On Monday this week, the Flight Planning Board met and set April 20, 2004 as the new launch date for Gravity Probe B. A launch time hasn't been set.

The spacecraft is in NASA spacecraft processing facility 1610 on North Vandenberg Air Force Base in California. The Experiment Control Unit (ECU) was returned to Palo Alto, Calif. late last week and is in Lockheed Martin facilities there. Repairs are currently under way. Two associated circuit boards contained in the ECU are being removed and replaced with ones slightly different in circuit design.

Meanwhile, the Delta II rocket is at Space Launch Complex 2 enclosed within the gantry-like mobile service tower. It has completed successfully all testing to date and will remain there until the GP-B spacecraft arrives.

No further status reports are planned to be issued on Gravity Probe B until January.

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.