They were seen on the most significant missions like Apollo, Skylab and the
Space Shuttle. They've been used for the SpaceX Falcon Heavy and they'll be there
on the upcoming SLS missions but they're hardly ever talked about and without
them who simply wouldn't be able to get the rockets off the ground, what are they?
they were the gateway to the moon and the starting point for every space
shuttle mission. NASA launch pads 39a and 39b so what do these massive feats of
engineering do and just how important are they.
NASA has over 40 launch pads in various locations from the US mainland to the
Pacific. Their position chosen to best get the spacecraft to the correct orbit
and to be safely away from population centers. Cape Canaveral in Florida is
better for launching spacecraft requiring a west-east orbit and others
like Vandenberg in California are preferred for spacecraft requiring a
north/south orbit but wherever they are the launch pads themselves are vitally
important pieces of equipment for first and foremost holding the rocket
vertically which is no mean feat when you consider the size of a Saturn 5
which at launch weighed 2938 tons and stood 17.6 meters taller
than the Statue of Liberty at a 110 meters the same as a 36
story building. The launch complex at Cape Canaveral started its rocket career
in 1948 after the Naval Air Station there was transferred from the Navy to
the Air Force for testing of captured German V2 rockets. This went on to
missile testing and rocket technology throughout the 1950s until NASA was
formed in 1958 and it became the future for manned and unmanned missions
including project mercury and Gemini. In 1961 when President Kennedy announced
the moon missions Cape Canaveral was chosen to be the base for Apollo this
also meant that it would need a massive expansion with NASA taking an extra 550
square kilometers of land and the launch complex 39 would be
designed to handle the most powerful rocket yet designed of a Saturn V.
Work started in 1962 and was completed by 1965 there were to be three launch
pad 39A, B and C and in two more D and E later. In the end only two ended up being
built named 39A and in just north of that 39B.
Because the area is just above sea level the flame trenches could not be placed
below ground level due to the water table being very close to the surface so
the launch pads were raised by 13 meters and look like concrete hills. Because of
the way NASA designed by Saturn V there was no permanent launch umbilical tower
at the launch pad. That's the part which is next to the rocket to take off and
supplies it with fuel electrical power and access for the crew. Instead the
tower was integrated into a mobile launcher platform. The Saturn V would be
assembled directly onto the platform along with the tower. This was part of
NASA's Assembly schedule that meant that the rocket was assembled vertically and
then moved with its tower to the launch pad. This contrasts with the Soviets
which assembled their rockets as they lay on their side and then moved them to
the launch pad horizontally where they were then lifted into the vertical
position before launch. Now you may well ask why did NASA choose a vertical
integration and the Soviets horizontal. Well when the Saturn was being designed
it was thought that even bigger rockets like the Nova would follow. NASA
concluded that it would be easier to assemble the rocket vertically directly
onto a mobile launch platform and then move the whole thing to the launch area
rather than assembling it and then moving it on its side and then lifting
it up at the launch pad. This was because they thought that the engineering
challenges of lifting a 110 meter or larger rocket were just not worth it and
but it would place too much stress on the rockets body. Now some of you will be
saying that a Soviet N1 was almost as big as the Saturn 5 and that was built
horizontally and cranked up to the vertical position but it required a huge
complex mobile structure to lift it and it was moved on to parallel railway
lines with two locomotives. Building the Saturn vertically required the largest
single storey building in the world the VAB or the Vehicle Assembly Building
which at a 160 meters tall is where the new SLS rocket will also be
assembled. Built between 1962 and 65 the VAB was capable of preparing up to four
Saturn V's at the same time and each of the four doors are the largest in the
world to allow a complete Saturn rocket assembly to go out to the launch pad. For
Apollo the pre-built sections of a Saturn 5 were delivered to the Vehicle
Assembly Building from around the US. Here they were stacked on top of each
other to form the rocket. On the Saturn 5 the rocket was held down to the launch
platform by massive hold down arms which would release at launch whereas the
shuttle was bolted to the platform through the solid rocket boosters using
frangible nuts, these are nuts which are explosively
split at liftoff rather than using explosive bolts. In order to get the
rocket and the mobile launcher platform from the VAB to the launch area there
were two crawler transporters which drive under the mobile launch platform
lifted up and then move it to the launch complex. When these 2700
ton vehicles were delivered in 1965 for the Apollo program they were
the largest self powered land vehicles in the world. Not only do they carry the
rocket and the mobile launcher at about 1.6 kilometers per hour they also keep a
whole assembly level as he ascends the 3%
ramp to the launch pad 39A and B. It's laser-guided leveling system could keep
the top of a Saturn V within 30 centimeters vertically of the base.
Once the mobile launch platform had reached the launch pad it was set down
and the crawler transporter returned to the Vehicle Assembly Building and no it
didn't need to do a massive three-point turn it could be driven from either end
so it just returned the way came. Even the road that connects the VAB to
the launch pad known as the crawlerway had to be specially built with a very
low friction surface due to the weight of the rocket the launcher platform and
the crawler which came in at some 8,165 tons. The material chosen was Alabama
River gravel for its unique combination of qualities and it's still in use today.
With the Apollo launches the Saturn 5 was attached of a launcher platform and
the launch umbilical tower or LUT. Although it looks like the tower is
holding the Saturn up that was done with hold down arms at the base of a rocket.
The tower was actually there to supply fuel electrical power and crew access
via the nine service arms which can be seen swinging away from the rocket at
launch. At the top of the LUT was the crew access walkway and the
white room from which the crews would then enter the command module. The pad
leader for every manned Apollo mission was Guenter Wendt. He would perform the
final checks, strapped for crew into the capsule, shake their hands and offer
words of support and then close the hatch. The last major piece of
infrastructure was mobile service structure or the MSS. This was a large
lattice like platform which has also moved around by the crawlers. At the top
of this which was a little shorter than the launch Tower was a section that would
completely enclosed the top of the Saturn 5 and the command module to
provide weather protection and access for technicians as well as a cleanroom
for preparations before the flight. The mobile service structure was also used
to place the linear explosive charges that would separate the stages in flight
and charges along the fuel and oxidizer tanks for "fuel dispersion" in
the event that the rocket had to be destroyed if it veered off course during
the launch. The MSS would be moved away from a Saturn 8 hours before the launch
and was parked between pads 39 a and B on the crawl away when not in use.
One of the other jobs that the launcher platform had to do when it was in
position was to precisely match up with the pipe work for the fuel and
electrical supply system which can be seen running up the side of the LUT.
The fuel which for Saturn 5 youth was RP-1, a highly refined version of kerosene
and LOX or liquid oxygen. This was used for the first stage and liquid hydrogen
and liquid oxygen were used for the second and third stages. This was pumped
aboard whilst the Saturn was at the launch pad. Other hypergolic fuels those
that combust on contact with each other were also pumped aboard at this time and
used for the ignition of the F-1 engines and for the lunar landers descent and ascent
engines. In the event of a problem like a major fuel leak whilst the Saturn was
being prepared and providing but it didn't just blow up on a spot
technicians and crews were trained in an escape procedure that used a special
high-speed elevator that would get them from the top of the tower to the
launch platform in under 30 seconds. From here they would then slide down a 61
meet a deceleration slide to the rubber room some 12 meters under the launch pad
and so-called because it was lined with rubber as a shock absorber. This anti
chamber led via a 15 centimeter thick steel blast door to a dome-shaped blast
proof room mounted on giant springs that was designed to withstand the explosion
of a fully fueled saturn v on the launch pad above. This room could hold up to 20
people with enough food and water and an air filtration system for 24 hours. Each
of the seats could hold a fully suited astronaut until such time it was
safe to leave a room via an escape tunnel but emerged some 366 meters away
from the pad. Now the launch platform under the rocket was not a flat surface
it had a 13.7 meter square blast shielded hole for the
rocket exhaust which allowed it to pass down and over the flame deflector. This
double-sided ramp was there to deflect the exhaust and stop it from coming back
up and enveloping the rocket. The 13 meter high ramp which was covered in
flames probe concrete and mounted on rails so could be more easily replaced,
deflected the exhaust down to 18 meter wide flame trenches which stretched a
174 meters and were also made from concrete and lined with
refractory bricks to protect it from a heat. The huge amount of smoke seen at the
launch isn't just rocket exhaust, it's mostly water from the deluge system
flashing to steam from the heat of the exhaust. The water was pumped onto the
launch pad just before takeoff to help protect the platform and act as an
acoustic dampener. In 1974 launch pad 39a was decommissioned and was reconfigured
for the space shuttle the same also happened to pad 39b in 1977. The reason for
the three-year gap was just in case Congress changed its mind and decided to
reinstate the Apollo program. Pad 39B wouldn't be used for the shuttle until
1986 when its first mission was for the ill-fated Challenger STS-51. After the
Apollo missions the mobile launcher platforms were also redesigned for the
shuttles. The launch umbilical Tower was removed and a permanent two-piece access
tower system the fixed service structure the FSS and the rotating service
structure the RSS were built at the launch pad 39A and B. This new structure
also replaced the old mobile service structure. Some of the old structures
were preserved in particular the white room from launch pad 39a which is now at
the Kennedy Space Center Visitor Center. Now just the shuttle stack, that's the
shuttle, the SRBs and the external fuel tank would be carried on
launcher platform. The platform was also modified for the solid rocket boosters
and the exhaust bays were expanded and the flame deflectors were also replaced.
As the shuttle was being tested it became clear that huge acoustic
shockwaves were bouncing off the launch platform and could endanger both crew
and the delicate insulation tiles of the shuttle. This also occurred during the
Apollo launches too but the Saturn was also much higher up and further away
from the engines and the Saturn didn't have any delicate heat-resistant tiles
either. So a new expanded deluge system was also added. This was supplied by a 90
meter high water tower which held 1.1 million litres of water and ran through
twin 2 meter wide pipes to 16 nozzles that sprayed the water over the launch
platform onto the flame deflector. The deluge system will be activated six
seconds prior to liftoff would emptied the 1.1 million liters of water in around 41
seconds and reduced for sound level by half to about a 142db.
With these massive metal structures like the Apollo launch tower
and the Saturn rocket itself there was the ever-present danger of lightning
strikes hitting a fully fueled rocket or causing electronic failures. To mitigate
against this the apollo launch tower used a lightning conductor on the top of
the tower. This provided a cone of protection for the vehicle and the
equipment within it but the Lightning could be still quite close to sensitive
electronics. When the shuttle came into service the electronics had shrunk in size
but also became more sensitive so the Lightning conductor was attached to two
catenary wires to direct the electrical discharge further away. For the now
canceled constellation program it was upgraded once more to the "rolling
spheres" system. Here three 150 meter towers are topped with 17 meter
fiberglass insulators and linked together with multiple
catenary wires around the launchpad which keeps the lightning much further
away. After the cancellation of a constellation program in 2010 and the
final flight of a space shuttle in 2011 the future of Launchpad complex 39 was
in doubt. So in 2013 NASA allowed bidding for the first commercial flights from
pad 39a and a 20-year lease was awarded to SpaceX for the exclusive use of a
launch pad. Unlike Apollo and shuttle SpaceX Rockets
were built horizontally and then lifted up at the launch pad so a new horizontal
integration facility was built at pad 39A. Pad 39B will be used for the SLS
system and that will use the same vertical integration method first used
in the Saturn V and when it's not in use for the SLS, 39b
will be available for other commercial launches. In 2015 a new launch pad called
39C was built and that's for use with smaller launch vehicles. They're also
plans for two more launch complexes LC 48 and LC 49 as the market for
commercial space increases and for use with other rockets like the Blue Origin
new Glen. So what's your thoughts about America's gateway to space
maybe you've worked there or maybe witnessed some of the launches, let me
know in the comments below, so don't forget to check out some of our other
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