This Week on Galileo - April 21-27, 1997
This week marks the midpoint between encounters for Galileo. While passing through apojove (the farthest point from Jupiter during any given orbit), the spacecraft is scheduled to execute another orbit trim maneuver. This maneuver will begin correcting errors the spacecraft's path in preparation for it next encounter with the Jupiter system.
The fields and particles survey of Jupiter's magnetosphere for this orbit ends early this week. It is schedule to resume just prior to Galileo's next encounter. However, two fields and particles observations recorded during the last encounter are scheduled for transmission to Earth this week. The first is an observation of the magnetosphere plasma sheet (ionized matter which is confined to a thin "sheet"). Together with observations performed during other orbits at different locations of the magnetosphere, this data will allow scientists to understand how the plasma is distributed and how it moves around in the magnetosphere. The second is an observation performed during closest approach to Ganymede. This observation will provide information regarding the interaction between Ganymede and the magnetosphere.
Observations performed during closest approach to Ganymede are highlighted this week on the playback schedule. These observations were designed to obtain data on a variety of bright, dark and dark-rayed regions. These regions and the features within them are believed to be associated with high energy impacts. The regions are circular, dome-shaped and contain grooves. Of particular interest is figuring out what these regions are made of and whether any of their characteristics are due to the remains of the impacting bodies. The role of volcanism in the resurfacing of these features may also be determined from the observations. These high resolution samples are complimented by data obtained during a global observation of Ganymede performed by NIMS (Near Infrared Mapping Spectrometer) and a darkmap observation performed by PPR (Photopolarimeter Radiometer)-- both also on the playback schedule this week.
Observations of Jupiter's small red spot continue to be returned this week, as are additional observations of Jupiter's atmosphere in the form of strips running North-South and East-West. These additional observations not only provide context information for the small red spot observations but also contribute to the construction of a global map of Jupiter, with regional resolutions.
The remaining schedule for this week is comprised of global observations of Europa and Callisto, observations of Europa and Io while eclipsed from the sun by Jupiter, and an observation of Thebe, all performed by SSI (Solid State Imaging camera). Observations monitoring Io's volcanic activity by SSI and NIMS are also returned this week. Finally, the playback schedule also includes a series of photometry (measurements of the intensity of light) observations performed by PPR of Io, Europa and Callisto at different solar phase angles.