Why Every Spacefaring Nation Builds Its Own Life Support Instead of Buying One

Aboard the International Space Station, roughly 93 percent of the water astronauts drink was, hours earlier, their own urine or exhaled breath. The system that does this, NASA's Environmental Control and Life Support System, or ECLSS, took decades of iteration, two catastrophic failures on the ground, and a complete redesign of the urine processor assembly before it worked reliably in orbit. No nation bought that knowledge. The United States built it, broke it, and built it again.
Life support is not a product category. There is no catalogue from which a space agency orders a closed-loop oxygen regeneration unit the way it might order a camera sensor or a battery pack. The systems that keep astronauts alive are so deeply integrated with the specific mass, volume, power budget, and mission profile of a given spacecraft that they must be designed together from the start. A life support module engineered for Russia's Soyuz cannot simply be transplanted into India's Gaganyaan crew module. The atmospheric pressure targets differ. The scrubbing chemistry differs. The failure response protocols differ. Every choice cascades.In 2003, after the Columbia disaster grounded the Space Shuttle, NASA became entirely dependent on Russia's Soyuz for crew transport to the ISS. That dependency was manageable for transport. Life support dependency would have been something else entirely. Control over the system that generates oxygen, removes carbon dioxide, and recycles water is control over whether the crew lives. No government hands that to another government's engineers.
Russia's Mir station ran its own Elektron oxygen generation system, which used electrolysis to split water into hydrogen and oxygen. When Elektron units failed repeatedly through the late 1990s, and they did fail, multiple times, the cosmonauts and NASA astronauts aboard fell back on solid-fuel oxygen generators called Vika canisters. One of those canisters caused a fire aboard Mir in February 1997. The crew survived. The lesson was that redundancy in life support is not a design preference; it is the design. And redundancy can only be engineered by the team that understands every layer of the primary system.
China built the Tiangong space station's life support entirely in-house. Its regenerative life support systems, oxygen generation, carbon dioxide removal, water recycling, are domestically developed. That was a deliberate choice made before the first Tiangong module launched. When the United States barred China from participating in the ISS program through the Wolf Amendment in 2011, China had already decided it would not be in a position where another nation's political decisions could cut off the air supply.India's first crewed spaceflight program, Gaganyaan, is building its Environmental Control and Life Support System domestically. The Vikram Sarabhai Space Centre in Thiruvananthapuram is leading that work. The system must maintain cabin pressure at approximately 101.3 kilopascals, keep oxygen partial pressure within a narrow band safe for the crew, scrub carbon dioxide using lithium hydroxide canisters, and regulate temperature and humidity across a mission duration of up to three days in the initial flights.

ISRO has been explicit that this is not a short-term workaround until a foreign system becomes available. The agency's astronaut candidates, Group Captain Shubhanshu Shukla, Group Captain Prashanth Balakrishnan Nair, Group Captain Ajit Krishnan, and Wing Commander Angad Pratap, are training on systems that Indian engineers designed. Shubhanshu Shukla is also assigned to the Axiom Space Mission 4 to the ISS, which gives ISRO direct operational exposure to how life support behaves in actual microgravity. That experience feeds back into the domestic program. The learning loop is intentional.When the Soviet Union collapsed, Russia inherited the life support expertise built across decades of the Salyut and Mir programs. That expertise sat inside specific engineers, specific test rigs, and specific failure databases. Some of it was documented. Much of it was not. Nations that tried to license or purchase components from the post-Soviet aerospace sector in the 1990s found that the hardware came without the understanding of why certain design choices had been made, what had failed before, what the margins actually were, what happened when two systems interacted in ways the manual did not anticipate.
This is the knowledge problem at the centre of every life support program. The recycling efficiency of a water processor, the exact concentration at which a carbon dioxide scrubber becomes saturated, the thermal behaviour of a pressure vessel at minus 120 degrees Celsius on the night side of an orbit, these are numbers that emerge from testing, failure, and redesign. They cannot be transferred in a contract. A nation that buys a finished life support system gets a box. The nation that built it gets the understanding of what is inside the box and why.

Oxygen generation aboard a spacecraft can use electrolysis, solid-fuel canisters, or stored compressed gas, each with different mass penalties, different failure modes, and different resupply logistics. Choosing between them requires knowing your mission architecture at a level of detail that is inseparable from the spacecraft design itself. That is why no serious spacefaring program has ever outsourced this decision to a vendor.The ISS operates at roughly 400 kilometres above Earth. At that altitude, a life support failure is not a supply chain problem. There is no replacement part on the next flight. There is no emergency call to a manufacturer's helpline. The crew and the ground team must understand the system well enough to improvise a fix with whatever is aboard. That requires the kind of deep, institutional knowledge that only comes from having built the system, tested it to destruction, and built it again.
This is why the question of buying versus building life support is, at its core, a question about what kind of space program a nation intends to run. A nation that can launch a satellite but cannot keep a crew alive in orbit is not a spacefaring nation in any meaningful sense. The life support system is where the ambition becomes real or it doesn't.

The water recycling loop on the ISS, the oxygen generation on Tiangong, the ECLSS work feeding into Gaganyaan, these are not parallel stories about engineering pride. They are the same story about what it means to operate in an environment where the atmosphere is something you brought with you, and the only people responsible for keeping it intact are the ones who built it.