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The Astronaut Training Pool

Season 1Apr 27, 2020

Before astronauts head to space, they have to dive into the Neutral Buoyancy Lab. Take a swim in NASA's underwater training ground with astronaut Nick Hague.

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About the Episode

Before astronauts head to space, they have to dive into the Neutral Buoyancy Lab. Take a swim in NASA’s underwater training ground with astronaut Nick Hague.


NASA's Curious Universe

NICK HAGUE: The Neutral Buoyancy Lab, or “the pool” as I like to call it, it’s a really remarkable place. It’s so massive… 200 feet long, 100 feet wide… and the water is crystal clear. And, if none of the safety divers have started to get in the water yet, the top is as still as it can be. The water is so clear you can just see straight through and see all the models down in the water. And so you get to see the magnitude of what you’re gonna go down and work on here shortly.


NICK HAGUE: It’s an amazing experience. When I first came down here, that was when I first put on the spacesuit and was lowered into the water and started floating around in the water… It felt like this is astronaut training. Hi, I’m Nick Hague. I’m an astronaut at NASA. I, uh, I explore space for a living.

HOST PADI BOYD: This is NASA’s Curious Universe. Our universe is a wild and wonderful place. I’m Padi Boyd, and in this podcast, NASA is your tour guide.

In this episode, we’re exploring the underwater training ground where astronauts train for space.


HOST PADI BOYD:There are humans in space right now. In fact, humans have lived in space continuously for nearly twenty years…on board the International Space Station.

NICK HAGUE:The International Space Station… it is gigantic. Imagine this space station floating around with these gigantic solar solar arrays, these wings of solar cells that are collecting the Sun’s energy, and that’s how we power the station… It’s the size of a football stadium. On the inside, it’s got kind of the volume of a large jumbo jet and so that’s the area we live and work in. We’re up there, you know, it took 100 launches, and it took 100 spacewalks to put this thing together. And we’ve been up there living inside the station. It’s been inhabited continually for two decades now.

The space station orbits around Earth, about 250 miles above ground. The international crew that lives and works on board is doing critical research that can’t be done anywhere else.

NICK HAGUE: We’re up there trying to perform this science, because on the space station, gravity isn’t the dominant force. You know, if you look around you, everything around you is controlled by gravity. Everything in the room you’re sitting in is held down to a table or to a floor because of gravity, and up there, all that goes away, and that’s when we can make some really key scientific discoveries.

The ISS is a unique place to study human health and medicine, on top of the more obvious scientific questions about astronomy and meteorology. Weightlessness helps us understand the possibilities for long-term human space exploration. And it helps us understand life here on Earth a little better, too.

NICK HAGUE:Our job, working on the space station, is to go up there and perform science experiments and try to discover new things, whether those are new materials that might help people on the ground or those may be new medical breakthroughs that might help people on the ground. And so we’re up there constantly kind of pushing the boundaries of what we know… helping scientists on the ground make breakthrough discoveries. It’s allowing us to learn more about ourselves, the human body, about the universe around us, and how to improve life on the ground… and how to take those discoveries and push further into the unknown, into space.

HOST PADI BOYD: Before embarking to a place where very few humans have been, astronauts train for two years. In that short time they are required to learn a lot more than you might expect…

NICK HAGUE: Astronaut training, in a nutshell, is you need to be a jack of all trades. You need to be able to do a little bit of everything.

HOST PADI BOYD: Repairing and servicing the International Space Station, learning Russian, and receiving medical training — astronauts must be prepared for every possible scenario. But before an astronaut ever sets foot aboard the space station, they have to train somewhere you might not expect…

[Deep plunge/cannonball splash sound]

HOST PADI BOYD:This isn’t just any old swimming pool… it’s the Neutral Buoyancy Lab located at NASA’s Johnson Space Center in Houston, Texas. This special pool contains 6.2 million gallons of water… enough to fit nine Olympic-sized pools inside. It’s where astronauts like Nick come to train.

NICK HAGUE:So the pool is this gigantic pool. It’s 200 feet long. It’s 100 feet wide, and it’s 40 feet deep. It is enormous. It’s still not big enough to fit the entire space station in it, but it fits full-scale large chunks of the station so that we can practice. And that’s, that’s our training ground.

HOST PADI BOYD:The pool is where astronauts first get acquainted with the armor that protects them from space… their spacesuit! And that can be its own challenge. First thing? You’ve got to suit up. It can take about 45 minutes and the assistance of multiple suit technicians to get the suit on — checking to make sure that every piece is fitted and working properly, from the helmet locking into place to the gloves fitting around every finger.

NICK HAGUE: You have to learn how to use the spacesuit. Because, it’s not like wearing clothes… It’s, it’s constraining, and it limits some of the things you can do. It’s fatiguing because of the pressure of having it stiff, and so you have to learn how to use it, and that takes hours underwater, getting to know your spacesuit.

HOST PADI BOYD:Once you have the suit on and it’s been double and triple checked, you can prepare to enter the Neutral Buoyancy Lab. Even though you’re not out in space just yet, the pool will simulate what you might feel once you’re out there. Why? Because being underwater simulates weightlessness.

NICK HAGUE:The Neutral Buoyancy Lab is there to train us, because that’s one of the places or one of the ways that we can try to simulate being weightless.. So that idea of nuetral buoyancy.

HOST PADI BOYD:It’s called “neutral buoyancy” because when you’re in water and you don’t sink but also you don’t float, you’re completely neutral. It’s like you’re “hovering” in place.

NICK HAGUE:And so it feels as though I’m weightless and I can maneuver myself around the outside of the space station and have the experience of working in a weightless environment. And so we’re constantly trying to balance out the weight of an object with its buoyancy so that things just float in front of you.

HOST PADI BOYD:Weights and flotation devices are carefully combined to let astronauts feel what it’s like to be weightless in space. When an astronaut is training in the pool, their backpack — the Primary Life Support Subsystem — is filled with air they can breathe and instruments that monitor their health.

NICK HAGUE: You’ve got to get everything straight because once you go underwater, that’s all you’ve got are the tools you took with you. You’re going to be down there for six hours.

HOST PADI BOYD:… that’s about the amount of time it takes for a spacewalk in actual space! Once you’re in the pool, waterproof instructions are attached to your arm, and you rehearse the spacewalk as if you were doing the real thing.

[NAT SOUND of TRAINING: “Alright, Nick, before you get started on that… If we could just… help me guide that out… much appreciated!]

The whole time, a team of people is watching every movement of your practice spacewalk. They monitor the pressure inside of the suit and the temperature.

And the test director is making sure that the whole process is going according to plan.

[NAT SOUND of TRAINING: “Good teamwork there. Exactly…” “So, I need to float a little higher on this end… alright, okay, so that’s good alignment]

HOST PADI BOYD:Trained scuba divers guide you around a replica of the outside of the International Space Station.

[NAT SOUND of TRAINING: “yeah, looks good here. Yep, we’re aligned down here…”]

NICK HAGUE: Having this full-size mock up of the space station underwater allows us to, to essentially memorize where every handrail is, where every handhold is, and if I’m going to work in a particular location, on orbit, I will have seen that and understand that location on the ground.

HOST PADI BOYD: Astronauts are explorers, and a pretty big part of their job is going on spacewalks.

NICK HAGUE:We practice doing spacewalks so that when we need to go outside and fix something, or increase a capability, add some new piece of equipment, we’re ready to do that.

HOST PADI BOYD:During a spacewalk, the only thing that stands between an astronaut and the vacuum of space is their spacesuit. And while they’re attached to the outside of the International Space Station, they’re orbiting the Earth at 5 miles a second. That’s like driving from Boston all the way to Philadelphia in just one minute.It’s difficult to replicate the sensation of being in space. But with the Neutral Buoyancy Lab… NASA can get pretty close. So close that it can feel pretty similar to the real thing.


NICK HAGUE: I got to tell you. When I did my first spacewalk, shortly after we went out the hatch, the Sun set and it got dark, and it felt exactly like I was in the pool. To the point where I remember having the thought go through my head, you know “Where all the bubbles?” Because normally in the pool you see all the bubbles from people breathing underwater. And I didn’t see any in space obviously because we weren’t underwater. But it was one of those things. I was like, wow, this is so close to what we’re doing underwater. It’s just amazing training.

HOST PADI BOYD:Space is unforgiving. Without the protection of the Earth’s atmosphere, the temperature can either soar or plummet by a range of over 500 degrees. And there’s only a little bit of time to get through your to-do list. Six-and-a-half hours is the usual ballpark for a spacewalk. And that might sound like a lot of time, but remember: there’s a finite amount of oxygen in your tank. You need to keep track of the power in your battery and monitor water for spacesuit cooling. And most importantly, you have to watch your carbon dioxide levels.

HOST PADI BOYD:The longer you’re in space, the more likely you are to get hit by flying debris. Micrometeoroids are a spacesuit’s worst enemy. Even a piece of metal that’s as small as a grain of sand can puncture your suit, which could cause air to leak out. Astronauts train for a wide range of scenarios they might encounter during all phases of their journey, from launch to the return to Earth. There’s a lot that could go wrong. And Nick knows that firsthand.


[MISSION COVERAGE: “3…2…1 and there is liftoff of the SOYUZ MS-10 to the International Space Station, carrying Nick Hague and Alexey Ovchinin. This, again, is Nick’s first time to uh launch to space…”]

NICK HAGUE:We train so that we can respond to the unknown. We are constantly not just training for when things go right. We’re constantly training against what we can predict will go wrong.

NICK HAGUE: In the training scenario, we’re fighting five or six different major failures so that we have the bandwidth to be able to on a real flight to handle the one big thing that’s thrown at you…

[MISSION COVERAGE: “Hearing there, that there uh… has been an issue with the booster… and we’re standing by for information as we continue to get it from the russian flight control team. “]

NICK HAGUE: I can tell you, in that moment, when life throws something at you like that, it is amazing how you just revert into that mindset of, ‘Hey, I was being vigilant up to this point. I’ve diagnosed something that’s wrong. We know what we need to do. This is our best way of being successful’…And then you follow those procedures as best you can. And you’re able to kind of block, you know, a lot of the other stuff out and focus on just what you need to do to survive..

[MISSION COVERAGE: Everything seems to be fine with the crew, we had good comm with them and they are okay. We’ll continue to wait for more information.]

HOST PADI BOYD: At that moment, Nick remembered his training.

NICK HAGUE:…We had an in-flight abort. We recovered from that one and I was able to launch successfully to the space station about five months after that.


HOST PADI BOYD:Nick ended up having successful and productive trips to the International Space Station thanks, in part, to his training at the Neutral Buoyancy Lab.

NICK HAGUE: The International Space Station. That international aspect of it is really a powerful part of the program. You’ve got astronauts that have been from 19 different countries, astronauts and cosmonauts working up there togethe. We’ve, you know, been able to perform 2,800 different experiments from researchers, you know, like 4,000 researchers from over 100 different countries. It has this ability to bring all of these very different people together in pursuit of that common goal of increasing human understanding.

HOST PADI BOYD: Nick returned to Earth last Fall, and he treasures his memories from his time in space…

NICK HAGUE: What it is really taught me is that when we understand this common purpose, and when we work shoulder to shoulder and elbow to elbow with each other, we start to realize we have so much in common and that gives us the foundation to be able to not necessarily look past differences, but to look at those differences, and, and the diversity that that comes to the to the team because of those differences and to celebrate those differences. And so the, the, approach that we’ve taken on the station and the two decades of collaboration in space, in the pursuit of knowledge, that’s something that we’re going to continue to carry forward as we go to the Moon. As we develop the Artemis program, when we start to explore the surface of the moon, and as we take what we learned there and we push on to Mars, I think ultimately, that is… that’s the amazing part of going to space. That’s, that’s, the real motivation is it’s such a powerful, positive example of pulling us together and accomplishing something great.

HOST PADI BOYD:In the coming years astronauts will continue to push the boundaries of human space exploration. The Artemis program will send the first woman and the next man to the Moon. Here on Earth, astronauts are already practicing how to move around, set up habitats, collect samples and deploy experiments just like they will on the Moon. We have a lot to explore on the Moon and Mars. But the Artemis astronauts’ first stop will be the pool…

HOST PADI BOYD:The Curious Universe team includes Elizabeth Tammi and Micheala Sosby. Our executive producer is Katie Atkinson. Special thanks to Thalia Patrinos (Thall-yuh Puh-TREE-nos), Eric Land, Gary Jordan, Brandi Dean and Ryland Heagy.

If you liked this episode, please let us know by leaving a review, tweeting about it @NASA and sharing it with a friend.

And join us next week as we meet NASA’s “space crafters”, who use some surprising tools to prepare missions for space.

Looking for more?

NASA’s Neutral Buoyancy Lab, or “the pool” as astronaut Nick Hague likes to call it, is large enough to fit nine olympic-sized pools inside!

You can take a dive into the pool in this 360-degree tour.

As part of our Artemis program, NASA will send the first woman and next man on the Moon by 2024. Learn how we’ll get it done at

Keep a look out for the International Space Station when you’re looking at the night sky. This tracker will help you figure out where it’s headed next.

Continue exploring the universe and discovering Earth with @NASA.