCIENCE55 ( 11 ) 1509 - 1517   2007年9月

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

      We conducted continuous spectroscopic observations of the Mercury's sodium exosphere with a 188 cm telescope and a high dispersion echelle spectrograph, for 1-6h in the daytime on December 4, 13, 14, and 15, 2005. To correct the images of the sodium emission blurred by Earth's atmosphere, the observed distribution was deconvolved with the point spread function which was obtained using Hapke's surface reflection model and the observed surface reflection. The average column density of sodium atoms was 1-2 x 10(11) atoms/cm(2) and significant diurnal changes were not observed. However, the sodium densities at low latitudes and high latitude changed during the observation and the rate of change in density at low latitude was higher than that at high latitude on December 14 and 15. Although the rates of suggested release processes are higher than the observed rate, the suggested release processes cannot explain the rapid change in density at low latitude. This may suggest the effect of transport of neutral atoms and the recycling of ions to the surface dominates the time variation in the spatial distribution of exospheric sodium atoms on Mercury. (C) 2007 Elsevier Ltd. All rights reserved.

      DOI: 10.1016/j.pss.2006.10.010

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    • Study of time variation in exospheric sodium density on Mercury

      Shingo Kameda

          2007年3月22日

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      記述言語:英語   掲載種別:学位論文(博士)  

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    • Ground-based observations of sodium in Mercuryüfs exosphere

      Kameda, S, Kagitani, M, Ono, J, Nozawa, H, Yoshikawa, I, Okano, S

      36th COSPAR Scientific Assembly. Held 16 - 23 July 2004, in Beijing, China   2384   2006年7月

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      記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

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    • Attempt to identify a source mechanism of Mercury's sodium exosphere by remote-sensing technique

      Yoshikawa, I, Hikosaka, K, Kameda, S, Okano, S, Nozawa, H, Yamazaki, A, Korablev, O, Rees, D

      36th COSPAR Scientific Assembly. Held 16 - 23 July 2004, in Beijing, China   1333   2006年7月

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      記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

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    • Observation of the sodium exosphere from mercury magnetospheric orbiter 査読有り

      Ichiro Yoshikawa, Hiromasa Nozawa, Shingo Kameda, Shoichi Okano, Hiroaki Misawa

      MERCURY, MARS AND SATURN38 ( 4 ) 659 - +   2006年

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      記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ELSEVIER SCIENCE LTD  

      The Mercury Sodium Atmosphere Spectral Imager (MSASI) in the BepiColombo mission will address a wealth of fundamental scientific questions pertaining to the Mercury's exosphere. Together, our measurements on the overall scale will provide ample new information on regolith-exo sphere-magneto sphere coupling as well as new understanding of the dynamics governing the 'surface-bounded exosphere'.
      It arises quite clearly from ground-based observations that the regolith of Mercury releases a fraction of its content to the exosphere. Some processes are identified up to now as leading to this ejection, e.g., photon-stimulated desorption. These processes are associated with different energies of ejection and behaviors in different regions of Mercury's surface. Therefore, different types of population are born from the surface, depending on the processes. The MSASI measurements definitely can identify the release processes, how exospheric sodium is born from the regolith. MSASI/BepiColombo is the first and unique opportunity to study the formation, circulation, and maintenance of the surface-bounded exosphere. (c) 2006 COSPAR. Published by Elsevier Ltd. All rights reserved.

      DOI: 10.1016/j.asr.2005.05.134

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    • 水星大気の生成メカニズムに関する研究 ~MMO搭載機器MSASIでの観測に向けて~ 査読有り

      吉岡和夫彦坂健太郎, 亀田真吾, 野澤宏大, 吉岡和夫, 山崎敦, 吉川一朗, 笠羽康正

      宇宙航空研究開発機構研究開発報告JAXA-RR-05-021 ( 1 ) 16   2006年

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    • Observation of the sodium exosphere from mercury magnetospheric orbiter 査読有り

      Ichiro Yoshikawa, Hiromasa Nozawa, Shingo Kameda, Shoichi Okano, Hiroaki Misawa

      ADVANCES IN SPACE RESEARCH38 ( 4 ) 659 - 663   2006年

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCI LTD  

      The Mercury Sodium Atmosphere Spectral Imager (MSASI) in the BepiColombo mission will address a wealth of fundamental scientific questions pertaining to the Mercury's exosphere. Together, our measurements on the overall scale will provide ample new information on regolith-exosphere-magnetosphere coupling as well as new understanding of the dynamics governing the 'surface-bounded exosphere'.
      It arises quite clearly from ground-based observations that the regolith of Mercury releases a fraction of its content to the exosphere. Some processes are identified up to now as leading to this ejection, e.g., photon-stimulated desorption. These processes are associated with different energies of ejection and behaviors in different regions of Mercury's surface. Therefore, different types of population are born from the surface, depending on the processes. The MSASI measurements definitely can identify the release processes, how exospheric sodium is born from the regolith. MSASI/BepiColombo is the first and unique opportunity to study the formation, circulation, and maintenance of the surface-bounded exosphere. (c) 2006 COSPAR. Published by Elsevier Ltd. All rights reserved.

      DOI: 10.1016/j.asr.2005.05.134

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    • Mercury Sodium Atmosphere Spectral Imager (MSASI) 査読有り

      Nozawa, H, I. Yoshikawa, S. Kameda, H. Misawa, S. Okano, M. Taguchi, A. Yamazaki, Y. Kasaba, K. Takamizawa, O. Korablev

      JAXA Research and Development Report   JAXA-RR-05-007E   2005年

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      記述言語:英語   掲載種別:研究論文(大学,研究機関等紀要)  

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    • Development of an extreme ultraviolet imaging spectrometer for the mercury mission 査読有り

      Yoshikawa I, Murachi T, Kameda S, Yamazaki A, Okano S, Nakamura M

      ADVANCES IN MIRROR TECHNOLOGY FOR X-RAY, EUV LITHOGRAPHY, LASER, AND OTHER APPLICATIONS5193   164 - 171   2004年

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    • Development of an extreme ultraviolet imaging spectrometer for the BepiColombo mission 査読有り

      Yoshikawa, I, A Yamazaki, T Murachi, S Kameda, H Sagawa, S Okano, T Okada, M Nakamura

      MERCURY, MARS AND SATURN33 ( 12 ) 2195 - 2199   2004年

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      記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

      Extreme and far ultraviolet imaging spectrometers are proposed for the low-altitude orbiter of the BepiColombo mission. The UV instrument, consisting of the two spectrometers with common electronics, aims at measuring (1) emission lines from molecules, atoms and ions present in the Mercury's tenuous atmosphere and (2) the reflectance spectrum of Mercury's surface. The instrument pursues a complete coverage in UV spectroscopy. The extreme UV spectrometer covers the spectral range of 30-150 nm with the field of view of 5.0degrees, and the spectrum from 130 to 430 nm is obtained by the far UV spectrometer. The extreme UV spectrometer employs multi-layer coating technology to enhance its sensitivity at particular emission lines. This technology enables us to identify small ionospheric signatures such as He II (30.4 nm) and Na II (37.2 nm), which could not be detected with conventional optics. (C) 2003 COSPAR. Published by Elsevier Ltd. All rights reserved.

      DOI: 10.1016/s0273-1177(03)00446-0

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    • 多層膜回折格子の開発 ~水星大気分光観測に向けて~ 査読有り

      亀田 真吾, 佐川 英夫, 村地 哲徳, 山崎 敦, 吉川 一朗, 中村 正人

      宇宙科学研究所報告124 ( 124 ) 1 - 14   2003年9月

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      記述言語:日本語   掲載種別:研究論文(大学,研究機関等紀要)   出版者・発行元:宇宙航空研究開発機構  

      "我々は,極端紫外領域にある水星大気の共鳴散乱光を分光する極端紫外分光撮像器(EUIS:Extreme Ultraviolet Imaging Spectrometer)を水星探査計画に向け開発している.本稿では,本観測器開発の鍵となる多層膜回折格子の性能試験について報告する.結論は以下の通りである.(a)機械刻線回折格子とホログラフィック回折格子のどちらが適しているか調査し,その結果迷光の少なさという点からホログラフィック回折格子が優れていると結論した.(b)ホログラフィック平面回折格子にMoとSiのペアからなる多層膜コーティングと金コーティングを施し,回折効率を比較した.多層膜回折格子が金単層膜回折格子よりも1桁ほど効率が高いことを確認した."

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    MISC

    • 火星衛星探査計画MMX ROVER搭載機器の科学目標と開発状況

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    • 火星衛星探査計画MMXのミッション運用検討(MOWT)

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    • 火星衛星探査計画MMXの進捗

      倉本圭, 倉本圭, 川勝康弘, 藤本正樹, BARUCCI Maria Antonella, LAWRENCE David J., 玄田英典, 平田成, 今村剛, 亀田真吾, 小林正規, 草野広樹, 松本晃治, MICHEL Patrick, 宮本英昭, 中川広務, 中村智樹, 小川和律, 小川和律, 大嶽久志, 尾崎正伸, RUSSEL Sara, 佐々木晶, 澤田弘崇, 千秋博紀, 寺田直樹, ULAMEC Stephan, 臼井寛裕, 和田浩二, 横田勝一郎

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      大木優介, 吉川健人, 竹内央, 池田人, 菊地翔太, 武井悠人, 佐伯孝尚, 津田雄一, 山田学, 神山徹, 亀田真吾

      宇宙科学技術連合講演会講演集(CD-ROM)64th   2020年

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

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    • DESTINY<sup>+</sup>搭載用小惑星追尾望遠モノクロカメラ(TCAP)およびマルチバンドカメラ(MCAP)

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      宇宙科学技術連合講演会講演集(CD-ROM)64th   2020年

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    • 火星衛星探査計画MMX:目指す科学とその推進

      倉本圭, 倉本圭, 川勝康弘, 藤本正樹, BIBRING Jean Pierre, LAWRENCE David, 玄田英典, 平田成, 今村剛, 亀田真吾, 松本晃治, 宮本英昭, 諸田智克, 長岡央, 中川広務, 中村智樹, 小川和律, 大嶽久志, 尾崎正伸, 佐々木晶, 千秋博紀, 橘省吾, 橘省吾, 寺田直樹, 臼井寛裕, 和田浩二, 渡邊誠一郎

      日本地球惑星科学連合大会予稿集(Web)2019   2019年

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    • 火星衛星探査計画MMXの進展とサイエンス

      倉本圭, 倉本圭, 川勝康弘, 藤本正樹, BIBRING Jean-Pierre, 玄田英典, 平田成, 今村剛, 亀田真吾, LAWRENCE David, 松本晃治, 宮本英昭, 諸田智克, 長岡央, 中川広務, 中村智樹, 小川和律, 大嶽久志, 尾崎正伸, 佐々木晶, 千秋博紀, 橘省吾, 寺田直樹, 臼井寛裕, 和田浩二, 渡邊誠一郎

      日本惑星科学会秋季講演会予稿集(Web)2019   2019年

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    • 多バンド可視観測による小惑星リュウグウとベヌーの比較

      杉田精司, 本田理恵, 諸田智克, 亀田真吾, 巽瑛理, 横田康弘, 横田康弘, 山田学, 松岡萌, 長勇一郎, 神山徹, 鈴木秀彦, 坂谷尚哉, 本田親寿, 吉岡和夫, 早川雅彦, 澤田弘崇, 渡邊誠一郎, 津田雄一

      日本惑星科学会秋季講演会予稿集(Web)2019   2019年

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    • DESTINY<sup>+</sup>搭載用小惑星追尾望遠モノクロカメラ(TCAP)およびマルチバンドカメラ(MCAP)

      石橋高, 亀田真吾, 鍵谷将人, HONG Peng, 山田学, 奥平修, 荒井朋子, 吉田二美, 石丸貴博, 佐藤峻介, 岡本尚也, 高島健, 岩田隆浩, 岡田達明

      宇宙科学技術連合講演会講演集(CD-ROM)63rd   2019年

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    • DESTINY<sup>+</sup>ミッションにおける小惑星3200Phaethonのフライバイ撮像観測

      石橋高, 洪鵬, 石丸貴博, 岡本尚也, 佐藤峻介, 鍵谷将人, 亀田真吾, 荒井朋子, 吉田二美, 山田学, 奥平修, 岩田隆浩, 岡田達明, 高島健

      日本惑星科学会秋季講演会予稿集(Web)2019   2019年

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    • リュウグウとメインベルト内帯の低アルベド小惑星族の可視スペクトル比較

      杉田精司, 巽瑛理, 長谷川直, 鈴木雄大, 上吉原弘明, 本田理恵, 亀田真吾, 諸田智克, 本田親寿, 神山徹, 山田学, 早川雅彦, 横田康弘, 坂谷尚哉, 鈴木秀彦, 小川和律, 澤田弘崇

      日本地球惑星科学連合大会予稿集(Web)2018   2018年

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    • 火星衛星探査計画MMXとそのサイエンス2018

      倉本圭, 倉本圭, 川勝康弘, 藤本正樹, 玄田英典, 平田成, 今村剛, 亀田真吾, 松本晃治, 宮本英昭, 諸田智克, 長岡央, 中川広務, 中村智樹, 小川和律, 大嶽久志, 尾崎正伸, 佐々木晶, 千秋博紀, 橘省吾, 寺田直樹, 臼井寛裕, 和田浩二, 渡邊誠一郎

      日本惑星科学会秋季講演会予稿集(Web)2018   2018年

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    • MMX着地運用ワーキングチームにおける検討状況

      宮本英昭, 今田高峰, 大槻真嗣, 小川和律, 亀田真吾, 馬場満久, 菊地紘, 坂谷尚哉, 逸見良道, 加藤裕基, 中村智樹, 新原隆史, 和田浩二

      宇宙科学技術連合講演会講演集(CD-ROM)62nd   2018年

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    • DESTINY<sup>+</sup>ミッションにおける小惑星3200Phaethonのフライバイ撮像観測

      石橋高, 亀田真吾, 鍵谷将人, 洪鵬, 荒井朋子, 吉田二美, 山田学, 奥平修, 石丸貴博, 佐藤峻介, 岡本尚也, 高島健, 岩田隆浩, 岡田達明

      日本惑星科学会秋季講演会予稿集(Web)2018   2018年

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    • 火星エアロキャプチャオービタの検討

      藤田 和央, 畠中 龍太, 西 顕太郎, 池永 敏憲, 鈴木 俊之, 春木 美鈴, 小澤 宇志, 野村 哲史, 臼井 寛裕, 宮本 英昭, 亀田 真吾, Fujita Kazuhisa, Hatakenaka Ryuta, Nishi Kentaro, Ikenaga Toshinori, Suzuki Toshiyuki, Haruki Misuzu, Ozawa Takashi, Nomura Satoshi, Usui Tomohiro, Miyamoto Hirdy, Kameda Singo

      平成29年度宇宙航行の力学シンポジウム = Symposium on Flight Mechanics and Astrodynamics: 2017   2017年12月

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      記述言語:日本語   出版者・発行元:宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)  

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    • 月、地球、火星、恒星を用いた はやぶさ 2 可視分光カメラの機上校正観測

      鈴木 秀彦, 山田 学, 神山 徹, 巽 瑛理, 亀田 真吾, 本田 理恵, 澤田 弘崇, 尾川 順子, 諸田 智克, 本田 親寿, 坂谷 尚哉, 早川 雅彦, 横田 康弘, 山本 幸生, 杉田 精司, Suzuki Hidehiko, Yamada Manabu, Kouyama Toru, Tatsumi Eri, Kameda Shingo, Honda Rie, Sawada Hirotaka, Ogawa Naoko, Morota Tomokatsu, Honda Chikatoshi, Sakatani Naoya, Hayakawa Masahiko, Yokota Yasuhiro, Yamamoto Yukio, Sugita Seiji

      第50回月・惑星シンポジウム = Proceedings of the 50th ISAS Lunar and Planetary Symposium   2017年8月

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      記述言語:英語   出版者・発行元:宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)  

      第50回月・惑星シンポジウム (2017年8月3-4日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)), 相模原市, 神奈川県著者人数: 15名資料番号: SA6000200016

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    • 火星衛星探査計画MMXとそのサイエンス2017

      倉本圭, 川勝康弘, 藤本正樹, 玄田英典, 今村剛, 亀田真吾, 松本晃治, 宮本英昭, 諸田智克, 中村智樹, 小川和律, 尾崎正伸, 佐々木晶, 千秋博紀, 橘省吾, 寺田直樹, 臼井寛裕, 和田浩二, 渡邊誠一郎

      日本惑星科学会秋季講演会予稿集(Web)2017   2017年

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    • 月・惑星探査用飛行時間型質量分析装置の開発

      今井優介, 斎藤義文, 横田勝一郎, 笠原慧, 齋藤直昭, 長勇一郎, 三浦弥生, 亀田真吾, 杉田精司

      日本地球惑星科学連合大会予稿集(Web)2017   2017年

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    • DESTINY+ミッション搭載用超望遠モノクロカメラ(TCAP)およびマルチバンドカメラ(MCAP)

      石橋高, 亀田真吾, 荒井朋子, 奥平修, 山田学, 石丸貴博, 佐藤峻介, 大槻真嗣, 岩田隆浩, 岡田達明

      日本惑星科学会秋季講演会予稿集(Web)2017   2017年

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    • 一番星へ行こう!日本の金星探査機の挑戦その30 〜1 umカメラで金星昼&夜〜

      岩上直幹, はしもとじょーじ, 澤井健太, 坂野井健, 高木聖子, 亀田真吾

      日本惑星科学会誌「遊星人」26 ( 1 ) 21 - 22   2017年

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    • はやぶさ2搭載 光学航法カメラの地球・月スイングバイ観測報告

      澤田 弘崇, 山田 学, 本田 理恵, 亀田 真吾, 諸田 智克, 本田 親寿, 鈴木 秀彦, 神山 徹, 杉田 精司

      宇宙科学技術連合講演会講演集60   5p   2016年9月6日

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      記述言語:日本語   出版者・発行元:日本航空宇宙学会  

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    • 火星衛星探査ミッションのサイエンス

      倉本 圭, 藤本 正樹, 玄田 英典, 今村 剛, 亀田 真吾, 川勝 康弘, 松本 晃治, 三桝 裕也, 宮本 英昭, 諸田 智克, 中村 智樹, 小川 和律, 尾崎 正伸, 澤田 弘崇, 橘 省吾, 寺田 直樹, 臼井 寛裕, 和田 浩二, 渡邊 誠一郎, MMXサイエンスチーム

      宇宙科学技術連合講演会講演集60   5p   2016年9月6日

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      記述言語:日本語   出版者・発行元:日本航空宇宙学会  

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    • DESTINY⁺による流星群母天体フライバイ計画—Meteor Shower Parent Bodies Fly-by mission with DESTINY⁺

      荒井 朋子, 小林 正規, 千秋 博紀, 石橋 高, 山田 学, 和田 浩二, 石丸 亮, 大塚 勝仁, 伊藤 孝士, 渡部 潤一, 亀田 真吾, 川勝 康弘, Sarli Bruno, 岩田 隆浩, 岡田 達明, 吉川 真, 船瀬 龍, 五十里 哲, 尾崎 直哉, 石黒 正晃, 浦川 聖太郎, 阿部 新助, 小松 睦美, 中村 智樹, 中藤 亜衣子, 中村メッセンジャー 圭子, 三河内 岳, 佐々木 晶, 薮田 ひかる, 廣井 孝弘, 橘 省吾, 木村 宏, 矢野 創, 並木 則行, Ralph Srama, Harald Kruger

      宇宙科学技術連合講演会講演集60   6p   2016年9月

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      記述言語:日本語   出版者・発行元:日本航空宇宙学会  

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      その他リンク: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-15K13604/

    • 火星着陸探査に向けた元素分析装置の開発

      亀田 真吾, 堀内 美沙, 長 勇一郎, 三浦 弥生, 杉田 精司, 岡崎 隆司, 笠原 慧, 横田 勝一郎, 齋藤 義文, Kameda Shingo, Horiuchi Misa, Cho Yuichiro, Miura Yayoi, Sugita Seiji, Okazaki Satoshi, Kasahara Satoshi, Yokota Shoichiro, Saito Yoshifumi

      第49回月・惑星シンポジウム = Proceedings of the 49th ISAS Lunar and Planetary Symposium   2016年7月

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      記述言語:日本語   出版者・発行元:宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)  

      第49回月・惑星シンポジウム (2016年7月20-21日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)), 相模原市, 神奈川県資料番号: SA6000059022

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    • 火星衛星探査ミッションとそのサイエンス

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      記述言語:日本語   出版者・発行元:日本惑星科学会  

      はやぶさ2に搭載された光学航法カメラ(ONC:Optical Navigation Camera)はその名の通り探査機のナビゲーションの役目を担うカメラであるが,科学観測においても中心的な役割を果たす.本稿では特に小惑星の力学進化過程の復元に向けた,ONC地形観測の戦略について紹介する.

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      日本地球惑星科学連合大会予稿集(Web)2015   2015年

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      日本惑星科学会秋期講演会予稿集2014   "P1 - 32"   2014年9月10日

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      日本惑星科学会秋期講演会予稿集2014   "O14 - 02"   2014年9月10日

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      記述言語:日本語   出版者・発行元:日本惑星科学会  

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      第47回月・惑星シンポジウム = Proceedings of the 47th ISAS Lunar and Planetary Symposium   2014年8月

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      荒井朋子, 小林正規, 春日敏測, 大塚勝仁, 川勝康弘, BRUNO Sarli, 渡部潤一, 伊藤孝士, 中村智樹, 中村良介, 中村メッセンジャー 圭子, 小松睦美, 中藤亜衣子, 三河内岳, 亀田真吾, 中宮賢樹, 阿部新助, 浦川聖太郎, 千秋博紀, 和田浩二, 大野宗佑, 石橋高, 石丸亮, 木村宏, SRAMA Ralph, KRUEGER Harald

      宇宙科学技術連合講演会講演集(CD-ROM)58th   2014年

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      地球電磁気・地球惑星圏学会総会及び講演会予稿集(CD-ROM)136th   2014年

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      地球電磁気・地球惑星圏学会総会及び講演会予稿集(CD-ROM)136th   2014年

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    • HISAKI/EXCEEDで観測された磁気嵐中・ジオコロナのLyman‐αの増光

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      地球電磁気・地球惑星圏学会総会及び講演会予稿集(CD-ROM)136th   ROMBUNNO.S001‐11   2014年

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    • O9-14 超小型深宇宙探査機搭載用ジオコロナ撮像装置の開発(口頭発表セッション9(はやぶさ),口頭発表)

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      日本惑星科学会秋期講演会予稿集2013   "O9 - 14"   2013年11月20日

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    • O9-09 はやぶさ2の試料採取地点の決定に向けた隕石反射分光実験(口頭発表セッション9(はやぶさ),口頭発表)

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      日本惑星科学会秋期講演会予稿集2013   "O9 - 09"   2013年11月20日

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      記述言語:日本語   出版者・発行元:日本惑星科学会  

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    • O12-02 真空紫外LIBSによるK-Ar年代測定方法の検証(口頭発表セッション12(分析・実験),口頭発表)

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      日本惑星科学会秋期講演会予稿集2013   "O12 - 02"   2013年11月20日

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    • P3-12 月・水星・小惑星のナトリウム大気(ポスターセッション3,ポスター発表)

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      日本惑星科学会秋期講演会予稿集2013   "P3 - 12"   2013年11月20日

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      記述言語:日本語   出版者・発行元:日本惑星科学会  

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    • DESTINY派性機による小惑星Phaethon探査

      荒井朋子, 春日敏測, 大塚勝仁, 中村智樹, 中藤亜衣子, 中村良介, 渡部潤一, 伊藤孝士, 小林正規, 川勝康弘, BRUNO Sarli, MESSENJA-NAKAMURA Keiko, 小松睦美, 三河内岳, 亀田真吾, 中宮賢樹, 千秋博紀, 和田浩二, 大野宗佑, 石橋高, 石丸亮, SRAMA Ralph, KRUEGER Harald

      宇宙科学技術連合講演会講演集(CD-ROM)57th   2013年

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    • P1-11 惑星探査機搭載に向けたLIBSの開発(ポスターセッション1,ポスター発表)

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      日本惑星科学会秋期講演会予稿集2012   106 - 106   2012年10月24日

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      日本惑星科学会秋期講演会予稿集2012   103 - 103   2012年10月24日

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      記述言語:日本語   出版者・発行元:日本惑星科学会  

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    • 月・惑星着陸探査用元素分析装置 : レーザ誘起絶縁破壊分光装置(LIBS)

      石橋 高, 亀田 真吾, 荒井 朋子, 和田 浩二, 小林 正規, 竝木 則行, 千秋 博紀, 大野 宗祐, 長 勇一郎, 杉田 精司, 松井 孝典

      遊・星・人 : 日本惑星科学会誌21 ( 3 ) 260 - 266   2012年9月25日

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      記述言語:日本語   出版者・発行元:日本惑星科学会  

      レーザ誘起絶縁破壊分光装置(Laser-Induced Breakdown Spectrometer; LIBS)は,測定対象試料上にパルスレーザを照射し,試料の一部をプラズマ化し,プラズマからの発光を分光分析することで,試料に含まれる元素の定量を行う元素分析装置である. LIBSはこれまでの惑星探査に用いられてきた元素分析装置には無い数々の長所を持ち,着陸月・惑星探査における次世代の元素分析装置として期待されている.特に,遠隔性を持ち,迅速な測定が可能であることから,ローバ探査においてその性能が発揮される. LIBSは,原理的に軽元素を含むほぼすべての元素測定が可能な汎用的な元素分析装置であるため,様々な天体における多様な科学目標に対して使用が可能である.現在,日本の次期月探査計画SELENE-2のローバへの搭載を目指して月探査用のLIBS(LIB-S2)を開発中である. LIBSの開発においては,定量正確度の向上,適切な光学系の開発,小型軽量化などの課題があるが, LIB-S2の開発について課題の説明と現状の報告を行う.

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    • その場年代計測装置による月惑星年代学探査(<特集>月惑星探査の来たる10年:第二段階のまとめ) 査読有り

      長 勇一郎, 諸田 智克, 三浦 弥生, 亀田 真吾, 吉岡 和夫, 岡崎 隆司, 並木 則行, 荒井 朋子, 小林 正規, 石橋 高, 大野 宗祐, 千秋 博紀, 和田 浩二, 橘 省吾, 渡邊 誠一郎, 古本 宗充, 本田 親寿, 杉原 孝充, 石原 吉明, 大竹 真紀子, 小林 直樹, 唐牛 譲, 武田 弘, 寺田 健太郎, 鎌田 俊一, 佐伯 和人, 小林 進悟, 國井 康晴, 大槻 真嗣, 杉田 精司

      遊・星・人 : 日本惑星科学会誌21 ( 3 ) 267 - 275   2012年9月25日

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    • 小惑星Phaethon 探査提案

      荒井朋子, 春日敏測, 大塚勝仁, 中村智樹, 中藤亜衣子, 中村良介, 伊藤孝士, 渡部潤一, 小林正規, 川勝康弘, 中村圭子, 小松睦美, 千秋博紀, 和田浩二, 亀田真吾, 大野宗祐, 石橋高, 石丸亮, 中宮賢樹

      日本惑星科学会誌(遊・星・人)21 ( 3 ) 239 - 246   2012年

    • S35-05P レーザー誘起絶縁破壊分光法(LIBS)による鉱物の分類と定量 : 月鉱物のその場測定に向けて(一般ポスターセッション3,ポスター発表)

      石橋 高, 荒井 朋子, 和田 浩二, 小林 正規, 大野 宗祐, 千秋 博紀, 竝木 則行, 松井 孝典, 亀田 真吾, 長 勇一郎, 杉田 精司

      日本惑星科学会秋期講演会予稿集2011   153 - 153   2011年10月23日

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      記述言語:日本語   出版者・発行元:日本惑星科学会  

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    • S21-01 Evidence of a meteoroid impact or variability of solar wind flux in Mercury's sodium tail

      亀田 真吾, 鍵谷 将人, 岡野 章一

      日本惑星科学会秋期講演会予稿集2011   36 - 36   2011年10月23日

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      記述言語:日本語   出版者・発行元:日本惑星科学会  

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    • 「かぐや」による子午面撮像が明らかにしたプラズマポーズの形成

      村上豪, 吉川一朗, 吉岡和夫, 山崎敦, 鍵谷将人, 田口真, 菊池雅行, 亀田真吾, 中村正人

      地球電磁気・地球惑星圏学会総会及び講演会予稿集(CD-ROM)130th   ROMBUNNO.B006-P009   2011年

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      記述言語:日本語  

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    • 115 惑星間空間ダスト分布と水星大気密度変動(オーラルセッション3 内惑星・ハビタブルプラネット)

      亀田 真吾, 鍵谷 正人, 岡野 章一, 石丸 亮

      日本惑星科学会秋期講演会予稿集2010   15 - 15   2010年10月6日

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      記述言語:日本語   出版者・発行元:日本惑星科学会  

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    • 301 真空環境下でのレーザー誘起絶縁破壊分光装置(LIBS)の定量精度(オーラルセッション7 衝突・破壊過程)

      石橋 高, 大野 宗祐, 亀田 真吾, 荒井 朋子, 小林 正規, 和田 浩二, 千秋 博紀, 後藤 和久, 竝木 則行, 松井 孝典, 長 勇一郎, 杉田 精司

      日本惑星科学会秋期講演会予稿集2010   52 - 52   2010年10月6日

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      記述言語:日本語   出版者・発行元:日本惑星科学会  

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    • 317 BepiColombo 日欧共同水星探査ミッション(オーラルセッション11 固体天体の科学・惑星探査II)

      早川 基, 小川 博之, 峯杉 賢治, 高島 健, 松岡 彩子, 中澤 暁, 亀田 真吾, 山川 宏, 笠羽 康正

      日本惑星科学会秋期講演会予稿集2009   2009年9月28日

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      記述言語:日本語   出版者・発行元:日本惑星科学会  

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    • BepiColombo/MMO搭載用ナトリウム大気光カメラMSASIの開発

      亀田真吾, 江沢福紘, 村上豪, 小川源太郎, 野澤宏大, 吉川一朗, 岡野章一, KORABLEV O, REES D

      太陽系科学シンポジウム29th   9 - 11   2008年3月

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      記述言語:日本語  

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    • BepiColombo水星探査計画に向けたMSASI搭載イメージインテンシファイアの性能評価

      小川 源太郎, 村上 豪, 江沢 福紘, 亀田 真吾, 吉川 一朗

      宇宙航空研究開発機構研究開発報告7   1 - 12   2008年2月

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      記述言語:日本語   出版者・発行元:宇宙航空研究開発機構  

      我々はBepiColombo 水星探査計画において計画されている磁気圏探査機(Mercury Magnetospheric Orbiter: MMO)に搭載する水星大気撮像カメラ(Mercury Sodium Atmosphere Spectral Imager: MSASI)の開発を進めている.水星大気撮像カメラ(MSASI)はファブリペロー干渉計を用いて水星ナトリウム大気が発するD_2 線を分光しその強度を測る.この装置にはイメージインテンシファイア(Image Intensifier)という微弱光を増幅する光検出器を用いる.今回我々は,以下の4 つの試験を行い,イメージインテンシファイアの性能を定量的に評価した.1.空間分解能の測定試験.2.暗電流の温度に対する特性試験.3.蛍光面(P 46)への放射線照射試験.4.入射光量に対する劣化試験.本論文では,その結果を報告する.

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    • BepiColombo水星探査計画に向けたナトリウム大気撮像カメラ用検出器の開発

      江沢福紘, 村上豪, 吉岡和夫, 小川源太郎, 亀田真吾, 吉川一朗

      地球電磁気・地球惑星圏学会総会及び講演会予稿集(CD-ROM)124th   ROMBUNNO.B009-P017   2008年

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      記述言語:日本語  

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    • 水星大気密度変動の地上観測

      亀田真吾, 小川源太郎, 江沢福紘, 村上豪, 吉岡和夫, 吉川一朗

      地球電磁気・地球惑星圏学会総会及び講演会予稿集(CD-ROM)124th   ROMBUNNO.B009-09   2008年

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      記述言語:日本語  

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    • 小型宇宙望遠鏡TOPSによる惑星電磁圏領域の科学目標

      土屋史紀, 寺田直樹, 山崎敦, 今井一雅, 深沢圭一郎, 二穴喜文, 鍵谷将人, 亀田真吾, 笠羽康正, 三澤浩昭, 森岡昭, 野澤宏大, 荻野竜樹, 佐藤毅彦, 垰千尋, 上野宗孝, 横田勝一郎, 吉川一朗, 渡部重十, 高橋幸弘

      地球電磁気・地球惑星圏学会総会及び講演会予稿集(CD-ROM)122nd   ROMBUNNO.B009-P028   2007年

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    • 極端紫外光分光撮像用のMo/Si 多層膜回折格子の開発

      村地 哲徳, 金尾 美穂, 亀田 真吾, 山崎 敦, 吉川 一朗, 中村 正人

      宇宙航空研究開発機構研究開発報告3   1 - 11   2004年3月

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      記述言語:日本語   出版者・発行元:宇宙航空研究開発機構  

      惑星大気圏から宇宙空間への原子の散逸量を測定する方法として,中性粒子・イオンの共鳴散乱光を観測して散逸量を求める方法がある.特に,H・He・O などの共鳴散乱光は極端紫外光領域にあり,極端紫外光を観測可能な光学系の開発が重要である.また,大気の空間分布やその時間変動を観測するためには撮像観測も必要である.この方法では従来,バンドパスフィルターと,その波長を強く反射するよう製作された多層膜反射鏡を組み合わせて,観測対象の散逸原子の共鳴散乱光のみを観測可能な光学系を作成し,衛星・ロケットに搭載して観測を行った.しかし,分光観測ではないので,1 つの光学系で観測可能な共鳴散乱光は1 波長に限られる.複数の原子の共鳴散乱光を同時に観測する場合は複数の光学系が必要となる.1 つの光学系で複数の共鳴散乱光を観測するには,通常,光学系に分光器を組み込んで観測を行う.だが,反射鏡と分光器を用いた場合を比較すると,一般的に分光器は光量の損失が多い.今回はヘリウムイオンの共鳴散乱光(30.4 nm)を強く反射するように,最上層にSi :5.0 nm,その下にMo : 4.4 nm とSi : 13.3 nm のペア20 層を回折格子に蒸着し,極端紫外光用のMo/Si 多層膜回折格子を製作し,性能評価を行った.多層膜を蒸着しても回折格子の溝が埋まらないことを原子間力顕微鏡で確認した.また,多層膜回折格子の反射効率は,ブレーズ型が最大2.2 %,ラミナー型が最大2.9 % であった.多層膜技術を用いることで,単層膜で得られる反射効率の限界を超え,Pt 単層膜の場合と比較して,Mo/Si 多層膜では約5 倍の反射効率を実現できた.

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    共同研究・競争的資金等の研究

    • 太陽系外地球型惑星の水環境進化

      科学研究費助成事業 

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      2018年4月 - 2023年3月

      資金種別:競争的資金

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    • 太陽系外地球型惑星の高層大気観測に向けた高感度紫外線検出器の開発

      日本学術振興会  科学研究費助成事業 

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      2019年4月 - 2022年3月

      資金種別:競争的資金

      配分額:18400000円 ( 直接経費:12880000円 、 間接経費:5520000円 )

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    • 強紫外線輻射を受ける地球型惑星のハビタビリティ

      自然科学研究機構  アストロバイオロジーセンター サテライト研究 

      亀田真吾

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      2018年4月 - 2021年3月

      担当区分:研究代表者  資金種別:競争的資金

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    • 高感度紫外線分光器の開発

      文部科学省  JAXA戦略的基礎開発予算 

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      2019年4月 - 2020年3月

      資金種別:競争的資金

      配分額:9100000円 ( 直接経費:8200000円 、 間接経費:900000円 )

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    • 宇宙望遠鏡搭載に向けた系外惑星観測用真空紫外線分光システムの検討

      宇宙航空研究開発機構  JAXA戦略的基礎開発予算 

      亀田真吾

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      2018年4月 - 2019年3月

      担当区分:研究代表者  資金種別:競争的資金

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    • 紫外線宇宙望遠鏡による太陽系外惑星大気の研究

      日本学術振興会  科学研究費助成事業 

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      2016年4月 - 2019年3月

      資金種別:競争的資金

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    • WSO-UV搭載用紫外線分光器とコロナグラフ装置の開発

      宇宙航空研究開発機構  JAXA国際共同ミッション推進研究 

      亀田真吾

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      2017年10月 - 2018年3月

      担当区分:研究代表者  資金種別:競争的資金

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    • MMX搭載望遠/広角分光カメラの機器性能試験手法および設備の開発

      宇宙航空研究開発機構  受託研究(一般受託研究) 

      亀田真吾

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      2017年4月 - 2018年3月

      担当区分:研究代表者  資金種別:競争的資金

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    • 光検出器を用いた年代計測装置の開発

      宇宙航空研究開発機構  JAXA搭載機器基礎開発実験費 

      亀田真吾

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      2015年4月 - 2016年3月

      担当区分:研究代表者  資金種別:競争的資金

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    • 超小型深宇宙機搭載観測機器の開発

      宇宙航空研究開発機構  共同研究(国内共同研究) 

      亀田真吾

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      2013年10月 - 2015年3月

      担当区分:研究代表者  資金種別:競争的資金

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    • 真空紫外分光によるK-Ar年代測定

      宇宙航空研究開発機構  JAXA搭載機器基礎開発実験費 

      亀田真吾

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      2012年4月 - 2013年4月

      担当区分:研究代表者  資金種別:競争的資金

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    • 水星大気光観測による磁気圏と固体表面の相互作用に関する研究

      科学研究費補助金 

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      2011年4月 - 2013年3月

      資金種別:競争的資金

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    • 惑星大気光観測用ファブリペロー干渉計の開発

      宇宙航空研究開発機構  JAXA搭載機器基礎開発実験費 

      亀田真吾

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      2010年4月 - 2011年3月

      担当区分:研究代表者  資金種別:競争的資金

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    • 月惑星大気光の超高分散分光観測に向けたファブリペロー干渉計用高精度平面鏡の開発

      科学研究費補助金 

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      2008年4月 - 2010年3月

      資金種別:競争的資金

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    ▼全件表示

    産業財産権

    • インターライン型CCDイメージセンサ及びこれを用いて移動体を撮像する方法

      亀田真吾

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      出願番号:特願2020-181074  出願日:2020年10月29日

      公開番号:特開2022-71936  公開日:2022年5月17日

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    • 光学機器に使用するための鏡をプレートに接着させる方法

      亀田真吾, 佐藤允基, 池澤祥太

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      出願番号:2015-028424  出願日:2015年2月17日

      公開番号:2016-150967  公開日:2016年8月22日

      特許番号/登録番号:6562341  発行日:2019年8月2日

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    • K-Ar年代測定装置及び方法

      亀田真吾

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      出願番号:特願2012-126314  出願日:2012年6月1日

      特許番号/登録番号:特許5930460  登録日:2016年5月13日 

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