Contemporary Aeroponics

Contemporary aeroponic techniques have been advanced research at NASA's research and commercialization center BioServe Space Technologieslocated on the campus of the University of Colorado in Boulder, Colorado including enclosed loop system research at Ames Research Center, where scientists were studying methods of growing food crops in low gravity situations for future space colonization.

In 2000, Stoner was granted a patent for an organic disease control biocontrol technology that allows for pesticide-free natural growing in an aeroponic systems.

Stoner received a patent in 2001 for a novel aeroponic method and apparatus utilizing a low pressure mist generated by centrifugal force utilizing a rotating cylinder device. The rotating cylinder device distributes liquid nutrient solution to the roots of plants by use of centrifugal force, thereby eliminating the need for a high pressure and low pressure pump and nozzles, including ultra-sonic misters. The geometrical shape of the enclosed root growth chamber is such that it allows for fractionated droplets to ricochet in multiple random directions thus completely surrounding the plant roots in 360 degree, in any plane.

21st Century Aeroponics

Aeroponics is an improvement in artificial life support for non-damaging plant support, seed germination, environmental control and rapid unrestricted growth when compared hydroponics and drip irrigation techniques that have been used for decades by traditional agriculturalists.



Modern aeroponics allows high density companion planting of many food and horticultural crops without the use of pesticides - due to unique discovers aboard the space shuttle.

Use of Seed Stocks

With aeroponics, the deleterious effects of seed stocks that are infected with pathogens can be minimized. As discussed above, this is due to the separation of the plants and the lack of shared growth matrix. In addition, due to the enclosed, controlled environment, aeroponics can be an ideal growth system in which to grow seed stocks that are pathogen-free.

The enclosing of the growth chamber, in addition to the isolation of the plants from each other discussed above, helps to both prevent initial contamination from pathogens introduced from the external environment and minimize the spread from one plant to others of any pathogens that may exist.

Pathogen Control & Disease Prevention

Plant are most susceptible to loss from pathogens during the first 21 days of their life cycle. The aeroponic technology developed by the PI utilizes a patented plant support structure that separates the plants from one another. In a hydroponic or aggregate-based system, pathogen infections can easily spread throughout the entire system due to the plants’ common source of water or medium. In the ideal aeroponic system pathogens can be reduced and controlled by:

a) separating the plants - thus preventing the pathogen from spreading infection from one plant to another.
b) applying disinfectants and fungicides to the aerial and root zones individually,
c) applying the water/nutrient at intervals that are best suited for plant development and growth,
d) allowing the plant to expand without interference of restricting physical barriers,
e) reducing the per plant exposure to surfaces where pathogens can linger or proliferate.

More Cost Effective

Aeroponic systems are more cost effective than other systems. Because of the reduced volume of solution throughput (discussed above), less water and less nutrients are needed in the system at any given time compared to other nutrient delivery systems. The need for substrates is also eliminated, as is the need for many moving parts, resulting in lowered manufacturing cost and reduced maintenance costs.



NASA aeroponic lettuce seed germination- Day 30

More User-Friendly

The design of an aeroponic system allows ease of working with the plants. This results from the separation of the plants from each other, and the fact that the plants are suspended in air and the roots are not entrapped in any kind of matrix. Consequently, the harvesting of individual plants is quite simple and straightforward. Likewise, removal of any plant that may be infected with some type of pathogen is easily accomplished without risk of uprooting or contaminating nearby plants.

Improved Nutrient Feeding

A variety of different nutrient solutions, for example, can be administered to the root zone using aeroponics without needing to flush out any solution or matrix in which the roots had previously been immersed. This elevated level of control would be useful when researching the effect of a varied regimen of nutrient application to the roots of a plant species of interest.



In a similar manner, aeroponics allows a greater range of growth conditions than other nutrient delivery systems. The interval and duration of the nutrient spray, for example, can be very finely attuned to the needs of a specific plant species. The aerial tissue can be subjected to a completely different environment from that of the roots.

More Control of Plant Environment

Aeroponics allows more control of the environment around the root zone, as, unlike other plant growth systems, the plant roots are not constantly surrounded by some medium (as, for example, with hydroponics, where the roots are constantly immersed in water).



NASA aeroponic lettuce seed germination (close-up of root zone environment)- Day 19

Less Nutrient Solution Throughput

NASA aeroponic lettuce seed germination- Day 3

Plants grown using aeroponics spend 99.98% of their time in air and 0.02% in direct contact with hydro-atomized nutrient solutionThe time spent without water allows the roots to capture oxygen more efficiently. Furthermore, the hydro-atomized mist also significantly contributes to the effective oxygenation of the roots. For example, NFT has a nutrient throughput of 1 L/minute compared to aeroponics’ throughput of 1.5 ml/minute.

The reduced volume of nutrient throughput results in reduced amounts of nutrients required for plant development.

Another benefit of the reduced throughput, of major significance for space-based use, is the reduction in water volume used. This reduction in water volume throughput corresponds with a reduced buffer volume, both of which significantly lighten the weight needed to maintain plant growth. In addition, the volume of effluent from the plants is also reduced with aeroponics, reducing the amount of water that needs to be treated before reuse.

NASA aeroponic lettuce seed germination- Day 12

The relatively low solution volumes used in aeroponics, coupled with the minimal amount of time that the roots are exposed to the hydro-atomized mist, minimizes root-to-root contact and spread of pathogens between plants.

Benefits of Aeroponics for Earth & Space

Aeroponics possesses many characteristics that make it an effective and efficient means of growing plants.

Less Nutrient Solution Throughput
More Control of Plant Environment
Improved Nutrient Feeding
More User-Friendly
More Cost Effective
Pathogen Control & Disease Prevention
Use of Seed Stocks

Mission to Mars

NASA's long range plans indicate for man's visit to Mars will utilize inflatable structures to house the spaceship crew on the Mars surface. Planning is under way to incorporate inflatable greenhouse facilities for food production.



NASA planning scenarios also reveal the Mars surface crew will spend 60% of their time on Mars farming to sustain themselves. Aeroponics is considered the agricultural system of choice because of its low water and power inputs and high volume of food output per sq meter.

NASA Inflatable Aeroponics

In 1999, Stoner, funded by NASA, developed an inflatable low-mass aeroponic system for space and earth for high performance food production. In 1999, Stoner, funded by NASA, developed an inflatable low-mass aeroponic system (AIS) for space and earth for high performance food production.




NASA low-mass Inflatable Aeroponics System (AIS) - achieved 1999

Abstract: Aeroponics International’s (AI’s) innovation is a self-contained, self-supporting, inflatable aeroponic crop production unit with integral environmental systems for the control and delivery of a nutrient/mist to the roots. This inflatable aeroponic system addresses the needs of subtopic 08.03 Spacecraft Life Support Infrastructure and, in particular, water and nutrient delivery systems technologies for food production. The inflatable nature of our innovation makes it lightweight, allowing it to be deflated so it takes up less volume during transportation and storage. It improves on AI’s current aeroponic system design that uses rigid structures, which use more expensive materials, manufacture processes, and transportation. As a stationary aeroponic system, these existing high-mass units perform very well, but transporting and storing them can be problematic.

On Earth, these problems may hinder the economic feasibility of aeroponics for commercial growers. However, such problems become insurmountable obstacles for using these systems on long-duration space missions because of the high cost of payload volume and mass during launch and transit.

The NASA efforts lead to developments of numerous advanced materials for aeroponics for earth and space.

Aeroponics for Space & Earth

In 1998, Stoner received NASA funding to develop a high performance aeroponic system for earth and space. Stoner demonstrated that dry bio-mass of lettuce can be significantly increased with aeroponics. Utilizing numerous aeroponic advancements Stoner had developed made NASA history

Abstract: The purpose of the research conducted was to identify and demonstrate technologies for high-performance plant growth in a variety of gravitational environments. A low-gravity environment, for example, poses the problems of effectively bringing water and other nutrients to the plants and effecting recovery of effluents. Food production in the low-gravity environment of space provides further challenges, such as minimization of water use, water handling, and system weight. Food production on planetary bodies such as the Moon or Mars also requires dealing with a hypogravity environment. Because of the impacts to fluid dynamics in these various gravity environments, the nutrient delivery system has been a major focus in plant growth system optimization.




NASA aeroponic lettuce seed germination- Day 30

There are a number of methods currently utilized (both in low gravity and on Earth) to deliver nutrients to plants. Substrate dependant methods include traditional soil cultivation, zeoponics, agar, and nutrient-loaded ion exchange resins. In addition to substrate dependent cultivation, many soilless methods have been developed such as nutrient film technique, ebb and flow, aeroponics, and many other variants. Many hydroponic systems can provide high plant performance but nutrient solution throughput is high, necessitating large water volumes and substantial recycling of solutions and the control of the solution in hypogravity conditions is difficult at best.

Aeroponics, with its use of a hydro-atomized spray to deliver nutrients, minimizes water use, increases oxygenation of roots, and offers excellent plant growth, while at the same time approaching or bettering the low nutrient solution throughput of other systems developed to operate in low gravity. Aeroponics’ elimination of substrates and the need for large nutrient stockpiles reduces the amount of waste materials to be processed by other life support systems. Furthermore, the absence of substrates simplifies planting and harvesting (providing opportunities for automation), decreases the volume and weight of expendable materials, and eliminates a pathway for pathogen transmission. These many advantages combined with the results of this research that prove the viability of aeroponics in microgravity makes aeroponics a logical choice for efficient food production in space.

Biocontrols in Space

In 1996, NASA sponsored Stoner’s research for a natural liquid biocontrol, known then as ODC (organic disease control), that activates plants of grow without the need for pesticides as a means to control pathogens in a closed-loop culture system.

By 1997, Stoner’s biocontrol experiments were conducted by NASA. BioServe Space Technologies’s GAP technology (miniature growth chambers) delivered the ODC solution unto bean seeds. Triplicate ODC experiments were conducted in GAP’s flown to the MIR by the shuttle space ; at the Kennedy Space Center; and at Colorado State University (J. Linden). All GAPS were housed in total darkness to eliminate light as an experiment variable.

NASA experiment was to study only the benefits of the biocontrol.NASA results confirmed that ODC elicited natural plant disease mechanisms when in sprouted beans. ODC now is a standard for pesticide-free aeroponic growing. Soil and hydroponics growers can benefit by incorporating ODC into their planting techniques.

Space Plants

Plants were first taken into Earth orbit in 1960 on two separate missions, Sputnik 4 and Discover 17 (for a review of the first 30 years of plant growth in space, see (Halstead and Scott 1990).



NASA life support GAP technology with untreated beans (left) and biocontrol treated beans (right) returned from the Mir space station aboard the space shuttle – September 1997

On the former mission, wheat, pea, maize, spring onion, and Nigella damascena seeds were carried into space, and on the latter mission Chlorella pyrenoidosa cells were brought into orbit.

Plant experiments were later performed on a variety of Soviet, American, and joint Soviet-American missions, including Biosatellite II, Skylab 3 and 4, Apollo-Soyuz, Sputnik, Vostok, and Zond. Some of the earliest research results showed the effect of low gravity on the orientation of roots and shoots (Halstead and Scott 1990).

Subsequent research went on to investigate the effect of low gravity on plants at the organismic, cellular, and subcellular levels. At the organismic level, for example, a variety of species, including pine, oat, mung bean, lettuce, cress, and Arabidopsis, showed decreased seedling, root, and shoot growth in low gravity, whereas lettuce grown on Cosmos showed the opposite effect of growth in space (Halstead and Scott 1990). Mineral uptake seems also to be affected in plants grown in space. For example, peas grown in space exhibited increased levels of phosphorous and potassium and decreased levels of the divalent cations calcium, magnesium, manganese, zinc, and iron (Halstead and Scott 1990).

Aeroponically Grown Food

In 1986 Stoner was the first person ever to market fresh aeroponically grown food to a national grocery chain. He was interviewed on and discussed the importance of the water conserving features of aeroponics for both modern agriculture and space.



Stoner, is considered the father of commercial aeroponics. Stoner's aeroponic systems are in major developed countries around the world. His aeroponic designs, technology and equipment are widely used at leading agricultural universities worldwide and by commercial growers.

Commercialization

Aeroponics eventually left the laboratories and entered into the commercial cultivation arena. In 1966, commercial aeroponic pioneer, B. Briggs, succeeded in inducing roots on hardwood cuttings by air-rooting. Briggs discovered that air-rooted cuttings were tougher and more hardened than those formed in soil and concluded that the basic principle of air-rooting is sound. He discovered air-rooted trees could be transplanted to soil without suffering from transplant shock or setback to normal growth. Transplant shock is normally observed in hydroponic tranplants.

In 1982, L. Nir, developed a patent for an aeroponic apparatus using comprised low pressure air to deliver a nutrient solution to suspended plants, held by styrofoam, inside large metal containers.



In 1983, R. Stoner filed a patent for the first microprocessor interface to deliver tap water and nutrients into an enclosed aeroponic chamber made of plastic. Stoner has gone on to develop numerous companies researching and advancing aeroponic, hardware, interfaces, biocontrols and components for commercial aeroponic crop production.

In 1985 Stoner's company, GTi, was the first company to manufacturer, market and apply large scale closed-loop aeroponic systems into greenhouses for commercial crop production.

The first commercial aeroponic greenhouse for aeroponic food production - 1986

Early Lab Research

Soon after its development, aeroponics took hold as a valuable research tool. Aeroponics offered researchers a noninvasive way to examine roots under development. This new technology also allowed researchers a larger number and a wider range of experimental parameters to use in their work.

The ability to precisely control the root zone moisture levels and the amount of water delivered makes aeroponics ideally suited for the study of water stress. K. Hubick [Hubick et al., 1982] evaluated aeroponics as a means to produce consistent, minimally water-stressed plants for use in drought or flood physiology experiments.

Aeroponics is the ideal tool for the study of root morphology. The absence of aggregates offers researchers easy access to the entire, intact root structure without the damage that can be caused by removal of roots from soils or aggregates. It’s been noted that aeroponics produces more normal root systems than hydroponics.

History of Aeroponics

It was W. Carter in 1942 who first researched air culture growing and described a method of growing plants in water vapor to facilitate examination of roots.

In 1944, L.J Klotz was the first to discover vapor misted citrus plants in a facilitated research of his studies of diseases of citrus and avocado roots. In 1952, G.F Trowel grew apple trees in a spray culture.

It was F. W. Went in 1957 who first coined the air-growing process as “aeroponics”, growing coffee plants and tomatoes with air-suspended roots and applying a nutrient mist to the root section.

Commercial Systems

Commercial aeroponic systems are comprise of hi-pressure device hardware and biological systems. The biological systems matrix includes enhancements for extended plant life and crop maturation.



Biological subsystems and hardware components include effluent controls systems, disease prevention, pathogen resistance features, precision timing and nutrient solution pressurization, heat and cooling sensors, thermal control of solutions, efficient photon-flux light arrays, spectrum filtration spanning, fail-safe sensors and protection, reduced maintenance & labor saving features, and ergonomics and long-term reliability features.

Commercial aeroponic systems, like the hi-pressure devices, are used for the cultivation of high value crops where multiple crop rotations are achieved on an ongoing commercial basis 24/7.
Advanced commercial systems include data gathering, monitoring, analytical feedback and Internet mode connections to various subsystems.

Types of Aeroponics : Hi-pressure Devices

Hi-pressure aeroponic techniques where the mist is generated by high-pressure pump(s) are typically used in the cultivation of high value crops and plant specimens that can offset the high setup costs associated with this method of horticulture.



Hi-pressure aeroponics systems include technologies for air and water purification, nutrient sterilization, low-mass polymers and pressurized nutrient delivery systems.