Short History Of... - Apollo 13

Episode Date: February 7, 2022

April 13th, 1970. 200,000 miles from Earth, three astronauts are approaching lunar orbit when they hear a noise. Deep in the spacecraft, a tiny wiring fault has caused an entire oxygen tank to explode. Now, it’s a race against time to save the lives of the crew of Apollo 13. It could have been the worst disaster in the history of manned space exploration. So how did things go so wrong? And who truly deserves the credit for the efforts to get the three men home again? This is a Short History of Apollo 13. Written by Duncan Barrett. Special thanks to Ben Feist of NASA, creator of the interactive multimedia website, ApolloinRealTime.org; and historian Rob Godwin, author of Apollo 13, The NASA Mission Reports. For ad-free listening, exclusive content and early access to new episodes, join Noiser+. Now available for Apple and Android users. Click the Noiser+ banner on Apple or go to noiser.com/subscriptions to get started with a 7-day free trial. Learn more about your ad choices. Visit podcastchoices.com/adchoices

Get groceries delivered across the GTA from Real Canadian Superstore with PC Express. Shop online for super prices and super savings. Try it today and get up to $75 in PC Optimum Points. Visit superstore.ca to get started. It's April the 13th, 1970. 200,000 miles from Earth. Astronaut Jim Lovell is floating in zero gravity. He's on his way to the moon, and not for the first time. Eighteen months ago as the command module pilot of Apollo 8,

Lovell was one of the first three men to reach lunar orbit, truly going where no one had gone before. In their ten circuits around the moon, they'd got a pretty good look at its surface. Lovell even named a distinctive geographical feature after his wife, Mount Marilyn. But Apollo 8 had been strictly a flyby, and the crew returned to Earth without ever touching down. Now, following in the footsteps of Armstrong and Aldrin nine months earlier, Lovell is preparing to make his own first small step onto alien ground. After two days in space, things appear to be going smoothly. Every NASA mission suffers a

glitch at some point, and they've already got theirs out of the way. During launch, one of the engines of the Saturn V rocket that would propel them into orbit shut down early. Admittedly, there was also the last-minute crew change, after the original command module pilot Ken Mattingly was exposed to the measles. But these were just hiccups. Lovell is far too rational to think that Apollo 13 will be unlucky. Indeed, Mattingly's young replacement, Jack Swigert, is doing a stellar job. It's his first journey into space,

but he's already proven more than competent on board the Odyssey spacecraft, as Apollo 13's command and service modules are collectively known. He's got them from Earth orbit almost to the Moon just as competently as his predecessor would have done. It's been a long day. Although night time is a rather meaningless concept in space, the astronauts do their best to preserve a regular sleep cycle. And right now they're ready to turn in. But before they get some much-needed shut-eye, Mission Control have one last request.

13, we've got one more item for you when you get a chance. We'd like you to stir up your cryo tanks. In Houston, Texas, the controllers have been getting some odd readings. They're from one of the tanks holding liquid oxygen used both to power Odyssey's fuel cells and to provide breathable air for the crew. In zero gravity the oxygen has a tendency to settle

so each tank is fitted with a fan to stir up the contents when needed. As instructed, Swigert starts flicking the switches to start the fans. But what he doesn't know is that one of the cryotanks has a fatal flaw. Deep in the bowels of the spacecraft, a tiny spark is emitted from a faulty bit of wiring. In the oxygen-rich environment, it's enough to start a serious fire. Less than two minutes later, the astronauts hear a bang, and the spacecraft shudders violently. Lovell's first thought is that the third member of his crew, Fred Hayes, has been playing another one of his pranks.

Only ten minutes earlier, Hayes sent Lovell's heart racing when he flicked open a repressurization valve, causing a noise loud enough to make the other astronauts jump. Annoyed, Lovell glances over at Hayes. But what he sees on the other man's face now is not the smug satisfaction of a prankster, but a look of pure fear. It wasn't me, Hayes tells him weakly. As warning lights start flashing on around the capsule, Swigert voices his concerns to ground control. They ask for confirmation, which Lovell duly gives. Houston, he tells them, we've had a problem.

It could have been the worst disaster in the history of manned space exploration. And yet, in many ways, the efforts to save Apollo 13 would prove to be NASA's finest hour. For the three astronauts, Lovell, Hayes and Swigert, chances of survival were slim. Their lives were in the hands of a team on the ground. Who would have to reinvent rocket science almost overnight in order to save them?

But less than a year after the first moon landing, how had NASA found itself in such a perilous situation? And who truly deserves the credit for the efforts to get them home again? I'm Paul McGann, and this is a short history of Apollo 13. At Mission Control in Houston, the explosion has triggered a string of alarming readings. Ben Feist is a historian at NASA and the creator of the interactive multimedia website, Apollo 13 in Real Time. Before the crew even called anything down, the people on the ground that had asked for that cryotank stir saw everything go haywire. And they started talking, what just happened? Do we have bad telemetry? What's happening? And then you hear the call down, we've got a problem here. And then no one was listening to what the crew had said because they were trying to work what was going on.

And then Jim Lovell got on the commander and they said, say again. And he said, Houston, we've had a problem. In in the control room responsibility for working out exactly what that problem is falls to Cy Liebergot the electrical environmental and consumables manager through his headset Liebergot is in constant communication with a team of engineers working in a back room to begin with though Liebergot can't quite believe what he's seeing. In fact, there are so many errors flashing up on his board at once that he tells flight director Gene Kranz it's an instrumentation error rather than a physical issue with the spacecraft.

The data he's receiving just can't be accurate. It's a mistake that will go on to haunt him for the rest of his life. As the minutes tick by, it becomes clear there's nothing wrong with Odyssey's instruments. One desk away from Liebigot, capsule communicator or Capcom, Jack Lausma, is speaking to the astronauts. Fred Hayes has some worrying information. And we hit a pretty large bank associated with the caution and warning there. Worse still, Jim Lovell has been taking a look outside. He doesn't like what he sees.

You see on our list today, looking at the ads, so we are betting something. He doesn't like what he sees. Meanwhile, Liebigott is still trying to get to the bottom of things. He started working the problem of trying to figure out what had gone wrong and how to remedy the situation. And as they tried things and as they moved forward through that problem solving, it got worse and worse. And the scope of the problem eventually got to the point where he said, I think we may have lost an oxygen tank. You know, he kind of has this realization. He's almost talking to himself when he says it at one point. As it turns out, Liebigott is right. Although no one yet has the full picture of what happened to the Odyssey and why,

the team on the ground are beginning to understand its implications. The explosion of the faulty oxygen tank took out a sizeable chunk of the service module, attached to the command module the astronauts are sitting in. And not only are oxygen levels flatlining, but Odyssey's fuel cells are shutting down as well. The spacecraft is losing electrical power. Liebigot begins working through possible solutions. They start trying things, you know, what if we shut this valve?

What if we do this? What if we do that? And they got to a list of things, of valves they wanted to close, that were react valves. And there is a flight rule that they had created when they created the flight plan that said, if you close the react valves, then the landing on the moon does not occur. In the NASA hierarchy, the flight director on shift has absolute authority. While a mission is running, not even the president can overrule him. But in a situation such as this, a mission can effectively be aborted by someone much further down the chain of command. So NASA excelled at this excellent approach to decision making where they pushed the decision down the hierarchy as far as possible. So it's the opposite of what we're all probably used to

in a corporate environment where big decision needs to be made. So you ask your boss and you keep going up. If it's a bigger decision, you've got to go further up the chain. It was the opposite at NASA. The person that knows the most about whether that decision should be made is at the bottom. They're the expert in that system. So that all the people up the hierarchy can do is support that decision and say, you are the one that knows the most about the situation inside Liebergot. You make the choice. Just how it worked. For Liebergot, the pressure is almost unbearable. In mission control, every console has a pair of handles on either side of it, and right now he's gripping onto both. As he'll later admit, the thought briefly crosses his mind of getting up and simply walking out of the room. But hard as the situation might be,

Liebigot knows what has to be done. He continues methodically working his way through a list of possible solutions. He is supported both by the engineers working underneath him in a backroom, and by the flight director of the new shift, Glyn Lunney. Liebigott's replacement is ready to take over too, but this is the most important seat in the control room. It's hardly the time to swap personnel. In fact, the next job on Liebergot's list is a decision which, thanks to the mission's inviolable flight rules, will mean cancelling the landing on the moon. So he got to the point where he said, I want to try closing these react valves and see if that stops the leak that we're seeing.

And they said, are you sure? You know, and Asai aside libra got i think was 32 years old you know he was this young engineer and he's just working the problem he's doing what his expertise is telling him to do and and glenn lonely says i want you to look at that again and and i want you to tell me if you really want to close those react valves and they all knew what that meant they weren't saying you're going to scrub the moon landing are you crazy they were just, are you sure? And he said, I'm sure. I think I'm out of ideas. I think this is what we need to do flight. And he said, all right, do it. And in that moment, they called it up and the crew again said, are you sure? They didn't want to lose landing on the moon and they closed those react valves and it still had no effect. So then they got into like disappointment.

Oh no, we're not going to land on the moon. And eventually they got to the point of, oh my goodness, we have to save the crew's lives. From the director of The Greatest Showman comes the most original musical ever. I want to prove I can make it. Prove to who? Everyone.

So the story starts. Better Man, now playing in select theaters. Power to the command module is rapidly failing, but the crew do have a lifeboat of sorts. The lunar module. The idea of using the LM, or LEM, in an emergency has been floating around NASA for some time, but no one has yet trained directly for this contingency, and no detailed plans exist for how to do it. First though, a decision must be made about the route the crew will take home. Stranded four-fifths of the way to the Moon and drifting into its sphere of gravitational influence, there are two options available. They can go for a direct abort, firing the service module engine to bring the Odyssey to a stop, and then powering back towards Earth.

Or, they can try a free return trajectory around the far side of the Moon. they can try a free return trajectory around the far side of the Moon. This way, they'll use the force of its gravity well to propel them home. The latter option will add an extra two days to the journey. That would give the team longer to come up with a new plan to re-enter the Earth's atmosphere. And it avoids relying on the engine in the service module, which may or may not have survived the explosion. But there are downsides too. As things stand, the astronauts don't have enough electrical power or water to survive the longer trip.

But at least the free return buys the ground crew time to come up with some workarounds. By now it's all hands on deck at Mission Control. Three of the four flight directors, Gene Kranz, Glenn Lunney, and Milton Windler, are debating the best course of action. Windler favors risking the faster direct-aboard procedure, even though it means jettisoning the lunar lander along the way. But Kranz and Lunny are in agreement. The free return around the moon is the safer option.

Despite Weindler's reservations, once the decision is taken, everyone is on the same page. And everyone has a part to play in securing a safe return for the astronauts. Lunny, Weindler and the final flight final flight director Gerald Griffin will take turns manning mission control with their teams. Meanwhile Krantz will take his own group, now nicknamed the Tiger Team, to a back room and come up with a rescue plan.

It's 10.30pm when the Tiger Team assembles in one of NASA's data rooms. It's a large square office with nowhere near enough chairs for the number of people crammed inside. The air is thick with cigarette smoke and the tension is palpable. Flight controllers are kneeling on the floor, studying reams of orange recorder paper spat out by their machines, trying to find clues to the cause of the explosion. Engineers and support staff perch on the edges of grey government tables, waiting for Kranz to issue his orders. One by one he assigns them to their new roles. A flight planner is tasked with developing a work plan, listing every decision that will

need taking and when. Another man is charged with developing a procedure for re-entry. Responsibility for consumables, electricity, water, heating and breathable air goes to another of Krantz's trusted experts. It's his job to ensure that those precious resources stretch to accommodate the longer rescue mission. Someone else is responsible for the adaptation of the lunar module. It was intended to carry two men on a two-day mission.

Now it needs to become a lifeboat capable of supporting three for twice that long. Over the next fifteen minutes, everyone in the room receives their new assignment. Then it's time for a bit of inspiring oratory. I don't give a damn about the odds, and I don't give a damn that we've never done anything like this before, Kranz tells them. This crew is coming home. 200,000 miles from mission control, the three astronauts are in the process of abandoning the Odyssey module and firing up the LEM. But before the Odyssey computer shuts down altogether, Commander Jim Lovell must copy down some crucial navigational data.

Rob Godwin is founder of Apogee Books and author of Apollo 13, the NASA mission reports. Even though you had two spacecraft, a lunar lander and a command module, they used different guidance settings between the two systems. And when they were docked together, they were obviously facing in different directions relative to their guidance system. One was pointing one way and one was pointing the other because they were docked nose to nose. So to transfer the guidance from the command module to the lunar module was something that they hadn't trained for extensively.

And so they had to work it out on the fly. Well, luckily for them, Jim Lovell was really good at math. Having said that he had to use you know a slide rule and a pen and paper to try and figure out how to set the guidance numbers from the command module over to the lunar module and he knew that he only had about 15 minutes to do that because the electrical power in the command module was dying rapidly. 15 minutes to do that because the electrical power in the command module was dying rapidly exhausted stressed and overwhelmed by the events of the past couple of hours lovell is beginning to doubt his own mathematical ability unsure of his calculations he asks capcom jack lausma to check them with his guidance team on the ground. OK, I want you to double-check my wrist and dick

to make sure we've got a good course of line. The roll count angle was minus 2 degrees. Command module angles were 355, 57, 167, 78, 351, 87. OK, Jim, we copied the roll count to minus 2.0. Command module was 355.57, 167.78, 351.87. It's an agonizing couple of minutes, but finally, Lausner reassures him that the arithmetic is correct. But for Lovell and Hayes, it's now a race against the clock.

They have to get the LEM up and running before the command module shuts down. It's sort of his night shift at this point and he's worrying. He's concerned that he's not going to get it done. But anyway, they get the numbers across from the command module to the lunar module just before they have to shut down the power system in the command module. And at that point they lose the computer. While Jack Swigert supervises the shutdown of the command module, Lovell and Hayes work to get the LEM online. This is normally an elaborate two-hour process,

but with help from the ground, they're able to get it up and running in a matter of minutes. They're able to get it up and running in a matter of minutes. Swigert joins them, relinquishing his piloting duties. From now on, until they begin the re-entry process, he will be little more than a passenger. As the mission's commander, Lovell takes the hot seat, assuming direct personal responsibility for getting his crew on course for Earth. Each astronaut was trained to fly a specific module, intensely trained to fly a specific module. So as it happened, Jack Schweigert was a command module pilot that had been trained to fly

the command and service module. And Jim Lovell and Fred Hayes were intensely trained on how to fly the lunar lander, to land it on the moon and come back from the moon. And so if you were going to pick somebody who was going to fly the lunar lander, Lovell was the obvious choice to do this. But he was also the commander, and I think there was a certain level of responsibility there that he was going to do this. One thing no one has trained for, however, is flying the LM while it's attached to the other modules.

When the team on the ground call for minor course correction, Lovell finds maneuvering it much harder than he expected. About five and a half hours after the explosion, they had to use the lunar lander to maneuver the entire stack of three modules into a slightly new trajectory. This is called a mid-course correction. And normally, all of that would have been done by the thrusters on the service module. But now, Jim Lovell was going to have to figure out how to fly this very unwieldy stack of three modules using the thrusters on the lunar lander. Nobody had ever done this before. Nobody ever trained for this before. The mass of the stack was generally located in the command service module area. That was where the center of mass was. So all of the weight was in the heavier end of the spacecraft. And by comparison, the lunar lander is quite light. So now it's sort of like trying

to like balance something on the end of a pencil because you're now doing all the maneuvering from the end of the pencil and all of this weight is on the other end so level had to figure out how to do this he had to essentially learn how to re-fly the lunar module from scratch fortunately though lovell is a quick learner, not to mention an experienced pilot. Using just the LEM engines, he is able to coax the unwieldy stack of three modules onto the correct course towards the Moon. Travelling at over 3,000 miles per hour, it's an impressive bit of piloting. Thanks to their new trajectory, the astronauts will soon be travelling further from Earth than anyone before them.

As they slingshot around the far side of the Moon, the blackout of their communications with Houston will be longer as well. The spacecraft is close enough to the Moon that when it goes behind it, it blocks view of the Earth completely and no radio transmissions can go through it. It's a period of time that all the astronauts have talked about is like very peaceful because they don't have mission control in their ear anymore, telling them what to do. But on Apollo 13, because it was not a, every other mission went into lunar orbit, which is very low in orbit. And this being a free return is the only one, it's the only mission that

had a free return trajectory. They went very far behind the moon before they came back compared to the other Apollo missions. So I think Apollo 13 holds the record of the furthest away any humans have been from the Earth. For the astronauts, this period of lunar occultation, as it's officially known, lasts about 25 minutes. They're plunged into darkness, with their headsets falling silent as the signal for birth is cut off.

Looking through the windows, they can't even make out the lunar surface, just an eerie black shadow where no stars can be seen. Gradually though, as they curb around the moon's gravity well and begin their journey back towards the Earth, a sliver of light breaks through the darkness. Swigert and Hayes stare transfixed, but Lovell is in no mood for sightseeing. Right now all he wants is to get his crew back home. For the three astronauts, this two and a half day return journey will be the most miserable part of the trip. In order to stretch their battery power out long enough to make it back to Earth, they

need to cut their electricity usage down to just 12 amps an hour. That's roughly what it takes to keep a pair of car headlights switched on. One by one, Lovell and his team are instructed to shut down the LEM's non-essential systems. The lights are extinguished, the computer is taken offline, the heating system is deactivated, and the temperature drops to only a few degrees above zero. deactivated, and the temperature drops to only a few degrees above zero. The state-of-the-art lunar lander is now little more than a tin can drifting through space. But electricity isn't the only thing that needs to be rationed.

Part of the problem with losing the electrical system on the command module is that the fuel cells on the command module, one of the byproducts of it was drinking water. You had to have water. You can go for days without food, but you can't go for very long without water. Add to that the fact that temperature is now down to freezing or almost freezing. And you've got a very serious situation, which is going to cause problems with people's cognition and thinking. And it got to the point where they literally put some stickers or tape over certain switches that could have aborted certain parts of the spacecraft just in case they got so punchy that they threw the wrong switch. As if the lack of water threatening the crew's cognitive abilities wasn't worrying enough,

they're also becoming seriously sleep deprived. The explosion happened just as they were about to bed down for the night, and now, 24 hours later, Lovell has barely slept a wink. On the ground, the chief of the astronaut office, Deke Slayton, is worried about the crew. He instructs CAPCOM to pass on a message. Deke says get a night's sleep. He says you've been working hard and you ought to relax a little bit and be ready for tomorrow. But, three minutes later, worried the message is not getting through, a testy Slayton gets

on the line himself. We think you guys are in great shape all the way around. Why don't you quit worrying and go to sleep? One thing keeping the astronauts from their beds is the dwindling quantity of breathable air. Their electricity usage and water consumption have been carefully rationed down to a bare minimum. But, short of holding their breath until they make it back to Earth, there's little they can do to limit the increase in CO2.

Jim Lovell shares his concerns with CAPCOM Jack Lausma. Okay, Jack, my only other concern now is the CO2 rise of the spacecraft. I guess you're keeping a handle on that. That's affirmed, Jim. We have you up to 10.6 now and we're willing to go a little higher on that. We just don't want to go to sleep here and forget about the noise deal, too. Roger. We're watching it for you. Okay, Jim, we estimate we've got one more hour on the primary cartridge and six or seven hours on the secondary. Right. Yeah, we know. Thank you.

The cartridges Lovell and Lausamer are discussing are known as CO2 scrubbers. They chemically extract carbon dioxide from the cabin so that the crew don't suffocate on their own outbreath. But the LEM was only designed to hold two people for 45 hours. Now, there are three astronauts living inside it, and they're still two and a half days away from Earth. Fortunately, there's another set of scrubbers in the command module.

But as things stand, there's no way of getting to work with the LEM systems. But as things stand, there's no way of getting to work with the LEM systems. The problem that was faced is that the scrubbers that take the CO2 out of the air, the ones in the command module were a different shape to the ones in the lunar module. One was a cylinder and one was a cuboid. So you couldn't take those scrubbers that hadn't been used yet in the command module and bring them through and put them into the environmental control system in the lunar lander because they were the wrong shape. It was literally a case of round peg square hole. You couldn't move one from one to the other.

So there's a problem. If you can't fix this problem, somebody's going to suffocate. Lovell knows that if the crew on the ground can't come up with a solution in time, he might have to make a very difficult decision. There were always protocols in place for catastrophic mission accidents, which might involve very, very difficult decisions. For example, somebody giving their life to save the others. This had certainly been considered during the mission of Apollo 11 when Neil Armstrong and Buzz Aldrin went down to the lunar surface and Mike Collins was merrily going around the moon in a perfectly functional spacecraft waiting for them to come back. Had the engine not fired on the lunar

surface and allowed the Aldrin and Armstrong to make their way back up, they had already written a speech for President Nixon to announce this terrible tragedy. And Mike Collins had already been trained and prepared for the idea that even though his crewmates might have been on the lunar surface still alive, there was no way that they could get back to dock with him. And so he'd be coming home alone as a very lonely command module pilot. And in the case of Apollo 13,

very tough decisions probably went through people's minds. Were they going to have to abandon one guy to his fate? The only way that they could possibly have done that, I think, in the circumstances of Apollo 13, would have been for one of them to go into the command module and close the tunnel and essentially give his life and suffocate in there. And then later they would have opened the tunnel again and powered the thing back up. It's down to Gene Kranz's Tiger team at Mission Control to come up with a solution to the problem.

But with the astronauts still hundreds of thousands of miles away, the materials at their disposal are extremely limited. Well, the guys on the ground knew that they could only work with what the crew up in space had on hand. An assortment of bits of pieces of paraphernalia, bits of spacesuits and food bags and water bags and clothing and anything that they could find were brought into a room at mission control. And then a bunch of very bright guys started to figure out how do you use this to reroute the airflow from the spacecraft into this wrong shaped canister and then back out into the environment of the spacecraft so that it

could do its job so it turns out the best way to do this was to combine some plastic bags with some duct tape and i believe there was a sock involved as well and essentially what they were creating was some on-the-fly plumbing that would allow the airflow to go out of this round pipe into a square box and then back out into the spacecraft through you know the environmental control system. All in all, it takes around 60 NASA personnel to design and build the new adapter. But making a prototype in Houston is only the first step. Next, Capcom Joe Kirwan must read detailed instructions up to Jack Swidert so that he can craft one of his own.

With no way of sending images up to the spacecraft, Kerwin is forced to rely on his powers of description. The first thing we want you to do, and we'll do this on one canister and then let you go ahead and repeat it on the second. So take one of the LCGs and cut off the outer bag by cutting along one of the heat seals. Do it carefully and close to the heat seal because we may have to use the outer bag if we damage the inner bag. So go ahead and do that and we'll do the next step. After almost an hour, Swigert puts the finishing touches on his adapter.

Now comes the moment of truth. The astronauts fire up the command module scrubbers and anxiously watch their gauges. Sure enough, the levels of carbon dioxide in the cabin begin to go down again. The three men face another two days in the freezing cold Lem, but at least they won't suffocate before making it back to Earth. It's a gruelling journey,

and by the time they begin approaching their home planet, the astronauts are struggling. Swigert's feet are damp and freezing after he spilled some of the crew's precious water ration on them. Hayes, meanwhile, has grown so dehydrated that he's developed a bladder infection. And with his immune system compromised after almost a week spent in zero gravity,

it's already begun to spread to one of his kidneys. But the crew will need their wits about them if they're to re-enter Earth's atmosphere safely. The stakes are as high as they get, with no room for error. Instinctively you would think, well, why didn't they come into Earth orbit and then maybe have another spacecraft go up and rescue them? The problem with that is that to stay in orbit around the Earth, you're moving at about 17,000, 18,000 miles an hour. The return speed from the Moon, you're essentially falling from the Moon a quarter of a million miles towards the Earth. And as you fall, the Earth's gravity

starts to really tug on you. And by the time you hit the atmosphere, you're moving at 25,000 miles an hour. So to go into Earth orbit, you've got to drop your speed from 25,000 miles an hour down to 17,000 miles an hour. And that requires a huge amount of rocket fuel that they just didn't have. Instead, the crew will have to perform a series of maneuvers on the fly to ready themselves for reentry without slowing down.

First, they must jettison the service module. Then, they'll need to power the Odyssey command module back up, since it's the only part of the spacecraft capable of surviving re-entry. Finally, the lunar lander will need to be ditched as well, before the astronauts begin their descent into the atmosphere. And all this in the space of just a few hours. Ejecting the service module is a relatively straightforward procedure. And once it's done, the men get their first glimpse at the damage caused by the explosion three days earlier. Well, the service module was where the explosion took place, and nobody had

ever put eyeballs on this up to that point. So they didn't really know exactly what had happened, how close to, you know, deaths they had been. So at that point, Jack Schweiger threw the correct switches and ejected the service module and they had to be certain when they did that, they navigated the command and lunar module away from it so that they didn't collide with each other. And then they were able to see the service module fly by the window. Lovell and Hayes, Phil, Capcom, Joe Kerwin in on what they see. Okay, I've got her right here, sir.

And there's one whole side of that spacecraft missing. Right by the high-gain antenna, the whole panel is blown out, almost from the base to the engine. Okay, Jim, we'd like you to get some pictures, but we want you to conserve RCS. Don't make unnecessary maneuvers. Man, that's unbelievable. Yeah, Joe, it looks like a lot of debris

is just hanging out to the side. Here's the S-band antenna. Roger, Jim. Seeing the extent of the damage, the crew realize how lucky they are to be still alive. But there's a disquieting detail that no one even dares to discuss. They could see that the entire side panel,

one of the panels on the side of the service module was gone from where the command module was mounted all the way to the big rocket engine at the bottom. Now, they weren't aware of that until that moment. And the implication of that was profound because that meant the damage could have actually affected the heat shield on the bottom of the command module. Everybody knew that. There was no redundancy in that case. If the heat shield was damaged by the explosion, it was the last straw that broke the camel's back. They wouldn't be able to do anything about it. And so they didn't even really discuss it.

As the Columbia disaster will tragically demonstrate three decades later, damage to the heat shield can be catastrophic. Every Apollo mission was coming in at absolutely blazing speed because that's how fast

you have to go in order to break the Earth's gravity well. And similarly, to come back from the moon, they're falling into that gravity well. So you can imagine they've been falling for three days and they're about to potentially hit the

ground. And they're going so fast that the atmosphere immediately turns the heat shield, parts of the heat shield into plasma. And the bottom of the heat shield breaks free and starts falling off, taking energy with it. This is called an ablative heat shield. It's designed to be used once and to break away and to fall away as the command module re-enters the Earth's atmosphere. If Apollo 13's heat shield fails, the enormous efforts to keep the crew alive over the past few days will have been for nothing.

The three men will be incinerated in the atmosphere. But hurtling towards the Earth at tens of thousands of miles per hour, there's no way for anyone to check it. In the meantime, the rescue mission must proceed as planned. It's time to bring Odyssey back online. Down in Mission Control, a new Capcom is ready and waiting. Apollo 13's original command module pilot, Ken Mattingly. Over the course of the next two and a half hours, he will talk his replacement Jack Swigert through the intricate process of waking up the dead spacecraft. It's something that has never before been attempted in space. And now they've got to very gingerly start to turn the spacecraft back on one switch at a time.

And back on the ground, Ken Mattingly, who was the original command module pilot that couldn't fly because he had been exposed to the measles, had been sitting in the simulator for days, trying to figure out how to bring the spacecraft back up to power without using more power than they had. They only had the amount of power for a light bulb. It was a ridiculously small amount of power that was available to them. He'd spent days figuring it out, figuring out how to actually do this and still have enough power to get the guidance information into the computer, have enough power to ignite the explosives that were going to put the

parachutes out, and all this kind of stuff. So it's absolutely critical that they get it all in the right order. And geniuses abound at NASA, and these guys had figured it all out. And they got back into their seats and then closed the tunnel hatch and the command module was back up and running. With Odyssey functioning again, it's time to say goodbye to the lunar module, the lifeboat that has kept the astronauts alive over the past few days. Normally the procedure for jettisoning the LM would be accomplished using pyrotechnic charges, but right now no one wants to risk using them.

Fortunately, NASA contractors north of Grumman, who built the lunar module, know who to ask about a workaround. The guys at Grumman contacted some university professors at the University of Toronto Institute for Aerospace Studies in the middle of the night phoned these guys up and said, you guys are the world's top guys on gas dynamics experiments. Can you tell us how much air we should leave in the tunnel so that when we detach the latches, it will push the lunar module away at a speed that it won't collide with the command module. And these guys at the University of Toronto got this phone call in the middle of the night, couldn't believe what they were hearing. Can you help us save the crew of Apollo 13?

And so they went out and pulled up all the numbers that they had. They were on the phone. They had kept an open phone line to Grumman on the ground and discussed the mass of the spacecraft and the volume of the tunnel and how much air could be left in the tunnel such that it would not damage anything. And so they gave them the numbers back over the phone and said, if you leave this exact amount of air in the tunnel, when you fire the latches, the lunar module will move away at just the right speed without having to fire any explosives. And so they did that and it worked.

And the lunar module moved away at just the speed they wanted it to and the direction they needed it to. And now the crew were sitting in their battery-powered command module. It's been three and a half days since the explosion that crippled the Odyssey, and now at last the crew are preparing for the most dangerous part of the mission, re-entering the Earth's atmosphere. Everyone knows it's touch and go whether their heat shield will make it through intact. Once re-entry begins, communications with Houston will go offline. But before that happens,

Jack Swigert has some final words for Capcom Joe Kirwan and the team on the ground. I know all of us here want to thank all you guys down there for the very fine job you did, Swigert says. On the ground, Kirwin understands the subtext. I tell you, we had a good time doing it, he tells the crew. By now, the whole world is watching. It's Friday lunchtime at the Lovell home in Timber Cove, Houston. Jim's wife Marilyn is surrounded by family and friends, anxiously glued to their TV screen. Across America, more than 40 million people are tuning into the live footage.

Millions more are watching around the globe, across every time zone. In the Vatican City, the Pope has been leading prayers for the crew's safe return. NASA's public affairs team is providing live updates on the state of the mission. Once you hit the entry interface during re-entry, once the command module starts to hit the very tenuous wisps of atmosphere, you know, there's really no going back. And at this point, they have no way of knowing whether the heat shield is going to work.

really no going back. And at this point, they have no way of knowing whether the heat shield is going to work. It had to withstand these incredibly hot temperatures, and it had to hit the atmosphere at exactly the right angle such that the spacecraft doesn't just melt. And bearing in mind that they're flying by the seat of their pants and the guidance has been pretty shaky for the last couple of days, once you hit the atmosphere at that point, shaky for the last couple of days. Once you hit the atmosphere at that point, the air around the spacecraft, as it gets thicker and thicker, it starts to being hit by the spacecraft. It's like a bullet hitting the air. It starts to ionize the air around the spacecraft. The electrons start stripping away from the atoms of air, and that creates interference around the spacecraft, and you lose communication with the ground. So now you're going to hit this moment in time where you can't even speak to them.

You don't know what's going on. Two minutes to go until entry. Velocity now reading 35,646 feet per second. Range to go 1,961 nautical miles. At Mission Control and around the world, everyone holds their breath. Until Capcom Joe Kirwan hears from the crew, there's no way of knowing whether or not they've survived. Apollo Control, Houston.

We've just had loss of signal from Honeysuckle with Apollo 12. Fly over. Ordinarily nasa can pinpoint the duration of communications blackout pretty precisely so they know when to expect to hear from the astronauts but at the designated time the air force's aria aircraft which relay the signal between ground and the capsule, are picking up nothing. Apollo 13 should be out of blackout at this time. We're standing by for any reports of ARIA acquisition. As the seconds tick by, the mood in the control room grows increasingly tense.

Flight Director Gene Kranz, now back in the center seat, asks his network controller for an update. Network, any reports of ARIA acquisition yet? Not at this time. Less than a minute later, Kranz asks again. Network, no ARIA contact yet? Not at this time. Almost a minute and a half behind schedule, ARIA contact is finally established. CAPCOM Joe Kerwin tries to raise Jack Swigert in the command module.

Odyssey, Houston, standing by, over. OK, Joe. OK, we read you, Jack. Thankfully, they came out of the blackout. And of course, the moment that they did, again, was a moment of sheer, utter glee, both with the families and mission control, but indeed around the world. I can remember it vividly that I was watching it, biting my fingernails. that I was watching it biting my fingernails. And when somebody suddenly got a camera on them and the chutes were deployed,

I mean, it was a moment of real unbelievable relief. I mean, you just couldn't believe that all of this had happened and that they'd pulled it off. So many things could have gone wrong, but they landed within three and a half miles of the ship. And, you know, they were able to put cameras on them and, you know, film the actual moment of splashdown.

After almost a week in space, the Apollo 13 astronauts are safely back on terra firma. When they arrive in Hawaii, President Nixon is waiting with medals for them. Across the planet, people of every nationality are united in relief. But for NASA, there are questions that will need to be answered. How could this disaster have happened in the first place? And how can it be prevented from ever happening again?

A congressional hearing is convened to get to the bottom of things. When you think of how many things that could go wrong in a spacecraft that complicated, bear in mind it was the most sophisticated machine ever built by man at that time. There were millions of components in the Apollo-Saturn structure. This whole thing had been precipitated by one tiny circuit that had been overseen. The same circuit had already flown to the Moon four times successfully. To put a lot of heat

on them for how could this possibly have happened seems a little unfair. But the congressmen wanted to make sure that they had answers. And so they concentrated on certain things like why were the carbon dioxide scrubbers incompatible between the command module and the service module? Why was there not NASA's traditional double redundancy in place? And part of that investigating committee, Neil Armstrong sat on that committee.

And Neil was a very sober, dry, laconic, very clear-headed guy. And when that was brought up in his typical way, he said, maybe we should change that. You know, it was not to coin the phrase rocket science to figure out that that was an oversight. Nine months after the return of Apollo 13, Apollo 14 sets off for the Moon,

now equipped with spare batteries and oxygen supply and a redesigned stirring mechanism for the cryotanks. The Apollo program has barely even stalled. But the legacy of the disaster casts a longer shadow. Perhaps the biggest impact of the Apollo 13 mission was a lack of nerve by the politicians. They decided that Apollo 18 and Apollo 19, which were scheduled to go to some very interesting places on the moon, be canceled. Even though the hardware had been built, they decided, nope, we don't want any more of these

chances taken, and it's time to move on. But the 2005 Apollo stacks for 18 and 19 ended up becoming lawn ornaments. It's very sad, but today you can go and stare at them in wonder. More than 50 years on, though, the Apollo 13 story continues to inspire new generations at NASA. The men and women that worked in mission control at that time were imperfect people, but they were perfect in that moment. We have recordings of what they actually did, and we get to see, we get to hear what their phone calls home sounded like. We get to hear what they were actually thinking in private to each other. They still complained about things. You can actually hear in some of the recordings, you know, they're complaining about how much overtime they're putting in. Then when the chips were down and they had to all perform, they literally

performed at perfection level for human performance and to such a level that it warranted them receiving the Presidential Medal of Freedom for their efforts. And I think that's an important thing for people to realize. You don't get to say things like, oh, that's back when we had the right stuff, and now people are different. They were just lumps and warts like we are today, but they had trained and were focused, and they had enough confidence in themselves to be able to do what they did. Next time on Short History Of... We'll bring you a short history of the Underground Railroad. So often, we in this country, not only in this country,

see the races as tragically at odds with each other and without a sense of shared community. But in the Underground Railroad, ordinary people were putting themselves on the line to assist each other and taking risks for each other. And I think if there's nothing else that we can learn today from the history of the Underground Railroad, it's that that kind of collaboration and cooperation is possible. That's next time on Short History Of.