This Week on Galileo - August 4-10, 1997
This week on Galileo, the spacecraft passes through apojove (the farthest point from Jupiter) for the current orbit. Achieving a maximum distance of 143 Jupiter Radii, or about 10.2 million kilometers (6.4 million miles), this apojove is different from all previous ones. This is the spacecraft's deepest pass through the region of Jupiter's magnetosphere known as the magnetotail (where Jupiter's magnetic field has been pushed into a long tail by the solar wind). On Thursday, just prior to apojove, the spacecraft's central computer will pause normal data playback from the tape recorder so the fields and particles instruments can perform a high-time resolution observation of the magnetotail environment. As part of an orbit-long series of recordings, the fields and particles data should tell us how the magnetotail is related to the overall dynamics of Jupiter's magnetosphere and the solar wind.
Playback of data recorded during Galileo's previous encounter with Callisto and the Jupiter system continues before and after the apojove recording. This week's playback schedule includes observations of Jupiter and its magnetosphere, the minor satellites, as well as Ganymede and Europa. SSI (Solid State Imaging camera) returns two observations of features in Jupiter's atmosphere -- one of the Great Red Spot and one of a plume head region. These are among the many observations that were coordinated with the other remote sensing instruments designed to completely characterize these features. SSI also returns two observations of the minor satellites Metis and Adrastea, part of the orbital-tour-long series that will result in increased knowledge of the shape and composition of these bodies.
The first couple of observations from the current campaign of magnetotail observations are also returned this week. An auroral map taken by NIMS (Near Infrared Mapping Spectrometer) will provide data that will be used to compare auroral activity on Jupiter with activity within the magnetosphere which will be provided by data taken by the fields and particles instruments. The data were taken at almost the same time, earlier in the orbit, when the spacecraft was only 65 Jupiter Radii, or 4.6 million kilometers (2.9 million miles), from Jupiter. Last on the playback schedule for this week are four observations of Ganymede, two by PPR (Photopolarimeter Radiometer) and two by NIMS, and one of Europa by NIMS.
Finally, on Thursday, the flight team will transmit the commands required to perform the apojove orbit trim maneuver. This maneuver will make the required corrections to the spacecraft's path so that it reaches its next encounter with the Jupiter system at the right place and time. The maneuver will execute on Friday.