NASA Spacecraft and Epxendable Vehicles Status Report 4 Sep 2003

MISSION: Gravity Probe B (GP-B)

• LAUNCH VEHICLE: Delta II
• LAUNCH PAD: SLC-2, Vandenberg Air Force Base
• LAUNCH DATE: November 13, 2003
• LAUNCH TIME: 7:22:26 p.m. PST

Gravity Probe B is at NASA spacecraft processing hangar 1610 on North
Vandenberg Air Force Base. In processing activities this week, the initial
filling of the dewar with cryogenic helium has been performed. This
prepared the dewar for the upcoming series of about 6 -7 cycles of pumping
down the tank to a near vacuum, then refilling as necessary, to achieve the
superfluid conditions. The first pump-down began on Wednesday, Sept. 3.

The electromagnetic interference (EMI) test and the Gas Management Assembly
(GMA) “rate of rise” test were successfully finished as scheduled.

The erection of the Boeing Delta II launch vehicle at Space Launch Complex 2
remains scheduled to begin on Sept. 15 with the erection of the first stage.
Attachment of the nine strap-on solid rocket boosters in sets of three is
scheduled for Sept. 17-19. The second stage is planned for mating atop the
first stage on Sept. 22. Gravity Probe B will be transported from the
spacecraft hangar to Space Launch Complex 2 on Oct. 29 and hoisted atop the
second stage. The Delta II fairing will be installed around the spacecraft
on Nov. 5 as part of final preparations for launch.

Gravity Probe B arrived at Vandenberg Air Force Base on July 11 from the
Lockheed Martin plant in Sunnyvale, Calif.

Gravity Probe B 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. Gravity Probe B
consists of four sophisticated gyroscopes to be launched into a
400-mile-high orbit for a mission lasting 18 months.