How does the space station never run out of oxygen?

For over 25 years, the International Space Station’s air supply systems have revolutionized space missions. Yet the need for regular maintenance, repairs, and upgrades has pushed engineers to develop even more reliable systems for future spacecraft. How do we create breathable air in space? And what does that look like for longer expeditions? Alvaro Romero-Calvo and Theo St Francis investigate in this Lazy Chief directed animation for TED-Ed.