Why NASA's Next Space Suits are not Pressurized to 14.7psi - Smarter Every Day 296

This is me trying to figure something out underwater. And those are NASA astronauts also trying to figure something out underwater. NASA is about to make a technical decision, and I want to try to explain why it's so important.

Like, if you could design an entire moon program, you're going to take people to the moon like they did with Apollo back in the day. However you take people to the moon, you're going to have to use a spacecraft. And inside that spacecraft, they're breathing oxygen so their bodies can stay alive. They'll then descend somehow to the surface of the moon. They'll touchdown. And then they'll get out and walk on the surface of the moon in a spacesuit, which also has oxygen in it. For the Apollo program, there was the A7L suit with a PLSS on the back, the Portable Life Support System. This device pressurized the spacesuit so that the human inside the spacesuit could breathe.

One thing we don't think about very often is going from the spacecraft to the spacesuit. That step is critical, and it plays into this big decision that NASA has to make for the architecture of Artemis. The Apollo program was incredible. It put flags and footprints from humans on the moon, which is one of the biggest deals ever. Ultimately, though, the Apollo program ended. The Artemis program is going back to stay. People are going to live on the moon. This video is crazy town. The fact that we got to do this is amazing.

So what we're going to do today is we're going to go observe a government test on a spacesuit, and then we're going to use that information to understand this big decision that NASA has to make. And the people we meet along the way are just incredible. Engineers, divers, astronauts, test conductors. All these people have a role to play in this big decision that will affect the architecture of the Artemis program. And I know the video is long. Got it. Whatever. It's worth it. I learned so much that I have to share with you, and I want you to go on this journey with me.

I thought I understood the physics of being on the surface of the moon in a spacesuit. I didn't. We're going to learn so much in this video. I'm going to show you footage I've kept for years I haven't shared. There's so many cool things in this video. I'm excited to share it with you. So let's go get Smarter Every Day, and let's start off at the neutral buoyancy laboratory at Johnson Space Center in Houston, Texas.

In order to do this test, we're going to Houston, Texas, to the Sonny Carter Training Facility, NASA's famous neutral buoyancy laboratory. Tim, the guy that made all this happen, met me at the door and escorted me in the facility where he introduced me to two very important people. The first person was Dominic del Rosso. Dom has done everything. He used to run the zero-gravity program that I got to participate in as an undergraduate where he did all kinds of research in early suit development and tools. He served as a fire chief. He's a backseater for NASA's WB 57 Canberra. Yeah. How cool is that? He's volunteered in Afghanistan. He's served as a test subject for NASA countless times. He's currently the chief engineer at the neutral buoyancy lab because he's a diving instructor trainer, and he also serves on the dive safety board. Yeah, Dom's the real deal.

The second person they introduced me to was Pat Keller. Pat is an incredibly experienced master scuba diver trainer that's trained thousands of people how to scuba dive in his off time. Pat is a safety jumper for some of those speed boats that you see. He's the guy that goes in and saves the pilot of the boat if they have a problem. These guys are incredible, and they're about to school me up so that we can learn what we need to know in order to even get in the pool with the astronauts.

Okay, we're here at the neutral buoyancy lab, and this is Pat. Are you the guy that's gonna keep me alive?

Pat: That's. Yeah, that's the goal.

Destin: Are you the instructor diver?

Pat: Yeah, I wanna be the instructor. What I do here is I run the maintenance department and I also run the scuba instructors here. So those are my two main jobs here. I also safety dive, float dive, but that's my main job. So when we get something like this.

Destin: Yeah, you're the one you're stuck with.

Pat: Well, that's debatable, I'm probably your problem.

Destin laughs

Destin: Okay, that makes sense. And this is Dom. Dom, you are the engineering manager, is that right?

Dom: Am I titled? I'm chief engineer here at the facility, but I wear a couple of different hats. I'm representing management here today as well. I'm also instructor trainer for diving and sit on our dive safety board. So I support Pat in what he has to do as well. So I'm going to be talking a couple different things, different areas.

Destin: You're making sure I'm staying, coloring in the lines?

Dom: Yeah, well, I'm the government guy, so anything bad happens, I have to do the paperwork. So everything's going to go really well.

Destin: So, Dom and I met each other a long time ago. I did the undergraduate reduced gravity student flight opportunities program when I was. I mean, that was like 20 years ago, and you ran the thing. I really enjoyed that period of my career.

Okay, so the neutral buoyancy lab, real quick. Really big swimming pool. It's amazing. You can do specific simulations that you can't do anywhere else in the world. There's some facilities like it, I think, in Cologne, Germany. They have a very, very small pool, but it's nothing like the NBL. This is a unique facility that the government has, right?

Dom: Yes, for our facility it is for our space program. There's one in Star City in Moscow. There's one JAXA has in Japan, but by far and away, this is the most utilized and heaviest used one.

Destin: Okay, and so you guys use. I'm gonna look at this picture on the wall over here. You guys use divers and, well, I guess you are the diver.

Pat: One of them.

Destin: And so you guys can simulate zero gravity or other environments by attaching weights and getting like, trim out buoyancy wise and all that good stuff.

Dom: We want you neutrally buoyant. We don't want you to. We don't want you to float and no preferred orientation. And that way, this is the only place you can do all three degrees of freedom and do that. You still have weight inside that suit, but you can do the entire space station end to end, six-hour run with you and your buddy out there. So, yeah, it's a pretty unique environment in the water. And I think we're going to talk about probably later about how now we're going to use it for lunar training.

So now I got to get you on the bottom 1/6 g. And then we also do stuff on the surface because we have to recover capsules. And that's our team here that trains our navy and air force PJ's to go out and help.

Destin: Air Force PJ's..

Dom: The Pararescue.

Destin: Oh, they're the people. Everybody, they're like, these guys are the best.

Dom: Yeah. The navy divers and air force pararescue men do the nominal recovery of the crew, but our people here train them. So we do that on the surface as well, as well as we also do aircraft water survival for our aviators and astronauts. So we do stuff on the water, under the water, on the bottom, all over, daylight conditions at night, put your night vision goggles on, depends on the orbit. So, yep, when you're outside space station, every 45 minutes, you're gonna go from light to dark for a 90 minutes orbit. Right? So it's gonna be full on bright for 45 minutes, full on dark for 45, and you're out there for 6 hours. So we turn the lights on and off. Same thing here. And only your headlights.

Destin: So you mess with the photopic and scotopic vision and the astronauts.

Dom: Yeah, and it's not again. And we're probably going to talk about this a little bit later. Each environment is valid in some aspects and not others. We have water drag, so we don't do stuff that is high drag in there. It's not realistic, it's negative. You're going to get the wrong answer. It's an invalid. So you put all these different environments together to get the picture for here. It's that end to end working together 3D kind of thing. It's not really, as you get back to your vision stuff, we're not doing lighting testing, evaluation like that, but we're giving them the operational sense.

Destin: Yeah

Dom: Same thing, we'll talk about lunar later. It's not doing soil studies here. It's underwater. I can't. But I do need to give you the same physical reaction environment so you know how to operate. When you do the other stuff.

Destin: You're putting their brain in the space and you're having to manipulate your arms and stuff.

Okay, so I'm talking too much. So what are we about to do?

Dom: Okay, so what we're gonna do is we want you to get in the water with the crew tomorrow to be able to see what they're doing up close and really get a sense of the scale and everything else. To do that, we need to qualify you as a diver. But what we're gonna do, since this is a one-off, we're gonna have Pat here as an instructor do an escorted dive for you. So your current recreational certifications with an escorted diver in our working environment, what we're gonna give you here is the difference between what we do here in a recreational dive. So you can dive here safely, get in and do your job. So we're going to get through this so you can get down to what you need to do.

As we move towards this big decision that NASA has to make, we have to understand some of the prerequisite information. And coincidentally, a lot of the physics has to do with scuba diving. This gets complicated. So obviously we should use a flannel graph. So the air we generally breathe is made up of several gasses. You get about 78% nitrogen, 21% oxygen with a tiny bit of argon, CO2, and some trace gasses.

When you dive in a swimming pool, the further down you go, the higher the water pressure becomes. And that has some implications. When the scuba diver breathes air from the tank, that air has to be compressed to the pressure of the depth that the diver is at. That means that the deeper you go, the more nitrogen enters your bloodstream. It's, like absorbed in your body, in your blood, nerve cells, basically, all your tissues.

If you then return to the surface, all that nitrogen has to work its way back out of your body, so it tries to get out of your tissues. Now, you've heard of this. It's called the bends. You've heard of divers getting the bends if they surface too quickly, right? So divers are always working to stay on the correct side of the math so that they don't stay down too long and get too much nitrogen in their blood, and they don't ascend to the surface too quickly, so that that nitrogen tries to rupture out of their body really quickly, causing the bends.

Scuba divers are always thinking about how much bottom time they have. If I go down, the nitrogen will get in my blood, and then I have to be very slow on my way up. In fact, I have to do what's called a safety stop. I'll come up to a certain depth and let that nitrogen work its way out of my body. I'm gonna watch the time, make sure that nitrogen gets to dissipate out. It's a very important part of scuba diving. People that dive all the time, they have this cheat code that lets them stay down longer. They have more bottom time. It's called EAN, or nitrox, and this basically is air, but they played with the percentages of oxygen versus nitrogen. You'll hear of nitrox 32. Nitrox 36. That's 32% oxygen, or 36% oxygen, instead of the normal 21% oxygen. It's. It's a really interesting way to offset the nitrogen buildup in your blood.

Now, at the NBL, they go even farther. They don't use normal nitrox that a professional diver would use. They use nitrox that's got even more oxygen in it. And the reason they do this is because the NBL is a pool that's only 40 foot deep, right? So they've done all the math ahead of time, and they realized if we have this special nitrox that we dive in here with the pool, people can have all the bottom time they want, and then they can come back up at any time. And they don't have to worry about the bends.

Long story short, the people at the neutral buoyancy lab, extremely smart. They develop this special nitrox blend so that people can dive for an extremely long period of time and come up safely, and they never have to worry about decompression sickness on the way out of the pool. It's fascinating. My understanding is we dive with nitrox here, but it's a special kind of nitrox.

Dom: It is, it is. It's a much higher mix than you can get out recreationally or industrially, because it's set up for the profile. So that astronaut in that pressurized suit is right now about four psi over ambient. So at the bottom, it's going to be the bottom pressure, plus four in for 6 hours. Well, I would be in decompression cycle at that point. If I was on an air dive for 6 hours at 40, well, 48 ft equivalent, I'd be in decompression. I can't do it. So I want higher oxygen, less nitrogen. But if I get too much oxygen, it becomes toxic, so I can't. Like on orbit, the real one is an oxygen rebreather. There's no nitrogen in the system for the on orbit suit, but I can't do that in the water because you'll be toxic. So we have this blend of 46%, so it splits that difference there so we can do that safely.

My brain was on fire. Clearly Dom has a lot of experience and he knows a lot of things, but I finally gained enough, like self-discipline, to quit asking questions so that we could move on to the dive preparation part of the meeting.

Pat: See, each subject has four divers on them. They have two safeties, one utility, and one float. So you have eight divers, two subjects in the water.

Destin: Eight divers, two subjects in the water. Is it four people per subject? Are those divers up on comms? Audible comms?

Pat: As you do, we hear them in the water because we have speakers. You'll hear us tomorrow. It's really cool. We hear everything the subject's saying and everything the TC and the TD are saying in the water. They can't hear us. It's a one way, but we hear everything that's going on. So they can make requests to us, they can talk to us, we can hear things, so we can prepare what we're going to do next. So, yeah, you'll hear that. It's very clear, and it's one of the rules we have about speakers. You can stay about 3ft away from them. Because they are very loud.

Destin: Okay.

Pat: All right. But you can hear them as if I'm talking to you right now.

Destin: Wow. As Pat went through the classroom instruction, it became clear to me that this is not a normal dive. These people are doing amazing things, nuances to what they do. For example, there's increased percentages of oxygen involved. So the fire hazards are different. They use a specific tank rig. The hand signals are different. All this stuff made it very clear to me that I'm not just dealing with professionals. I'm dealing with people who have been hand-selected because of their unique temperament and their skills and their ability to react under pressure. The people that dive at the NBL, they're amazing.

So it's time to talk about spacesuits. Now, when it comes to spacesuits, I have a unique insight into what it feels like to be inside a spacesuit, because nine years ago, I actually got to wear a NASA spacesuit. Now, it feels strange releasing this footage now because I did it nine years ago. At the time, I was an aspirational young man that wanted to apply to be an astronaut, and that's what I was doing. And so it didn't feel right to release this footage back then. But I'm going to release it now because it helps illustrate a point.

I know what it feels like to be in the suit, and I want to talk about it a little bit. Just for the record, I want to let you know what I feel about this footage. It's odd looking at it because it reminds me of, like, what could have been. But I keep my astronaut rejection letters right there in the shot of every Smarter Every Day video. I've got them all stacked up in this little frame. It reminds me that NASA made the right call. The people that are astronauts right now are absolutely incredible.

So I feel weird looking at this footage because it feels almost selfish. Like, man, I really wanted to do that, but that wasn't God's plan for me. And I just have comfort knowing that God had a different plan for my life. And we get to talk about spacesuits right now, together because of this.

Now, if you think about it, the spacesuits currently worn by astronauts on the International Space Station, they're not made for walking because the astronauts move around by grabbing handholds and moving with their arms, right? Well, the spacesuits that are about to be used on the moon, they do require boots that are made for walking. Right. The suit I got to try on years ago was the older style, and I learned things by trying this on. First of all, I had to wear an undergarment.

Now, if you think about a spacesuit as a self-contained spaceship, you have heat that your body is generating, and that has to go somewhere. On Earth, the heat dissipates through the air, but in space, it can't do that. So you have to wear this suit full of tubes that will dissipate the heat from your body by actually contacting your body and pulling the heat away. It's fascinating. Keep in mind, this is the older suit I'm putting on. And so getting into the hard upper torso from the bottom was very difficult. Then you just gotta kind of worm your way up.

There you go.

Young Destin: Elbows don't do that. Go ahead and lift. Yeah, there you go. Gotta try to come straight up, Destin. There you go. There you go. And it's a boy.

Destin: It's a boy. Also, as you put the suit on and they put the helmet on, it was quite the moment, by the way, the first thing you realize when they pressurize the suit is that it feels like a balloon. My hand was inside a glove, and the glove, as it pressurized, had a state that it wanted to be in, like at rest. The fingers wanted to be in a certain position. As I closed my hand, I could feel my fingers having to work against the suit to close the hand, because it was like being on the inside of a balloon, if you can imagine what that feels like.

So what that means is, the higher the pressure in the suit, the harder it would be to close your fingers. It's a fascinating feeling, and it was also very heavy. I found that the suit was very difficult to walk in, and I was kind of scared that I was going to fall forward or fall backwards. It was an interesting experience, and I'm grateful to have had that opportunity because it helped me understand the things that Dominic was about to teach me.

So the change in pressure between what's inside the suit and what's outside, that determines how stiff the balloon is.

Dom: So the current space station suit, which is a derivation of the shuttle suit, is 4.3 psi delta over whatever it is. If it's in a vacuum, it's 4.3, absolute. If it's, you know, here, it's going to be whatever pressure you're at in the water, plus 4.3. So it's going to feel and act the same way.

Destin: Okay.

Dom: And this suit, these suits that we'll show you will review later. These are all downgraded flight hardware, and they're sized for you. So it is exactly what you would be using. It is exactly the same delta pressure. Like I said, our environment here, the biggest thing is water drag.

And so we don't do stuff where drag is in the equation, because that's not valid. The other stuff is, so.

Destin: So are you going to do a higher pressure run tomorrow? That's understanding, that's what the test is.

Dom: Tomorrow's a higher pressure run so the crew members can evaluate can. And we're going to do it in the blind. We're not going to tell them what pressure they're at. So that can they one, there's no bias on that, right. Because it is subjective to an extent. And then they're going to compare their fatigue levels between this run and the next run they do, which will be different pressure in the next run type thing.

Destin: I had an interview one time with Johnny Kim, and he was telling me that a senior astronaut, I think it was Chris, told him, don't fight the suit.

Dom: You'll lose.

Destin: What does that mean?

Dom: So the suit is designed with joints and with bearings. And so if there's a joint there and it's sized perfectly, it's going to be just a little bit of friction. It's going to bend. What if you're fighting, like, if you want to reach out? Okay, don't do that in the suit. Why? Because there's a bearing here. So you want to roll your shoulder, then you want to extend this because there's a joint here, and then you want to come over because there's one here and then you didn't fight the suit. If I do this, I'm having to force all these things over by going this way, and it's got to force it to roll it over.

Destin: Oh, so you literally find the path of least resistance.

Dom: Yep. If you understand how the suit's designed and where it's designed to move and where it's not, you move that way, and then you're not fighting the suit and your fatigue level drops way off.

Destin: Alright, it's time to talk about the sponsor of this video. I've got two things to tell you right off the bat. So, number one, this room is never this clean. I'm not going to pretend like this is the way it is. Number two, I am concerned about making this sponsorship spot too long because I love this product.

Today, this video is sponsored by eight sleep. This is a product that I fell in love with on my own before they reached out to sponsor Smarter Every Day. My wife likes to sleep cold. I like to sleep more warm. And so I arrived at eight sleep and decided to invest in this technology.

So you remember how earlier in the episode, I explained that there's this undergarment that astronauts wear to keep their bodies cool inside the spacesuit? Well, that's exactly what this is. But for your bed, well, it's not exactly what it is, but it's the same technology. You have these cooling tubes and liquid runs inside, and that liquid will keep your body at whatever temperature is ideal for sleep.

So there's two elements to the eight sleep pod. The COVID that goes over your mattress and has the cooling and heating channels in it. And then there's the hub, which sits to the side of your bed that contains the water and does the heating and cooling. The whole thing is controlled by an app on your phone that provides all sorts of really useful feedback on the quality of your sleep.

The fact that I get a sleep score every day, it's made me mindful about my rest. This has sensors in it to get your heart rate, your temperature. It can measure when you're in deep sleep, light sleep, REM. And I like looking at all those metrics and imagining, like, what is causing my heart rate to fall later than normal? Is it caffeine? Is it because I was exercising? What is it? Just for fun? Here's a flir image. You can see my wife's side of the bed is colder than mine.

Eightsleep.com/smarter gets $200 off the pod. When eight sleep agreed to sponsor Smarter Every Day, I said, will you please send me one cut in half so I can look at it because I'm a nerd? They said yes. And check this out. Okay. It's different than I thought. It's not like tubes. They must have a large stamp that they can heat. Weld it together. And look, they make this grid right here. There's a seam down the middle for one side of the bed versus the other. But look at this. They. So it's like a mesh. You see that all the water runs through there, and they have the sensors integrated here. This is the controller. I would love to know how that works. There's got to be a data card in here. The data must go. It's just ribbon cables. No, that's a USB type interface there. So the flow, like the valves, must be over here in the hub. That must be how it works.

I did a, like a broad market analysis for the Sandlin family. Decided to make the plunge very happy. I did. My wife loves it. I love it. Eightsleep.com/smarter $200 off the pod. Even if now is not the time for you to make the investment, at least check it out, see what you think. That would be great.

So anyway, that's it. Let's go back and check out the spacesuits and see how these things work. Okay, so we're talking about teaching modern astronauts how to walk across the surface of the moon. And when you first think about it, you think, well, the earth is one g and the moon is 1/6th g. Therefore, it must be easier to walk on the surface of the moon, at least from an exertion standpoint. Now, it seems on the surface that it would be that way, but it's actually quite complicated.

Think about it. So your weight, yes, is one 6th as much, but your mass is the same, which means the inertia is the same. A while back, I talked about how to land on the surface of the moon, and I really like the illustration that we use. Like we compared it to a helicopter. I like the animation and it explains this problem in a very interesting way.

So let's go back and watch that. If you think about a helicopter, it has to offset its own weight, right? So if you've got the weight here, then you have lift that's pulling it up at a certain amount to offset that, right. If you decide to translate forward, meaning you want to tilt the helicopter forward and you want to move in that direction, you still have a vertical component of lift that's going to offset that weight.

But you also have this horizontal component that will let you accelerate forward. Now that makes sense on earth. But the problem is if you're in a spacecraft and your spacecraft has one 6th the weight of a helicopter, even if they're the same mass, you have to go with me here. Think about it. If you have a very small thrust required to lift that thing, if you tilt it over and try to translate in the same acceleration moving forward, it's not going to work because as you tilt that thing forward, the horizontal component of your acceleration is far lower because you're not thrusting as much.

So in order to get the same acceleration in the horizontal direction, you would have to tilt the spacecraft over much farther than you would a helicopter. This is the problem they had to figure out how to solve. They considered a helicopter and a lunar vehicle of the same mass over earth in the helicopter. And if there were no drag, the horizontal component of acceleration would be approximately proportional to the tilt angle of the rotor.

Over the moon, where there is definitely no drag and weight is only one 6th of Earth, the same amount of acceleration requires nearly six times the tilt angle that Neil Armstrong, pretty smart guy. So just like flying on the moon is different, walking on the moon is different, and it has to do with the fact that your inertia is the same, that the amount of force it takes to move that mass is the same, but the weight is different.

It's a fascinating problem. So think about it. If you're walking on the surface of the moon, like right now, if my cg is right here, the center of gravity of my whole body here, I just have to keep that up. And when I walk, I lean forward just a little bit. On the moon, you have to translate that force into the ground, and you might have to lean a different amount. If I have to move my cg more in order to tilt forward and walk, I put my CG out over my feet, and so I have to catch up to it.

So a lot of the falls that you'll see of the Apollo astronauts, it's mismanagement of the CG. They're bumbling around trying to get their feet under the CG. It's fascinating once you think about the physics of what's involved here. Another way to explain this phenomenon is a quote by Arthur C. Clarke in 2001: A Space Odyssey. He said that you are six times more sluggish than your weight would suggest, which is interesting because it means, like, if I'm walking straight, I'm okay, but the moment I have to change directions, my inertia wants to keep going forward.

So knowing that, watch a couple of the Apollo astronauts walk around and see the moment that they mismanage their cg and it gets out over their feet.

Astronauts speaking: They say give it a slight rotation clockwise as they're lifting out. I mean, material is not white. It's just the same as it. Ah, rat. Oh, here we go again. Give me a help. Flight science. Go ahead.

Did you see? It's amazing, isn't it? Once you start seeing the complicating factors, it's like, wow, this is just physics.

Now, there's another physics thing that we have to consider, because we're in the neutral buoyancy lab. So on the moon, there's no drag. In the neutral buoyancy lab, there is drag. So the rate at which you fall would be different. That's one thing. But if we're going to have this simulate the fact that we are in 1/6th the weight we have to figure out how to float five, six of our weight away. Right. And that's exactly what they do in the neutral buoyancy lab. But you have to do that in a very special way that I didn't understand.

And Dom does a great job of explaining how they do this.

Dom: So your suit's 4 psid delta. So it's essentially inflated. It's going to be buoyant. I need to make sure that your center of mass is where it's going to be predicted for your flight unit. But I also have to co-locate that with your center of buoyancy because otherwise you'll be too stable all the time or too. Even though I'm 1/6th g weight. But now it's giving me a riding moment. So these need to be together. So my trick is to locate those two together. I know where they should be.

Destin: So that this.. So that the center of buoyancy isn't a thing.

Dom: Correct.

Destin: Because if they're at the same location, it's like, it's not even.

Dom: No orientation. No preferred orientation, just like zero g. It's not going to roll. It's not going to flip.

Destin: Is that what you're about to show me here?

Dom: Yep, and so how do we figure that out? How do we actually measure that in a suit? So aircraft, when we weigh and balance those, we put them on three jack stands, and there's load cell in each one, and it will give me a resultant axis. And then I tilt it 20 degrees and I get a second axis. And where they cross is my center of mass.

Now I gotta do that with you in a spacesuit.

Destin: Okay.

Dom: So here are my three jack stands and my load cells.

Destin: This is a load cell.

Dom: It's a load cell right here.

Destin: Okay.

Dom: And so I'm on three point and I'm going to stand in here and lock my suit in up here and hold on to those handles up there so I know exactly where I am. You'll be able to see this tomorrow. It'll be.

Destin: Is this like a seesaw?

Dom: Yep. Because this whole thing will rotate 20 degrees. This whole thing will rotate. I'm not going to rotate it now. Okay. But I'll unpin it and you'll see this whole thing will rotate that person in that spacesuit that day, 20 degrees. And I'll get a resultant. And there's going to be a little dive display underwater, and it's going to show the diver where that is. And he's going to move, or she is going to move the weights around until those line up.

Destin: It just clicked.

So what Dom just said blew my mind. And in order to understand it, I kind of need to work it backwards. So let's pretend we have an astronaut here, and we have the center of gravity of that astronaut right here. So that would create an imaginary gravity vector going straight down. You see that? That's the weight of the astronauts. If you were to tilt this astronaut forward, the gravity vector would still be pointing down. Do you see that?

Now, here's the interesting thing. If you were to just go back like this, you can see that those two points intersect each other. Now, let's think about this backwards. Let's say that we have this scale set up that Dom tells us about. We've got some scale parts there in front of the astronaut, some behind. In fact, let's just have the top view of the astronaut here. Here. So you can see it like this.

So we've got one scale thing there. We've got one back here, and we've got one here. If we were to place the astronaut in there and weigh things on this scale, let's say, for example, we have some weight here on this one right here, and we measure some other weight here. Now, the same happens back here. If you were to average out the force of those three points, you would get the center of gravity.

So you basically take the position times the weight, and then you average it all, and then you end up with a center of gravity. The same works here. But if you look at it, if we have more weight on this side, that's going to make the center of gravity move this way.

If we were to reverse it, we were to put more weight over here than over here, then that center of gravity is going to shift forward. Do you see that?

So what's actually happening on the astronaut, because you've got the PLS on the back, the big backpack, is you've got more weight in the back, which means the center of gravity is back here to the back. Now, the interesting thing about using load cells like this is you can only get one position for the center of gravity. You're not getting a 3D position like this. You're only getting a line straight up and down. You see that?

So the center of gravity is somewhere along that line because it's kind of like a seesaw, right? Now, when we tilt this thing forward, the same thing happens.

And so we can do that again. And then we can, just like we did before, where those two lines intersect, we now know what the center of gravity of the astronaut is, which is fascinating.

Now, when we take this thing and we put it down in the pool, we come up with another position, and this is called the CB, the center of buoyancy. The interesting thing about the center of buoyancy is that it might not be where you want. It might be off and up like that. And if that's the case, you have a problem because you have offset forces.

So to explain this instability, I have another view of an astronaut from the front on here. And you can see the CG of the astronaut is right here in the middle. Right. Let's say that they get down there and they start weighing everything out. The CG is the weight of the astronaut there. So you've got a force down. And then the center of buoyancy, after getting on the tilty scale underwater, is calculated to be, like, right here.

And the goal of that, of course, is to offset five, six of the weight of the astronaut. Now, let's say they're not lined up. The center of buoyancy is too far to the right of the CG. Now, if you look at it, that's going to create this floaty force up there, and it's going to create a torque. And if you think about that, you can kind of see how that would happen. And so the astronaut's leg over here would be doing more work than over here, and it would not be a good run.

This would not be good data for a lunar run. So what you want is the divers to trim out the astronaut such that the center of buoyancy is at least aligned with the CG. Right. Because then you. Well, there's still a problem, right. Because now the top of the astronaut is going to be pulling up, right? And so it's going to be easier to stand, right.

Well, if the center buoyancy is too far below, then your legs are going to want to flip over your head. So what do you do in order to get that center of buoyancy right on top of the center of gravity?

Now, the divers and the team running the test are pretty clever about this. They have all these weights in these conformal pockets around the astronaut. And what they can do is if they notice that the CG and the CB are not quite where they're supposed to be, what they can do is they can start moving these weights. They can say, oh, I need to take some from this pocket over here.

And as long as it still equals out to one six, the weight, that'll move the CG, and they can do things all over the astronaut. You could even add foam blocks to make it float in certain places. So you can change the center of buoyancy until the CG and the CB are right on top of each other and the astronaut has a stable lunar run. It's like they're walking on the surface of the moon.

I never would have thought about this. And the fact that you can use this tilty astronaut mechanism to determine the CG and the CB if you do it underwater, I think that's really clever.

Now, you can't directly measure the CB. You have to infer that from the data. That's a little more complicated, but it's fascinating. I never thought that you'd have to calculate the three-dimensional position of the center of gravity and the center of buoyancy. And that would help you emulate a lunar run at the bottom of a swimming pool. It's amazing.

What do you call this when you put them on the scale? I'm gonna call it the scale.

Dom: Okay. This is. We call this our partial gravity weigh out system. So this will be on the bottom of the pool tomorrow when you dive.

Destin: Really?

Dom: And you'll be able to see. And see what's going on that way. But we'll take them down, we'll trim them out to make sure we know where that center of buoyancy is. Then we'll swim them over to here, plug them in, put the extra weights on, make sure they line up. They're in the correct spot. Now go. Go. Do your. Go. Do your testing.

Destin: It's unclear where we are, but we're like, the pool is there. That's where I did the. Put your mask on first thing. Back in the day, there's a big crane up there, and so I'm assuming you're going to pick this thing up with a crane and put it in.

Dom: Correct. And we only need it for the lunar runs. That's why it's out here, and we don't leave it underwater. So. But it will be in before you show up tomorrow. So I wanted you to be able to see it, see it today.

So what Dom just showed us is extremely important, and we'll revisit that later. But we know we're at the NBL to run a test on spacesuits. So let's go learn about the specific test we're running today.

Alright, so now we're with Adam. Adam, you're a test director, right? Tester, conductor? What do you say?

Adam: Test conductor, yes.

Destin: Okay, engineer type?

Adam: I am an engineer, yes. By training. But I'm in the operations team at NASA now.

Destin: So you're going to be running the test tomorrow that I'm going to be observing?

Adam: That's correct.

Destin: Okay. And how long have you been planning this?

Adam: About two and a half months.

Destin: Really?

Adam: Yeah.

Destin: Just doing the paperwork for this one test.

Adam: Yes. And actually, that is a very quick turnaround. But, yeah, now we're executing the test, and it's very exciting.

Destin: So I'm a. I'm a test engineer by training. So what are you, what are your objectives? What are you trying to figure out?

Adam: Okay, this test is about characterizing EVA performance at an elevated suit pressure. On the space station, right now, the EMU spacesuit operates at 4.3 psi. We want to see what this spacesuit, what it would look like to operate at 6.2 psi or even higher pressures. But right now, we're focused on this 6.2 number.

Destin: Okay, so I'm a newbie to all this.

Adam: Yeah.

Destin: But I'm assuming, it sounds to me like if you operate at six point, what was it?

Adam: 6.2.

Destin: 6.2? If you operate at 6.2 psi, that sounds like more oxygen, which sounds like a waste of resources. So there must be a reason why you want to do that because it sounds like the suit is going to be inflated more, it's going to be harder to operate, and you're going to use more oxygen. So why would you want to do this?

Adam: Yeah, that's a great question. And it all has to do with pre-breathe time. And so that's the amount of time it takes you to get from the pressure that you're at in your space habitat or your vehicle to the pressure that you're going to be at in your space suit. And so, using the ISS as an example, the ISS is at 14.7 psi, similar to us here on Earth. And the spacesuit is at 4.3 psi.

Just like scuba divers have to deal with decompression sickness, going from a higher pressure to a lower pressure, it's the same thing with astronauts. And so getting to 4.3 psi takes time. Like, literally three, three and a half hours suited up.

Destin: So they're in the suit for three or four hours?

Adam: They are,

Destin: or just in an airlock?

Adam: Yeah, part of it, they are breathing 100% oxygen. Not in the suit. Part of it, they depress the entire volume of the quest airlock. And the crew lock, still not in the suit, to 10.2 psi. And then they get in the suit, and they do about an hour of what's called in suit, light exercise. So they alternate between, like, 15 minutes of rest and 15 minutes of light exercise, like moving their arms and legs. And so, yes, like, that entire process before they start to depressurize the airlock to even start their EVA is almost three and a half hours long.

Destin: Okay. I didn't realize that. So, question, why? I'm assuming it has something to do with oxygen or nitrogen in the blood, and the bends or, but like, physiologically, why do they have to do that?

Adam: Yeah, exactly right. As you go to higher pressures, the nitrogen is dissolved into your bloodstream at that pressure. And so if you decrease the pressure too fast, then those nitrogen bubbles, they can bubble and create these. The bends. And, you know, just keeping it simple. There's. There's a lot of bad things that can happen.

Destin: Oh, so because they're going to a lower pressure, you could get the bends just walking out of the airlock or, you know, just starting your EVA. So you have to first get. It's like decompressing when you're going up in altitude, so to speak, in a scuba situation.

Adam: Exactly.

Destin: Same thing.

Adam: It's all about the speed at which you decompress. And so in scuba diving, you go down, depending on how long you stay at the bottom tells you how long it should take you to get to the top.

Destin: So by doing a higher pressure run in the suit, there's trade-offs. So it's good because you don't have to pre breathe as much, I assume?

Adam: That's the goal. We're trying to reduce the amount of time.

Destin: Do we know the amount of time it would take? Have we done the math?

Adam: Well, so it all depends on what atmosphere your vehicle is designed for. And so, really, it's that distance. It's a distance between what your vehicle's at and what your suit is at. And so you can reduce the pressure of your vehicle that the astronauts live at and keep the suit pressure the same about 4.3. And that lowers the gap and reduces the pre breathe time.

Another way to do it is increase the pressure of your suit, which also brings those closer together. And so, in an ideal world, the pressure of the suit would equal the pressure of your space vehicle, and that would be the zero pre breathe scenario, where all you have to do is get in your spacesuit, do all your leak checks and everything, and then you walk out the door.

Destin: I think in a science fiction environment, or, like, when you're reading books and stuff like that, that's what you think happens. I'm just going to put my suit on, go outside. It's not what happens at all.

Adam: No. And I don't think people realize it. Like, astronauts go and do spacewalks that are like, 6 hours, 7 hours, 8 hours long sometimes. And that in itself is one of the hardest things that they ever do. Not only that, they are doing this pre-reset for, like, three, three and a half hours before that. So they're in the suit for a very long time.

So we want to minimize that pre-breathe portion so that we can maximize their time doing a spacewalk in the spacesuit and getting our science objectives or whatever objectives completed.

Destin: Okay, so I'm assuming the suit was designed for a certain pressure. Like, what suit are we going to be doing the test in?

Adam: So this will be what's called the XEMU. This is the NASA government reference design suit that they've been working on for the last few years. And so it's actually been designed with this in mind. So its pressure rate was rated to operate, I think, up to 8.2 or eight psi somewhere around there. And so this is all within normal bounds because we knew this was going to be something we were going to want to look at.

Destin: So it's like a pathfinding type test. You'll get the data, you'll apply it moving forward, and then you'll know what to do in space.

Adam: Correct.

Destin: Do we know what the chamber, chamber pressure is in the term? You can tell. I'm a mechanical engineer. Do we know what the habitat pressure is going to be on HLS?

Adam: There are, yes, we do know that, and I'm not sure how much I can speak on that topic directly, but.

Destin: It is a known thing.

Adam: It is a known thing, and it's one of the knobs that we can turn, so.

Destin: We know where we're going to be, and we know what we're going to run the suit at. And that tells us what our pre-breathe time is going to be.

Adam: That's right. Yes. The program management folks are looking at all the different knobs, and we're just trying to understand how do we minimize the pre-breathe time? Because this really has to do with our timeline. When we're on the surface of the moon.

In these early missions, we'll be on the surface for six days. We want to do four eight-hour EVAs, if possible, right? If we have to spend an hour and a half, 2 hours, 3 hours doing pre-breathe, that's wasted time.

Destin: That's a long day.

Adam: Yeah. So that's kind of what all this effort is. And there's trades with all of these decisions, right, regarding the atmosphere and stuff. So it's a complex decision to make.

Destin: Will they start the run at four psi and then go to six? Or will this be a high-pressure run the whole time?

Adam: So that's actually something that's really interesting about this test, is the subjects will be blinded to the pressure they're operating at.

Destin: Really?

Adam: Yes, I am blinded, and the rest of the test team is blinded. So only a few people, as part of our test leadership, and obviously the people here at the NBL that turn the dials and stuff, know what the pressure is, but the astronauts will not know.

We have the ability to run each of them at a different pressure. So one person may be at a higher pressure, one person may be at a lower pressure. We don't know what decisions were made by the leadership.

The next morning, I showed up, and the first order of business was to fill out some paperwork and do a pre-dive medical check, where they just confirmed, from a health standpoint, that I was safe to dive. Remember the hypoxia video? She saved my life.

Yeah. Pat took me poolside and introduced me to the person in the red shirt, who today was Mike Caldill. Whoever's wearing a red shirt is in charge of the whole pool. And you don't wear a red shirt unless you're that designated person. We checked out the equipment and, well, mainly my ability to work the equipment.

And then I headed upstairs to catch a bit of the pre-dive meeting where the various departments involved were going over the specifics for the day. The two astronauts who'd be doing the dive are Jessica Meir and Randy Bresnik. Both are seasoned astronauts with a combined time of over a year in space. These are seasoned spacewalk experts. You can see through all this footage that they have a lot of time in microgravity, and they know what they're doing.

This, however, will be their first dive training with these new suits in this lunar environment. I headed down to the pool deck as the operations began.

Okay, so we're poolside now. I see the thing in the pool.

Dom: Yeah, yeah.

Destin: What's it called again?

Dom: So this is our partial gravity weigh out stand.

Destin: Yeah.

Dom: And that's gonna go all the way to the bottom. Right now, we're just trying to get the temperature to equalize because the. Those load cells are, you know, the accuracy and precision if your thermal is off a little bit. So the 86 degree water is not the same as the air. So we put it in. We're doing a little warm soak right now. That'll go all the way to the bottom, and then by the time the crew gets in, they'll be able to walk right on do their way out.

The divers will adjust that. They'll have a good 1/6th, and they'll be good to go for their run.

Destin: So here's the weigh out stand. And I'm seeing rocks over there. And. I'm sorry, how is this working?

Dom: Okay, so this semicircular here is a representative of the human landing system, the lander. And so we'll have, there's an airlock that's straight down under here, mock up. So they'll walk out of that airlock. They'll go into this little front porch area, which is actually representative of the elevator that would take them down to the surface, because this actual, this would be the elevator that descends to the surface. The rectangular part out there.

Destin: Got it.

Dom: And then they'll walk off that ramp. Normally, it'd be about a 30 foot lower, but there's no reason a 30 foot lower. We just walk out here. They do that. They close up. They get used to that. They open the door. I've lowered to the bottom. I walk out, and I start my EVA on the surface.

And so the rocks are there. So when we have our lighting intensity, it throws those shadows, gives them the area, and gives them an area to work in.

Destin: So these models in the neutral buoyancy lab are what's called low fidelity mockups. They're mostly made out of materials that won't corrode, like stainless steel and plastic, but they also can't trap air. That's why you see the grating down there. And so when I looked at this ring, I was like, eh, it's a ring. You know, it's just a. It's a psychological representation of the diameter of that rocket.

And then I was like, wait a second. That's a big rocket. And then I got excited. I started thinking about all the engineers designing things to go in there and, like, what it was going to look like in the end. And so I got excited about it. But at the same time, right now, it's just like, this is a 3D space that we can use. It's like a little playground.

And so I thought that was really interesting, and it took my mind to weird places, realizing that this is a lot bigger than what Neil and Buzz went to the moon in. And so this is the first moment that I got really excited.

So I'm thinking about the gloves because that's going to be affected by the pressure. And they're putting the gloves on now. Randy's requesting a certain tension in the gloves, so that's going to be affected by the pressure inside the suit. So there's actually a bar across the palm. Right? Right where it folds there. Yeah. And that's what they were tightening and cinching up in the back. So it pulls that part in so.

It's not just a balloon coming out from the palm.

Yeah. So after they finish getting the astronauts in their suits, they hoist them on a platform and lower them down into the pool.

Female voice over com: TDECs system alarms are enabled. Verified. No alarms present that will impact testing.

Greg: Copy that, no alarms. Good morning, safety divers. This is Greg, your test director. How do you read me this morning?

EV-1: Copy on one.

EV-2: Copy two.

Greg: Let me check this back up. Alright, safety divers. And won't back up. How do you read me, EV-1 safety.

EV-2: EV-1 loud and clear.

EV-2: EV-2 loud and clear.

Greg: Loud and clear on backup. Alright, safety divers. Purge all air trapped by the delta pressure valve adjustment knob. Please give me an okay sound when complete.

EV-1: Copy on two.

Greg: Safety divers. Thank you. And copy on one. Safety divers. Thank you.

Destin: So at this point, we have astronauts in the pool, which is awesome. They have, like, 6 hours of dive time, and I, as an observer, have a little over two. So I decided I was going to stagger when I got in the pool so I could observe the actual test taking place.

So while they were doing their leak checks, I checked in with Adam.

Destin: So does this get old?

Adam: Does this get old? It does not get old. Yeah. I'm actually a test conductor in training, so this is my certification run, so that this is my third time kind of running the show, so to speak. And it is just so much fun. I mean, look at this, this is one of the premier underwater training facilities in the world for astronauts, and I get to be the person that talks to the astronauts and help to work through the test team, and you can just see how many people it takes to do this, not only to pull it off in general, but just to pull it off safely. And so it's just. It's a dream come true to be here.

Destin: So, at the end of the day, you'll be certified, hopefully.

Adam: At the end of the day, hopefully I will be certified. I have somebody evaluating me, and. And hopefully I'll get thumbs up.

Destin: Who is that? I got to know, who's that?

Adam: Her name is Tess. She's up there sitting in my seat right now covering the room, so.

Destin: Oh, I got to talk to Tess.

Adam: Yeah. She'll be my partner in crime.

Destin: Okay.

Adam: And my evaluator.

Destin: Okay, great. Alright. We'll see how you do Adam.

Adam: yes, thank you.

Destin: We're gonna be judging you from now on.

Adam: That's all right. You know, if you're. If you can't handle pressure, well, this isn't the job for you, right? There's a lot of people. It's very dynamic. But I love the pressure. It's kind of like being a flight controller. Okay. Just a different flavor of it.

Destin: That's cool.

As Randy and Jessica made their way to the bottom of the pool to begin the trimming and weighing out of the spacesuits, I was able to catch up with one of the suit engineers as she waited.

Destin: What was your name?

Christine: So, my name is Christine Davis, and I'm an advanced suit engineer for the advanced suit team here at NASA.

Destin: So I saw Joel over here working with Randy. And you were working with Jessica to get her suited up?

Christine: Yes.

Destin: So what's your background?

Christine: I went to Kansas State University to get mechanical engineering degree, and.

Destin: That is the correct type of engineering.

Christine: I know, and then I started full time in 2016, and I've been working on the team since then.

Destin: Okay, so what were you doing with Jessica? Getting her ready.

Christine: So I was getting her ready because I'm her suit test engineer. So I'm going helping through all the procedures of getting her suited up. So that's suit donning, making sure that her cooling garment's connected, there's no leaks. Getting her comfortably in the suit. Making sure that all of our straps are tight, so we have boot tightening straps to make sure our boots have good fit. Same with her gloves. Making sure she can reach her valsalva in her drink bag and making sure that then when she gets pressurized, that we stay safe through that pressurization.

Destin: Now, the valsalva, my understanding, like, I'm about to dive here, and when I go down, I hold my nose to clear my ears.

Christine: Yep. And you can't do that in the suit.

Destin: So what do you do?

Christine: So you use that valsalva device. So it's basically a foam block that the crew members can use to block their nostrils, similar to, like, when you squeeze your nose when you're diving. And it helps just for you to clear your ears. And some people don't need to use it. They can just swallow or move their jaw. But sometimes you need that extra little bit of umph to get the valsalva cleared. So they use that device.

Destin: Oh, that's awesome. So how long have you been doing this?

Christine: So, I've been doing this for eight years full time since in March.

Destin: Do you love it?

Christine: I love it, yeah. So much fun.

Destin: Yeah. You like working with the astronauts?

Christine: Yeah, so much fun. It's always a great day when we get to do testing.

EV-2: On the bottom.

Greg: Copy that. EV-2's on the bottom. Alright, we're gonna go ahead and do a final comm check. I'll turn it over to Mister Peterman, our comm technician.

Destin: So are you dedicated to Jessica's suit, or you work for all the different?

Christine: So I work on the XCMU. Specifically, I'm one of our suit test engineers, so I help run some of our suit tests. I also am supporting the XC Bas contract. So XCBAs is the exploration suits that we're gonna be working with Aceiom and Collins, two suit vendors on. So I'm helping on the insight team. So, from the government, kind of reviewing their documents, reviewing their suit design, making sure that suit's being developed safely, so that we transition from the XCMU government reference to their suits for flight.

Destin: You're wicked smart. It's so good talking to a fellow mechanical engineer. That's great. Well, this is fantastic. Thank you so much.

Down on the bottom, the divers trimmed out the astronauts to first make them completely neutrally buoyant. They tipped them over and spun them around and adjusted weights and foam to various positions until no matter what orientation they placed them in, they would float completely still. Once they had obtained neutral buoyancy, they then had them stand on the bottom and added more weights evenly to create the one 6th gravity pushing down on them.

After that, they walked over to the partial gravity weigh out system and take an upright measurement that gives them a vertical vector of the location of the center of gravity between the three load cells. Then the divers tip them forward 20 degrees, which gives them another vector. And the intersection of those two vectors is where the center of gravity is in three-dimensional space.

The team topside analyzes this information and compares it with the computer models of where they want the center of gravity and center of buoyancy to be. In this case, Jessica's suit requires an adjustment because the data revealed she has a riding moment.

Greg: Safety divers for EV-2. Let me get you to take a two-pound snake weight off of each leg. And, Jessica, just some additional words here. So, looking at the numbers, your CB and CG measurement is just a little bit further away than we've seen in previous runs.

So the team is just going to remove these two leg weights to try to better align your CB and CG and also get you closer to the one sixth mark. All right, here we go. Got the suit on. Yep. We're good to go. Yep.

Okay. It was time to do the dive. I was very excited. Even though they keep the pool at a balmy 86 degrees, I decided to wear a shorty because if you're in the water for several hours, you could get cold still. So we got everything suited up, made sure the equipment worked, and then Pat led the way.

Once we first descended into the water, it's like an entirely new world opened up. It was surreal to swim over a life-size model of the International Space Station. My favorite thing was the Canadarm was right there. It's a mockup that they use only it doesn't use electrical actuators that uses an oil pump to move Canadarm. It was amazing.

I kind of got my bearings, and then we went all the way down 40ft deep to the bottom of the pool. As we approached the bottom, Pat gave me very clear instructions on where I could go and where I couldn't. And I wanted to be a good little diver and I wanted to obey everything that Pat said. So I made sure that I asked for permission every time I did anything.

As I approached the bottom of the pool, I realized that all the attention was on the two suited individuals before me and even the individuals themselves. They were focused on the task at hand wringing the truth out of these suits. And it was at this moment that I realized I was jealous. I wanted to know which of these suits was at a higher pressure. And I was jealous of the technicians that turned the knobs that knew the answer to that.

But for now, it was as simple as picking up rocks to test mobility. At some point, Pat told me that I could explore if I wanted to, and I certainly did. So I swam up to some of the ISS modules and I got to poke my head up into one of the nodes and look around, and I could see how difficult it would be to. To manipulate the latches and locks if I had big gloves on.

I'm pretty familiar with the International Space Station. I've been in mockups before, so I have a 3D model in my head. But floating in the International Space Station was a completely different thing. Like the fact that I was in a 3D interaction with it instead of walking through it like a hall.

It felt different, and it instantly made me understand why the neutral buoyancy lab was so important. Important. While I was exploring, I found some of the weights they used to trim out the astronauts, and I was surprised by how heavy they were.

After exploring a little bit, Pat took me down to the lunar simulation area of the NBL, which was awesome because there were little bitty Easter eggs that the engineers designed in. You remember when Alan Shepard hit the golf ball, Apollo 14? Where did the ball go? I'll tell you where it went right here. The engineers put it into the rock. I thought that was awesome.

Also, Pat took me down to the bottom of the pool, and I was surprised to see the footprint of that real smart gentleman that we heard from earlier explaining one 6 g to us, Neil Armstrong's boot print.

Okay, to begin the lunar run, I'm going to show you what the astronauts would see. They would begin inside HLS in an airlock, and then they would go out into a lock, larger room before going out onto what will be the elevator, but in this case, it's just a ramp. Then they'll go out onto the lunar surface and start exploring. So, of course, I wanted to position myself just outside of HLS, so I could see them coming off the elevator, and that's just what I did.

Thank you so much. And, diver, do you have a go-to? Once the astronauts came out and started exploring the lunar surface, I was surprised to find that mission control was kind of micromanaging them a little bit. They would say, go get this specific shovel from the cart. Now go retrieve this, put this marker down.

I would expect them to say, hey. You're on the moon. Go explore. But it was different than I expected, which makes me realize the test conductor, Adam, in this case, was probably trying to control all the variables so they could compare the runs between all the different astronauts. At least that's my assumption.

For example, there was a pegboard-like structure with a hose that they had to detach and reattach. I'm assuming every astronaut had to manipulate these to test their ability to use their gloves.

One of the signs of a good scuba diver is the ability to control your buoyancy so that you can stay in one spot. I was having to kick and fin all over the place to keep myself where I wanted to be, whereas these divers clearly had a command of their whole body and in the area around them, they didn't have to do anything. They could just float where they wanted to be.

This told me that they knew exactly what they were doing. The different tasks that the different divers had started to become more clear to me; some people were just trying to keep the hoses out of the way from the astronauts. Others were a safety observation. They were making sure that the astronauts were safe at all times.

The camera operators were making sure that the test conductors could see exactly what was happening in the pool. It was like a beautiful, choreographed dance, all happening in three dimensions, and people were controlling their own buoyancy. And I was just trying to stay out of the way. Pat was so much better at swimming around than I was.

So at one point, I gave him the camera, and I said, Pat, I want a shot of the wheels on that cart. I want to see how they're interacting with the lunar regolith. Can you go get that shot for me? And of course, he did. Look at how much the astronaut is having to lean over to push the cart.

This goes back to that one. Six g we were talking about. They're not actually getting a lot of purchase in the soil because they don't weigh as much, so they're having to lean really, really hard to make that thing go. Think back to that quote earlier. You're six times more sluggish than your weight would suggest. You can see it happening right here.

The most incredible thing I saw happen right in front of my face. Randy was working on his knees, and the transition off of his knees created a fall, and why he fell is something that you're going to recognize. Let's watch the whole thing play out first, and then we'll go back and replay it, and we'll talk about it.

Man over the PA: The last thing you'll need is the tongs. And so you walk back to the cart to grab that, and then you can collect your sample.

Did you see what happened? Watch it again, and let's talk about it. So Randy kind of mismanages his cg just a little bit because he's too close to the ground. And then it starts to take him over. Now, anyway, when Randy falls, watch what the diver does. She comes over and she says, are you okay? And then Randy apparently tells her, yes, you have another diver getting the hoses out of the way. And then she makes Randy struggle through on his own. He has to figure it out, and he does.

He figures out how to get back up, and they celebrate this together. And all the while, everybody's taking the data. And I thought that was amazing. It was so cool to see this at the bottom of the pool. I was feet away from this when it was happening, and I'm excited to share this with you because we are getting to see an astronaut learn how to walk on the moon. Randy's having to figure out how to manage his cg, and that's important for walking on the lunar surface, and that's all going to factor in to make Artemis successful, right.

As they started testing the suits, walking up a grade, the dive supervisor announced that my time was up. I wanted to stay on the moon, but obviously it was time to go. As I swam back up, I was thinking to myself what an amazing opportunity. I was so thankful to be able to do this. And when I got to the top, I thanked Pat for such an amazing dive and for watching over me and keeping me safe.

After I was cleared from the test supervisor, I hit the showers, washed off, and I went up to the control room in time to hear Adam doing some of the qualitative assessments with the astronauts.

First up is perceived exertion. So this is that zero to ten scale. Thanks again. You all did awesome and looking forward to talking more about it when you're out of the suits.

Sounds good. So thank you. A lot of fun. Sorry ISS, this is way more fun.

So this was Adam doing his checkout, right?

Tess: Yeah.

Destin: And you were observing Adam as,

Tess: Oh, I'm about to be put on the spot. That's what's about to happen.

Destin: So how did he do?

Tess: He did great.

Destin: Did he?

Tess: Adam's a really strong TC. I think we all kind of knew going in that he was going to kick butt.

Destin: Yeah?

Tess: And he did not decide disappoint in any way. It's fun with these guys because they've been astronauts for quite some time, and so they've gone through the basics of learning how to do EVA for ISS.

So they learned how to move in that suit, they learned how to do those tasks, and this is almost resetting them back to EVA 101 with a new suit and new tasks. And so they understand the mindset for learning these things, which is you can fail, and it's okay.

Go see what the astronauts thought about the run. Let's start by talking to Randy.

Destin: I noticed that you were having trouble at one point standing up because you had to learn. It's the first time you had to learn that, right?

Randy: The way out is what you have to get used to. Where's that center of gravity and how much does it tip you over, and you start falling. And so without as much traction on the ground when you go into the sand now, it's tough to get leg out there and stabilize yourself or swing it around.

And so there's one point where I ended up falling onto my back, and where I was on the hard ground, I was able to get enough traction with the boot to be able to get me up on a shoulder and then be able to get over and then stand up.

When I was in the simulator, I was like. I felt like I was break dancing. I was just spinning around until I finally got a purchase and I was able to get the center of gravity up over my arm, get on my front.

Destin: So it was interesting why watching that, because you were problem-solving in real time, and it was pretty cool because you get to figure that out here instead of, you know, on the lunar surface.

You'll say, oh, well, with this suit, it has mobility in this direction. I can do this. I can't do that. Do you learn things like that?

Randy: Absolutely. And that's the whole reason why we have this facility and do our EVA training for zero g in this facility as well, because you figure out that we've come in everything with this one g orientation, up is up and down is down, and we can go in here with the space station and train for microgravity in every position as possible.

And you have to force yourself to get out of those positions that are heads up to get in the right position for the best one for work. Or maybe it's even inverted, and that allows you to then have this whole toolkit, a whole array of attitudes that your brain thinks of. And so that was the same thing, exactly what you, you observed going, okay.

Well, that didn't work. Okay, that didn't work. Alright, let's try this. Okay, let's try this leg back instead of this leg, you know? And so it was trial and error, and then found something to work.

Destin: What do you think about the tools they gave you to work with on the surface?

Randy: They were evaluating and evolving tools. We