Energetic particle observations near Ganymede

This paper combines data from the Galileo spacecraft plasma and energetic particle instruments. Data are included from two Ganymede flybys when the spacecraft was at northern Ganymede latitudes. Electron intensities from the two instruments are in very good agreement. Fits to 60 electron energy spec...

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Bibliographic Details
Published in:Journal of Geophysical Research, Washington, DC Washington, DC, 1999-08, Vol.104 (A8), p.17459-17469
Main Authors: Paranicas, C., Paterson, W. R., Cheng, A. F., Mauk, B. H., McEntire, R. W., Frank, L. A., Williams, D. J.
Format: Article
Language:English
Subjects:
Astronomy
Earth, ocean, space
Exact sciences and technology
Ionospheres
magnetospheres
Jupiter
Planetary, asteroid, and satellite characteristics and properties
Planets, their satellites and rings. Asteroids
Solar system
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Summary:This paper combines data from the Galileo spacecraft plasma and energetic particle instruments. Data are included from two Ganymede flybys when the spacecraft was at northern Ganymede latitudes. Electron intensities from the two instruments are in very good agreement. Fits to 60 electron energy spectra are presented. We find the power of precipitating 0.5–3.0 keV electrons into both polar caps of Ganymede is ∼3 × 109 W. By assuming the instruments are intercalibrated, we infer that sulfur dominates the ion intensities at least in the tens of keV energy range. Furthermore, fits to the ion data indicate that the intensities are dominated by heavy ions below about 100 keV. Fits to these data are also used to estimate the sputtering rate of Ganymede's icy surface. It is found that ∼2 × 1026 water molecules/s are sputtered from Ganymede's polar caps which, when not redeposited on the surface, give an erosion rate of ∼8 m/Gyr.
ISSN:0148-0227
2156-2202
DOI:10.1029/1999JA900199