Science & Technology

Spacewalking: Spacesuits

Chris Hadfield

Lesson time 17:57 min

Chris gives a head-to-toe tour of an EMU (Extravehicular Mobility Unit), explaining how it keeps astronauts alive while spacewalking and conducting work outside the ship.

Chris Hadfield
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Most of the time that I've been in space, I've been on the inside of a spaceship. And we can do most of the stuff outside with the robots, the big, robotic extensions of ourselves. But sometimes we need the dexterity of a human hand. We need the sensitivity of a set of arms to maybe turn a bolt or do something that requires judgment and the tactile nature of our interaction ourselves. And that's when we need to put on a suit like this and go outside. This is a spacewalking suit. EVA, Extravehicular Activity, going outside. Not intra-vehicular, extra. This is a suit that lets us do it. The environment outside is extremely unfriendly. Of course, the number one big difference is there's absolutely no air. So the suit has to be pressurized with a breathable environment inside. It's also wickedly hot and wickedly cold at the same time outside. In the sun, it's 120 degrees Fahrenheit on the outside of this suit. But in the shade on the other side, it's minus 100 degrees. The suit has to protect you from those big temperature extremes. You're also subject to getting hit by all the little tiny particles of the universe, like you're being sandblasted the whole time you're outside. This suit has to protect you from that. So it's not really a suit. It's more like a one-person spaceship, completely self-contained and different from the ship that you crawl out of. Here's how it works. On your back is a life support system. We call it the Personal Life Support System, the PLSS. And it has your oxygen purification system, it has your battery power, it has a radio, it has a cooling system. This is sort of the nuts and bolts, the guts of your suit that keeps you alive. We keep the suit as low a pressure as we possibly can, because if you pressurize this suit to the full same pressure as you get here at sea level, you'd be in a balloon where you could never even bend your elbow or close your fist. So we only run the suit down about one-third of the pressure that's around me right now. Instead of 14.7 PSI, we run the suit at about 4.3 PSI, because that's the trade off between what I need to keep my body healthy and how bendable we can make the elbows and the fingers on board this suit. What gas do you put inside the suit? We could have air. We could have a mixture of other gases. But if you're going to run down at just 4.3 PSI, then you really need all the oxygen you can get. And so we decided a long time ago the gas that's inside the suit is 100% oxygen, just down at a low pressure. Let me go over the suit top to bottom. Here at the top is a camera for the ground to watch what's happening. You reach up blind, you push this button right here, the little green light comes on, and these cameras are activated. If you push the button multiple times, it changes lenses, and that way everybody down in mission control can look over your shoulder and make sure you're doing all the things that you need to do, but also as you finish working in one part of t...

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Impossible things happen. At age nine, Chris Hadfield knew he wanted to go to space. He eventually went there three times, becoming a commander of the International Space Station. In his MasterClass, Chris teaches you what it takes to explore space and what the future holds for humans in the final frontier. Learn about the science of space travel, life as an astronaut, and how flying in space will forever change the way you think about living on Earth.


Students give MasterClass an average rating of 4.7 out of 5 stars.

Chris, you are such an inspiration to me. Your eloquent way of speaking about the most magical topic imaginable was sensational. There wasn't a single second that I wasn't listening! Thank you!!!!!

Chris Hatfield is so unbelievably accomplished. He is probably an alien transplant.

What a wonderful class. Colonel Hadfield, you are sublime.

Makes me want to travel to Mars with Elon Musk, and I wonder if Chris will be on board the Starship in 2024!


Jane S.

Loved this part - knowing how the space suit is designed and how it works while wearing it

Denny C.

I am a "Gear-aphile" meaning I really get into the technical aspects of the equipment. Love this part!

Ugo A. D.

Loved it. Very interesting. Ability to walk outside in the total vacuum space, must be extremely interesting to see the world from that view.

Pedro C.

I really liked to know about some of the challenges at space and the amazing ingeneering needed for spacewalking suits. It would be wonderful to know more about the space challenges, including radiation, pressure, micrometeorites, temperature, etc. It would also be wonderful to know more about the different layers, roles, design requierements, materials, tests, dangers, possible contingencies, emergencies procedures, etc.


Wow! A little world within that spacesuit. That was incredible to watch. The life of an astronaut is more understood with this class. It's all about education and taking this class has given me such great love and admiration for our space program.

Ramona T.

This is the first lesson that left me realizing how incredibly dangerous, isolating and amazing the life of this astronaut was.

Rob G.

So how are the surface of suits decontaminated before reentry back into the ISS?

Chris M.

What percentage of suit design features were built into the suit prior to the first space walk as compared to subsequent spacewalks. I'd be fascinated to know how many things these folks thought of before they went out there...and then after they tried it out.

Hank W.

Is there a way to clean the space suit if it's contaminated? I'm thinking of firefighters who go into a toxic environment and collect bad stuff on their gear, and don't want to bring that into the station or truck.

Terry W.

Awesome! Keeping it simple and easy to understand, this video is like one of Cmdr Hadfield's one-pagers for Space Suits. The suit is much more complex than I had imagined. I was not aware of the Jet pack capability, but it sure makes sense to be able to return to the station autonomously should an emergency arise outside the space station. Joysticks? I liked that pop out control system.