| Project/Area Number |
12640413
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
固体地球物理学
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| Research Institution | The Institute of Space and Astronautical Science |
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Principal Investigator |
MIZUTANI Hitoshi The Institute of Space and Astronautical Science, Professor, 惑星研究系, 教授 (00011578)
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| Co-Investigator(Kenkyū-buntansha) |
HAYAKAWA Masahiko The Institute of Space and Astronautical Science, Assistant, 惑星研究系, 助手 (40228557)
TANAKA Satoshi The Institute of Space and Astronautical Science, Associate Professor, 惑星研究系, 助教授 (30249932)
FUJIMURA Akio The Institute of Space and Astronautical Science, Professor, 惑星研究系, 教授 (70173458)
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| Project Period (FY) |
2000 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2002: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2001: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2000: ¥2,800,000 (Direct Cost: ¥2,800,000)
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| Keywords | moon / heat flow / Prospector / Clementine / lunar crust / gravity / lunar toppography / finite element method |
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| Research Abstract |
Since lunar heat flow provides us with a unique means to estimate the bulk abundance of refractory elements in the moon, it is very important to re-assess the heat flow data obtained in the Apollo 15 and 17 missions, in terms of new global data obtained by recent lunar missions. In this paper, we analyze the Apollo heat flow data combining the topography, gravity field, and Thorium abundance data by Prospector mission and Clementine mission.
First we investigated the effect of topography variation and mega-regolith thickness variation on the measured heat flow, using a finite element method. This effect is believed to be very significant on Apollo heat flow values, because the measurements at the both Apollo 15 and 17 sites are made near the boundary of lunar mare and highland where the topography and mega-regolith thickness changes drastically. The result of the numerical experiments show that the observed heat flow values at Apollo 15 and 17 sites are 10 to 20 % larger than the representative values of those sites.
We construct two crustal-structure models by analyzing the topography and gravity field data one model (thick crust model) has a mean crustal thickness of 61 kin, and the other model (thin crust model) has a mean crustal thickness of 48 km. Combing these crustal models with Prospector's Thorium abundance map, we calculated the surface heat flow expected from the crustal models. Comparison of the theoretical heat flow values with the reevaluated Apollo heat flow values indicates that the bulk U abundance in the Moon is 20 to 30 ppb which is more or less similar to that of the upper mantle of the Earth. This suggests that refractory elements in the Moon are not so much enriched as those proposed by previous many workers on chemistry of returned lunar samples. The conclusion has significant influence of our view of the lunar origin.
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