| 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’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. |
