Study of lunar internal structure by combining geophysical observation and thermochemical constraints

• Project/Area Number: 17K05643
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Solid earth and planetary physics
• Research Institution: National Astronomical Observatory of Japan
• Principal Investigator: Matsumoto Koji 国立天文台, RISE月惑星探査プロジェクト, 准教授 (30332167)
• Project Period (FY): 2017-04-01 – 2021-03-31
• Project Status: Completed (Fiscal Year 2020)
• Budget Amount: ¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000); Fiscal Year 2019: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000); Fiscal Year 2018: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000); Fiscal Year 2017: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
• Keywords: 月内部構造 / 月マントル組成 / 潮汐加熱 / マントル組成

Outline of Final Research Achievements

We developed a formulation to calculate density and elastic modulus of the lunar mantle from composition and temperature as parameters. Based on Markov Chain Monte Carlo method we constructed lunar internal structure models that are consistent with both the latest geodetic observation data and Apollo seismic travel time data. The results suggest the existence of at least a two-layered chemical composition of the lunar mantle. If low-velocity and low-viscosity layer is composed of Ti-rich basalt, a mechanism is required to keep this layer hotter than the overlying mantle layer for which candidate is tidal heating.

Academic Significance and Societal Importance of the Research Achievements

内部構造は、月や惑星の起源・進化を考える上で非常に重要な情報であるが、身近な天体である月でさえ観測が限られており、内部構造の不確定性はまだ大きい。本研究では、月についてアポロ時代の月震データと最新の測地データに熱化学的制約を加えることにより、マントル部分の組成を含む月内部構造モデルを構築した。温度の仮定は残るものの、マントルの化学的な成層構造や月深部の潮汐加熱を示唆する結果が得られた。この手法は将来新たな観測データ得られた際の内部構造解析にも適用できると考えられる。

Research Products

• [Int'l Joint Research] ベルナツキー地球化学・分析化学研究所 (GEOKHI RAS)(ロシア連邦)
• [Int'l Joint Research] 澳門科技大学太空科学研究所(中国)
• [Int'l Joint Research] ベルナツキー地球化学・分析化 学研究所（GEOKHI RAS）(ロシア連邦)
• [Int'l Joint Research] 澳門科技大学太空科学研究所(中国)
• [Int'l Joint Research] ベルナツキー地球化学・分析化 学研究所（GEOKHI RAS）(ロシア連邦)
• [Int'l Joint Research] 澳門科技大学太空科学研究所(中国)
• [Int'l Joint Research] ベルナツキー地球化学・分析化学研究所（GEOKHI RAS）(ロシア連邦)
• [Int'l Joint Research] 澳門科技大学太空科学研究所(マカオ)
• [Journal Article] Joint inversion of geophysical (seismic and selenodetic) and geochemical data for internal structure and composition of the Moon (2018)
  • Author(s): E. Kronrod, K. Matsumoto, O. Kuskov, V. Kronrod, R. Yamada, and S. Kamata
  • Journal Title: IOP Conf. Series: Materials Science and Engineering Volume: 468 Pages: 012015-012015
  • DOI: 10.1088/1757-899x/468/1/012015
  • Open Access / Int'l Joint Research
• [Presentation] Adjustment of geophysical and geochemical models of the Moon (2018)
  • Author(s): E. Kronrod, K. Matsumoto, O. Kuskov, V. Kronrod, R. Yamada, and S. Kamata
  • Organizer: The 49th Lunar and Planetary Science Conference
  • Int'l Joint Research