Measurements of reflectance spectra of ion-bombarded ice and application to surfaces in the outer Solar System
Abstract
A number of the icy satellites of the outer planets exhibit interesting hemispherical differences in brightness1-5 which have been attributed to enhanced bombardment by the local plasma of one hemisphere. The plasma bombardment is thought to erode the icy surfaces and implant species, thereby altering the surface reflectance spectra2,3, as well as producing fresh plasma6. Here we present the first results of laboratory measurements of the wavelength dependence of the alteration of the visible reflectance spectra of H2O ice irradiated by keV ions. When the implanted species is chemically neutral, absorption is slightly enhanced below 0.55 μm. For an incident species containing sulphur, a strong absorption feature is produced at 0.4 μm corresponding (probably) to S3. This occurs at too large a wavelength to account for the absorption feature observed at Europa by Voyager and therefore casts doubt on the recent interpretations7-9 of the reflectance data of Europa.
- Publication:
-
Nature
- Pub Date:
- May 1988
- DOI:
- 10.1038/333240a0
- Bibcode:
- 1988Natur.333..240O
- Keywords:
-
- Gas Giant Planets;
- Ice;
- Ion Irradiation;
- Plasma Interactions;
- Satellite Surfaces;
- Spectral Reflectance;
- Brightness;
- Cosmic Plasma;
- Europa;
- Natural Satellites;
- Solar System;
- Sulfur;
- Lunar and Planetary Exploration; Planets;
- PLANETS;
- REFLECTANCE;
- SPECTRA;
- ICE;
- SURFACE;
- BOMBARDMENT;
- IONS;
- PLASMA;
- ICY BODIES;
- SATELLITES;
- BRIGHTNESS;
- LABORATORY STUDIES;
- JUPITER;
- EUROPA;
- ALTERATION;
- IRRADIATION;
- ABSORPTION;
- SULFUR;
- WAVELENGTHS;
- SIMULATIONS;
- SPACECRAFT OBSERVATIONS;
- VOYAGER MISSIONS