Science & Tech

Spacewalking: Spacesuits

Chris Hadfield

Lesson time 17:56 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.

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

Topics include: Stay Focused and Aware • The Spacewalk Experience • The First Canadian Spacewalk


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...

About the Instructor

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.

Featured Masterclass Instructor

Chris Hadfield

The former commander of the International Space Station teaches you the science of space exploration and what the future holds.

Explore the Class
Sign Up