This Week on Galileo - June 9-16, 1997
Having passed through its furthest point from Jupiter for this orbit, the Galileo spacecraft speeds toward its next encounter with the Jupiter system -- Callisto 9. Playback of data recorded during its previous encounter, Ganymede 8, is again the primary activity on the spacecraft this week. Playback plans are devoted to a second pass through the encounter data allowing return of previously unselected data, the filling of gaps in data created by communications problems and any re-play of particularly interesting data.
Data from observations taken during Galileo's close flyby of Ganymede is the main focus for playback this week. Remote sensing observations seek to provide clues regarding construction and destruction of features on the surface of Ganymede. Among the mysteries of Ganymede's surface are the replacement of old dark material by younger lighter material, the formation of craters with very different characteristics -- containing large central domes, multiple rings, dark halos and dark rays, and the formation of other grooves, furrows and sulci. Some of the regions on Ganymede's surface that are observed in this group of observations are the Osiris Crater (central dome, ray craters, furrows), Uruk Sulcus (sulci, grooves, furrows, dark halo craters), and Marius Regio (light vs. dark terrain). Fields and particles data returned from the Ganymede flyby consists of a 45 minute high-time-resolution recording. These data will provide more information on the interaction of the Ganymede and Jupiter magnetosphere.
Observations of Io from two different monitoring campaigns are returned this week. SSI (Solid State Imaging camera) images of the Kanehikili plume contribute to the plume monitoring campaign performed during the G8 encounter. Surface and chemistry monitoring observations performed by NIMS (Near Infrared Mapping Spectrometer) contribute to the mission-long campaign of mapping and understanding where, why and how frequent changes occur on Io.
The playback schedule is complete with the inclusion of three observations from the not-so-distant flyby of Callisto. These observations include an image (SSI) of the Adlinda crater region, a global observation by NIMS and a photometry observation at high solar phase angle also by SSI. Data is also returned from the fields and particles observation taken as the spacecraft descended from a lobe of Jupiter's magnetosphere into the heart of the plasma sheet. Finally, a couple of distant observations of the minor satellite Adrastea are returned this week. These observations were taken with a known star in the background. By comparing the location of Adrastea to the star, the models of Adrastea's orbit can be improved and will help ensure accurate future observations of Adrastea.