Today on Galileo - March 30, 1997
The encounter period for Galileo's return to Ganymede starts today at 8 am (PST). During the next eight days, the spacecraft will once again fly through the Jupiter system and perform observations of Jupiter, its magnetosphere, all of the Galilean moons and some minor satellites. On the evening of April 4th, the spacecraft will fly by Ganymede, the featured satellite for this orbit, at an altitude of 3095 km. The encounter period also includes a non-targeted (not the "intended" satellite target) flyby of Europa. The Europa closest approach will occur on the evening of April 3rd at an altitude of approximately 25,000 km.
The first day of the encounter period features the resumption of the magnetosphere survey being performed by the fields and particles instruments. In addition, the fields and particles instruments will perform a high rate observation of the magnetosphere as the spacecraft flies across the region known as the plasma sheet (ionized matter which is confined to a thin "sheet". Together with observations performed in previous orbits - which occurred at different locations of the magnetosphere, the data will allow scientists to understand how the plasma is distributed and how it moves around in the magnetosphere.
Also today, the UVS (Ultraviolet Spectrometer) instrument will be performing remote observations of the "neutral torus" regions around the orbits of Callisto and Ganymede. It is believed that neutral particles are somehow being stripped from these satellites and that these particles then remain in the orbits of the satellites. These observations are expected to find if the particles are there, what they are, and possibly explain how and why they remain in the satellite orbits.