- Press Release
- Nov 28, 2022
NASA Spacecraft and Expendable Vehicles Status Report 31 Mar 2004
MISSION: Gravity Probe B (GP-B)
LAUNCH VEHICLE: Delta II
LAUNCH PAD: SLC-2, Vandenberg Air Force Base
LAUNCH DATE: April 17, 2004
LAUNCH TIME: 1:09:12 p.m. EDT (10:09:12 a.m. PDT)
The 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.
The spacecraft 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
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 April 8.
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 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.
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
LAUNCH VEHICLE: Delta II Heavy
LAUNCH PAD: 17-B
LAUNCH DATE: July 30, 2004 NET
LAUNCH WINDOW: 2:17:44 a.m. – 2:17:56 a.m. EDT
MESSENGER is at the Astrotech Space Operations facilities near
Kennedy Space Center where it is undergoing prelaunch testing. Testing
of the spacecraft’s radio system uplink and downlinks through the
KSC/JPL interface with the Deep Space Network is underway. This testing
will last about ten days. Autonomy testing is also underway. This
verifies MESSENGER’s ability to operate on its own when not in direct
contact with Earth. Installation of thermal blankets continues.
On April 13, the spacecraft will be moved from its current
location in the hazardous processing facility where it has been since
arrival to an adjacent non-hazardous payload processing facility. The
remainder of its final assembly and testing will be completed there.
The spacecraft will return to the hazardous processing facility when
ready for fueling, spin balance testing and mating to the upper stage.
MESSENGER has been built for NASA by the Johns Hopkins
University Applied Physics Laboratory in Laurel, Maryland.