Just hours before the lunach of Apollo 11, a NASA engineer was sent to fix a hydrogen leak on the launch tower. The scary thing is, this was 60 meters up and he was standing right next to a partially fueled Saturn V. At launch, the Saturn V contained over two and a half thousands tonnes of propellant. If the rocket suddenly exploded, it would have the force of an atomic bomb – and everyone at the pad would be killed. But if there was an emergency that gave them time to react, like an uncontrolled fuel leak, there was a chance that they could survive.
Located 12 meters below the launch pad is a place called the rubber room, a 1960’s bunker that was designed to save astronauts and crew in the event of a disaster. We modeled the entire thing – and in this article, we’re going to look at what’s inside the bunker and how a group of 20 people could survive in here for several days.
If the Saturn V had exploded on the pad it would have created a fireball that was half a kilometer wide and over a thousand degrees in temperature. And so, in the event of an imminent disaster, workers at the pad would immediately have to make their way to the bunker – and they needed to get there fast. But the bunker was buried deep beneath the concrete pad. So how did they actually get there?
Getting to the underground bunker
The crew had to make their way to level A inside the mobile launch platform, the massive 2 storey structure that supported the Saturn V. Once it arrived at the pad, a small hatch in the platform would connect to a structure that stuck out from the launch pad. This was a 60 meter long slide that started inside the platform and went down through the concrete launch pad until it reached the bunker. At the top of the slide, a sprinkler would spray the crew with water to help them slide down the chute more easily.
In just seconds, they would start to pick up an immense amount of speed as they plummeted into the depths of the launch pad. After falling down a steep drop they would burst into a place known as the rubber room.
This room was lined by thick walls of rubber, some as thick as 60cm, in order to absorb the energy from an explosion. The rubber at the end of the slide was also designed to slow the crew down – but this didn’t always work.
During testing, the water would build up at the bottom of the slide and instead of slowing them down, it caused them to slide all the way to the end at an incredible speed. One worker actually broke several bones in his body after crashing into the end. From here, the crew would make their way through this enormous blast-proof door, where the actual bunker was.
After making their way down the slide, the crew would find themselves in the rubber room. From there, they would enter through a passageway and into the blast room, a dome-shaped room featuring 20 chairs that the crew would strap themselves into.
The dome itself was made out of super thick steel and concrete, capable of surviving a blast pressure of up to 500 psi. To put this into perspective, the blast pressure from an explosion starts to become lethal for humans at around 40 psi.
Blast proof design
In order to protect everyone inside from the immense shockwaves, the entire floor was floating on a series of 24 giant springs. These disconnected the room from the surrounding concrete, meaning the vibrations had less material to travel through. The blast from an explosion could cause an acceleration of up to 75G’s, roughly double what you’d expect to feel in a car crash. These springs would absorb most of that acceleration and reduce it to just 4G’s, keeping the crew inside perfectly safe.
But if such a large explosion occurred, it would create a shockwave so immense that it would travel all the way down the slide in an instant and kill the crew inside. That’s where these enormous blast-proof doors came in. Made from several inches thick steel, these doors would seal the crew inside and protect them from the shockwaves.
These could be locked from either side by turning a wheel which, causing 8 giant pins to hook into the wall. Once the crew were locked inside, they would remain in their seats and wait until the danger had passed. But with up to 20 people in a sealed room, the carbon dioxide levels would quickly start to rise and breathing would become very difficult.
And so, to treat the air, a carbon dioxide scrubber was placed in the center of the room. This machine worked by passing the ambient air through a special filter which would attract the CO2 molecules and separate them from the air.
The clean air was then pumped back out of the machine, keeping the CO2 levels low. In order to create more oxygen, there was a supply of oxygen candles which would burn iron powder and sodium chlorate at around 600 degrees to produce oxygen. For every 1kg of mixture inside, each candle could produce around 6 hours of oxygen per person.
Next to all of this was the storage area which contained all of the food and water supplies. The food was mainly C-rations and K-rations, a type of canned food that was developed during the 2nd World War. The K-rations came in three separate boxes for breakfast lunch and dinner. Each meal contained stuff like meat, cheese, cereal, fruit, biscuits, coffee and cigarettes – giving each crew member around 3,000 calories a day.
There was an industrial waste bin in the center of the room and a toilet placed behind one of the seats. Although it would be an unpleasant place to go, the crew could take care of business with a little bit of privacy.
All in all, there was enough food and water to last for about 4 to 5 days. But in most circumstances, the crew would have only stayed for a few hours until the toxic fumes around the launch pad had dissipated. But how would they actually escape the bunker?
Escaping the bunker
When it was time to leave, the crew had two main escape routes. After leaving the bunker through the other blast door they would enter into a narrow tunnel. This was 360 meters long and would take them all the way to an air-intake building on the edge of the launch site. This building was essentially a giant fan that would suck in clean air and direct it into the rooms below the launch pad.
After walking for around 10 minutes through a very cramped and dark space, the crew could finally escape to freedom. But if the tunnel was somehow blocked from the explosion, the crew would have to go back and choose the alternative escape route.
Right next to the tunnel was a door that led directly into the environmental control rooms, a labyrinth of rooms and corridors beneath that pad that would eventually lead to the outside world.
But with such a large explosion, the damage to the pad would be catastrophic – and NASA were concerned that the crew could become completely trapped inside the bunker. And so, to add to the list of safety precautions, they placed an emergency escape hatch at the top of the blast room. This didn’t actually lead anywhere.
But in the event of the escape routes being blocked, NASA could dig through the concrete and sand within the launch pad to reach the hatch and free the crew. Thankfully, none of this ever needed to be done.
The bunker was never used – and after the Apollo missions ended, it was abandoned, leaving an incredible piece of NASA history frozen in time. Over the years, the bunker fell into disrepair and various animals made their way into the bunker. Now, only a select group of people have access to this old relic, which will most likely remain untouched for many more decades.
