* Astronomy

On August 28, 1993, the Galileo probe flew within 2,400 kilometres of asteroid (243) Ida. The probe discovered that Ida had a small moon, dubbed Dactyl, only 1.4 km in diameter which was the first asteroid moon discovered. Measurements using Galileo's solid state imager, magnetometer and NIMS instrument were taken. From subsequent analysis of data, Dactyl appears to be an SII subtype S type asteroid and is spectrally different from 243 Ida. It is hypothesised that Dactyl may have been produced by partial melting within a Koronis parent body (Ida belongs to the "Koronis" family of asteroids that travels in the main Asteroid Belt between Mars and Jupiter) while the 243 Ida region escaped such igneous processing.
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Ganymede 1 Flyby was 27 June 1996

Galileo's first flyby of Ganymede on 27 June was the first of the satellite flybys to have all the instruments taking observations. (During the Io flyby in December 1995, no images were taken to ensure that all the probe data were captured.) During this encounter, the Energetic Particles Detector (EPD) went into a safe mode and did not make any observations close to Ganymede. In addition, following the flyby, the Near Infrared Mapping Spectrometer (NIMS) experienced some difficulties in playing back some of its data. Both problems have been fixed by ground engineers and are not expected to reoccur.
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20th Anniversary of the Galileo spacecrafts Venus flyby

Title: Galileo dust data from the jovian system: 2000 to 2003
Authors: Harald Krueger, D. Bindschadler, S. F. Dermott, A. L. Graps, E. Gruen, B. A. Gustafson, D. P. Hamilton, M. S. Hanner, M. Horanyi, J. Kissel, D. Linkert, G. Linkert, I. Mann, J. A. M. McDonnell, R. Moissl, G. E. Morfill, C. Polanskey, M. Roy, G. Schwehm, R. Srama

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.

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