| The
Gravity Probe B spacecraft is in NASA’s Payload Processing
Facility 1610 on North Vandenberg Air Force Base in California.
It is awaiting the return of the reworked Experiment Control Unit
(ECU).
The ECU is
currently in Lockheed Martin spacecraft facilities at Sunnyvale,
Calif. The reworking of the circuit board, installation into the
ECU, functional testing and thermal vacuum chamber testing are
all complete. The work has gone better than expected and the ECU
will be returned to Vandenberg Air Force Base tomorrow Thursday,
Feb. 5. Meanwhile this week, GP-B spacecraft test team members
have been returning to Vandenberg in preparation for the arrival
of the ECU.
In other
planned spacecraft processing, battery reconditioning is scheduled
for Feb. 6-8. The ECU will be reinstalled Feb. 9. Cryogenic servicing
of liquid helium is scheduled for Feb. 16. Operations to reinstall
the solar arrays are planned for Mar. 7–19. The spacecraft
is currently scheduled to be transported to Space Launch Complex
2 on Apr. 1 and mated to the Delta II rocket.
Meanwhile,
the Delta II rocket is at Space Launch Complex 2 enclosed within
the gantry-like mobile service tower. It has successfully completed
all testing to date and will remain there until the GP-B spacecraft
arrives.
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.
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