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Chapter 1: What were the near-disasters faced during the Apollo 11 mission?
57 years ago, we went to the moon. But what appeared to many like an effortless feat was not all plain sailing. This mission nearly failed, and not just once. The entire endeavour was fraught with mishaps, many of them potentially lethal. It took an army of 400,000 engineers
scientists and experts to send Buzz Aldrin, Michael Collins and Neil Armstrong to the moon, but also to bring them home alive. How did they do it, and how much of it came down to sheer luck? I'm Alex McColgan, and you're watching Astrum Extra. Join me today as we uncover the incredible science that made the Apollo 11 mission possible.
We'll explore the launch, journey through space and descent onto the moon, digging into the meticulous maths, manoeuvres and materials that kept the Apollo 11 team alive, that most people don't even know existed.
The next time you go out at night, look up, find the moon, hopefully you can't really miss it, and now imagine going there, travelling more than 384,000 kilometres away from everything and anyone any human being has ever known, and actually landing on the moon. It blows my mind to think about, but nearly 60 years ago, three humans did just that.
On Wednesday, the 16th of July 1969, an estimated half a million people descended on the roads and beaches around Cape Canaveral. They were here to witness the launch of Apollo 11, humanity's first attempt at a manned moon landing. A 110-meter Saturn V rocket shimmered in the distance. The excitement was palpable.
But what none of these lawn chair lounging enthusiasts knew was that a problem was about to unfold that could stop the mission before it even got off the launch pad. Just as the crew arrived on site, a leaking hydrogen replenish valve was discovered 60m up, in the third stage of the Saturn V. Not something you want to see just before you're set to take off.
Because liquid hydrogen is kept at a bone chilling minus 252 degrees Celsius, it constantly boils off into gas as the rocket sits on the pad. So, the replenish valve allowed the tank to be constantly topped up, keeping it at 100% capacity. This was vital.
Without a completely full tank, the rocket would not be able to complete its trans-lunar injection, the burn that would take the craft out of Earth's orbit and towards the moon. The leak was so severe, it could have caused an explosion. So, fuel loading was immediately stopped and the lines were quickly drained.
It was only just over two years since the tragic Apollo 1 fire where three crew members had died, so there was no room for error and certainly no appetite for risk. If the leak remained unaddressed, the mission would be over before it even left the pad.
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Chapter 2: How did engineers address the hydrogen leak before launch?
Normal air is 78% nitrogen, so only taking oxygen meant that they didn't need heavy tanks of nitrogen, and allowed for the use of a lower pressure within the craft. Combined, this made for a lighter weight spacecraft. Win-win, right? Well, not really. Oxygen is very flammable, and this was a contributing factor in the Apollo 1 fire I mentioned before.
After that fire, the gas makeup NASA used was tweaked to a mix of 60% oxygen, 40% nitrogen to make it less flammable. They also pressurized it at a much higher 16 psi, so if any leaks occurred, the air would flow out and not let the humid Florida air in. Once they were safely in orbit, the composition would then gradually be changed to pure oxygen at a lower pressure of 5 psi.
But even this amended launch mix caused problems. As I mentioned, normal air is around 78% nitrogen and 21% oxygen. This mix meant that humans have a significant amount of nitrogen dissolved in our blood. Early testing showed that if astronauts took off like this, when the cabin pressure dropped, the nitrogen formed bubbles in their blood and joints, causing a potentially lethal condition.
It was therefore mandatory for all the astronauts to change their internal makeup before they even set foot on a rocket. They did this by breathing pure oxygen for roughly two hours beforehand to flush out the nitrogen from their blood, which is why you see them attached to what looks like suitcases as they walk to the rocket. That's the oxygen.
Having successfully purged the nitrogen from their veins to survive the launch, the crew was ready to go.
10, 9, ignition sequence start, 6, 5, 4, 3, 2, 1, 0. All engines.
But this was just the beginning of their journey. Now they actually had to get to the moon. The astronauts started to prepare themselves for translunar injection, the engine burn that would send them out of low Earth orbit towards the mysterious moon. This was a particularly dangerous part of the journey, as it required some exacting maths to ensure the correct trajectory.
Get it wrong, and they risked being lost to deep space. And they still had to make it out of the lethal radiation field that blankets the Earth – the Van Allen radiation belts. The Van Allen radiation belts are essentially two concentric donuts of radiation held in place by Earth's magnetic field. Normally, they act as a shield, protecting our planet and us on it from the solar wind.
But for a spacecraft passing through them, they are a high-energy gauntlet. And in the 1960s, the lethality of these belts was a terrifying unknown. Scientists were so concerned that they even conducted high-altitude nuclear tests, including a mission called Starfish Prime, to see if they could physically blow a hole in the belts to create a safe passage for astronauts.
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