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Kamata Shunichi

Faculty of Science　Earth and Planetary Sciences　CosmosciencesAssociate Professor

Researcher basic information

■ Degree
  • 博士（理学）, 東京大学
■ URL
researchmap URLホームページURL■ Various IDs
J-Global ID■ Research Keywords and Fields
Research Field
  • Natural Science, Space and planetary sciences
■ Educational Organization

Research activity information

■ Papers
  • Overview of Hayabusa2 Extended Mission’s Flyby of Near-Earth Asteroid (98943) Torifune
    Masatoshi Hirabayashi; Masahiko Hayakawa; Yuya Mimasu; Naru Hirata; Takuya Iwaki; Shunichi Kamata; Kohei Kitazato; Toru Kouyama; Naoya Sakatani; Hajime Yano; Koki Yumoto; Masahiro Fujiwara; Sumito Shimomura; Takanao Saiki; Hiroshi Takeuchi; Eri Tatsumi; Yuichi Tsuda; Yasuhiro Yokota; Makoto Yoshikawa; Satoshi Tanaka
    The Planetary Science Journal, 7, 5, 121, 121, American Astronomical Society, 01 May 2026
    Scientific journal, Abstract

    The Hayabusa2 extended mission, nicknamed Hayabusa2# ( # is pronounced SHARP, which stands for the Small Hazardous Asteroid Reconnaissance Probe), is JAXA’s small body explorer to conduct science and engineering investigations in space. After the successful return to the Earth with the samples from the carbonaceous asteroid (162173) Ryugu on 2020 December 6, Hayabusa2 diverted away from Earth to start its decade-long extended mission. The major scope includes an engineering demonstration of long-term maintenance strategies for spacecraft and operation systems and scientific investigations during various mission phases. Major scientific investigations include spacecraft-based telescopic observations of exoplanets and zodiacal dust observations during the cruise phase, flyby observations of the near-Earth asteroid (98943) Torifune in 2026 July, and rendezvous observations of near-Earth asteroid 1998 KY26 in 2031. This study overviews Hayabusa2#’s flyby and the physical properties of Torifune. Although the flyby operation planning is still ongoing, the mission will attempt to fly by the target at a distance (from the asteroid’s center) of 1–10 km. The flyby speed is planned to be 5.25 km s −1 , while the encounter location is 0.81 au from the Sun. The mission plans to fix the spacecraft’s orientation during the flyby, only allowing for a very limited pointing change to attain higher-resolution imaging. The mission will attempt to obtain science and engineering returns during the flyby. The planned investigations will offer stronger insights into material transport mechanisms in the inner solar system and a demonstration of planetary defense technologies.
  • Hayabusa2#’s (98943) Torifune flyby in July 2026: Rapid asteroid characterization using an already-flying spacecraft for planetary defense
    Masatoshi Hirabayashi; Makoto Yoshikawa; Masahiko Hayakawa; Yuya Mimasu; Naru Hirata; Takuya Iwaki; Shunichi Kamata; Masanori Kanamaru; Kohei Kitazato; Toru Kouyama; Naoya Sakatani; Sumito Shimomura; Hiroshi Takeuchi; Satoshi Tanaka; Eri Tatsumi; Yasuhiro Yokota; Koki Yumoto
    09 Jul. 2025
  • Low Rock Mass Fraction Within Trans‐Neptunian Objects Inferred From the Spin–Orbit Evolution of Orcus–Vanth and Salacia–Actaea
    S. Arakawa; S. Kamata; H. Genda
    Journal of Geophysical Research: Planets, 130, 4, American Geophysical Union (AGU), 22 Apr. 2025
    Scientific journal, Abstract

    Satellites play a crucial role in understanding the formation and evolution of trans‐Neptunian objects (TNOs). The spin–orbit evolution of satellite systems depends on their thermal histories, allowing us to constrain the rock mass fraction within TNOs based on their current spin–orbit states. In this study, we perform coupled thermal–orbital evolution calculations for two satellite systems around undifferentiated TNOs: Orcus–Vanth and Salacia–Actaea. Our results demonstrate that the current spin–orbit states of these systems are consistent with a rock mass fraction of approximately 20%–30%. Additionally, we estimate the organic mass fraction within the TNOs and find that it is comparable to the rock mass fraction. These findings suggest that the chemical composition of TNOs closely resembles that of comets.
  • Poroviscoelastic Gravitational Dynamics
    S. Kamata
    Journal of Geophysical Research: Planets, 128, 7, American Geophysical Union (AGU), 24 Jul. 2023
    Scientific journal, Abstract

    Global‐scale periodic deformation has been studied using the (visco)elastic gravitational theory, which assumes a planetary body consists of solid or liquid layers. Recent planetary exploration missions, however, suggest that a global layer of a mixture of solid and liquid exists in several planetary bodies. This study provides a theory of periodic deformation of such a layer unifying the viscoelastic gravitational theory with the theory of poroelasticity without introducing additional constraints. The governing equation system and a formulation suitable for numerical calculation are given. Equations used to calculate the energy dissipation rate are also given. The analytical solutions for a homogeneous sphere are obtained using an eigenvalue approach. Simple numerical calculations assuming a homogeneous sphere reveal that a numerical instability occurs if a thick porous layer, a low permeability, or a high frequency is assumed. This instability can be avoided by choosing an appropriate interior structure model that is numerically equivalent. Different simple numerical calculations adopting a multilayered, radially varying interior profile reveal that the radial profile of the tidal heating rate for a fluid‐saturated porous layer and that for a low‐viscosity solid layer are completely different. In addition, the radial variation in porosity can lead to a factor of ∼100 increase in the local heating rate. These results indicate that future studies should consider a wider variety of detailed interior structure models.
  • Title: Demonstration of deep-space synchronous two-way laser ranging with a laser transponder aboard Hayabusa2
    Hirotomo Noda; Hiroki Senshu; Toshimichi Otsubo; Hiroshi Takeuchi; Clément Courde; Hiroo Kunimori; Christopher Moore; Ulrich Schreiber; Naoko Ogawa; Takanao Saiki; Yuto Takei; Mourad Aimar; Julien Chabé; Johann Eckl; Shun'ichi Kamata; Arika Higuchi; Takayuki Hirai; Grégoire Martinot-Lagarde; Hervé Mariey; Koji Matsumoto; Nicolas Maurice; Jun'ichi Nakazono; Duy-Hà Phung; Julien Scariot; Ryo Suetsugu; Jean-Marie Torre; Alex Pollard; Hervé Viot; Noriyuki Namiki; Takahide Mizuno
    Advances in Space Research, Elsevier BV, Jan. 2023
    Scientific journal
  • The Ganymede Laser Altimeter (GALA) for the Jupiter Icy Moons Explorer (JUICE): Mission, science, and instrumentation of its receiver modules
    Keigo Enya; Masanori Kobayashi; Jun Kimura; Hiroshi Araki; Noriyuki Namiki; Hirotomo Noda; Shingo Kashima; Shoko Oshigami; Ko Ishibashi; T. Yamawaki; Kazuyuki Tohara; Yoshifumi Saito; Masanobu Ozaki; Takahide Mizuno; Shunichi Kamata; Koji Matsumoto; Sho Sasaki; Kiyoshi Kuramoto; Yuki Sato; Takeshi Yokozawa; Tsutomu Numata; Satoko Mizumoto; Hiroyuki Mizuno; Kenta Nagamine; Akihiko Sawamura; Kazuo Tanimoto; Hisato Imai; Hiroyuki Nakagawa; Okiharu Kirino; David Green; Masayuki Fujii; Satoru Iwamura; Naofumi Fujishiro; Yoshiaki Matsumoto; Kay Lingenauber; Reinald Kallenbach; Christian Althaus; Thomas Behnke; Jan Binger; Anna Daurskikh; Henri Eisenmenger; Ulrich Heer; Christian Hüttig; Luisa M. Lara; Alexander Lichopoj; Horst Georg Lötzke; Fabian Lüdicke; Harald Michaelis; Juan Pablo Rodriguez Garcia; Kerstin Rösner; Alexander Stark; Gregor Steinbrügge; Pascal Thabaut; Nicolas Thomas; Simone del Togno; Daniel Wahl; Belinda Wendler; Kai Wickhusen; Konrad Willner; Hauke Hussmann
    Advances in Space Research, 69, 5, 2283, 2304, 01 Mar. 2022
    Scientific journal
  • MMX geodesy investigations: science requirements and observation strategy
    Koji Matsumoto; Naru Hirata; Hitoshi Ikeda; Toru Kouyama; Hiroki Senshu; Keiko Yamamoto; Hirotomo Noda; Hideaki Miyamoto; Akito Araya; Hiroshi Araki; Shunichi Kamata; Nicola Baresi; Noriyuki Namiki
    Earth, Planets and Space, 73, 1, Dec. 2021
    Scientific journal
  • Application of the mixing length theory to assess the generation of melt in internally heated systems
    K Vilella; S Kamata
    Geophysical Journal International, Oxford University Press (OUP), 26 Nov. 2021
    Scientific journal, Summary

    Melting in planetary mantles plays a key role in their thermo-chemical evolution. Assessing the amount and location of melting generally requires the 3D temperature fields of the system, such that 3D numerical simulations are in principle necessary prohibiting us from exploring wide ranges of conditions. To overcome this issue, we propose a new 1D analytical framework estimating at first order the amount and depths of melting for a simplified convective system. To do so, we develop an approach, partly based on an extended version of the mixing length theory, able to estimate the distribution of the hottest temperatures in natural systems. The approach involves several free parameters that are calibrated by fitting 3D numerical simulations. We demonstrate that our algorithm produces melting profiles at steady-state and long-term evolutions in fairly good agreement with 3D numerical simulations. We then apply our framework to a wide variety of planetary sizes and heating rates. We find that an increase in planetary radius R increases the depth of melting for small planets (R < 800 km) but decreases it for larger planets. This is caused by the pressure dependence of the solidus.
  • 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 RESEARCH, 68, 3, 1533, 1555, Aug. 2021
    English, Scientific journal
  • Stability of the subsurface ocean of pluto
    Jun Kimura; Shunichi Kamata
    Planetary and Space Science, 181, 104828, 104828, Elsevier {BV}, Feb. 2020, [Peer-reviewed]
    Scientific journal
  • Pluto’s ocean is capped and insulated by gas hydrates
    Shunichi Kamata; Francis Nimmo; Yasuhito Sekine; Kiyoshi Kuramoto; Naoki Noguchi; Jun Kimura; Atsushi Tani
    Nature Geoscience, 12, 6, 407, 410, 20 Jun. 2019, [Peer-reviewed]
    Scientific journal
  • Global classification of lunar reflectance spectra obtained by Kaguya (SELENE): Implication for hidden basaltic materials
    Hareyama Makoto; Ishihara Yoshiaki; Demura Hirohide; Hirata Naru; Honda Chikatoshi; Kamata Shunichi; Karouji Yuzuru; Kimura Jun; Morota Tomokatsu; Nagaoka Hiroshi; Nakamura Ryousuke; Yamamoto Satoru; Yokota Yasuhiro; Ohtake Makiko
    ICARUS, 321, 407, 425, 15 Mar. 2019, [Peer-reviewed]
    Scientific journal
  • Science objectives of the Ganymede Laser Altimeter (GALA) for the JUICE mission
    Kimura, J; H. Hussmann; S. Kamata; K. Matsumoto; J. Oberst; G. Steinbrügge; A. Stark; K. Gwinner; S. Oshigami; N. Namiki; K. Lingenauber; K. Enya; K. Kuramoto; S. Sasaki
    Trans. JSASS Aerospace Tech. Japan, 17, 17, 234, 243, Japan Society for Aeronautical and Space Sciences, 2019, [Peer-reviewed]
    English, Scientific journal
  • Enceladus: Evidence and Unsolved Questions for an Ice-Covered Habitable World
    Yasuhito Sekine; Takazo Shibuya; Shunichi Kamata
    Astrobiology, 399, 407, Springer Singapore, 2019, [Peer-reviewed]
    In book
  • 固体惑星物理学における諸問題
    鎌田俊一
    日本惑星科学会誌 遊・星・人, 27, 4, 286‐295, Dec. 2018, [Peer-reviewed], [Invited]
    Japanese
  • Lunar impact history constrained by GRAIL-derived basin relaxation measurements
    Jack W. Conrad; Francis Nimmo; Caleb I. Fassett; Shunichi Kamata
    Icarus, 314, 50, 63, Academic Press Inc., 01 Nov. 2018, [Peer-reviewed]
    English, Scientific journal
  • Ocean tidal heating in icy satellites with solid shells
    Isamu Matsuyama; Mikael Beuthe; Hamish C.F.C. Hay; Francis Nimmo; Shunichi Kamata
    Icarus, 312, 208, 230, Academic Press Inc., 15 Sep. 2018, [Peer-reviewed]
    English, Scientific journal
  • One-Dimensional Convective Thermal Evolution Calculation Using a Modified Mixing Length Theory: Application to Saturnian Icy Satellites
    Shunichi Kamata
    Journal of Geophysical Research: Planets, 123, 1, 93, 112, Blackwell Publishing Ltd, 01 Jan. 2018, [Peer-reviewed]
    English, Scientific journal
  • Geophysical Investigations of Habitability in Ice-Covered Ocean Worlds
    Steven D. Vance; Mark P. Panning; Simon Stähler; Fabio Cammarano; Bruce G. Bills; Gabriel Tobie; Shunichi Kamata; Sharon Kedar; Christophe Sotin; William T. Pike; Ralph Lorenz; Hsin-Hua Huang; Jennifer M. Jackson; Bruce Banerdt
    Journal of Geophysical Research: Planets, 123, 1, 180, 205, Blackwell Publishing Ltd, 01 Jan. 2018, [Peer-reviewed]
    English, Scientific journal
  • Spectral decomposition of asteroid Itokawa based on principal component analysis
    Sumire C. Koga; Seiji Sugita; Shunichi Kamata; Masateru Ishiguro; Takahiro Hiroi; Eri Tatsumi; Sho Sasaki
    ICARUS, 299, 386, 395, Jan. 2018, [Peer-reviewed]
    English, Scientific journal
  • Interior thermal state of Enceladus inferred from the viscoelastic state of the ice shell
    Shunichi Kamata; Francis Nimmo
    ICARUS, 284, 387, 393, Mar. 2017, [Peer-reviewed]
    English, Scientific journal
  • The Charon-forming giant impact as a source of Pluto's dark equatorial regions
    Yasuhito Sekine; Hidenori Genda; Shunichi Kamata; Taro Funatsu
    NATURE ASTRONOMY, 1, 2, Feb. 2017, [Peer-reviewed]
    English, Scientific journal
  • Reorientation and faulting of Pluto due to volatile loading within Sputnik Planitia
    James T. Keane; Isamu Matsuyama; Shunichi Kamata; Jordan K. Steckloff
    NATURE, 540, 7631, 90, +, Dec. 2016, [Peer-reviewed]
    English, Scientific journal
  • Tidal deformation of Ganymede: Sensitivity of Love numbers on the interior structure
    Kamata, Shunichi; Kimura, Jun; Matsumoto, Koji; Nimmo, Francis; Kuramoto, Kiyoshi; Namiki, Noriyuki
    Journal of Geophysical Research-Planets, 121, 7, 1362, 1375, 2016, [Peer-reviewed]
    Scientific journal
  • Internal structure of the Moon inferred from Apollo seismic data and selenodetic data from GRAIL and LLR
    Koji Matsumoto; Ryuhei Yamada; Fuyuhiko Kikuchi; Shunichi Kamata; Yoshiaki Ishihara; Takahiro Iwata; Hideo Hanada; Sho Sasaki
    GEOPHYSICAL RESEARCH LETTERS, 42, 18, 7351, 7358, Sep. 2015, [Peer-reviewed]
    English, Scientific journal
  • Tidal resonance in icy satellites with subsurface oceans
    Shunichi Kamata; Isamu Matsuyama; Francis Nimmo
    JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS, 120, 9, 1528, 1542, Sep. 2015, [Peer-reviewed]
    English, Scientific journal
  • High-precision potassium measurements using laser-induced breakdown spectroscopy under high vacuum conditions for in situ K-Ar dating of planetary surfaces
    Yuichiro Cho; Seiji Sugita; Shingo Kameda; Yayoi N. Miura; Ko Ishibashi; Sohsuke Ohno; Shunichi Kamata; Tomoko Arai; Tomokatst Morota; Noriyuki Namiki; Takafumi Matsui
    SPECTROCHIMICA ACTA PART B-ATOMIC SPECTROSCOPY, 106, 28, 35, Apr. 2015, [Peer-reviewed]
    English, Scientific journal
  • The relative timing of Lunar Magma Ocean solidification and the Late Heavy Bombardment inferred from highly degraded impact basin structures
    Shunichi Kamata; Seiji Sugita; Yutaka Abe; Yoshiaki Ishihara; Yuji Harada; Tomokatsu Morota; Noriyuki Namiki; Takahiro Iwata; Hideo Hanada; Hiroshi Araki; Koji Matsumoto; Eiichi Tajika; Kiyoshi Kuramoto; Francis Nimmo
    ICARUS, 250, 492, 503, Apr. 2015, [Peer-reviewed]
    English, Scientific journal
  • Lunar mare volcanism: Lateral heterogeneities in volcanic activity and relationship with crustal structure
    Tomokatsu Morota; Yoshiaki Ishihara; Sho Sasaki; Sander Goossens; Koji Matsumoto; Hirotomo Noda; Hiroshi Araki; Hideo Hanada; Seiichi Tazawa; Fuyuhiko Kikuchi; Toshiaki Ishikawa; Seiitsu Tsuruta; Shunichi Kamata; Hisashi Otake; Junichi Haruyama; Makiko Ohtake
    Geological Society Special Publication, 401, 127, 138, Geological Society of London, 2015, [Peer-reviewed]
    English, Scientific journal
  • Impact basin relaxation as a probe for the thermal history of Pluto
    Shunichi Kamata; Francis Nimmo
    JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS, 119, 10, 2272, 2289, Oct. 2014, [Peer-reviewed]
    English, Scientific journal
  • Interpretations of lunar geodetic data based on viscoelastic deformation theory : Implications for the lunar evolution
    Kamata S
    Planetary People, 22, 4, 200, 206, 日本惑星科学会, Dec. 2013, [Peer-reviewed]
    Japanese, 地質学的時間スケールにおける大規模地形の粘性緩和は,固体惑星の熱進化を反映し,その痕跡は測地データに反映される.本論文では,月周回衛星「かぐや」で得られた測月データと,熱進化を考慮した長期粘弾性変形計算を突き合わせることで,月内部温度構造の変遷を制約した.前ネクタリス期4(PN4)以前に形成した衝突盆地下のマントル隆起はほぼ緩和しており,同時代までマグマオーシャンが未固化であったことが示唆された.その後形成した盆地下にはマントル隆起が見られ,月上層の冷却が大きく進行したことが分かった.また,海全体が傾いていることから大波長変形が示唆された.これは,海形成以後も深部は熱かったことを示唆している.
  • Viscoelastic deformation of lunar impact basins: Implications for heterogeneity in the deep crustal paleo-thermal state and radioactive element concentration
    Kamata Shunichi; Sugita Seiji; Abe Yutaka; Ishihara Yoshiaki; Harada Yuji; Morota Tomokatsu; Namiki Noriyuki; Iwata Takahiro; Hanada Hideo; Araki Hiroshi; Matsumoto Koji; Tajika Eiichi
    JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS, 118, 3, 398, 415, Mar. 2013, [Peer-reviewed]
    Scientific journal
  • Viscoelastic deformation of lunar impact basins: Implications for heterogeneity in the deep crustal paleo-thermal state and radioactive element concentration
    Shunichi Kamata; Seiji Sugita; Yutaka Abe; Yoshiaki Ishihara; Yuji Harada; Tomokatsu Morota; Noriyuki Namiki; Takahiro Iwata; Hideo Hanada; Hiroshi Araki; Koji Matsumoto; Eiichi Tajika
    Journal of Geophysical Research E: Planets, 118, 3, 398, 415, 2013, [Peer-reviewed]
    English, Scientific journal
  • Lunar and planetary chronological missions based on the in-situ geochronology instruments
    CHO Y; MOROTA T; MIURA Y. N; KAMEDA S
    Planetary People, 21, 3, 267, 275, 日本惑星科学会, Sep. 2012, [Peer-reviewed]
    Japanese, 月面クレータ記録とアポロ試料の年代測定結果との対応付けによって,クレータ年代学という絶対年代計測の手段が獲得され,我々は太陽系内側部における天体衝突史や月惑星表面上で生起したさまざまな現象を時間軸の目盛り入りで理解するに至っている.しかし太陽系の年代学には未だ大きな不確定性があり,後期重爆撃期や巨大惑星大移動の有無,火星絶対年代スケールの獲得などが重要問題として残されている.将来の月惑星着陸探査によってこれらを解決し,太陽系進化の描像をより具体的に得ることは今後の重要な科学目標である.我々は,今後10年の惑星探査に不可欠な手段と考えられる「その場年代計測装置」の開発と,それを月探査に応用したミッション提案を行ってきた.本稿では着陸探査による年代計測の科学的重要性,装置開発の進捗状況と現状の問題点,及びミッション提案の概要について説明する.
  • A new spectral calculation scheme for long-term deformation of Maxwellian planetary bodies
    Shunichi Kamata; Seiji Sugita; Yutaka Abe
    JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS, 117, Feb. 2012, [Peer-reviewed]
    English, Scientific journal
  • A ground-based observation of the LCROSS impact events using the Subaru Telescope
    Peng K. Hong; Seiji Sugita; Natsuko Okamura; Yasuhito Sekine; Hiroshi Terada; Naruhisa Takatoh; Yutaka Hayano; Tetsuharu Fuse; Tae-Soo Pyo; Hideyo Kawakita; Diane H. Wooden; Eliot F. Young; Paul G. Lucey; Kosuke Kurosawa; Hidenori Genda; Junichi Haruyama; Reiko Furusho; Toshihiko Kadono; Ryosuke Nakamura; Shunichi Kamata; Taiga Hamura; Tomohiko Sekiguchi; Mitsuru Soma; Hirotomo Noda; Jun-ichi Watanabe
    ICARUS, 214, 1, 21, 29, Jul. 2011, [Peer-reviewed]
    English, Scientific journal
  • Overview of Differential VLBI Observations of Lunar Orbiters in SELENE (Kaguya) for Precise Orbit Determination and Lunar Gravity Field Study
    Hideo Hanada; Takahiro Iwata; Qinghui Liu; Fuyuhiko Kikuchi; Koji Matsumoto; Sander Goossens; Yuji Harada; Kazuyoshi Asari; Toshiaki Ishikawa; Yoshiaki Ishihara; Hirotomo Noda; Seiitsu Tsuruta; Natalia Petrova; Nobuyuki Kawano; Sho Sasaki; Kaori Sato; Noriyuki Namiki; Yusuke Kono; Kenzaburo Iwadate; Osamu Kameya; Katsunori M. Shibata; Yoshiaki Tamura; Shunichi Kamata; Yukihiro Yahagi; Wataru Masui; Koji Tanaka; Hironori Maejima; Xiaoyu Hong; Jinsong Ping; Xian Shi; Qian Huang; Yusufu Aili; Simon Ellingsen; Wolfgang Schlueter
    SPACE SCIENCE REVIEWS, 154, 1-4, 123, 144, Jul. 2010, [Peer-reviewed]
    English
  • Same-beam VLBI observations of SELENE for improving lunar gravity field model
    Q. Liu; F. Kikuchi; K. Matsumoto; S. Goossens; H. Hanada; Y. Harada; X. Shi; Q. Huang; T. Ishikawa; S. Tsuruta; K. Asari; Y. Ishihara; N. Kawano; S. Kamata; T. Iwata; H. Noda; N. Namiki; S. Sasaki; S. Ellingsen; K. Sato; K. Shibata; Y. Tamura; T. Jike; K. Iwadate; O. Kameya; J. Ping; B. Xia; T. An; Q. Fan; X. Hong; W. Yang; H. Zhang; Y. Aili; B. Reid; W. Hankey; J. McCallum; G. Kronschnabl; W. Schlueter
    RADIO SCIENCE, 45, Apr. 2010, [Peer-reviewed]
    English, Scientific journal
  • High-accuracy same-beam VLBI observations using Shanghai and Urumqi telescopes
    Liu QingHui; Shi Xian; Fuyuhiko Kikuchi; Huang Qian; Shun'ichi Kamata; Koji Matsumoto; Hideo Hanada; Hong XiaoYu; Yu AiLi; Ping JingSong; Fan QingYuan; Xia Bo; An Tao; Qian ZhiHan; Yang WenJun; Zhang Hua; Wang Zhen; Wang Na
    SCIENCE IN CHINA SERIES G-PHYSICS MECHANICS & ASTRONOMY, 52, 12, 1858, 1866, Dec. 2009, [Peer-reviewed]
    English, Scientific journal
  • Comparative Study of Compensation Mechanism of Lunar Impact Basins
    NAMIKI Noriyuki; SUGITA Seiji; ISHIHARA Yoshiaki; NODA Hirotomo; SASAKI Sho; IWATA Takahiro; HANADA Hideo; ARAKI Hiroshi; KUROSAWA Kosuke; MATSUMURA Mizuho; YOKOYAMA Masanori; KAMATA Shunichi; KUBO Naohiro; MORI Asako; SATO Mari
    Journal of the Geodetic Society of Japan, 55, 2, 291, 305, The Geodetic Society of Japan, Jul. 2009, [Peer-reviewed]
    Japanese, On the basis of the gravity model of the Moon developed by SELENE (Kaguya), we propose new classification and compensation mechanism of lunar impact basins. Impact basins on lunar far side and limb are classified into Type I and II basins depending on the magnitude of central gravity high in free-air and Bouguer gravity anomalies. Among previously known gravity anomalies, most typical mascons are referred as primary mascon basins. Topographic depression and rim of both Type I and II basins show good correlation between topography and free-air gravity anomaly suggesting elastic support of lunar lithosphere. Central gravity high of Type I basin is inferred to be a result of mantle uplift at the time of basin formation, and is elastically supported, too. On the other hand, free-air anomalies at the center of Type II basins are lower than Bouguer anomalies indicating brittle deformation of the basins. Topographic depression and rim of primary mascon basins on near side of the Moon show little to no free-air gravity anomalies. This indicates a result of elastic relaxation that occurred probably after eruption of mare basalts. Plateau-like signature of gravity anomalies of primary mascon basins implies viscous relaxation at crust-mantle boundary beneath the basins and significant heat (or volatile) transport by basaltic magma.
■ Other Activities and Achievements
■ Syllabus
  • 物質進化学特論１, 2024年, 修士課程, 理学院
  • 宇宙理学特別講義１, 2024年, 修士課程, 理学院
  • 惑星学, 2024年, 学士課程, 理学部
  • 物理学Ⅱ, 2024年, 学士課程, 全学教育
  • 地球惑星科学特別講義, 2024年, 学士課程, 理学部
  • 情報実習, 2024年, 学士課程, 理学部
■ Research Themes
  • 水星バルク組成制約に向けたマントルー金属核間の元素分配に関する研究
    科学研究費助成事業
    01 Apr. 2021 - 31 Mar. 2025
    鎌田 俊一
    本年度は、まず熱力学データベースの取得・整理を行った。本研究で利用する冶金分野のデータは多数の研究グループにより精力的に整備が進められているが、各々が独自に最適化を行っている。そのため、不適切な組み合わせをしてしまうと、計算の精度が著しく低下してしまうという問題があることが発覚した。このような問題を回避するため、本年は今後の本研究の発展性も考慮したうえで、最も適切なデータベースを選定する作業を精力的に行った。選定基準としては元素組成や温度のカバー範囲や推定精度である。
    また、本研究では「活動度」と呼ばれる熱力学量のモデル化が重要な要素となるが、その選定も行った。すでに予備研究でいくつかの先行研究で提案されたモデルについて比較したが、引き続き様々なモデルについて本研究における有用性を検証した。検証項目としては、活動度の推定精度やパラメータの数である。簡略化されすぎていると推定精度が低く本研究に用いることができない一方で、パラメータの数が多すぎると実験データがないために本研究に用いることができない。現時点では、比較的な古典的な「準格子モデル」を採用することにした。
    また、本研究を遂行するためのハードウェア・ソフトウェアの整備を行った。ハードウェアとしては、多数の計算を効率よく計算するためのマルチコアワークステーションを中心に、ソフトウェアとしては熱力学平衡計算ソフトを中心に整備した。前者については、本研究開始以前の計算機と同様に操作ができるような環境整備（ネットワーク接続環境など）を行った。後者については講習会などに参加し、今後の研究に必要な操作を習得した。
    日本学術振興会, 基盤研究(C), 北海道大学, 21K03637
  • Modeling of water and material circulations in the solar system objects
    Grants-in-Aid for Scientific Research
    30 Jun. 2017 - 31 Mar. 2022
    玄田 英典; 高橋 芳幸; 鎌田 俊一; 倉本 圭; 黒川 宏之; 市川 浩樹
    本研究では、太陽系天体における水・物質循環に関する実証可能な物理モデルを構築し、多様な水環境を有する太陽系天体が、いかにして作られたのかを明らかにすることを目的としている。最終年度までには、実験班により定量化された化学過程を、各天体の物理モデルに組み込み、探査・分析データを実証として、太陽系天体の水・物質循環の歴史を紐解くこと目指す。本年度は、前年度までに構築 した小惑星母天体（微惑星）の水循環過程を組み込んだ熱進化計算と、小惑星形成に伴う衝突による衝撃変性・脱水などの計算結果を用いて、「 はやぶさ2」のリモセンデータと相互参照することによって水を含んだ微惑星の進化理論を構築した。火星においては、前年度までに行った地下水循環モデルを用いて古火星表層環境を局所的にモデル計算と、火星探査（リモセン・ローバー）によって得られているデータと比較検討することによって古火星表層環境の復元を行った。氷衛星に関しては、水-氷-岩石間の化学反応過程を考慮した長期熱進化モデルを様々な氷天体に応用し、内部海の成立条件や進化過程について調べた。初期地球に関しては、地球誕生時の岩石と鉄の分化過程、およびマグマオーシャンの固化過程を考慮したモデルを用いて、宇宙空間に接続している大気からマントル、コアまでを統一的な視点から水・揮発性元素の分配過程を調べた。対象とする天体の大きさや組成に応じて、水が関与する化学反応過程・物質循環の空間的・時間的スケールが異なるため、それぞれの物理モデルを用いる必要がある。小惑星母天体に関しては、玄田(代表)が担当し、火星の大気大循環モデルに関しては、倉本(分担)、高橋(分担)、火星の古環境復元に関しては、黒川(分担)が、氷衛星に関しては、鎌田(分担) が、初期地球に関しては玄田(代表)と黒川(分担)が主体となって行った。
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area), Tokyo Institute of Technology, 17H06457
  • 氷衛星の長期進化：氷殻と内部海のカップリング
    科学研究費助成事業
    24 Jul. 2019 - 31 Mar. 2021
    鎌田 俊一; VILELLA KENNY
    本研究では、固体天体の長期進化を解き明かす、1次元ー3次元結合モデルの開発を行った。2年度目は特に1次元モデルと3次元モデルの対比によって、内部の溶融のモデル化手法を検討した。地球などの岩石の天体内部の一部は溶融してマグマが形成され、火山活動などが引き起こされる。一方、氷を主体とする天体では融解によって内部海や内部湖が形成する。このような内部溶融は、天体の熱輸送や物質輸送に大きく影響するため、固体天体進化において重要である。溶融は温度が局所的にソリダスを超える場所で起こるため、本質的に水平不均質を考慮しなくてはならず、3次元数値計算が必須である。しかしそのような計算は非常に計算コストが大きいため、数十億年という長い時間を計算することは非現実的である。したがって、内部溶融はそもそも無視されるか、極めて簡略化されてモデル化されてきた。本研究では、1次元モデルの局所的適用を通して、この課題克服の可能性を探った。まずは第1ステップとして、内部発熱のみの系を考え、3次元計算を再現する1次元計算手法の開発を行った。その際、受入研究者がこれまで発展させてきた混合距離理論モデルを応用した。その結果、対流層の平均温度や最大温度の鉛直分布を1次元計算によって比較的高精度に求めることができ、これらの鉛直分布から溶融量や溶融深さを比較的精度よく求められることができることが分かった。この結果をまとめた論文を執筆した（査読中）。
    日本学術振興会, 特別研究員奨励費, 北海道大学, 19F19023
  • Evolution of icy planetary bodies inferred from large-scale deformation
    Grants-in-Aid for Scientific Research
    01 Apr. 2016 - 31 Mar. 2020
    Kamata Shunichi
    In this study, I investigated the long-term evolution of icy planetary bodies such as icy satellites and icy dwarf planets in terms of large-scale deformation. For the Saturnian icy satellite Enceladus, I investigated long-term viscoelastic deformation of the ice shell and constrained the energy budget of the satellite. For the Jovian icy satellite Ganymede, I quantified the effect of the interior structure on tidal deformation (short-term large-scale deformation) to assess the possibility of interior structure exploration through geodetic observations. For the icy dwarf planet Pluto, I investigated long-term viscoelastic deformation of the ice shell and constrained the thermal and structural evolution of the dwarf planet.
    Japan Society for the Promotion of Science, Grant-in-Aid for Young Scientists (B), Hokkaido University, 16K17787
  • Derivation of a new lunar geologic map for understanding lunar evolution
    Grants-in-Aid for Scientific Research
    01 Apr. 2014 - 31 Mar. 2018
    OHTAKE Makiko; KIMURA Jun; KOBAYASHI Naoki; KAROUGI Yuzuru; HAREYAMA Makoto; HIRATA Naru; ISHIHARA Yoshiaki; NAGAOKA Hiroshi; KAMATA Shunishi
    The current lunar global geological map was generated in 1980’s. It has been used widely and contributed greatly to the lunar science. The goal of this study is to generate new global lunar geological map, which includes new rock types we found from recent lunar exploration data, and to understand the lunar evolution history based on that.
    Firstly, we generated a geological unit map based on the SELENE (Kaguya) Spectral Profiler data by applying mathematical analyses method. Then, we evaluated and gave geologic interpretations to the units and generated the global lunar geologic map. And from the map, we found that total surface area of the old mare hidden under the surface layer (or crustal intrusion of basaltic composition) is significantly (max. 2 times) higher than the previous estimation. This finding is very important to understand volcanic history of the Moon. We submitted a paper discussing our results and it is currently under the revision.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Japan Aerospace EXploration Agency, 26287107
  • 長期粘弾性対流モデルから迫る惑星内部進化の研究
    科学研究費助成事業
    01 Apr. 2013 - 31 Mar. 2015
    鎌田 俊一
    固体惑星の内部熱進化と、表層地形の長期粘弾性変形のカップリングに取り組んだ。研究対象としては、地球の月や冥王星、さらには土星の周りを回る氷衛星など様々な天体を選択した。
    まず、簡略化した熱進化モデルを用いた粘弾性変形問題を月に適用した。月の地形や内部構造について、LROやGRAIL探査機により得られた最新のデータを解析した。その結果、約半数の巨大クレータがほぼ粘性緩和しきっていることが分かった。これを説明する熱進化モデルを、膨大なパラメータ空間から探すということを行った。その結果、地形が緩和しきるのに必要な温度は地殻下端で1300 K以上であり、それは月マグマオーシャンの固化から約50 Myr以内でしかありえそうにないことが分かった。このことは、月の巨大クレータの約半数はマグマオーシャン固化から間もない時期に形成したことを示している。これは内側太陽系における巨大衝突史を解き明かす鍵となる結果であり、国際誌Icarusに報告された。
    また既存の3次元熱対流モデルを用いた地形変形問題を冥王星に適用した。冥王星についてはまだ探査データがないが、New Horizons探査が迫っている。そこで得られるデータから冥王星の内部物質（放射性元素量）が推定できるであろうことを明らかにした。具体的には、巨大クレータの緩和割合やクレータ内部の断層方向（放射状か同心円状か）は表層の冷たく硬い層（弾性リソスフェア）の厚さで支配されており、この厚さは岩石核中のコアで決まることを明らかにした。この結果は国際誌JGR-Planetsに報告された。
    さらに、粘弾性変形プログラムとカップリングしやすい熱対流計算コードの開発も進めた上、氷衛星レアの進化における研究も行った。これらの結果は国際学会LPSCで発表された。
    日本学術振興会, 特別研究員奨励費, 北海道大学, 13J02356