2005 Fiscal Year Final Research Report Summary
A study of three-dimensional structures of interplanetary dust by imaging x-ray microtomography.
| Project/Area Number |
15340186
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Petrology/Mineralogy/Science of ore deposit
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| Research Institution | Osaka University |
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Principal Investigator |
TSUCHIYAMA Akira Osaka University, Graduate School of Science, Professor, 大学院・理学研究科, 教授 (90180017)
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| Co-Investigator(Kenkyū-buntansha) |
TAKEUCHI Akihisa JASRI/Spring-8, Researcher, 利用研究促進部門II, 研究員
UESUGI Kentaro JASRI/Spring-8, Researcher, 利用研究促進部門II, 研究員 (80344399)
NOGUCHI Takaaki Ibaragi University, Faculty of Science, Associate Professor, 理学部, 助教授 (40222195)
NAKAMURA Tomoki Kyushu University, Graduate School of Science, Associate Professor, 大学院・理学研究院, 助教授 (20260721)
NAKANO Tsukasa AIST, Geological Survey of Japan, Principal Researcher, 地球科学情報研究部門, 主任研究員 (90212092)
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| Project Period (FY) |
2003 – 2005
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| Keywords | interplanetary dust particles / micrometeorites / Stardust / cometary dust / SPring-8 / microtomography / subtraction method / fractal dimension |
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| Research Abstract |
Three-dimensional structures of cosmic dust (interplanetary dust particles and unmelted micrometeorites) and cometary dust that was collected by NASA Stardust mission were examined using x-ray microtomography at SPring-8. Three-dimensional structures with ultra-high spatial resolution of less than 100 nm has been obtained at the end of the term of this project by imaging tomography using attenuation contrast by overcoming troubles in an optical system for enlargement of x-ray beams and a sample rotation stage. We have also examined some samples by projection CT with the spatial resolution of about 0.5 μm. Physical properties of the samples, such as porosities and densities, were obtained from the three -dimensional structures of the cosmic dust samples. Furthermore, fractal dimensions of the samples were successfully obtained. The fractal dimensions of cosmic dust which was considered to be derived from comets are significantly less than 3. This may suggest evidence of aggregation of c
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onstituent particles of the dust in the early stage of the solar system. The Stardust sample analysis, which was performed as one of the members of preliminary examination team of Stardust, revealed the three-dimensional structures of impact tracks in aerogel collectors and terminal particles in the tracks. These results gave information about the impact processes as well as basic textural information for further detailed destructive analyses. Experimental studies of infrared spectrum of cosmic dust minerals in connection with infrared astronomical observation have been also made for comprehensive research on cosmic dust. Furthermore, development of the tomography system at SPring-8 and evaluation of its performance have been done. Brightness of CT images was quantitatively formulated. By using this formulation, we have established a technique for three-dimensional element mapping of Fe and Cs using the subtraction method. The results were applied to meteorites and other terrestrial samples as well as cosmic dust samples. Less
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