Cold Open

It’s the evening of April 13th, 1970, two hundred thousand miles from Earth, and two days into Apollo 13’s mission to land on the moon.

Inside the spacecraft, Jack Swigert, a square-jawed astronaut from Colorado, floats through zero gravity to the main control panel. The other two members of the crew, lunar module pilot Fred Haise, and commander Jim Lovell, are busy packing away equipment. But there’s a routine task Mission Control wants Jack to complete. The spacecraft is equipped with vital hydrogen and oxygen tanks that help power the systems on board and provide air for the astronauts to breathe. But in the deep cold of space, these tanks require regular stirring. So they’re equipped with fans to churn up their contents. Now, Mission Control wants Jack to turn on one of these fans.

So he reaches over to a panel… and flicks the necessary switches. Then Jack waits a few moments for the fans to do their work… before switching them off again.

But then, from somewhere behind him in the spacecraft… Jack hears a loud, dull thump. The spacecraft shudders, and Jack glances back at his Commander, Jim Lovell. They both have the same thought: this must be a joke and stare daggers at the third crewman, Fred, who’s been playing tricks on them ever since they left Earth’s orbit. But Fred looks back nervously. Whatever the noise was, he had nothing to do with it.

Then the master alarm goes off: a warning that something serious is wrong with the spacecraft. As the other two astronauts hurry to the control panel, Jack’s eyes flash across the gauges and dials in front of him. His face pales when he sees that the command module is losing power and spinning off course. Keeping his voice calm, he radios Mission Control:

"JACK: Okay, Houston, we’ve had a problem here."

Around them the spacecraft creaks and twists. Grabbing the thruster controls, Jack struggles to keep Apollo 13 from spiraling into space. Looking out a side window, commander Jim Lovell spots venting gas. The hazy vapor drifting away from the spacecraft is oxygen. It’s then that the astronauts of Apollo 13 realize that they haven’t just lost their shot at a moon landing, they’re in danger of losing their lives as well.

Apollo 13 is America’s third lunar landing mission. Astronaut Neil Armstrong led the historic first landing on Apollo 11 last July. Apollo 12 followed in November. And next, it was the turn of Jim Lovell, Fred Haise, and Jack Swigert. Their mission seemed routine. Unexciting even. Unlike previous Apollo missions, this crew’s broadcasts from space weren’t even shown on American television networks. But Apollo 13 quickly turned into something much more dire. The crew’s voyage to the moon was transformed into a desperate race to get home following a devastating explosion that crippled their spacecraft on April 13th, 1970.

Introduction

From Noiser and Airship, I’m Lindsay Graham and this is History Daily.

History is made every day. On this podcast—every day—we tell the true stories of the people and events that shaped our world.

Today is April 13th, 1970: The Flight of Apollo 13.

Act One: Lifeboat

It’s late evening on April 13th, 1970, half an hour after the explosion on the spacecraft Apollo 13.

Astronaut Jack Swigert glances out of the window. With each passing moment, the crew of Apollo 13 are speeding further away from Earth, and getting closer to the moon, which grows ever larger outside. Jack wants to fire the main engine, turn the spacecraft around and get back home. But he knows that’s impossible. The explosion has damaged so many systems that even attempting to light the main engine might cause the whole thing to blow.

Jack glances at his crewmates, floating beside him in front of the control panel. They all know the ship is dying. What they need is a lifeboat. And thankfully, they just might have one.

Apollo 13 is formed of two ships joined together. The command module, called Odyssey, has the most powerful main engine. While the lunar module Aquarius has a smaller engine designed for landing on the moon. The explosion has crippled Odyssey, which is rapidly running out of oxygen and power. But the lunar model, Aquarius, seems undamaged. And it might have enough oxygen and fuel on board to get them home.

So, commander Jim Lovell orders Fred Haise, the lunar module pilot, to power up Aquarius and get her ready as quickly as possible. Fred ducks away from the control panel and floats through a short tunnel toward Aquarius. Then he begins to boot up the spacecraft. Normally, it’s a process that takes a minimum of two hours, but they don’t have that much time. Odyssey is running out of power, and before the command module shuts down completely, the astronauts need to transfer its navigation data to the computer on Aquarius. But the navigation data alone aren’t enough. The two spacecraft are very different; new equations are needed to account for differences in mass and engine power.

And it’s not a simple calculation. During his training, Jim messed up the numbers on more than one occasion. Any mistake now could be deadly. If the navigation data are not loaded correctly into the Aquarius computer, then the astronauts won’t know where they are in space and won’t be able to get home.

But once Jim is certain he has his calculation right, he hurries through the tunnel to Aquarius and orders Fred to punch the numbers into the computer. Then, as the lunar lander comes to life, Jack shuts down the final systems still operating on Odyssey. The three astronauts must now rely on Aquarius alone to transport them, and the badly damaged Odyssey, back to Earth.

***

A few hours later, early in the morning on April 14th, 1970, Jack Swigert hovers awkwardly at the back of the cramped Aquarius lander. As the command module pilot, he’s not familiar with this lunar vessel. He feels useless just perching here as a spectator, while the other two men hunch over the Aquarius’ control panel.

Jack wasn’t even supposed to be on this flight. He was part of the backup crew. The original command module pilot was a man named Ken Mattingly. But just days before the launch of Apollo 13, Ken was exposed to somebody with German measles. He’d never had the illness before so he had no immunity. The bosses at the American space agency, NASA, were concerned that he would become ill during the voyage to the moon. So, at the last minute, he was replaced with rookie astronaut Jack Swigert. Jack was delighted at the time. But now, floating on the stricken Apollo 13 spacecraft, hundreds of thousands of miles from home, Jack can’t help but curse his sudden promotion.

But these thoughts are interrupted by his commander Jim Lovell, who tells Jack that they’re ready for their next maneuver. The plan is to light the small engine on Aquarius in order to push the spacecraft in a slightly different direction. They’re not turning around completely – the engine on the lunar lander isn’t powerful enough for that. Instead, they’re tweaking their course just a little so their spacecraft will slingshot around the moon and head back to Earth on what’s called a “free return trajectory”.

If the maneuver works, they should be able to make it home. But if it doesn’t, Apollo 13 will miss the Earth and hurtle out into space, dooming the astronauts to become the first human beings never to return to their home planet.

Fred and Jim look at one another. Then they both look at Jack. All three men nod to signal that they’re ready. At 2:42 AM, Jack feels a rumble beneath his feet as the Aquarius engine fires up. The burn lasts for 31 seconds before the ship’s computer automatically shuts it down, precisely as planned. Then the astronauts wait nervously for a verdict from Mission Control. Finally, there’s a crackle on the radio. NASA has analyzed the burn and the maneuver worked.

But Jack and the other astronauts have a long way to go. Even as they celebrate their success in this maneuver, another danger is building up in the air around them: carbon dioxide. The three astronauts exhale more of the deadly gas with every breath they take. And unless they do something about it soon, Jack, Fred, and Jim will all suffocate long before they reach home.

Act Two: Breathe Easy

It’s the morning of April 15th, 1970, a day and a half after the explosion on Apollo 13 ended its crew’s hopes of landing on the moon.

On duty in Aquarius, Jack Swigert rubs his tired eyes. Although the astronauts have tried to rest, none of them have slept properly since the accident. Jack feels uncomfortable in the lunar module as well. It all seems so fragile to him – he’s been warned to be careful around its windows and walls. In certain spots, there’s just a thin layer of aluminum separating the crew from outer space. Still, the commander, Jim Lovell, has assured Jack that Aquarius is sturdy enough to get them home.

After the successful burn to change course, Apollo 13 swung around the back of the moon. Jack and Fred crowded around the windows to take photos and marvel at the pockmarked gray surface gliding by below. Jim took a back seat. He’d seen it before, on an earlier Apollo mission. And his thoughts were elsewhere – not on the moon, back on planet Earth.

Aquarius was designed to support two men for 45 hours. But now, it’s being asked to support three men for twice as long. The math is simple. If they are to survive, they have to ration everything. That means turning off the ship’s computer, the lights, and the heating to save power. But the most pressing problem isn’t what they lack – it’s what they have too much of: carbon dioxide.

The spacecraft is equipped with chemical “scrubbers” which remove carbon dioxide from the air. But these need to be replaced often. And with three men on Aquarius instead of two, the scrubbers are wearing out faster than normal. The astronauts don’t have any suitable spares. The only ones they do have were left over from Odyssey. But Odyssey’s scrubbers are square, and Aquarius’ are round. If the NASA technicians on the ground don’t come up with a solution to this problem, the astronauts will die. 

So Jack and his compatriots are very relieved when Mission Control finally radios in to say they have a plan. They will walk the astronauts through the process of constructing an ad hoc adapter that will allow a square scrubber to fit into a round hole.

The Apollo program has cost billions of dollars. But the lives of the astronauts now depend on an improvised adapter made from cardboard, tape, a plastic bag, and a spare sock. Building the two makeshift air purifiers takes the astronauts around an hour. Once they’re done, the crew carefully attaches the two new devices to the round vents. With a whir, air begins to flow through the scrubbers and the levels of carbon dioxide begin to lower.

The crew has survived the immediate danger of suffocation. But they’re not free from peril yet. Before long, their craft will drift off course, forcing them to pull off the most crucial and difficult maneuver of their long, improvised journey home.

***

Later that evening, Jim and Fred stand at the Aquarius control panel. They flex their frozen fingers and try to wipe the condensation off the switches and dials which have become slick with moisture in the cold. Behind them, Jack perches in his now familiar position at the back of the lunar module. He may feel like an outsider in Aquarius, but right now, they’ll all have to work together to make this burn work.

The previous maneuver around the moon was controlled by the Aquarius computer. But there isn’t enough power to switch the computer back on now. So this time, the burn has to be done manually, by the crew. And they have to get it right. For hours, Apollo 13 has been drifting off course – if the astronauts don’t correct it, then they won’t be able to return to Earth.

Jack’s job is to time the burn just right. He stares at his watch, his eyes fixed on the second hand clicking round and round. The other two men wait, poised at their controls. Finally, Jack calls out – go!

Jim hits the switch, and, with a low rumble, the Aquarius engine lights up once again. Jack feels the ship dart forward. He begins counting the seconds out loud as Fred and Jim fight to pull the skittish spacecraft back on course. Fourteen long seconds later, Jack shouts for them to stop and Jim hammers the shutdown button. The engine cuts off and the spaceship is silent once again. After a torturous wait, NASA's ground control informs the astronauts that the burn successfully shifted their course and accelerated the astronauts toward Earth.

Aquarius has carried them almost all the way home. But the last stage of the journey will be impossible for the lunar lander. Aquarius has no heat shield to protect it from the high temperatures of reentry into the Earth’s atmosphere. So, the astronauts will have no choice but to leave Aquarius behind and finish the journey in the badly damaged command module Odyssey.

Act Three: Home

It’s April 17th, 1970, four days after the explosion on the Apollo 13 spacecraft.

On board the command module Odyssey, Jack Swigert sits opposite the control panel beside his two fellow astronauts. The men are all pinned back in their seats by gravity as the ship plummets through the Earth’s atmosphere. Out the window, the air is a blazing red and orange; a trail of fire streaking across the sky at thousands of miles an hour.

There was a time in the mission when Jack thought they would never get this far. But even now, with home so tantalizingly close, he knows they are not safe from danger. Nobody can know whether the command module’s all-important heat shield was damaged in the explosion. And if there’s even the slightest vulnerability, Odyssey will burn up in the atmosphere. 

For six excruciating minutes, the astronauts sit in their seats, the spacecraft rattling violently around them, until at last, out the window, Jack sees blue sky instead of flames. Then the parachutes burst open above their craft in a plume of red and white. The radio, which was in blackout as Odyssey fell to Earth, bursts to life with a voice from mission control welcoming them home. Minutes later, the command module, swinging gently through the air from its parachutes, splashes down in the Pacific Ocean. A US Navy recovery team is quickly on the scene, and all three American astronauts are safe at last.

The television networks once shunned the Apollo 13 mission as routine and boring. Now, millions tune in as they broadcast the dramatic pictures of the splashdown live.

A NASA inquiry will later trace the explosion that crippled the spacecraft to a fault in one of its oxygen tanks. The crew was not to blame for what happened. Instead, the skill and bravery of Jim Lovell, Fred Haise, and Jack Swigert ensured their flight would be remembered, not as a tragic accident, but as a heroic triumph against the odds, after their mission to the moon suddenly turned into a dramatic fight for survival on April 13th, 1970.

Outro

Next on History Daily. April 14th, 1865. At Ford’s Theater in Washington D.C., the actor, John Wilkes Booth, assassinates U.S. President Abraham Lincoln.

From Noiser and Airship, this is History Daily, hosted, edited, and executive produced by me, Lindsay Graham.

Audio editing by Muhammad Shahzaib.

Sound design by Mollie Baack.

Music by Lindsay Graham.

This episode is written and researched by William Simpson.

Executive Producers are Steven Walters for Airship, and Pascal Hughes for Noiser.