Space environment of an asteroid preserved on micrograins returned by the Hayabusa spacecraft
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- Eizo Nakamura
- The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Study of the Earth’s Interior, Okayama University, Misasa, Tottori 682-0193, Japan; and
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- Akio Makishima
- The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Study of the Earth’s Interior, Okayama University, Misasa, Tottori 682-0193, Japan; and
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- Takuya Moriguti
- The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Study of the Earth’s Interior, Okayama University, Misasa, Tottori 682-0193, Japan; and
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- Katsura Kobayashi
- The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Study of the Earth’s Interior, Okayama University, Misasa, Tottori 682-0193, Japan; and
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- Ryoji Tanaka
- The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Study of the Earth’s Interior, Okayama University, Misasa, Tottori 682-0193, Japan; and
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- Tak Kunihiro
- The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Study of the Earth’s Interior, Okayama University, Misasa, Tottori 682-0193, Japan; and
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- Tatsuki Tsujimori
- The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Study of the Earth’s Interior, Okayama University, Misasa, Tottori 682-0193, Japan; and
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- Chie Sakaguchi
- The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Study of the Earth’s Interior, Okayama University, Misasa, Tottori 682-0193, Japan; and
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- Hiroshi Kitagawa
- The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Study of the Earth’s Interior, Okayama University, Misasa, Tottori 682-0193, Japan; and
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- Tsutomu Ota
- The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Study of the Earth’s Interior, Okayama University, Misasa, Tottori 682-0193, Japan; and
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- Yusuke Yachi
- The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Study of the Earth’s Interior, Okayama University, Misasa, Tottori 682-0193, Japan; and
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- Toru Yada
- Japan Aerospace Exploration Agency, Yoshinodai 3-1-1, Chuo, Sagamihara, Kanagawa 252-5210, Japan
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- Masanao Abe
- Japan Aerospace Exploration Agency, Yoshinodai 3-1-1, Chuo, Sagamihara, Kanagawa 252-5210, Japan
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- Akio Fujimura
- Japan Aerospace Exploration Agency, Yoshinodai 3-1-1, Chuo, Sagamihara, Kanagawa 252-5210, Japan
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- Munetaka Ueno
- Japan Aerospace Exploration Agency, Yoshinodai 3-1-1, Chuo, Sagamihara, Kanagawa 252-5210, Japan
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- Toshifumi Mukai
- Japan Aerospace Exploration Agency, Yoshinodai 3-1-1, Chuo, Sagamihara, Kanagawa 252-5210, Japan
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- Makoto Yoshikawa
- Japan Aerospace Exploration Agency, Yoshinodai 3-1-1, Chuo, Sagamihara, Kanagawa 252-5210, Japan
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- Jun’ichiro Kawaguchi
- Japan Aerospace Exploration Agency, Yoshinodai 3-1-1, Chuo, Sagamihara, Kanagawa 252-5210, Japan
書誌事項
- 公開日
- 2012-02-27
- DOI
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- 10.1073/pnas.1116236109
- 公開者
- Proceedings of the National Academy of Sciences
この論文をさがす
説明
<jats:p> Records of micrometeorite collisions at down to submicron scales were discovered on dust grains recovered from near-Earth asteroid 25143 (Itokawa). Because the grains were sampled from very near the surface of the asteroid, by the Hayabusa spacecraft, their surfaces reflect the low-gravity space environment influencing the physical nature of the asteroid exterior. The space environment was examined by description of grain surfaces and asteroidal scenes were reconstructed. Chemical and O isotope compositions of five lithic grains, with diameters near 50 μm, indicate that the uppermost layer of the rubble-pile-textured Itokawa is largely composed of equilibrated LL-ordinary-chondrite-like material with superimposed effects of collisions. The surfaces of the grains are dominated by fractures, and the fracture planes contain not only sub-μm-sized craters but also a large number of sub-μm- to several-μm-sized adhered particles, some of the latter composed of glass. The size distribution and chemical compositions of the adhered particles, together with the occurrences of the sub-μm-sized craters, suggest formation by hypervelocity collisions of micrometeorites at down to nm scales, a process expected in the physically hostile environment at an asteroid’s surface. We describe impact-related phenomena, ranging in scale from 10 <jats:sup>-9</jats:sup> to 10 <jats:sup>4</jats:sup> meters, demonstrating the central role played by impact processes in the long-term evolution of planetary bodies. Impact appears to be an important process shaping the exteriors of not only large planetary bodies, such as the moon, but also low-gravity bodies such as asteroids. </jats:p>
収録刊行物
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- Proceedings of the National Academy of Sciences
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Proceedings of the National Academy of Sciences 109 (11), E624-, 2012-02-27
Proceedings of the National Academy of Sciences
