urban agriculture and space habitats

I’ve been thinking a lot about space, recently. As in, spaceships and stars and planets. I know, I know, that sounds like it has nothing to do with our fledgling smallholding – but in reality it has quite a lot to do with it.

When I say I’m thinking about space, I mean I’m thinking about humans going to space. Space habitats and the ecosystems we’ll need to support them, producing enough food not just for a few scientists but for entire villages of people living in colonies on the moon, or Mars, or Venus, or even in permanent space station habitats orbiting the Earth. Recycling water and air, nitrogen and carbon and all the micronutrients and elements that we need to survive.

I think that a lot of the techniques which are useful for urban agriculture and peri-urban (urban fringe) agrculture in the here-and-now are also applicable to setting up self-sufficient space habitats and extra-terrestrial colonies. And equally, a lot of the techniques that might be researched and developed for use in space are also applicable, with minor modifications, to urban agriculture. Aquaponics and aeroponics are the most obvious examples, recycling water and nutrients to produce fish and vegetables (in an aquaponics system) or to use minimal water for maximum vegetable production (in an aeroponics system). Insect farming is another example, everything from raising crickets as a food source for ourselves or for fish (fun fact: you can also include crickets in the diet of chickens, for the protein, and even in the food for your cat or dog) to composting with black soldier flies, the larvae of which again provide high quality fish and poultry feed. The main point is to have closed systems, or as closed as possible when we are removing nutrients by eating some of the produce.

Composting toilets are also a thing, since recycling those nutrients is going to be essential in space and is increasingly essential here on Earth. The amount of soil which is being lost to erosion each year means that we need to do absolutely everything we can to retain and enrich the soil we have. Of course that includes composting food waste and animal manure as well as humanure, since nutrients are nutrients.

Any sort of ecosystem that we were to set up in space – or in an urban environment, as a relatively closed or self-sufficient system – requires careful planning around the types of plants and animals that we raise. We need enough different foods to provide both the nutrition and the energy (calories or kilojoules) that we need to live, and if we keep animals at all then we need enough food to provide them with their nutritional and energy needs as well. And, as any biodynamic practitioner will tell you, we also need enough carbonaceous materials (e.g. the stems of cereals and grasses) to allow for effective composting. Unless we use only hydro-, aero-, or aquaponic (water based) systems, in which case we still need some way of recycling the nutrients in waste food, non-food plant parts, and manure.

What combinations of plants provide us with the minimum viable diversity of diet to live well? Which ones combine nutritional efficiency with high production – and what does that mean for our diet? Rice is far more productive than wheat or corn under ideal conditions (yields of 4 – 8, and up to 22 tonnes per hectare for rice, compared to 1 – 4.5 tonnes per hectare for wheat accoirding to google), so should we try to move away from our western, wheat-based diet? Or should we try to breed more productive wheat varieties? And what animals should we keep, to maximise production while minimising the space we need to use?

Fish seem to be an obvious choice, along with insects to feed them, but which species of fish? Trout, tilapia (illegal to keep in Australia) and carp have been raised in aquaculture systems very successfully, and both will breed in captivity without outside intervention. Barramundi are harder to raise because they are more inclined to cannibalism when crowded, and they do not breed naturally in captivity. Catfish grow well and will breed in captivity, but they do not like being crowded and will fight and injure one another.

Then you start down the road of poultry (chickens, pigeons, ducks, quail, ..) and small ruminants (miniature goats or sheep, or even miniature cattle). Smaller animals such as rabbits or guinea pigs are possible too. Or will we simply have vats to produce artificial meat instead? And what about pets? Do pets have a place in the system, even if the only work they do is to provide us humans with companionship and the associated psychological benefits? (We’ve decided that they do, that both cats and dogs have a place on our farm simply because we believe that we, as humans, are poorer and lonelier when we don’t have dogs and cats in our lives).

I don’t have answers, but I’m working on it. I want to go into space one day.