NASA Gravity Probe B Launch Status 25 Nov 2003

Gravity Probe B is in NASA spacecraft processing facility 1610 on North Vandenberg Air Force Base in California.  Last week, in preparation for the repair necessary to the spacecraft, the payload attach fitting was removed which is used in mating it to the Delta II.

The solar arrays are beginning to be removed from around the spacecraft for access to the experiment control unit (ECU).  Yesterday, one of the four solar arrays was taken off, and a second array is being removed today. A third array will be removed today if time permits; otherwise, the third and fourth arrays will be removed next Monday and Tuesday after the spacecraft team returns from the Thanksgiving holidays.

A decision has been made that the cryogenic helium will not need to be offloaded from the spacecraft to remove the ECU for rework.  Because decisions remain to be made on what will be necessary to restore Gravity Probe B to flight readiness, it is not possible at this time to determine a new launch date.

At Space Launch Complex 2, the Boeing Delta II rocket remains at the pad, enclosed within the gantry-like mobile service tower until the GP-B spacecraft arrives.

The Gravity Probe B mission is a relativity experiment developed by NASA’sMarshall SpaceFlightCenter, Stanford University and Lockheed Martin.  The spacecraft will test two extraordinary predictions of Albert Einstein’s general theory of relativity that he advanced in 1916: the geodetic effect (how space and time are warped by the presence of the Earth) and frame dragging (how Earth’s rotation drags space and time around with it).  Gravity Probe B consists of four sophisticated gyroscopes that will provide an almost perfect space-time reference system.  The mission will look in a precision manner for tiny changes in the direction of spin.  Gravity Probe B will be launched into a 400-nautical-mile-high polar orbit for a 16-month mission.

Government oversight of launch preparations and the countdown management on launch day is the responsibility of NASA’s John F. Kennedy Space Center.  The launch service is provided to NASA by Boeing Launch Services. 

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