Science & Tech

The ISS: Life Support Systems

Chris Hadfield

Lesson time 12:39 min

Learn about the many systems that work together to keeps astronauts alive aboard the ISS and how those systems are evolving so that we can travel even further in space.

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

Topics include: Oxygen • Water • Prepackaged Food • Growing Food • BEAM: Testing Systems for the Future


Inside the space station right now, there are six people, living and working, running the experiments, exercising to keep their bodies strong. Breathing in, breathing out. Every time you breathe in, almost a magical thing happens in your lungs, where your body extracts the oxygen from the air and then extracts the carbon dioxide from your blood and does an exchange, so that when you breathe out, it's a different gas. You breathed in oxygen-rich, you breathe out some certain percentage of carbon dioxide. And here on earth, that's not such a big deal, because the entire planet is evolved to expect that. We have plants that take the carbon dioxide and process them using the energy from the sun and photosynthesis to release oxygen. It's a lovely big balance that's evolved on the planet. But what do we do on a spaceship? When you breathe out in space, how does that wasted or poisonous gas of carbon dioxide get reabsorbed? And where does the new oxygen come from? It's one of the problems we needed to solve. The best answer would be if we could just have a mini earth, and somehow completely recycle our oxygen. Maybe we could fill the whole space station with trees, and that way we could just use photosynthesis and the natural processes. But even if you-- say you planted beans. If you have a crop failure, everybody dies. And so, at least in this stage of space exploration, rather than counting on being able to grow plants to do that chemical transformation for us, we thought it would be better if we built machinery that we can count on and repair. And so on board the space station, we have carbon dioxide removal equipment. There are various ways to trap the gas, and through absorbent beds and different type of chemical processes to extract the carbon dioxide from the air. And if we do it properly, then we can separate the carbon from the oxygen, release the oxygen back into our atmosphere again, and then either trap the carbon or get rid of the carbon. And there are designs that trap that CO2 and then rotate the trapped gas to the vacuum of space, heat it so that it releases the gases you don't want and still keeps the oxygen, and then release the gas of oxygen back into the ship. But it's still not perfect. No machine is perfect. No recycling program is 100% perfect. And so in addition to doing the best we can to maintain the oxygen on board, we also have to bring up oxygen from Earth. Every resupply ship that comes up-- every one of these little ships that comes up and docks-- brings some quantity of fresh oxygen from Earth. Sometimes just the air that's inside it. Sometimes we've over pressurized that thing so that it's bringing just a free little bit of oxygen. Or sometimes, we actually bring up oxygen in pressurized tanks, even liquid oxygen, at times, in order to be able to resupply the ship to keep us healthy on board. To go to Mars, we aren't going to be able to resupply our oxygen on board. We're going to have to continue to invent ...

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