Science & Technology

Defying Gravity: Plants in Space

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Imagine you live hundreds of years in the future.  You’re on a ship, hurtling through space.  There are no resupply stations; you have to depend only on what you brought with you.  How would you keep yourself and your crew fed?
Even today there are a variety of methods to grow grains and vegetables outside of traditional agriculture.  One popular method is hydroponics, where plants are grown using a nutrient rich water solution instead of soil.  Experiments on Earth have shown that when certain plants are provided with right range of oxygen, nutrients, and light, their yields are larger than they would be if they were grown using conventional methods.  Eliminating soil from the process reduces the weight needed to be launched into space, and also eliminates the problem of replenishing the soil’s nutrients.

Another method of food production is aeroponics, where plants grow their root systems in open air.  Nutrients are transmitted to the roots using micro-droplet sprays of water.  Some advantages of this system include that it has been shown to reduce the risk of plant disease, because there is less contact between individual plants. Reducing the risk of sick plants will make food production more reliable, such that supply disruptions are less likely.  Also, this system conserves water, allowing the available water supply to be used for other purposes.

It may be unlikely that future spacecraft designers will incorporate a livestock processing section into the ship to provide a meat supply to astronauts. To do so would require space, grain, and water supplies that could be used by humans instead of animals. Also, it would take years to raise an animal to a point where it can be harvested. Due to these resource constraints, future astronauts may likely be vegetarians or vegans.  However, there are possible solutions to these concerns.  In an effort to introduce sustainable meat into an astronaut’s diet, aquaponics provides another possible solution to food supply.  Aquaponics creates a symbiotic ecosystem where hydroponic plants co-exist with fish in the nutrient solution.  The fish provide fertilizer for the plants, while the plants provide food for the fish.  Humans harvest the excess fish and plants, leaving the ecosystem intact, allowing for the continued supply of food in the next harvest cycle.
One of the main challenges with growing food in space is the effect of microgravity on plant growth. Currently, there is little readily available scientific data that sheds light on the subject. Scientists aboard the International Space Station are conducting experiments on plant growth in low gravity in environments. The results of these experiments are pending, but if they are successful then it makes travelling the solar system or interstellar space easier. Growth in microgravity would eliminate the need to develop expensive, complex mechanisms to simulate Earth-like gravity.

Growing different plants in space may also require different environmental conditions such as heat, light, humidity, oxygen, and nutrient content. This requires that any growth facility have environmental barriers to separate plants so that they may grow under optimal conditions. This would also contain the spread of disease in the case of an outbreak.
The advantages of growing food in space extend beyond food supply. Growing plants in space will help regulate the astronauts’ habitat, remove carbon dioxide, and provide oxygen. This will reduce strain on the systems to store and provide oxygen in space.

Aquaponics, hydroponics, and aeroponics are potential solutions to the problem of food supply in space. Each carry with them their own set of benefits and drawbacks that will be essential in future spacecraft design. In order to carry astronauts to the planets, and into the beyond, it will require that these problems be researched so that these challenges may be overcome. Being able to biologically regulate your environment instead of using a mechanical system will help put less strain on the ship’s power consumption and space limitations, bringing humanity one step closer to living in deep space.

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