Today on Galileo - December 17, 1997
Galileo starts the first cruise period of the Galileo Europa Mission, a two-year extension of the primary mission, as the encounter set of computer commands finishes executing at 10 a.m. Plans to initiate processing and transmitting of data stored on the spacecraft's tape recorder have been put on temporary hold due to a fault in the attitude control subsystem electronics.
Late Monday night, the spacecraft's fault protection systems transferred some attitude control functions to the backup set of electronic hardware. In spite of this event, all available information indicates that the spacecraft continues to execute all commands properly.
Processing of recorded data has been put on hold until the cause of the hardware swap is understood. The attitude control electronics in question are also used by the spacecraft's compression programs in preparing science data for transmission to Earth. Data compression allows the spacecraft to transmit only scientifically valuable information, while minimizing or eliminating less valuable data (such as the dark background of space).
As some flight team members investigate, others will continue to prepare for an orbit trim maneuver scheduled for Saturday. This maneuver is used to correct any errors in the spacecraft's path accumulated during the Europa flyby earlier this week.
Note: All times of day listed correspond to the Pacific Time zone and spacecraft event time. Radio signals indicating that an event has occurred on the spacecraft reach the Earth 35 to 50 minutes later, depending on the time of year.