NASA’s Water Recycling System

After last week’s Wednesday post, Lead Sales Guy Scott has told me no more sewer blogs. He really values his breakfast. Luckily for me, that’s a request I’m happy to oblige, with a loophole a mile wide: you don’t call it a sewer when it’s in space. In space, we call that Waste Water Reclamation or Recycling.

Water In Space

Water is a basic human need. If there is no water, there will eventually be no humans there either. Its probably possible to have life without water, but that won’t be us any time soon. We’re giant blobs of water wrapped in a soft, squishy membrane for all intents and purposes. We’re 60% water, which makes us water with some contaminants. Our bodies however, constantly excrete that water. We sweat, exhale water vapor, and lose it in our waste. Consequently, we need to constantly refill ourselves with more water.

On Earth, this isn’t much of an issue. We can return the water to the environment and find more. If necessary, we can build an enormous processing plant and turn ocean water into drinkable water. In space however, that’s not an option. In a best-case scenario, it costs about $2500 per POUND to put anything in space.

Cost of Water Per Astronaut Without Recycling
1/2 Gallon of Water X 8.34 LBs/Gallon X $2500/LB
$10,425/Day Per Astronaut

Water For The Longest Stay on the International Space Station

438 Days x $10,425/Day
$4.6 Million Per Astronaut

It would be incredibly expensive to supply astronauts with water if they didn’t recycle it. We would end up sending more on launching water than on launching science projects to do actual research. Space Travel is only feasible if you recycle every drop of water possible, no matter where it came from.

Extreme Recycling

Nearly every drop of water on the International Space Station is captured for reuse. Water used for cleaning is captured. Urine is captured. Water vapor from sweat and breathing is captured. The process is slightly more difficult in space than it is on Earth due to the microgravity environment. This isn’t something that stops NASA.

The first step of the process is to sterilize the urine as much as possible. This is done with a distillation process. The ISS’s massive solar array means electrical power really isn’t much an issue. There is no third party electrical utility to pay for free power. The waste material is pumped into what is essentially a drum and heated until it produces steam.

On Earth, steam is less dense and tends to rise up into the air. In space however, there is no ‘up’ or ‘down’. The steam and the solid matter that didn’t evaporate just float there. The heated keg doubles as a centrifuge. It’ll spin rapidly, flinging the heavy, solid matter to the outside of the container and leave the steam in the center

The steam from the urine process is added to the main water filtration system and treated like any other source of water. This water is pushed through a series of filters that will remove most contaminants. The final stage of processing uses a catalytic reactor, essentially a fancy chemical system that removes anything left that isn’t H2O.

From this point, waste water is tested and if it passes the test, considered safe to drink. The water is passed to the rest of the ISS’s main water supply. Water from that supply isn’t just used for drinking. Some of the water is fed to the Oxygen Generator, which uses Electrolysis to generated Hydrogen and Oxygen.

Astronauts effectively eat, drink, and bathe in water that was once their own urine. Solid waste isn’t recycled yet. Maybe NASA is saving that for Mark Watney’s Martian Potato Farm.

The Non-Recyclers

It’s worth noting: the Russian Cosmonauts on the International Space Station don’t recycle urine. They have a separate filtration system. The Astronauts sometimes collect and recycle the cosmonauts urine for the NASA side of the lab. This is viewed by NASA and Astronauts as a good thing. The Cosmonauts have a separate water system. In the event of a complete and total disaster, this means researchers from either nation have not only a back up supply of water, but also an emergency water source if needed.


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