How spacecraft produce life-saving air for astronauts

In the vacuum of space, where Earth’s breathable atmosphere is absent, providing astronauts with a continuous supply of oxygen is essential. This necessity has led to the development of sophisticated systems aboard spacecraft to ensure a safe and sustainable environment for crew members.

Each astronaut consumes approximately 2 pounds (about 0.9 kg) of oxygen per day. Maintaining a cabin atmosphere similar to Earth’s, at about 14.7 psi pressure and 21 per cent oxygen concentration, is crucial for comfort and health. Given the extended durations of missions, especially aboard the International Space Station (ISS), relying solely on stored oxygen is impractical. Onboard oxygen generation systems are therefore essential.

1. Oxygen Generation Assembly (OGA): The OGA aboard the ISS uses electrolysis to split water into oxygen and hydrogen. This process provides breathable oxygen and contributes to water recovery, as the hydrogen produced is used in other chemical processes aboard the station.

2. Elektron System: Operated by the Russian segment of the ISS, the Elektron system performs a similar function, generating oxygen through electrolysis. It is a critical component in maintaining the station’s atmosphere and supports the OGA in oxygen production.

3. Advanced Closed Loop System (ACLS): Developed by the European Space Agency, the ACLS improves oxygen production efficiency by integrating carbon dioxide removal and water recycling. This system reduces the need for resupply missions by recovering oxygen from waste products.

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Even with reliable onboard systems, contingency options exist:

1. Solid Fuel Oxygen Generation (SFOG) Canisters: These chemical generators produce oxygen by decomposing lithium perchlorate into oxygen gas.

2. Pressurized Oxygen Tanks: Stored oxygen is available for immediate use during emergencies or spacewalks.

During extravehicular activities, astronauts rely on the Extravehicular Mobility Unit (EMU), which includes a Primary Life Support System. The PLSS provides a portable supply of oxygen, temperature regulation, and carbon dioxide removal, ensuring astronaut safety in the vacuum of space.

Advancements in oxygen production continue to evolve. Technologies are being developed to recover oxygen from carbon dioxide, significantly reducing dependence on Earth resupply. Such innovations are crucial for long-duration missions, including potential human expeditions to Mars.