This Week on Galileo - March 24-30, 1997
This week contains the final days for playback of the data gathered during Galileo's Europa 6 encounter period. In this final week, a variety of observations are transmitted to earth. Included in this set is a fields and particles observation of Europa's interaction with Jupiter's magnetosphere and an observation of the equatorial region of the magnetosphere. Europa data contains information regarding the composition of Europa's surface (NIMS - Near Infrared Mapping Spectrometer) including an observation that should allow scientists to distinguish between new and old ice and images of bright plains and craters (SSI - Solid State Imaging camera) that should shed light on the formation processes of these features. Io observations include data on the changes in Io's surface (SSI), Io's surface while eclipsed from the sun by Jupiter (SSI), surface chemistry (NIMS) and volcanic activity (NIMS).
A single Amalthea observation (SSI), a White Oval (NIMS) observation, and a North-South strip thermal observation of Jupiter's atmosphere (NIMS) are also returned this week. Finally, global observations (SSI, NIMS) of Ganymede and Callisto are also on the playback schedule.
Preparations for Galileo's next satellite encounter occur toward the end of the week. The encounter period is scheduled to start on Sunday, March 30th. The main encounter will be with Ganymede on Friday, April 4th at an altitude of about 3100 km. Playback is completed this Friday and is followed by some maintenance activities: flushing the thruster lines (to prevent the lines from becoming blocked by debris) and conditioning the tape recorder.
Eight optical navigation images of the Jupiter system are taken on Friday and Saturday. Remember that these images allow navigators to better determine the path of the spacecraft and decide whether it has to be adjusted prior to its Ganymede flyby. These are expected to be the last of the optical navigation images for the remainder of Galileo's mission at Jupiter. After several months of navigating around Jupiter's system, the models of the orbits of the Galilean satellites have been significantly improved. Specifically, the optical navigation images have reduced the uncertainties in the satellite positions (and velocities). These reductions have allowed navigators to better determine the spacecraft's flight path and more accurately predict satellite encounter conditions. At this point, optical navigation images are beginning to lose their value and will no longer be required.
The encounter set of commands is transmitted to the spacecraft on Saturday and becomes active on Sunday. Stay tuned for the return of Today on Galileo.