Gravity Probe B is in NASA spacecraft processing facility 1610 on North Vandenberg Air Force Base in California. In work this week, the Experiment Control Unit (ECU) was removed yesterday, Tuesday, Dec. 9, and will be returned to Stanford University in Palo Alto, Calif., tomorrow, Thursday, Dec. 11.

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 on Dec. 1.

The Delta II rocket is at Space Launch Complex 2 enclosed within the gantry-like mobile service tower and will remain there until the GP-B spacecraft arrives. The cryogenic helium remains aboard the spacecraft and will be topped off prior to going to the launch pad.

While no new launch date has been established, a Flight Planning Board meeting is planned for next week 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.