Here on Earth, it is easy for most of us to get as much water as we need just by turning on the faucet! However, in the vacuum of space, everything that is needed for survival must be brought along. Water is a vital resource, necessary for both hydration and sanitation. While just as precious as air, water is much harder to transport. Because astronauts have to bring all the water they need with them, they have developed many ingenious methods of recycling and reusing water in space.
The average American uses about 35 gallons of water per day. A gallon of water weighs a little more than 8 pounds. Lifting off thousands of gallons of water per astronaut requires a lot of resources. Most of us remember dehydrated “astronaut food”. In the early missions to space, concerns about cutting weight led to them removing the water from their food to help make the ships as light as possible. Obviously, astronauts don’t have the luxury of using 35 gallons of water a day, and have to learn to use water very differently than us on Earth.
On the International Space Station (ISS), each astronaut uses a mere 3 gallons of water a day for all of their needs. Conservation of water is vital in space because all the water on the space station must be brought from Earth. Astronauts don’t get to take showers but instead conserve every drop with sponge baths. Zero gravity “space” toilets use air, instead of water, to direct waste flow. Astronauts face strict restrictions on how much water they can use. Without careful recycling, it would take 40,000 pounds of water per year to meet the minimum needs of the ISS.
On the shuttle, water is produced, in part, by the fuel cell power plants as a by-product. Water and electricity are the products of the chemical reaction of oxygen and hydrogen that takes place in the fuel cells. Condensed water vapor from the fuel cells gets pressure-fed into potable tanks in the lower crew decks. The International Space Station is employing even more ingenious ways of recycling water, going so far as to condense it right out of the breath of the crew. The Environmental Control and Life Support System (ECLSS) aboard the ISS reclaims waste water from fuel cells, urine, oral hygiene, hand washing and by condensing humidity from the air, putting it through a purification process to make it reusable pure water. After going through the complex filtration process, this reclaimed waste water is cleaner than the water coming out of most of our taps!
For manned missions farther away than the ISS, resupplying from Earth won’t be feasible. Scientists are working on ways to recover more usable mass from waste matter to make far-reaching manned missions possible. The Marshall Center, which developed and tested the ECLSS, is working on a Carbon Dioxide Reduction Assembly that will recover additional water from carbon dioxide removed from the cabin atmosphere. Advancements in water recycling and purification systems continue to put us closer not only to our goal of longer manned space missions, but also to having clean water for everyone here on Earth.