Plants in Space: The New Frontier of Hydroponics

As NASA’s astronauts prepare to embark on increasingly longer missions, scientists are trying to find a way to adequately feed them.  As we haven’t yet found soil that can support life in space, and the logistics of transporting soil are impractical, hydroponics could hold the key to the future of space exploration.

Plants offer a promising solution in providing food to astronauts thousands of miles from Earth. They could grow crops that would not only supply astronauts with a fresh source of food, but also remove toxic carbon dioxide from the air inside their spacecraft and provide life-sustaining oxygen through the plant’s natural growing process. This is important for long-range habitation of both space stations and other planets.

In a Galaxy Far, Far Away
“Imagine a bright flower on a plant in a crystal clear growth chamber on the surface of the Moon, with the full Earth rising above the moonscape behind it” says Jane Poynter, president and founder of Paragon Space Development Corporation, “these are the ideas that got me interested in space.”

That vision of the first flower grown on the Moon may likely become a reality in our lifetimes.  In recent years, NASA has performed extensive research into the field of hydroponics, which can benefit current space exploration, as well as future, long-term colonization of Mars or the Moon.

To accomplish this vision, technology and biology have to meet in a way never before achieved. Teams combining engineers and horticulturists will work together, perhaps an entire team dedicated to each species that will be grown.

NASA’s Research Into Hydroponics
In an effort called Vision for Space Exploration, NASA is taking steps to learn how hydroponics can benefit the space frontier and even life on Earth. Researchers cannot just send the right equipment to outer space and expect to grow plants. There are many considerations to be made, including light, temperature, and even gravity.

Why would all of this matter? One main concern is the competition of plants for light, based on how they grow. If one species grows taller and spreads out wider than the species beside it, the larger plant may block the light from the smaller plants. For that reason, NASA is investigating dwarf varieties of crop plants, such as wheat and rice, which only grow to be a foot or so tall.

Temperature is another important challenge to overcome, as conditions on the Moon are well beyond what ordinary plants could survive. Temperatures can drop well below freezing and the plants would have to endure high levels of solar ultraviolet radiation.

Gravity is also a very important part of plant growth. Plants use gravity to direct which way their roots should grow and which way their shoots should grow.  Without the influence of gravity, the water used to grow plants won’t stay in one place on its own accord. How do you grow plants in a puddle of water that is floating in the middle of the cabin? And how do plants react to zero-gravity? Do they still grow up towards the light to maximize light intensity, or will they grow sideways to maximize plant surface area? Towards that end, NASA has been conducting research on plants for years, and has flown plants on board the Space Shuttle and Space Station to learn more about how they grow in space.

Growing Plants with Moon Dust
Here on Planet Earth, many gardeners use a material called perlite, often as part of a potting soil mix, or in the case of hydroponics, as a growing medium on its own. Perlite is actually made of expanded volcanic glass. The mineral is heated to temperatures of 850-900 degrees Celsius until it pops like popcorn. Water trapped in the structure of the material vaporizes and escapes, which causes the expansion of the material to 7–16 times its original volume.

Recently scientists found hardened lava, tiny beads of volcanic glass that contain water (which presumably would vaporize and escape when heated) and may be similar to perlite.  If so, it is possible that these materials could be mined, heated up, and used as growing media for hydroponic systems in space.

Farming for the Future
Aeroponics systems, which utilize a high-pressure pump to spray nutrients and water onto the roots of a plant, may be an essential part of space missions in the future. Aeroponic growing systems provide clean, efficient, and rapid food production. Crops can be planted and harvested year round without interruption, and without contamination from soil or pesticide use. Plants grown in aeroponic systems have also been shown to take in more vitamins and minerals, making the plants healthier and potentially more nutritious.

Aeroponic greenhouses could easily be assembled in space, seeded for farming, and then disassembled when food stores are replenished.  These ‘space gardens’ could provide up to half of the required calories for the astronauts though tomatoes, potatoes, and other fruits and vegetables. It can also help to recycle nutrients, provide drinking water and create oxygen in space. It could even provide building materials.

Ultimately, any technology produced by NASA could have far-reaching effects.  As these technologies are developed for space exploration, the same innovations can be applied back here on Earth. For example, space research could help develop faster growing trees to regenerate lost forest areas.  It could also help produce safe, high-quality food in places like sub-Saharan Africa, where destructive floods are often followed by severe droughts.

Though getting plants to grow in conditions in outer space, where there is no gravity, sunlight, or air movement, is no easy challenge, planetary scientist Chris McKay remains optimistic: “The first plant to grow from seed and complete its life cycle on another world will be a significant step in the expansion of life beyond the earth. The sooner we do it, the better.”

Source: House & Garden