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 wouldn’t be able to get the rockets off the ground. What are they? They are Nasa’s Gateway to Space.
The gateway to the moon
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 engineering feats do, and how important are they.
NASA has over 40 launch pads in various locations from the US mainland to the Pacific. Their position chose to get the spacecraft to the correct orbit best and 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.
How tall was Saturn V?
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 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. It became the future for human-crewed and crewless missions, including project mercury and Gemini.
When did President Kennedy choose the base?
In 1961 when President Kennedy announced the moon missions, Cape Canaveral was chosen to be Apollo’s base. 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 three launchpads 39A, B, and C and two more D and E later. 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 looked like concrete hills. Because of how NASA designed Saturn V, there was no permanent launch umbilical tower at the launch pad.
That’s the part 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 Saturn V rocket was assembled vertically and then moved with its tower to the launch pad.
Why did NASA choose a vertical integration?
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 Soviet’s 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 at the launch pad.
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 rocket’s body.
Soviet N1
Some of you will be saying that a Soviet N1 was almost as big as Saturn 5 and 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-store building globally, the VAB or the Vehicle Assembly Building, which at 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 simultaneously, and each of the four doors is the largest in the world to allow a complete Saturn rocket assembly to go out to the launch pad.
Vehicle assembly building
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 Saturn V, 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 that are explosively split at liftoff rather than explosive bolts.
To get the rocket and the mobile launcher platform from the VAB to the launch area, two crawler transporters that drive under the mobile launch platform lifted up and then moved it to the launch complex. When these 2700 ton vehicles were delivered in 1965 for the Apollo program, they were the world’s largest self-powered land vehicles. 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 pads 39A and B.
Saturn V Crawler-transporter
Its 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 crawler way had to be specially built with a shallow friction surface due to the rocket’s weight and the crawler that came in 8,165 tons.
Launch umbilical tower or LUT
The chosen material was Alabama River gravel for its unique combination of qualities and is still in use today. The Saturn 5 was attached to a launcher platform, and the launch umbilical tower or LUT with the Apollo launches. 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.
Who was Guenter Wendt?
At the top of the LUT were the crew access walkway and the white room from which the crews would enter the command module. The pad leader for every human-crewed Apollo mission was Guenter Wendt. He would perform the final checks, strap for crew into the capsule, shake their hands, offer words of support, and close the hatch.
The last major piece of infrastructure was the mobile service structure or MSS. This was a large lattice-like platform that has also moved around by the crawlers.
The Saturn V launch tower
At the top of this, which was a little shorter than the launch tower, was a section that would completely enclose 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 with the fuel and oxidizer tanks for “fuel dispersion” if 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.
What was the fuel for Saturn V?
One of the other jobs that the launcher platform had to do when it was in position was to precisely match up with the pipework for the fuel and electrical supply system, which can be seen running up the LUT side.
The fuel 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.
Explosion of a fully fueled Saturn V
This was pumped aboard whilst the Saturn was at the launch pad. Other hypergolic fuels that combust on contact with each other were also pumped aboard and used to ignition 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 provided. Still, it didn’t just blow up on the 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 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.
The launch platform under the rocket
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 covered in flames probe concrete and mounted on rails so it could be more easily replaced, deflected the exhaust to 18-meter wide flame trenches that stretched 174 meters and were also made from concrete and lined with refractory bricks to protect it from 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.
When was launch pad 39A decommissioned?
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.
Kennedy Space Center Visitor Center
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 pads 39A and B. This new structure also replaced the old mobile service structure.
Some of the old structures were preserved, particularly the white room from launch pad 39A, which is now at the Kennedy Space Center Visitor Center. Now just the shuttle stack, the shuttle, the SRBs, and the external fuel tank would be carried on the 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, huge acoustic shockwaves were bouncing off the launch platform and could endanger both crew and the delicate insulation tiles of the shuttle.
During the Apollo launches, the Saturn was also much higher up and further away from the engines, and Saturn didn’t have any delicate heat-resistant tiles either.
Apollo launch tower
So a newly expanded deluge system was also added. This was supplied by a 90-meter high water tower that held 1.1 million liters 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 before liftoff would empty the 1.1 million liters of water in around 41 seconds and reduce for sound level by half to about 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 tower’s top.
This provided a cone of protection for the vehicle and its equipment, but the lightning could still be relatively close to sensitive electronics.
“rolling spheres”
When the shuttle came into service, the electronics had shrunk in size. They became more sensitive, so the Lightning conductor was attached to two catenary wires to direct the electrical discharge further. The now-canceled constellation program 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.
SpaceX
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 launchpad.
Unlike Apollo and shuttle, SpaceX Rockets were built horizontally and then lifted 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 launchpad 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 commercial space market increases and for use with other rockets like the Blue Origin new Glen.
Thank you for taking the time to read this, and please feel free to browse my website for more exciting facts about the mission to the Moon, and especially Apollo 11.