1
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I never thought a laboratory would have a swimming pool.

2
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Me either. I wonder what they do here.

3
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I'm glad you asked. You two must be the treehouse detectives.

4
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Yes, we are.

5
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Well, my name is Mr. Utley, and this is the Neutral Buoyancy Laboratory, or NBL.

6
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We use this tank to simulate a weightless environment just like you'd see in space.

7
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It sure is big. Just how big is it?

8
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The NBL is 202 feet long, it's 102 feet wide, and 40 feet deep.

9
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That means it holds just over 6.2 million gallons of water.

10
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That's as big as 12 Olympic-sized swimming pools all put together.

11
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Wow, that is big. Why do you need such a big tank? I mean, laboratory.

12
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Well, the International Space Station components are really big,

13
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so we need to have an environment that was big enough to be able to have astronauts practice putting all the components together.

14
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How do the astronauts train in the NBL?

15
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Well, instructors coach the astronauts on tasks and techniques in spacewalks

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that they're going to have to do while living and working in orbit.

17
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Spacewalks? Why would they need to walk in space?

18
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Well, sometimes astronauts have to go outside of their space home to do such things as assemble the space station

19
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or even fix the Hubble Space Telescope.

20
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Is there anything else they do in the NBL?

21
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Yes, as a part of spacewalk training, they train on tasks like connecting power supplies,

22
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deploying radiators, deploying solar arrays, or even changing batteries.

23
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Changing batteries? That doesn't sound very hard.

24
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Why do you have to train for such easy jobs?

25
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It may sound easy, but working in space is very challenging.

26
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There is no up or down, and so objects may not be in the same orientation they were in when they were training here in the NBL.

27
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At least all the heavy stuff doesn't weigh as much as it does on Earth.

28
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Well, actually, even though it's weightless in orbit, objects still have their mass,

29
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so you have to be very careful about moving a large object quickly because it will build up momentum,

30
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so astronauts have to train to be able to move things very slowly and deliberately.

31
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This is a lot more complex than we thought.

32
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Why do you use water?

33
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We create a weightless environment by using the principle of neutral buoyancy.

34
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What is neutral buoyancy?

35
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Well, neutral buoyancy is when an object has the same tendency to float as it does to sink,

36
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and that just hovers in the water, and that is the same property as being weightless on orbit.

37
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So you can take a 190-pound astronaut, put them into a 200-pound spacesuit,

38
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pressurize the suit, and add weights to the chest, back, and arms and legs just so that they're hovering around in the water,

39
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and that gives them the same reactive forces that they would have in orbit.

40
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So when you push yourself away from something, your body is going to continue to float away from it.

41
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If the suit weighs 200 pounds, how do you get them out of the pool?

42
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Actually, we're taking the astronauts out of the water right now.

43
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Wow, those suits are awesome.

44
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If you really want to know more about spacesuits, you should talk to Dr. Ross here at Johnson Space Center.

45
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That would be great.

46
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Well, give her a call and let her know you're coming.

47
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Thanks, Mr. Rutley.

48
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Bye.

49
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Bye.