Irradiation history of itokawa regolith material deduced from noble gases in the hayabusa samples

Keisuke Nagao; Ryuji Okazaki; Tomoki Nakamura; Yayoi N. Miura; Takahito Osawa; Ken Ichi Bajo; Shintaro Matsuda; Mitsuru Ebihara; Trevor R. Ireland; Fumio Kitajima; Hiroshi Naraoka; Takaaki Noguchi; Akira Tsuchiyama; Hisayoshi Yurimoto; Michael E. Zolensky; Masayuki Uesugi; Kei Shirai; Masanao Abe; Toru Yada; Yukihiro Ishibashi; Akio Fujimura; Toshifumi Mukai; Munetaka Ueno; Tatsuaki Okada; Makoto Yoshikawa; Junichiro Kawaguchi

doi:10.1126/science.1207785

Irradiation history of itokawa regolith material deduced from noble gases in the hayabusa samples

Keisuke Nagao^*, Ryuji Okazaki, Tomoki Nakamura, Yayoi N. Miura, Takahito Osawa, Ken Ichi Bajo, Shintaro Matsuda, Mitsuru Ebihara, Trevor R. Ireland, Fumio Kitajima, Hiroshi Naraoka, Takaaki Noguchi, Akira Tsuchiyama, Hisayoshi Yurimoto, Michael E. Zolensky, Masayuki Uesugi, Kei Shirai, Masanao Abe, Toru Yada, Yukihiro IshibashiAkio Fujimura, Toshifumi Mukai, Munetaka Ueno, Tatsuaki Okada, Makoto Yoshikawa, Junichiro Kawaguchi

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

120 Citations (Scopus)

Abstract

Noble gas isotopes were measured in three rocky grains from asteroid Itokawa to elucidate a history of irradiation from cosmic rays and solar wind on its surface. Large amounts of solar helium (He), neon (Ne), and argon (Ar) trapped in various depths in the grains were observed, which can be explained by multiple implantations of solar wind particles into the grains, combined with preferential He loss caused by frictional wear of space-weathered rims on the grains. Short residence time of less than 8 million years was implied for the grains by an estimate on cosmic-ray-produced ²¹Ne. Our results suggest that Itokawa is continuously losing its surface materials into space at a rate of tens of centimeters per million years. The lifetime of Itokawa should be much shorter than the age of our solar system.

Original language	English
Pages (from-to)	1128-1131
Number of pages	4
Journal	Science
Volume	333
Issue number	6046
DOIs	https://doi.org/10.1126/science.1207785
Publication status	Published - 2011 Aug 26
Externally published	Yes

ASJC Scopus subject areas

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Nagao, K., Okazaki, R., Nakamura, T., Miura, Y. N., Osawa, T., Bajo, K. I., Matsuda, S., Ebihara, M., Ireland, T. R., Kitajima, F., Naraoka, H., Noguchi, T., Tsuchiyama, A., Yurimoto, H., Zolensky, M. E., Uesugi, M., Shirai, K., Abe, M., Yada, T., ... Kawaguchi, J. (2011). Irradiation history of itokawa regolith material deduced from noble gases in the hayabusa samples. Science, 333(6046), 1128-1131. https://doi.org/10.1126/science.1207785

Nagao, K, Okazaki, R, Nakamura, T, Miura, YN, Osawa, T, Bajo, KI, Matsuda, S, Ebihara, M, Ireland, TR, Kitajima, F, Naraoka, H, Noguchi, T, Tsuchiyama, A, Yurimoto, H, Zolensky, ME, Uesugi, M, Shirai, K, Abe, M, Yada, T, Ishibashi, Y, Fujimura, A, Mukai, T, Ueno, M, Okada, T, Yoshikawa, M & Kawaguchi, J 2011, 'Irradiation history of itokawa regolith material deduced from noble gases in the hayabusa samples', Science, vol. 333, no. 6046, pp. 1128-1131. https://doi.org/10.1126/science.1207785

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title = "Irradiation history of itokawa regolith material deduced from noble gases in the hayabusa samples",

abstract = "Noble gas isotopes were measured in three rocky grains from asteroid Itokawa to elucidate a history of irradiation from cosmic rays and solar wind on its surface. Large amounts of solar helium (He), neon (Ne), and argon (Ar) trapped in various depths in the grains were observed, which can be explained by multiple implantations of solar wind particles into the grains, combined with preferential He loss caused by frictional wear of space-weathered rims on the grains. Short residence time of less than 8 million years was implied for the grains by an estimate on cosmic-ray-produced 21Ne. Our results suggest that Itokawa is continuously losing its surface materials into space at a rate of tens of centimeters per million years. The lifetime of Itokawa should be much shorter than the age of our solar system.",

author = "Keisuke Nagao and Ryuji Okazaki and Tomoki Nakamura and Miura, {Yayoi N.} and Takahito Osawa and Bajo, {Ken Ichi} and Shintaro Matsuda and Mitsuru Ebihara and Ireland, {Trevor R.} and Fumio Kitajima and Hiroshi Naraoka and Takaaki Noguchi and Akira Tsuchiyama and Hisayoshi Yurimoto and Zolensky, {Michael E.} and Masayuki Uesugi and Kei Shirai and Masanao Abe and Toru Yada and Yukihiro Ishibashi and Akio Fujimura and Toshifumi Mukai and Munetaka Ueno and Tatsuaki Okada and Makoto Yoshikawa and Junichiro Kawaguchi",

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AU - Nagao, Keisuke

AU - Okazaki, Ryuji

AU - Nakamura, Tomoki

AU - Miura, Yayoi N.

AU - Osawa, Takahito

AU - Bajo, Ken Ichi

AU - Matsuda, Shintaro

AU - Ebihara, Mitsuru

AU - Ireland, Trevor R.

AU - Kitajima, Fumio

AU - Naraoka, Hiroshi

AU - Noguchi, Takaaki

AU - Tsuchiyama, Akira

AU - Yurimoto, Hisayoshi

AU - Zolensky, Michael E.

AU - Uesugi, Masayuki

AU - Shirai, Kei

AU - Abe, Masanao

AU - Yada, Toru

AU - Ishibashi, Yukihiro

AU - Fujimura, Akio

AU - Mukai, Toshifumi

AU - Ueno, Munetaka

AU - Okada, Tatsuaki

AU - Yoshikawa, Makoto

AU - Kawaguchi, Junichiro

PY - 2011/8/26

Y1 - 2011/8/26

N2 - Noble gas isotopes were measured in three rocky grains from asteroid Itokawa to elucidate a history of irradiation from cosmic rays and solar wind on its surface. Large amounts of solar helium (He), neon (Ne), and argon (Ar) trapped in various depths in the grains were observed, which can be explained by multiple implantations of solar wind particles into the grains, combined with preferential He loss caused by frictional wear of space-weathered rims on the grains. Short residence time of less than 8 million years was implied for the grains by an estimate on cosmic-ray-produced 21Ne. Our results suggest that Itokawa is continuously losing its surface materials into space at a rate of tens of centimeters per million years. The lifetime of Itokawa should be much shorter than the age of our solar system.

AB - Noble gas isotopes were measured in three rocky grains from asteroid Itokawa to elucidate a history of irradiation from cosmic rays and solar wind on its surface. Large amounts of solar helium (He), neon (Ne), and argon (Ar) trapped in various depths in the grains were observed, which can be explained by multiple implantations of solar wind particles into the grains, combined with preferential He loss caused by frictional wear of space-weathered rims on the grains. Short residence time of less than 8 million years was implied for the grains by an estimate on cosmic-ray-produced 21Ne. Our results suggest that Itokawa is continuously losing its surface materials into space at a rate of tens of centimeters per million years. The lifetime of Itokawa should be much shorter than the age of our solar system.

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Irradiation history of itokawa regolith material deduced from noble gases in the hayabusa samples

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