Galileo Status Report - August 30, 1996
PUBLIC INFORMATION OFFICE JET PROPULSION LABORATORY CALIFORNIA INSTITUTE OF TECHNOLOGY NATIONAL AERONAUTICS AND SPACE ADMINISTRATION PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011 http://www.jpl.nasa.gov
The Galileo spacecraft has been recovered from its safing event last weekend, and is now being configured for its second flyby of Jupiter's moon Ganymede on Sept. 6.
On Wednesday, Aug. 28, Galileo's main onboard computer was restored so that both sides were operating; following the safing event, the computer had been running on only one of its sides. On Thursday morning, new software installed shortly before the first Ganymede encounter in June that is required for processing observations from science instruments was restarted. The science instruments themselves will be powered up and configured as necessary beginning early Saturday morning, Aug. 31.
According to Galileo Project Manager Bill O'Neil, engineers are confident that they now have a complete understanding of what caused the safing event and will be able to prevent a recurrence of this particular fault. The safing was initiated when excessive commands in a software buffer caused the main onboard computer's processors to overrun the allotted time to complete the required calculations.
Beginning at about noon Pacific time Saturday, the command sequence that will control Galileo during its upcoming Ganymede flyby will be transmitted to the spacecraft. That sequence will begin to execute at 9 a.m. Pacific time Sunday, Sept. 1.
On Tuesday, Aug. 27, Galileo fired its thrusters very briefly to fine-tune its flight path for the Ganymede flyby. Galileo will now fly within 262 kilometers (163 miles) of the jovian moon at 19:00 Universal Time (12 noon Pacific time) Sept. 6. On Monday, Sept. 2, Galileo will take two optical navigation images of Ganymede which will be used to check the accuracy of its trajectory. If appropriate, an additional thruster firing will be commanded on Wednesday, Sept. 4.