NASA Gravity Probe-B Launch Status Report 3 Dec 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 in California.  In preparation for the repair necessary to the spacecraft, the payload attach fitting was removed on Nov. 20.  The first of the four solar arrays was removed on Nov. 24, the second and third arrays were removed Nov. 25, and the last array was removed this week on Monday, Dec. 1.

A decision has been made that the cryogenic helium will not need to be offloaded from the spacecraft to remove the Experiment Control Unit (ECU) which is expected to occur late next week.  The return to the factory of the ECU is expected on or about Dec. 15.  Meanwhile, 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.

While no new launch date has been established, a Flight Planning Board meeting is planned for mid-December, and the outcome could determine a possible target date or at least a new launch time frame.

The Gravity Probe B mission is a relativity experiment developed by NASA’s Marshall Space Flight Center,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.