冥王代の天体重爆撃による生命誕生場への電気化学的擾乱

• Project Area: Hadean Bioscience
• Project/Area Number: 15H01067
• Research Category: Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)
• Allocation Type: Single-year Grants
• Review Section: Science and Engineering
• Research Institution: Chiba Institute of Technology
• Principal Investigator: 黒澤 耕介 千葉工業大学, 惑星探査研究センター, 研究員 (80616433)
• Project Period (FY): 2015-04-01 – 2017-03-31
• Project Status: Completed (Fiscal Year 2016)
• Budget Amount: ¥7,540,000 (Direct Cost: ¥5,800,000、Indirect Cost: ¥1,740,000); Fiscal Year 2016: ¥3,510,000 (Direct Cost: ¥2,700,000、Indirect Cost: ¥810,000); Fiscal Year 2015: ¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000)
• Keywords: 生命誕生場 / 天体重爆撃 / 地球 / 金星 / 火星 / 高速度天体衝突 / 電気化学勾配 / 数値衝突計算 / 天体衝突 / 冥王代地球 / 表層初期進化 / 冥王代 / 酸化還元電位勾配 / 高強度レーザー / 珪酸塩鉱物 / 衝撃圧縮 / モンテカルロ法

Outline of Annual Research Achievements

本研究は原始地球における生命誕生時期が天体衝突が頻発していた「天体重爆撃期」に重なっていることに着目した. 研究目的は天体衝突が生命誕生場に与える擾乱を定量的に明らかにすることである. 単発の天体衝突で引き起こされる物理化学過程を検討し, 初期数億年間に地球質量のおよそ1%におよぶ天体群が金星・地球・火星に衝突した場合に何が起こるか？を明らかにするために研究を遂行した. 得られた主要な成果を以下に述べる. (1)数値衝突計算コードであるiSALE shock physics codeを計算出力を後処理し, 衝突後の衝突天体が辿る熱力学経路を計算する後解析コードを作成した. マルチコア計算機を導入し, 数値衝突計算と後述の100万回に及ぶ天体衝突を扱う確率論的重爆撃モデル計算を幅広いパラメータ空間を効率よく埋めるための計算環境を構築した. (2)天体衝突時に衝突天体が蒸発することで発生する気相化学種を衝突速度の関数として明らかにした. 特に酸素分子の生成効率が衝突速度に強く依存していることから, 天体衝突による非生物的酸素生成が生命誕生場への新たな自由エネルギー源となり得ることを提唱した. また原始地球や火星に過渡的に酸素を含んだ大気が発生した場合に特殊な地質試料が残される可能性があることから仮説の実証に向けた新たな研究を開始した. (3)天体重爆撃期に頻発した天体衝突の重畳された情報を紐解くため, モンテカルロ法を用いた確率論的重爆撃モデルを構築した. (4)確率論的重爆撃モデルを用いて原始金星の表層変動を解いた. 天体衝突によって発生する大量の細粒岩石と高温の初期金星大気の間の化学反応を検討し, 天体重爆撃が初期金星を極度に乾燥した状態に導いたとする新説を提唱した. 本モデルは火星の大気進化を扱う計算にも流用され, 初期火星の大気全圧下限を制約するという成果を挙げている.

Research Progress Status

28年度が最終年度であるため、記入しない。

Strategy for Future Research Activity

28年度が最終年度であるため、記入しない。

Research Products

• [Journal Article] 天体衝突による物質放出過程 (2017)
  • Author(s): 黒澤耕介
  • Journal Title: 天文月報 Volume: 110 Pages: 105-110
  • Acknowledgement Compliant
• [Journal Article] Shock vaporization/devolatilization: Toward understanding the evolution of the surface environments on planetary bodies in the Solar system using an experimental approach (2016)
  • Author(s): 黒澤耕介
  • Journal Title: Planetary People - The Japanese Society for Planetary Sciences Volume: 25 Issue: 4 Pages: 136-148
  • DOI: 10.14909/yuseijin.25.4_136
  • NAID: 130005313140
  • ISSN: 0918-273X, 2423-897X
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Impact-induced chemical reactions: Toward understanding the surface environment on the Hadean Earth by using an experimental approach (2016)
  • Author(s): 黒澤耕介
  • Journal Title: Chikyukagaku Volume: 50 Issue: 3 Pages: 135-154
  • DOI: 10.14934/chikyukagaku.50.135
  • NAID: 130005267110
  • ISSN: 0386-4073, 2188-5923
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Recovery of shocked samples from ~100 GPa to Hugoniot elastic limit (2016)
  • Author(s): Nagaki, K., T. Kadono, T. Sakaiya, T. Kondo, K. Kurosawa, Y. Hironaka, K. Shigemori, and M. Arakawa
  • Journal Title: Meteoritics and Planetary Science Volume: 印刷中 Issue: 6 Pages: 1153-1162
  • DOI: 10.1111/maps.12654
  • Peer Reviewed
• [Journal Article] Impact-induced chemical reactions: Toward understanding the surface environment on the Hadean Earth by using an experimental approach (In Japanese) (2016)
  • Author(s): 黒澤耕介
  • Journal Title: 地球化学 Volume: 印刷中
  • Peer Reviewed
• [Journal Article] Impact-driven planetary desiccation: The origin of the dry Venus (2015)
  • Author(s): Kurosawa, K.
  • Journal Title: Earth and Planetary Science Letters Volume: 429 Pages: 181-190
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Planetary and meteoritic Mg/Si and d30Si variations inherited from nebula chemistry (2015)
  • Author(s): Dauphas, N., F. Poitrasson, C. Burkhardt, H. Kobayashi, and K. Kurosawa
  • Journal Title: Earth and Planetary Science Letters Volume: 427 Pages: 236-248
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Dynamics of hypervelocity jetting during oblique impacts of spherical projectiles investigated via ultrafast imaging (2015)
  • Author(s): Kurosawa, K., Nagaoka, Y., Senshu, H., Wada, K., Hasegawa, S., Sugita, S., and Matsui, T.
  • Journal Title: J. Geophys. Res. Volume: 120 Issue: 7 Pages: 1-15
  • DOI: 10.1002/2014je004730
  • Peer Reviewed
• [Journal Article] Ultra-high-speed photography and optical flash measurement of nylon sphere impact phenomena (2015)
  • Author(s): Yanagisawa, M., K. Kurosawa, and S. Hasegawa
  • Journal Title: Procedia Engineering Volume: 103 Pages: 657-662
  • Peer Reviewed
• [Journal Article] Possibility of Production of amino acids by impact reaction using a light gas gun as a simulation of asteroid impacts (2015)
  • Author(s): Okochi, K., T. Mieno, K. Kondo, S. Hasegawa, and K. Kurosawa
  • Journal Title: Origins of Life and Evolution of Biospheres Volume: ORIGINS14 Issue: 1-2 Pages: 1-11
  • DOI: 10.1007/s11084-015-9419-4
  • Peer Reviewed / Open Access
• [Presentation] Hydrocode modeling of the material ejection by spallation (2017)
  • Author(s): Kurosawa, K., T. Okamoto, and H. Genda
  • Organizer: 48th Lunar and Planetary Science Conference
  • Place of Presentation: The Woodlands, TX, USA
  • Year and Date: 2017-03-20
  • Int'l Joint Research
• [Presentation] Generation of reduced carbon compounds by “low” velocity impacts (2017)
  • Author(s): Ishibashi, K., K. Kurosawa, T. Okamoto, and T. Matsui
  • Organizer: 48th Lunar and Planetary Science Conference
  • Place of Presentation: The Woodlands, TX, USA
  • Year and Date: 2017-03-20
  • Int'l Joint Research
• [Presentation] Dust sensor with a large detection area using polyimide film for martian moons exploration (2017)
  • Author(s): Kobayashi, M., O. Okudaira, K. Kurosawa, T. Okamoto, H. Senshu, K. Wada, S. Sasaki, H. Kimura, and M. Nakamura
  • Organizer: 48th Lunar and Planetary Science Conference
  • Place of Presentation: The Woodlands, TX, USA
  • Year and Date: 2017-03-20
  • Int'l Joint Research
• [Presentation] The Hellas basin on Mars: Further exploration of its anomalous shape (2017)
  • Author(s): Komatsu, G., T. Ruj, H. Miyamoto, J. M. Dohm, J. Ormo, and K. Kurosawa
  • Organizer: 48th Lunar and Planetary Science Conference
  • Place of Presentation: The Woodlands, TX, USA
  • Year and Date: 2017-03-20
  • Int'l Joint Research
• [Presentation] Detection of lunar lava tubes by lunar radar sounder onboard SELENE(Kaguya) (2017)
  • Author(s): Haruyama, J., T. Kaku, R. Shinoda, W. Miyake, A. Kumamoto, K. Ishiyama, T. Nishibori, K. Yamamoto, K. Kurosawa, A. I. Suzuki, S. T. Crites, T. Michikami, Y. Yokota, R. Sood, H. J. Melosh, L. Chappaz, and K. C. Howell
  • Organizer: 48th Lunar and Planetary Science Conference
  • Place of Presentation: The Woodlands, TX, USA
  • Year and Date: 2017-03-20
  • Int'l Joint Research
• [Presentation] Tracing the origin and evolution of volatiles on Mars: Constraints from elemental and isotopic compositions of nitrogen and noble gases (2017)
  • Author(s): Kurokawa, H., K. Kurosawa, and T. Usui
  • Organizer: 48th Lunar and Planetary Science Conference
  • Place of Presentation: The Woodlands, TX, USA
  • Year and Date: 2017-03-20
  • Int'l Joint Research
• [Presentation] Impact-driven water removal on steam-covered Venus-like planets (2016)
  • Author(s): Kurosawa, K.
  • Organizer: 47th Lunar and Planetary Science Conference
  • Place of Presentation: The Woodlands, Texas, USA
  • Year and Date: 2016-03-21
  • Int'l Joint Research
• [Presentation] Shock vaporization of water ice in an open system investigated using a two-stage light-gas gun (2016)
  • Author(s): Kurosawa, K., T. Okamoto, H. Yabuta, G. Komatsu, and T. Matsui
  • Organizer: 47th Lunar and Planetary Science Conference
  • Place of Presentation: The Woodlands, Texas, USA
  • Year and Date: 2016-03-21
  • Int'l Joint Research
• [Presentation] Laboratory simulation of shooting stars by using a two-stage light-gas gun (2016)
  • Author(s): H. Senshu, K. Kurosawa, Okamoto, T., and T. Matsui
  • Organizer: 47th Lunar and Planetary Science Conference
  • Place of Presentation: The Woodlands, Texas, USA
  • Year and Date: 2016-03-21
  • Int'l Joint Research
• [Presentation] Ultra-high-speed imaging of the impact ejecta: Comparison with a SPH simulations (2016)
  • Author(s): Okamoto, T., K. Kurosawa, H. Genda, and T. Matsui
  • Organizer: 47th Lunar and Planetary Science Conference
  • Place of Presentation: The Woodlands, Texas, USA
  • Year and Date: 2016-03-21
  • Int'l Joint Research
• [Presentation] A lower limit of atmospheric pressure on early Mars inferred from nitrogen and argon isotopes (2016)
  • Author(s): Kurokawa, H., K. Kurosawa, and T. Usui
  • Organizer: 47th Lunar and Planetary Science Conference
  • Place of Presentation: The Woodlands, Texas, USA
  • Year and Date: 2016-03-21
  • Int'l Joint Research
• [Presentation] An atmospheric response against from impact bombardments on Earth and Venus: The role of impact ejecta (2016)
  • Author(s): Kurosawa, K.
  • Organizer: The 4th ELSI International Symposium
  • Place of Presentation: 東京工業大学地球生命研究所(東京都目黒区)
  • Year and Date: 2016-01-12
  • Int'l Joint Research / Invited