Standing 347 feet high, the new FSS would have 12 floors, 20
feet apart. Each floor is actually not solid, but metal grates,
so looking down at your feet you can actually see down a
number of floors. The exception is the 195 foot level where
the crew accesses the orbit, it has solid floors because, well
you’ll find out later in the story. It had three access arms that
provided services or access to the Shuttle. On top of the
structure was a new 80 foot tall lightning mast, and just below
the mast, an Apollo era Hammerhead crane was installed to
be used for any heavy lifting operations needed at the pad.
The crane was removed in 1994 when cost analysis revealed
it to be more cost effective to bring in mobile cranes when
needed rather than to maintain the Hammerhead crane.
Located between the 207 foot and 227 foot level of the
FSS was the Gaseous Oxygen Vent Arm. On the end of that
arm was a 13 foot diameter hood, known as the “Beanie
Cap.” The cap would heat gaseous oxygen that vented
from the Shuttle’s External Tank that could freeze and form
potentially dangerous ice. The oxygen travels just a few feet
away from the hood where it is safely released into the atmo-
sphere. The arm would be in place before fueling and would
be swung away approximately 2.5 minutes prior to launch.
The Beanie Cap served an important
purpose – preventing extremely cold
oxygen that vented from the External
Tank from turning into ice and poten-
tionally damaging the launch vehicle.
Headed down the FSS, we next find the External Tank Hy-
droge n Vent Umbilical and Intertank Access Arm located
at the 167 foot level. The 48 foot long arm gives the pad
crew access to the External Tank intertank compartment if
needed. It also allows for mating of the External Tank umbili-
cal and vent lines. Around five days prior to launch, the arm
is retracted leaving just the umbilical vent line connected to
the External Tank to support tanking and launch. The vent
line part of the umbilical serves basically the same purpose
as the Beanie Cap, except venting hydrogen from the tank.
Also rather than releasing the hydrogen close by, it is taken
through the line, into a venting system that takes it far away
from the pad where it is safely burned off. The line itself de-
taches at first motion of the vehicle at launch and is pulled
away downward away from the vehicle and secured.
Finally at the 147 foot level you would find the Orbiter Ac-
cess Arm. At 65 feet long, 5 foot wide, and 8 feet high, it’s the
largest arm on the FSS. This metal bridge provides access to
the crew compartment of the orbiter. Located at the end of
the arm is the “White Room,” an environmentally controlled
chamber which mates with the orbiter and can hold up to
six people. After the crew is loaded and all the pad person-
nel have left, the arm remains in place until 7 minutes and
24 seconds prior to the launch to serve as an emergency
escape if needed. After that time it can be repositioned in
about 15 seconds if any emergency arises.
34
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Looking like a giant erector set, Launch Pad 39A underwent major
renovation in the1970s to evolve it from the Apollo era ‘clean’ pad
to include more fixed structures to support Space Shuttle launches.
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