| タイトル | Charged-particle induced alterations of surfaces in the outer solar system |
| 本文（外部サイト） | http://hdl.handle.net/2060/19920001620 |
| 著者（英） | Johnson, R. E. |
| 著者所属（英） | Virginia Univ. |
| 発行日 | 1991-06-01 |
| 言語 | eng |
| 内容記述 | Researchers calculated the plasma bombardment profiles of the surfaces of the icy Saturnian satellites in order to interpret reflection spectra and the effect of charged particles on the surfaces (mantles) of Pluto and of comets in the Oort cloud. Pluto's exposure to cosmic rays results in a slow alteration of the reflectance if the methane condensed on its surface. The UV absorbed in the atmosphere can produce precipitates. The researchers showed that, depending on the rates of the competing regolith processes and rates for replenishment of the methane, the surface can appear bright, red, or dark. Using laboratory data, they showed that the amount of darkening occurring in one orbit is small. Therefore, transport, burial, and re-exposure of organic sediments must control the reflectance, and the average reflectance is established by the radiation altered species accumulated over many orbits with the observed spatial, and possible temporal, differences in albedo due to transport. The cosmic rays, although producing changes in reflectance slowly, do so inevitably. Therefore, the fact that the surface is not dark everywhere implies that it is active and the exposure rates vs. depth into the surface of Pluto can be used to constrain turnover rates. Comets in the Oort cloud experience similar rates. |
| NASA分類 | LUNAR AND PLANETARY EXPLORATION |
| レポートNO | 92N10838 |
| 権利 | No Copyright |
| URI | https://repository.exst.jaxa.jp/dspace/handle/a-is/130429 |
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