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Space Shot

  • Written by  Sara Bernard

Astronaut planting in spaceAstronaut planting in space

Hydroponic gardens give astronauts a nutritional and psychological boost.

What’s the value of a fresh salad? Ask an astronaut.

The men and women who head into orbit are confined to a space shuttle for weeks, months, or even years, dining on the outer space equivalent of TV dinners. Even though the diets of astronauts have come a long way since dehydrated ice cream (sample fare now includes shrimp cocktail and beef fajitas), there may be psychological, physiological, and—if a mission is long enough—economical benefits to building a garden while in orbit.

There’s only one problem: In the spacecraft, there is no gravity, soil, or natural light.

Enter hydroponics, which the National Aeronautics and Space Administration (NASA) began researching more than 50 years ago, when it started studying hydroponically grown algae as a way to produce oxygen and remove carbon dioxide from the air inside a spacecraft.

Today, the NASA scientists who figure out how to make shuttles more livable work in a field referred to as “bioregenerative life support,” or self-sustaining regulatory systems that help manage waste and air quality, and, sometimes, produce fresh food. The Exploration Life Support Project (formerly called Advanced Life Support, with activities spread across NASA’s Kennedy, Ames, Marshall, and Johnson centers) focuses more on chemical options than on botanical strategies, due to cost.

Plant-based systems “seem to pay off when you go farther and stay longer,” says Raymond Wheeler, a plant physiologist and lead for the Exploration Life Support activities at the Kennedy Space Center. “We’re not really worried about living on Mars for 10 years yet. The first thing we want to do is go to the moon and stay there for two weeks. That’s what drives the [research and development]. Chemical engineering approaches to generate oxygen and scrub the carbon dioxide—as opposed to biological approaches—trade favorably in terms of short missions.”

John Hogan, an environmental scientist at NASA’s Ames Research Center, agrees. “Plants can do a lot of the life-support functions that we often use physical and chemical treatments to do,” he says. But, he adds, a plant-based strategy won’t be economically feasible until shipping food and materials from Earth is too far a journey to make (read: a mission to Mars).

Still, there are several current projects in the works, including a few small plant-growth chambers at the International Space Station—the Earth-orbiting research station and largest artificial satellite to date—that examine “how plants respond in a weightless environment,” says Wheeler. While the plants are not yet having any impact on things like oxygen production (“when you use high light intensities and hydroponic approaches, you probably need 20 to 25 square meters of plants to produce enough oxygen”), they may still help supply a token amount of fresh food as a supplement to astronauts’ diets.

Space shuttle lift offSpace shuttle lift offWheeler’s team is exploring a commercially developed expandable plant chamber, aptly referred to as Veggie (put out by Madison, Wisconsin–based Orbital Technologies Corp.), that it aims to send to the International Space Station soon to do some demonstration tests. “It’s like a clear, flexible bellows,” Wheeler explains. “You can squash it down, which is nice for shipping into space. When you get it up there, you can unfold it and deploy it.” It’s a simple, low-cost approach that may be a viable way to grow fresh food.

Hogan calls it a “salad machine.” Basically, while NASA has yet to create a system that would supply a significant level of caloric intake via hydroponic gardens, a small salad once in a while may offer “a psychological boost.” (This is actually a legitimate field of study, adds Wheeler; it’s called horticultural therapy. “There are all sorts of ways of dealing with psychological stress in confinement,” he says. “Plants might be a way of mitigating that stress.”)

But even if it isn’t happening in a big way yet in outer space, the research that NASA has done over the years also lends itself well to agricultural practices and green technologies on Earth. “We’ve got a keen eye on potential Earth based applications for the technology we’ve developed,” says Hogan. “A lot of the problems we’re trying to solve on Earth are the problems we’re trying to solve in space.”

This is because the kinds of constraints NASA scientists face in their designs take Earth-based hydroponics look like a walk in the park. “In a space capsule or a habitat, you need to think about where every molecule is going,” says Hogan. Even in greenhouses, nutrients come in and out, and greenhouse gardeners, unlike NASA scientists, “don’t have to worry about oxygen and carbon dioxide levels, or growing plants in an airtight chamber.” Therefore, he says, NASA has developed a “tremendous amount of knowledge about how to make these systems as efficient as possible.”

For instance, NASA scientists—Raymond Wheeler among them—were the first to develop what’s called the nutrient film technique (NFT), a hydroponic approach used on potatoes so that the roots don’t have to be fully submerged in water (which they don’t particularly like, Wheeler says). Many farmers now use NFT to grow seed potatoes in greenhouses. “What you might refer to as recirculating hydroponics” is particularly well suited to both outer space and sustainable agriculture, he explains. With recirculating systems, “you keep the water going around the loop all the time with the nutrient solution.”

Borevitz labBorevitz labAnother example is light-emitting diode, or LED, lights. “The idea of using LED lights to grow plants was first proposed by NASA around 1990,” says Wheeler. Now “LEDs are showing up on a pretty wide scale for plant production in controlled environments. That’s another one of these things that probably would have happened anyway, but NASA was in front of the curve.” Although NASA’s plant research has been deemphasized over the past few years (and the agency is waiting for orders from the current administration regarding the time frame for a mission to Mars), hydroponics is nevertheless “constantly in the background and a very important part of future exploration,” says Hogan. “We anticipate a reinvestment.”

By Sara Bernard
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Last modified on Friday, 28 October 2011 18:37

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