It’s a Matter of Health
Did you know that NASA is one of the strongest proponents of aeroponics? Space agencies around the world, including NASA, are planning extended interplanetary missions and lengthy tours of duty in low-gravity environments such as the ISS. There are plenty of well-documented health effects of space travel, and a severely limited diet of fresh foods can have both physical and psychological effects over extended periods of time. It’s well known that from the 15th to the 19th centuries, scurvy was endemic among sailors, a result of vitamin C deficiency. Anemia, rickets and goiters are other common diseases associated with vitamin deficiency.
For sailors, the management of scurvy was fairly simple -- carry along a supply of citrus fruits and juices. Vikings relied on cloudberries, and Native Americans tribes like the Iroquois relied on a decoction based on leaves and bark of Arborvitae trees and shrubs. While these feel like old fashioned solutions, the fact is that modern solutions like vitamin pills lose their potency over time and aren’t suitable for interplanetary travel or colonization.
Preventing vitamin deficiency isn’t the only role played by fresh produce. Certain foods like berries, some beans, and other foods rich in antioxidants can actually provide a certain level of protection against cumulative damage from space radiation.
While it seems like growing a few tomato plants, blueberries and some delicious baby spinach would be an easy way to meet this need, low and zero-gravity environments present significant challenges for gravity-adapted plant life. Imagine, if you will, the challenge of providing water to plants in a way that ensures it will penetrate the roots and allow recovery of any liquid that isn’t absorbed. Since plentiful exposure to oxygen is a critical element in rapid growth and production, “simple” solutions like confining plants in bags of water will suppress production and likely drown the plants altogether. Complicating matters further, the properties of fluid dynamics change as gravity changes. So a solution that’s effective in high Earth orbit may not work in interplanetary space or on the surface of Mars.
How Does Your Garden Grow (in Low Gravity)?
Gravity is an important player in the health and development of terrestrial plants. Teaching plants which direction to grow is relatively simple compared to the question of how to control the flow of both liquids and gases in low gravity environments. Since liquids tend to form bubbles in low gravity, it’s possible on the one hand, for air bubbles to form around roots leaving them high and dry, or conversely, for bubbles of water to envelop a root ball and drown the plant. In fact, low gravity in soil-based environments can lead to buildups of toxic gas and eventually suffocation when the movement of gas isn’t aided by gravity.
The ability of plants to absorb certain minerals also seems to be affected by gravity. For example, studies have shown that peas grown in space had higher levels of phosphorus and potassium but lower levels of important nutrients like calcium, magnesium, manganese, zinc, and iron. This is an area where aeroponics can shine, since a highly oxygenated environment combined with periodic mists of nutrient solution provides ideal conditions for maximum absorption and metabolization.
Payload Planning
If solving the problems of how to maintain healthy plants in low gravity isn’t a big enough challenge, some pretty thorny practical considerations can’t be ignored. Payloads, for example, are the cargo, people, equipment, and supplies that need to be delivered to space. Since moving a spaceship off the surface of the planet takes a lot of energy, every increase in payload must be balanced with an increase of fuel just to get the vehicle launched.
This is a critical consideration when weighing the pros and cons of different food production systems for space travel. Water is extremely heavy, after all, and the less included in the total payload, the more weight (mass) can be devoted to other important purposes. Other payload elements like nutrient concentrate, lighting systems, support structures, pumps, containers, and growth media all take up space and contribute mass. However, each ounce of food and water that can be produced aboard the spacecraft reduces the amounts that have to be transported, allowing space for other critical cargo.
Interior space is also at a premium onboard spacecraft, so food production systems that are compact, support many plants, and yet maintain healthy growing conditions are a necessity. Aeroponics are uniquely suited to provide each of these conditions. Automated aeroponics systems can even regulate conditions such as lighting, humidity, misting intervals, and air circulation, so that crews aren’t burdened by time-consuming management. .
The Aeroponics Advantage
All in all, as we increase exploration of the solar system and beyond, and colonization of other planets becomes a reality, aeroponics will prove to be the most suitable food production system overall. Advantages such as improved nutrient control, lower space requirements, high nutrient intake, low water requirement, less waste, fast growth and germination rate, fewer chances of disease transmission and better utilization of water supply are unmatched by other food production systems.
- Aeroponics systems allow detailed optimization of growth environments, down to the needs of individual crops. Timing of feed cycles, the type and concentration of nutrient solutions, and the humidity of the root chamber can all be set and adjusted using an automated system. Since the root chamber and the canopy chamber are completely separate, conditions there can also be independently controlled.
- Absorption and utilization of nutrients is rapid and complete, thanks to the system’s fundamental design. In aeroponics systems, roots receive maximum exposure to oxygen, punctuated by periodic misting of a hydro-atomized nutrient solution. These conditions allow roots to absorb nutrient solution instantaneously with zero waste.
- Well-tuned aeroponics systems can reduce water usage by 98 percent, use of fertilizer by 60 percent, and eliminate the need for pesticides altogether.
- The fundamental basis of aeroponics, i.e., growing plants without substrates, eliminates the potential for growth or transmission of pathogens. This efficiency also decreases volume and weight of both payload and minimizes waste materials that would otherwise have to be processed by a spacecraft’s or colony’s life support systems.
- Aeroponics systems allow crops to be grown at extremely high density, producing maximum yields in minimum space, a key element in an environment where space is at an absolute premium.
- In contrast to both traditional hydroponics and soil-based food production, the nutrient delivery mechanisms in both high pressure aeroponics and fogponics work just as efficiently in microgravity as in normal Earth gravity.
- Aeroponics systems require minimal disinfection, use minimal power, require relatively little space, and are flexible for use in a variety of gravity situations.These advantages mean that crew-time requirements are minimized.
