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Science & Tech

Spaceships: Capsule Design

Chris Hadfield

Lesson time 19:42 min

Learn the virtues and drawbacks of using the capsule model for human transport to space as Chris analyzes the designs of the Apollo, Gemini, Lunar Lander, and Soyuz.

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


A spaceship is essentially a little sample of the earth taken off the planet, a little bubble of life away from the natural place where we all began. You need to bring along the things that keep you alive. You need to bring air, oxygen, something to breathe. You need water. We can't go very long without water. You need to control the temperature so it doesn't get too hot, too cold. Eventually you're going to need food. You need something that can process the body's waste, the waste gases that I breathe and all the rest of the waste the body produces. A spaceship needs to provide all of those normal earthly things, but away from the planet. In order to make a machine that can keep at least one astronaut alive way out in the thermal vacuum of space is extremely complicated. If we were willing to have astronauts die all the time, it gets way simpler. But if we actually want to have the astronaut live, then you have to try and think of everything. And on top of the thermal requirements and the air-pressure requirements and the water and the waste and everything, you're also weightless. Nothing is going to behave the same on the spaceship as it does back on earth. The fluids won't go to the bottom of the tank. Will the astronaut be able to swallow and breathe? What will happen the blood-pressure regulation? How do you do everything when heat doesn't rise, when there's no gravity? It's a whole new world of problems, and it was one that took several decades to get to the state that we're at right now. So what do you actually need to keep a crew alive and healthy and productive inside a spaceship? If we just look at an airplane of course, this little early jet could just barely take us out of the bubble where we can naturally live. It could go high enough where the air was so thin that we couldn't just fly along with the canopy open like this. We had to have a way, in this early F-86, of being able to pressurize the cockpit, to have a little bubble of life way up in the sky in an environment where otherwise life couldn't exist. And sort of that's like the initial early stages of a spaceship, taking a little bubble that provides just the minimum that, in this case, the pilot needs in order to safely survive somewhere away from the cradle of earth itself. But to go higher, this little bubble needs to get more and more complicated and more and more capable. One of the earliest spaceships was the Gemini capsule. It looked a lot like the Mercury capsule. You can tell this is a Gemini because it's got the twins, two seats, Gemini. But this was one of the very first space ships, as simple as we could make it, but a big tradeoff between all of the things we needed. Essentially it's a little cockpit. It has air pressure inside. And it's got this whole section here for systems to keep you alive, to take your breath and process it through some carbon dioxide removal system so that you can continue to breathe oxygen. It's got a thermal regulat...

Explore the unknown

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.

Wonderful class. Wonderful instructor. I have taken many insights into how to manage life decisions out of his teachings.

Highly interesting Masterclass, that gives an insight into the job of an astronaut as well as technical knowledge and also inspires to think about big questions and to research more about the topic on your own.

I'm in isolation with my family due to the virus and wanted to explore something outside my own frame of reference. I'm a baseball executive with no baseball being played so Chris and this class took me to places I never thought I'd go and taught me so many things I never thought of understanding.

This class was simply amazing. Chris Hatfield explained space exploration in one of the most effective ways I have ever seen from a instructor.


Bernardo F.

I didn't know what Chris mentions about studying earthquakes on the moon (moonquakes?). However, I remember to hear that the missions who got to the moon usually left many things on the surface, like toilet waste and some tools that they weren't going to use anymore so that the reentry was lighter.

A fellow student

My understanding is the Service Module provided life-support functions (for example: power, water, breathable air, communications, computer, etc) but the astronauts didn't actually live in there. Rather, they were confined to the Command Module and the LM.

William D.

Ignores how capsules are controlled during reentry. Mercury had up to 8 g's for reentry. Gemini and Apollo were not as violent using controlled reentry rather than just a ballistic path. Little information on the ablative nature of the heat shield. Yes, the whole capsule was designed for just 1 mission. Attitude control of capsule during reentry was by Hydrogen Peroxide Thrusters in Mercury but both Gemini, Apollo and Shuttle used Hypergolic Propellants. New capsules by Boeing and Space-X will be used multiple times. Synopsis talked about Soyuz but nothing was mentioned about them at all.

Mário Filipe P.

Captivating and very informative lecture about capsule design and the incredible amount of things you need to have into consideration when conceiving an autonomous/life sustaining spacecraft. Some of which I've never though about before! Everything works so differently and counterintuitively once you remove the atmosphere and the effects of gravity out of the equation... it's an incredible fascinating new world, unlike anything we've experienced here on Earth.


This was a fascinating lesson. My question - How do we decide on the number and position and orientation of thrusters on a orbiting spacecraft? I imagine it is related to the 6 degrees-of-freedom (roll, pitch, yaw, and the 3 translational) but why do they look so different on the various designs over the years? For example, the thrusters on the SpaceX Dragon designs are very different to the Apollo command/service modules and the soyuz. Thanks in advance.

Patty R.

Wait, so you crash in the ocean, hope the Navy is nearby, open the door and climb out after having been weightless for an extended amount of time? How do your muscles and body respond to that? Is it adrenaline that is helping you get out of the capsule? Chris, you are such a Boss! That story was crazy!

Patty R.

How could the lunar lander that was disposed of and crashed on the moon cause an earthquake if there is no gravity? What were the results of observing and measuring that impact?

Patty R.

Why was there color blasts when the lunar lander took off from the moon? How hard was it to dock to the Command Module that was orbiting the Moon? How fast was it going and how long did it take to dock? How did the Astronauts practice docking back on Earth?

Maddie W.

I loved the way Chris used models to illustrate some of the designs and features he was talking about. I also have some spaceship models including an entire space shuttle so it is really cool to see these things explained from an engineer's point of view. It really makes the models so much more meaningful and helps the audience understand why spaceships are built a certain way and how engineers can solve technological problems. Another fantastic and engaging lesson from Chris Hadfield!

Steve H.

I appreciate having videos interspersed with his explanations. The models look simple when compared to the complexity of the actual spacecraft. His explanations make the complex seem simple for our understanding.