5 research outputs found
Galileo dust data from the jovian system: 2000 to 2003
The Galileo spacecraft was orbiting Jupiter between Dec 1995 and Sep 2003.
The Galileo dust detector monitored the jovian dust environment between about 2
and 370 R_J (jovian radius R_J = 71492 km). We present data from the Galileo
dust instrument for the period January 2000 to September 2003. We report on the
data of 5389 particles measured between 2000 and the end of the mission in
2003. The majority of the 21250 particles for which the full set of measured
impact parameters (impact time, impact direction, charge rise times, charge
amplitudes, etc.) was transmitted to Earth were tiny grains (about 10 nm in
radius), most of them originating from Jupiter's innermost Galilean moon Io.
Their impact rates frequently exceeded 10 min^-1. Surprisingly large impact
rates up to 100 min^-1 occurred in Aug/Sep 2000 when Galileo was at about 280
R_J from Jupiter. This peak in dust emission appears to coincide with strong
changes in the release of neutral gas from the Io torus. Strong variability in
the Io dust flux was measured on timescales of days to weeks, indicating large
variations in the dust release from Io or the Io torus or both on such short
timescales. Galileo has detected a large number of bigger micron-sized
particles mostly in the region between the Galilean moons. A surprisingly large
number of such bigger grains was measured in March 2003 within a 4-day interval
when Galileo was outside Jupiter's magnetosphere at approximately 350 R_J
jovicentric distance. Two passages of Jupiter's gossamer rings in 2002 and 2003
provided the first actual comparison of in-situ dust data from a planetary ring
with the results inferred from inverting optical images.Comment: 59 pages, 13 figures, 6 tables, submitted to Planetary and Space
Scienc
Dust measurements in the Jovian magnetosphere
Dust measurements have been obtained with the dust detector onboard the Galileo spacecraft inside a distance of about 60R(J) from Jupiter (Jupiter radius, R-J = 71, 492 km) during two periods of about 8 days around Galileo's closest approaches to Ganymede on 27 June and on 6 Sept 1996. The impact rate of submicrometer-sized particles fluctuated by a factor of several hundred with a period of about 10 hours, implying that their trajectories are strongly affected by the interaction with the Jovian magnetic field. Concentrations of small dust impacts were detected at the times of Ganymede closest approaches that could be secondary ejecta particles generated upon impact of other particles onto Ganymede's surface. Micrometer-sized dust particles, which could be on bound orbits about Jupiter, are concentrated in the inner Jovian system inside about 20R(J) from Jupiter