There’s currently an exciting competition underway called the Mars City Design Competition. Teams are invited to submit designs for a future Martian city capable of supporting “several tens of thousands” of residents.
The Mars Settlement Research Organisation (a Facebook group I started in 2012) has assembled a crack team of savvy space settlement designers, and we are now working on our concept submission for our city, which is named “Sagan City”.
As part of our planning and design for Sagan City, it’s one of my interests and responsibilities to design the food system.
Of the various options available, the best choice would seem to be aquaponics, which is a symbiotic combination of hydroponics and aquaculture. Both of these are currently experiencing a massive surge of interest and investment, and will probably represent the future of food on Earth for many people.
Hydroponics is advantageous in a Mars settlement, where food will be grown indoors in a small area. Hydroponics permits crops to be effectively grown in stacks, which is very space-efficient; this has led to the current trend in vertical farming, and production of plant crops inside buildings and shipping containers. Vertical farms require the use of artificial light instead of natural sunlight, but energy requirements can be optimised by using LEDs that only produce photons of the wavelengths used by plants, i.e. blue, red, and a little infra-red.
Crops growing under red and blue LED lights
Although hydroponics requires a large amount of water compared with alternatives such as aeroponics or geoponics (growing food in dirt), the water can be recycled within the system, meaning that overall water consumption can be kept low.
Aquaculture (fish farming) has grown exponentially in recent years, to the point where humanity now consumes almost as much farmed fish as wild-caught fish. Very soon, farmed fish will be dominant.
Both hydroponics and aquaculture systems, when operated separately, have drawbacks. Both systems require expensive nutrients, and produce waste that needs to be disposed of. When the two are combined, however, these negatives become positives. The waste products produced by the fish becomes food for the plants; thus, nutrient-rich water from the fish tanks is circulated through the hydroponics system, the plants effectively clean the water for the fish, and the water is circulated back into the fish tanks. This symbiosis reduces water wastage and the cost of plant nutrients, and saves time.