Tour the ISS Air & Water Recycling Loops

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ECLSS SYSTEM OVERVIEW — REV. 2.5 (2025)

ISS Life Support: The Closed Loops

Air to water. Water to air. Life, on repeat.

© NASA · JSC · Public Reference

Introduction

Two hundred and fifty miles above Earth, every breath, every drop, every molecule counts. The International Space Station isn’t just a laboratory — it’s a living, breathing prototype for survival beyond our planet.

Inside its sealed walls, NASA’s Environmental Control and Life Support System (ECLSS) keeps humans alive by mastering the art of reuse. Up here, nothing is wasted. Everything is transformed.

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Simplified schematic — ECLSS closed-loop

Air ⇄ Water — the loop that keeps life alive

Key Systems

WRS — Water Recovery System

Recycles humidity, sweat, and urine into pure water. Up to 98% recovery in recent upgrades; typically around ~90% reclaimed in operations.

ARS — Air Revitalization System

Removes exhaled CO₂ using molecular sieves and filters, keeping cabin air safe for continuous living.

OGA — Oxygen Generation Assembly

Uses electrolysis to split water into O₂ and H₂. Oxygen refreshes the cabin; hydrogen feeds the next reaction.

Sabatier Reactor

Combines captured CO₂ with H₂ to make H₂O and CH₄. Water re-enters the loop; methane is vented.

Why This Matters

What the ISS does daily is the essence of sustainability: creating abundance in isolation. In space, recycling isn’t an option — it’s survival. On Earth, it’s our blueprint for resilience.

The station doesn’t just orbit the planet — it reflects our potential to live within limits and still thrive.

Key Facts for the Curious

• The ISS reclaims up to 98% of its water with recent system upgrades.
• ECLSS integrates air, water, and waste into a self-sustaining loop.
• The Sabatier reaction turns CO₂ + H₂ → H₂O + CH₄.
• A tighter loop means fewer resupply missions — and a safer path to Mars.

Up here, every breath is recycled. Every drop reborn. You start to realize — Earth is just another closed system.

ECLSS · Systems: WRS · ARS · OGA · Sabatier · © NASA / ESA Collaboration · Public ReferenceDoc ID: ECLSS-OVR-CL-2025 · Simplified for clarity

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