The remaining encounter activities include the close flyby of Jupiter's moon Callisto , an observation by the Radio Science team and one by the Utraviolet Spectrometer . Following the encounter , the spacecraft begins playing back data acquired during the previous several days and stored on its onboard tape recorder. Data playback is interrupted once during this week. On Thursday, August 19, the spacecraft performs a small flight path correction. Back here on Earth, flight team members are in the process of analyzing engineering data to determine the cause of four spacecraft anomalies seen during the encounter.
Preliminary theories implicate Jupiter's intense radiation environment as the primary culprit.
Onboard fault protection software was successful in keeping encounter operations going, although during one incident the spacecraft's tape recorder temporarily stopped recording. The change in Perijove distance is not seen until Galileo's next encounter, however, because the Callisto flyby has occurred after this encounter's Perijove passage. During the Callisto flyby, the spacecraft passes behind the moon as seen from the Sun and the Earth. As the spacecraft flies behind the moon, its radio signal will be weakened and refracted by Callisto's tenuous atmosphere. These changes will be measured by the Radio Science team back here on Earth, which will allow scientists to study the structure of Callisto's atmosphere.