Gravity Probe B Launch Status 20 Nov 2003

• MISSION: Gravity Probe B (GP-B)
• LAUNCH VEHICLE: Delta II
• LAUNCH PAD: SLC-2, Vandenberg Air Force Base
• LAUNCH DATE: TBD
• LAUNCH TIME:  TBD 

Gravity Probe B is in NASA spacecraft processing facility 1610 on North Vandenberg Air Force Base inCalifornia.  After a final review of test data before going to the launch pad, spacecraft management made a decision to reschedule the launch of Gravity Probe B.  They want to address an issue of electronic noise on one of the two output channels of the No. 1 experiment gyro. This problem was found during testing and could compromise the quality of the data from the gyro.  While a work around of the problem was considered, engineers decided that fixing the problem will provide the greatest chance of success over the planned 16-month life of the mission.  This repair will restore full redundancy to the output of the experiment gyro.

Meetings are set to begin at Vandenberg Air Force Base on Friday.  These will determine the approach to be taken for repair and thus how long the launch postponement will be; however, launch cannot occur during December.  The difficulty has been found to be within the spacecraft’s experiment control unit (ECU).

Meanwhile, in preparation for the repair, the payload attach fitting used in mating to the Delta II is being removed today from the base of the spacecraft.

At Space Launch Complex 2, the rocket has successfully completed the scheduled prelaunch preparations up to this time, and there are no issues or concerns with the Delta II.  The current plans are for it to remain at the pad, enclosed within the gantry-like mobile service tower until the spacecraft arrives.