Krüger, H., A. Krivov, D.P. Hamilton, and E. Grün. Discovery
of an impact-generated dust cloud around Ganymede. Nature 399,
558-560.
Dust is ubiquitous in the solar system, being especially concentrated
in the Zodiacal cloud and in the ornate ring systems surrounding the
giant planets. Individual dust grains in each of these environments
are thought to be generated by impact ejection from larger parent
bodies, but until now no direct measurements of this important
physical process have been made. Here we report on the first in-situ
detections of a significant amount of sub-micrometre dust within a few
radii of Jupiter's massive icy satellite Ganymede. Measurements of
impact directions, impact speeds, and the mass distribution of the
dust indicate that the dusty material emanates from Ganymede, and the
data are consistent with secondary ejecta kicked off the moon's
surface by the hypervelocity impacts of interplanetary dust. Enhanced
dust fluxes near Callisto and Europa suggest that these icy satellite
are also good sources of dusty debris.
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Last modified: Sun Jul 14 22:34:27 2002