Aquaponics in Space

Aquaponics, Ideas June 11th, 2010

Wow. What an interesting idea. At lunch today we had a really good discussion about this.

Firstly – why would you do it? Well you can grow some protein onboard your ship – you can’t exactly grow livestock so apart from protein in legumes etc this might be the only way.  Secondly, this is dirt free, so you don’t need to worry about dirt getting in your systems and cutting them to pieces.  Space ships are all about recirculation, this is a very low tech recirculation system.  The added bonus being that the plants scrub the air of carbon dioxide.

Space throws up a whole bunch of problems. Firstly, how would you do it? Well I’d do it by grabbing an asteroid that’s mostly water ice, and build a structure around it. You then add another module which has hydroponic trays full of plants.  The biofiltration is done by a barrels of “bioballs”, or possibly just by bacteria growing on the walls of the structures.

Do we need gravity? Maybe not, the plants will grow towards light, and the roots will grow towards water, but gravity is useful. For starters, how would you keep the water inside the grow trays? I think you’d be fighting a losing battle, but if you had gravity – it doesn’t need to be much, then at least the water will stay “down”, and can be made to flow along the bottom of the channel. Dunno how fish like zero gravity – they have a swim bladder which enables them to go up and down in the water column, so I guess we need SOME gravity. Maybe fish have fine enough control of their swim bladder to handle low grav?

I’m not fluid physicist, but so long as the fish tank was “full enough” then you wouldn’t have too many problems with the fish getting stuck in a bubble of air and expiring. Plus I think the fact that you’re in a gravity-less environment would mean that the fish “flipping” about would actually have some effect on the air/water around it and eventually it would find itself back in the water. A bit of gravity might help with this as well, maybe you could pressurise the sides of the tank so the water stays as a ball in the middle? I dunno, probably not possible.

The fish need oxygen in the water – this might be a problem. The plants provide oxygen, but whether they provide enough oxygen for the fish to consume is another questionable. (Aside: I wonder why astronauts don’t have a massive vat of algae to do their CO2 to O2?). We wouldn’t want the whole system to consume oxygen.

Apparently water ice asteroids in space have quite a bit of Ammonia in them. Sheesh, that’s exactly what an Aquaponics system excels at. So when the ice has melted down, you can run the system for a couple of months and it’ll consume the Ammonia (and the plants will grow! Hurrah!) and by the time you’re ready for fish, it’ll be all cycled because it’s consumed the Ammonia present in the ice asteroid, ready for the Ammonia produced by the fish. Maybe NASA should explore using this high Ammonia ice to grow plants without the fish as this could be done right now. By product is drinkable water or oxygen if you want to go to the effort of splitting H2O.

A spinning ship provides the slight gravity that you need, it also means that you can emulate night and day.

Heating is another issue, it’s cold up there.  I think you’d have to filter the sunlight – I think direct sunlight is very dangerous, and the plants would probably get smashed by it (that’s why our ozone layer is so important), so we might need to have some sort of filter there. But if we had that, we’d essentially already have a greenhouse. I suppose you could do everything with closed boxes and awesome insulation for your modules, and use growlights for the plants, but I like the idea of using the sun.

I suppose we really need to close the cycle a bit more – the fish would need to eat plants, maybe we could use plant waste and turn it into worms (or even the worms compost our bodily wastes ….). Otherwise you’re going to need to take up a whole bunch of food for the fish. Though if you’ve got carbon dioxide, water and sunlight, you should be able to grow food for fish like you can grow plants for humans. Maybe you’d need to create more of a food chain (i.e. watersnails which convert algae to protein, fish which eat the watersnails and grow).

I dunno  – there are probably a million flaws with the idea, but it’s very blue sky dreaming and I love that kind of thinking. Give it thirty years! “Every deep space ark ship should be fitted with an Aquaponics system, and for the best space Aquaponics systems around, you need to talk to the experts“.

2 Responses to “Aquaponics in Space”

  1. BayouFilter Says:

    The first Aquaponicist in space will probably be an Australian. But I volunteer Right Now to tend the aquaponic garden on the first city-ship to be launched. And I’ll be training my grandkids for the job ’cause it’ll probably take a few generations to get it built!
    That said, I’d like to dig my teeth into an idea sparked by your article, some *pre-processing* of *ice-teroids* done in advance (maybe waay in advance) of humans getting close to said ice. The goal would be to use a “seed bomb” to begin work on transforming a chunk of ammoniated water into a floating pond of liquid H20 plus some life in it.
    Seed bomb might, as its first step, stick to the target and coat one hemisphere of the ice with something dark on the outside and it could be reflective on the inside. This would start to absorb heat and when the coated side faces away from the sun, bounces light around the inside.
    Stage two is where nitrifying bacteria thaw out (or their spores do) and begin chowing down on that yummy yummy ammonia. Three, some seeds emerge from their time-release coating and germinate. Let’s brainstorm about what series of plants we want to establish! We will want oxygenation, shading, heat absorption (+ some diffusion?) and some plants will be grown in order to die off and rot and produce more ammonia. So this little pond / biosphere will be just hanging there when the motile meatbags (US) arrive and stick a straw in it.
    Do we want some higher organisms involved? I’m leaning toward doing the whole thing with plants and bacteria… Critters might evolve while waiting for us and if we take too long, we’d meet someone smarter than us!

  2. gemmell Says:

    Good idea – if the seed bomb had some kind of technology which “knitted” a shell around the asteroid (self replicating nano tech style) then we can then have fully processed water ‘modules’ for when we arrive in space.

    Getting the ice to melt might be complicated, but it might not. I get the feeling that the suns rays are pretty harsh, and that if you start to contain the heat via our knitted shell then it will start to melt of it’s own accord. i.e. we’ve knitted a kind of greenhouse around it. Like you say, the side on the “dark side” (facing away from the sun) could have some kind of black absorbent material, the side on the light side could be thermally efficient glass or something.

    Give the iceteroid some spin and the water will come off as it melts and collect around the edges. So what I’m imagining is a shell a fair bit bigger than the asteroid, with a lake around the outside of it (because it’s spinning, so like a washing machine it’s all being “flung” to the outsides) with a spinning iceteroid in the middle. When the iceteroid is melted, you get a volume of water smeared around the outside and a kind of void in the middle. Maybe you can grow your plants in there?

    I dunno about vegetables or anything in this style of thing, but definitely bacteria to process. And algae to consume. Then maybe when we get up there we have a biofuel source and drinkable water… or maybe you put some fish in the mix which eat the algae…

    I wonder how much carbon is in those iceteroids. Maybe we need to smash a carbon dioxide ice asteroid into it to get enough carbon dioxide for the algae to start producing oxygen. Anyway, the key components seem to be up there…

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