In the near future, NASA and other space agencies plan to send crews beyond Low Earth Orbit (LEO) to perform long-duration missions on the Moon and Mars. To meet this challenge, NASA is developing life support systems that will sustain crew members without the need for resupply missions from Earth. These systems must be regenerative and closed-loop in nature, meaning they will recycle consumables like food, air, and water without zero waste. Currently, crews aboard the International Space Station (ISS) rely on an Environmental Control and Life Support System (ECLSS) to meet their needs.
This system recycles air aboard the station by passing it through filters that scrub excess carbon dioxide produced by the crew’s exhalations. Meanwhile, the system uses advanced dehumidifiers to capture moisture from the crew’s exhalation and perspiration and sends this to the Water Purification Assembly (WPA). Another subsystem, called Urine Processor Assembly (UPA), recovers and distills water from astronaut urine. To boost the WPA’s efficiency, the crew integrated a new component called the Brine Processor Assembly (BPA), which recently passed an important milestone.
International Space Station Commander Chris Hadfield “lifts the lid” on the Water Recovery System, the first liquid recycling system to be flown in space that cleans almost all the “water” (greywater, urine, sweat) produced by crew members so that it can be used again. As previous space station resident Don Pettit has said, “Yesterday’s coffee becomes today’s coffee.”
Previously, Russia’s space station Mir recycled cosmonaut’s sweat, but this system on the ISS can recycle about 93 percent of the liquids it receives. The ISS’s water recycler uses a distiller that looks like a keg. On Earth, distilling is a simple process of boiling water and cooling the steam back into pure water. But without gravity, the contaminants in water never separate from the steam no matter how much heat is used. So, the keg-sized distiller spins to produce an artificial gravity field while boiling the water. The contaminants in the urine or greywater press against the sides of the drum while the steam gathers in the middle and is pumped to a filter.