Gravity Probe B spacecraft is in NASA’s Payload
Processing Facility 1610 on North Vandenberg Air Force
Base in California, and preparations are on schedule for
a launch on April 17.
was mated to the payload attach fitting (PAF) on March
25. Closeouts to Gravity Probe B in preparation
for going to the launch pad have been completed.
Today the spacecraft is being installed into the transportation
canister in preparation for being moved to Space Launch
Complex 2 on Thursday, April 1 and mated to the Boeing
Delta II rocket.
At the pad,
the rocket is enclosed within the gantry-like mobile service
tower and is powered up. A Simulated Flight
test, which is a plus count, has been completed successfully.
This test activated the electrical and mechanical flight
systems on the vehicle as they will occur from liftoff
through spacecraft separation. A countdown
test with the first stage loaded with liquid oxygen was
successfully completed on March 18.
The next major
test is the Flight Program Verification to be conducted
on April 5. This is an integrated test of the Delta
II vehicle and the Gravity Probe B spacecraft. Installation
of the fairing around the spacecraft is scheduled for
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).
B consists of four sophisticated gyroscopes that will
provide an almost perfect space-time reference system.
The mission will look in a precise 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.
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.