Astronauts Have Drunk Space Pee. Are Stillsuits Next?

By Eric Wolff | May 26, 2009 2:40 pm

Even on the harsh deserts of Arrakis, the the water recycling capacity of a stillsuit prevent the wearer from would only lose a thimbleful  of water a day.  If you figure a thimble holds about 10 milliliters of water, and an astronaut normally consumes 2.7 liters of water per day through eating and drinking, that’s only a loss of .4% of the body’s daily water. Pretty impressive for a desert race with long life but limited resources. (In case this wasn’t clear, I’m talking about George Frank Herbert’s Dune here.)

Until recently, there was no need for us to try and engage with this sort of water recycling technology. In general, water has been plentiful in this world, and if it wasn’t we just piped it in. (I just re-saw Chinatown, so I’m feeling up on all this.) But increasingly short supplies of water in the American southwest and elsewhere have turned eyes to water recyling as at least a part of the long-term water supply solution. But to take a more extreme situation, let’s look at the final frontier, where there’s really no water at all. In fact, to transport water up to the International Space Station costs $15,000 a pint if we let the Russians do it, more if we send it up on Endeavor or Atlantis.

But today we got the marvelous news that instead of having to truck tons of water of space, the astronauts can just drink their own pee! (Yay?) Today marked  a successful test of the International Space Station’s water recycling system. The astronauts marked the occasion by raising a baggie (no glass in space) of recycled water (née urine) in a toast,  and taking it a sip. They deemed it delicious, and, after taking a few questions from reporters, went about their day.

The system is actually surprisingly basic. Most of the water comes from the toilets, though dehumidifiers in the oxygen regeneration system remove three liters of water a day from the atmosphere. For the moment the atmospheric water is being hydrolyzed to provide oxygen for the workers, but eventually it will be put into the recycling system with everything else.

The wastewater goes through a seven-step filtration system. First, they strain out the solids. Yes, this includes poop, which is 75% water to begin with, and thus cannot be flung out with the trash. Then the water is boiled, and the steam trapped in a system that behaves remarkably like a still. As the steam runs through the pipes, it cools and condenses until it’s pumped through a series of filters that are similar to water treatment down here on Earth. NASA says the water would pass muster in most municipal water systems.

In the end, though, they only recapture 93% of the water, no where close to the Fremen’s skill. Of course, the actual stillsuit would have some pretty serious technical barriers to actually working, as detailed by NASA scientist John C. Smith in his stillsuit chapter of The Science of Dune (edited by SciNoFi pal Kevin Grazier). Among other problems, it would be unpleasantly warm, especially after a day in the desert; the human body doesn’t provide enough kinetic energy to power the thing as author Frank Herbert suggested; and there would be great difficulties in cooling the evaporated water back into liquid. But, as Smith points out, Dune is set 13,000 years in the future. If today we can already make a unit the size of two-refrigerators for a space station, perhaps in 13 millenia we’ll have a real, wearable stillsuit up and running.

Image courtesy of NASA

CATEGORIZED UNDER: Space

Comments (11)

  1. Adam

    it’s Frank, not George, Herbert. Neat idea, however.

  2. Brian

    Re “… it would be unpleasantly warm, especially after a day in the desert; the human body doesn?t provide enough kinetic energy to power the thing…”

    Um, heat is a form of energy, hello? If the kinetic energy just isn’t there, you’ve got this heat source, right there…

    OK, maybe that’s not exactly the way Frank Herbert envisioned the thing working. But the whole point of the stillsuit, and the Fremen culture, was that it was honed by a life of hardship. Water was life and the most precious of all resources. You treat it carefully or you die.

    Herbert said that the Fremen stillsuits were better than any of the offworlder’s suits. That was one detail among thousands that sounded right, felt right.

  3. The people in the American Southwest can postpone having to wear stillsuits if they get rid of their Eastern style gardens, lawns, and outdoor swimming pools. They are the most irresponsible waterwasters in the private sector. When you move to a desert you live according to the environment.

  4. Egaeus

    Brian, heat alone is not a source of power. You need a heat differential to be able to use the energy, like with boiling water to power steam turbines, stirling engines, etc. You can’t just suck the heat energy out of the environment and put it to use. Entropy doesn’t flow that way. If it did, then we’d have a free energy source, and would be concerned about global cooling.

  5. Brian

    @Egaeus,

    D’oh! Of course you’re right.

  6. One of the other problems with the stillsuit is that, at least as Herbert explained it, it’ll probably run up against the laws of thermodynamics.

    Then again, I’m sure his son will find a way to explain that while further destroying one of the most spectacular science fiction franchises of the 20th century.

  7. That’s nothing, Singaporeans have been drinking pee for most of the last decade. (I’m from Malaysia, so am making fun of them gratuituously). http://en.wikipedia.org/wiki/Newater

    About the stillsuit energy source problem – couldn’t you create a heat gradient by having some parts of the suit be insulated (from either or both the wearer’s body or the ambient heat) and some not?

  8. Let’s get our sceince fiction brains together and think of cheap ways to desalinate the oceans first. That is some major energy suckage trying to do that right there. Get rid of the salt and we’ve got good water and lower sea levels from consumption! Localised, coastal methods first. I love Dune, have to agree with Thomas about the new books.

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