Grün, E., H. Krüger, A.L. Graps, D.P. Hamilton, A. Heck,
G. Linkert, H.A. Zook, S. Dermott, H. Fechtig, B.A. Gustafson,
M.S. Hanner, M. Horanyi, J. Kissel, B.A. Lindblad, D. Linkert,
I. Mann, J.A.M. McDonnell, G.E. Morfill, C. Polanskey, G. Schwehm and
R. Srama. Galileo Observes Electromagnetically Coupled Dust
in the Jovian Magnetosphere. JGR
103, 20,011-20,022.
Measurements of dust coupled to the jovian magnetosphere have been
obtained with the dust detector onboard the Galileo spacecraft. We
report on data obtained during the first four orbits about Jupiter
that had flybys of the Galilean satellites: Ganymede (orbit number: 1
and 2), Callisto (3), and Europa (4). The most prominent features
observed are highly time variable dust streams. The impact rate varied
by up to two orders of magnitude with a 5 and 10 h periodicity, that
shows a correlation with Galileo's position in the jovian magnetic
field. Around 20 $R_J$ (Jupiter radius, $R_J = 71492$km) inbound a dip
in the impact rate has been found consistently. At the same times
reversals by 180 in impact direction occurred. This behavior can be
qualitatively explained by strong coupling of nanometer sized dust to
the jovian magnetic field. At times of satellite flybys enhanced rates
of dust impacts have been observed which suggests that all Galilean
satellites are sources of ejecta particles. Inside about 20 $R_J$
impacts of big particles have been recorded that could be particles on
bound orbits about Jupiter.
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