Source(s):
Kevin Folta kfolta@ifas.ufl.edu, 352-392-1864
John Sager john.c.sager@nasa.gov, 321-861-2949
GAINESVILLE, Fla. — Kevin Folta has seen the future of agriculture — and it looks a lot like a photographer’s darkroom.
In a windowless room in his University of Florida laboratory, Folta grows dozens of plants in small trays, under the glare of light-emitting diodes — the same kind of tiny “bulbs” that light the face of your watch or tell you when the coffee is done.
It may not look like much, but Folta’s “darkroom” may be the model for gardens that would feed astronauts on future Moon base or mission to Mars. Here on Earth, the same technology could be used in greenhouses where farmers use light, rather than chemicals, to control the growth of plants.
“If you want to take plants into space for long periods of time, you’re going to have to take your light sources with you,” said Folta, an assistant professor of horticultural sciences at UF’s Institute of Food and Agricultural Sciences. “And on an 18-month trip to Mars, you can’t just turn around and go back when a light bulb burns out — you need something that will last.”
Folta is one of a growing number of researchers who are exploring the agricultural applications of light-emitting diodes, or LEDs. Because they last much longer and burn far less electricity than standard incandescent lightbulbs, LEDs may be the perfect light source for “greenhouses” on spacecraft on an extended voyage.
While detailed plans for future missions to Mars or the Moon have yet to be laid out, it’s quite likely that when humans do again venture beyond Earth orbit, they’ll take a few crop plants with them. Lifting things into space is expensive, and a spaceborne garden might offer more bang for the buck than canned food, space agriculture advocates say.
“If you collected enough food to feed a person for a year and put it in one place, it would easily fill a room,” said John Sager, an agricultural engineer at Kennedy Space Center. “It would probably be better to fill at least some of that room with a garden, where you could grow a constant supply of food, freshen the air and recycle waste.”
In his lab at the space center, Sager grows common food crops such as lettuce in “growth chambers” of the sort that might one day be found on a Moon base or Mars-bound spacecraft. Some of his growth chambers — rough drafts for future space gardens — are lit by bright banks of LEDs.
“When you talk about a garden in space, people usually think of plants growing under some sort of transparent dome,” he said. “But in fact, that approach has a lot of drawbacks. The plants around us have spent millions of years adapting to the light conditions on Earth, and they’re very sensitive to changes in light patterns.”
On the dimly-lit surface of Mars or during the month-long “day” on the lunar surface, astronauts will need an artificial light source to illuminate their spaceborne gardens, Sager said. And incandescent light bulbs — which last only about 1,000 to 2,000 hours before burning out — aren’t the best option for a trip that could last months.
“An individual light-emitting diode can easily last 50,000 hours, which is probably more than enough to get you through a mission to Mars, without having to carry spare bulbs,” Sager said.
But there’s another advantage to using LEDs on spaceborne crops: they may allow future gardeners to control the growth patterns of plants at the touch of a button.
Each individual LED is a tiny semiconductor, which produces light only in a small portion of the spectrum — red, for instance, or blue. Put dozens or hundreds of different-colored LEDs together, and you can produce a white light as bright as anything that comes out of an incandescent bulb.
But unlike a traditional light bulb, a bank of LEDs can be easily adjusted to allow for minute changes in the color or light it produces. If you want light with a slight bluish tinge, for instance, you can turn up the power on blue diodes and turn down the power on other colors.
Folta is using LED banks to explore the effects these subtle light changes have on the growth patterns of plants. By applying the right combination of colors at the right times, he said, it may be possible to tell spaceborne plants when to bloom, or how high to grow — or to replicate the conditions of a perfect growing season on Earth.
“The idea of light color affecting plant growth is nothing new,” he said. “That’s been known for decades. But we’re just now beginning to truly map out the effect that different parts of the spectrum — both visible and invisible — have on plants as they grow.”
In earthbound greenhouses, Folta said, adjustable LED banks could one day replace plant growth regulators — the hormones that farmers currently apply to plants to trick them into blooming at specific times, or growing to specific sizes. Growth regulators can be expensive, and applying them safely is often a complicated and labor-intensive process.
Of course, LEDs can also be expensive. At current prices, Folta said, it would cost hundreds of thousands of dollars to equip a commercial greenhouse with banks of LEDs similar to the ones in his lab.
But those prices are rapidly dropping. The drop is due in part to new advances in LED technology, and partly because researchers such as Folta are finding newer, cheaper ways to incorporate the diodes into devices with agricultural uses.
Folta’s own lab is a good example. The researcher says the LED arrays used in his research could easily cost around $100,000 if ordered from a scientific supply company: he and his graduate students assembled their equipment from off-the-shelf parts for only about $3,500.
“With prices coming down as fast as they are, greenhouse growers may begin adopting this technology within a decade,” he said.
Research associated with a future Mars mission could play a major role in bringing LED prices down, Folta said. The space program has a long history of turning fundamental scientific research into technologies people use every day on earth.
“If you look at the technologies that have become available to consumers in the past 40 years, you see the residues of the space program everywhere,” he said.
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