| タイトル | SEM and TEM Observation of the Surfaces of the Fine-Grained Particles Retrieved from the Muses-C Regio on the Asteroid 25413 Itokawa |
| 本文（外部サイト） | http://hdl.handle.net/2060/20110008121 |
| 著者（英） | Konno, M.; Nakato, A.; Tanaka, M.; Zolensky, Michael E.; Ogami, T.; Okada, T.; Fujimura, A.; Ishibashi, Y.; Ueno, M.; Noguchi, T.; Mukai, T.; Hashimoto, T.; Nakamura, T.; Shirai, K.; Okazaki, R.; Yada, T.; Abe, M. |
| 著者所属（英） | NASA Johnson Space Center |
| 発行日 | 2011-03-07 |
| 言語 | eng |
| 内容記述 | Surface materials on airless solar system bodies exposed to interplanetary space are gradually changed their visible to near-infrared reflectance spectra by the process called "space weathering", which makes the spectra darker and redder. Hapke et al. proposed a model of space weathering: vapor deposition of nanophase reduced iron (npFe(sup 0)) on the surfaces of the grains within the very surface of lunar regolith. This model has been proved by detailed observation of the surfaces of the lunar soil grains by transmission electron microscope (TEM). They demonstrated that npFe(sup 0) was formed by a combination of vapor deposition and irradiation effects. In other words, both micrometeorite impacts and irradiation by solar wind and galactic cosmic ray play roles on the space weathering on the Moon. Because there is a continuum of reflectance spectra from those of Q-type asteroids (almost the same as those of ordinary chondrites) to those of S-type asteroids, it is strongly suggested that reflectance spectra of asteroids composed of ordinary chondrite-like materials were modified over time to those of S-type asteroids due to space weathering. It is predicted that a small amount of npFe(sup 0) on the surface of grains in the asteroidal regolith composed of ordinary chondrite-like materials is the main agent of asteroidal space weathering. |
| NASA分類 | Astrophysics |
| レポートNO | JSC-CN-22745 |
| 権利 | Copyright, Distribution as joint owner in the copyright |
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