Forty years ago this month, Apollo 10 astronauts spread “meat salad” on slices of white bread for a cosmic-cuisine “first”: the first sandwiches made in space. Up until that moment, food on NASA missions meant either dehydrated (freeze-dried) meals or bite-size, ready-to-eat foods that were consumed directly from their plastic packaging. None of it bore much resemblance to earthbound food, so fresh bread (which had made an illegal appearance in space once before, when astronaut John Young smuggled a corned-beef deli sandwich aboard the Gemini 3 mission in the ’60s) was a real treat.
Space snacking has come a long way since those days, to be sure. Astronauts now eat foods as varied as kimchi, beef enchiladas, and the occasional meal from Alain Ducasse, Emeril Lagasse, or Rachael Ray. But fresh produce is scarce and is limited to sturdy items like oranges and apples.
That all could change in coming years, as researchers perfect methods for what they hope will be the future of space food: cosmic gardening. The thinking is that fresh crops would sustain astronauts on long-term missions to the Moon and Mars, creating variety in their diets, helping reduce the high cost of replenishing food supplies, and providing both nutritional and psychological benefits (anecdotal evidence indicates that a diet of healthy, tasty foods and the presence of plants both help to decrease the stress of long missions). NASA’s plant growth experiments began in earnest during the 1990s, and gearing up for missions to the Moon and Mars was a NASA priority under President Bush, so the agency has put effort and funding behind horticultural research for the past two decades, with impressive results: Astronauts have successfully grown plants—including soybeans, potatoes, tomatoes, wheat, peas, and more—in space (though they haven’t made them a regular part of their diet yet), and earthbound researchers have experimented with growing additional species including peppers, strawberries, onions, and herbs in conditions that mimic those in space.
Now, due at least partially to funding cuts, many researchers are shifting their focus toward ways of making agriculture more sustainable here on earth—and their work has the potential to revolutionize farming worldwide, from major urban centers to remote desert and mountain villages.
Growing plants in space presents unique problems: The absence of wind and insects means some crops need to be pollinated by hand; natural light isn’t available inside space bases; crops can’t be too labor- or energy-intensive, as bases have limited manpower and natural resources; and of course there is no naturally available water source, so water efficiency is extremely important. According to Ray Wheeler, a plant physiologist at NASA’s Kennedy Space Center, scientists have been largely successful in tackling these challenges. “Over the years of testing, NASA-sponsored research has shown that you can push the yields of many crops beyond what people thought was possible—beyond world records,” he says, explaining that this increase in yield has been accomplished mainly by using high-intensity lighting, creating optimal CO2 environments for the plants, and growing them in hydroponic cultures.
Wheeler has done extensive research on lighting, specifically looking at LED lights (like the ones pictured above), which “are very convenient for little space chambers,” he says. “They don’t have mercury or vapor in them, and the high-quality ones last a long time,” which helps bring down the overall cost of crop production. LEDs are also cool to the touch, says Cary Mitchell, director of the NASA Specialized Center of Research and Training for Advanced Life Support at Purdue University—so unlike most conventional lights, LEDs can be placed very close to (or even touching) plants, providing a concentrated light source with minimal wasted light. Mitchell and colleagues have developed LEDs that can stand right next to plants and shed light under and around the leaves, instead of just lighting from above (he calls these LEDs “lightsicles” because of their vertical, icicle-like shape). “We’re able to run the LEDs at fairly low power, because it doesn’t take a lot of power to get the light levels we need to grow the crops,” Mitchell explains. He adds that different species of plants have slightly different light preferences, so “you could actually custom-develop a lighting array for plants that emits the colors that the pigments in those leaves prefer,” he says.
The hydroponic systems being developed for space can also be tailored to specific plants, which are grown in a soil-free, recirculating stream of nutrients housed within a growth chamber (the process is called nutrient-film technique, or NFT). And these crops could pull double duty as water purifiers: Research has shown that plants in NFT hydroponic cultures can process soap-containing water with minimal effects on plant growth. “You can take waste water and regenerate that into potable drinking water, as opposed to doing it with chemical means,” says Gene Giacomelli, director of the Controlled Environment Agriculture Program at the University of Arizona. If the system can also harness the oxygen generated by the plants and the CO2 generated by humans, it moves toward the “closed loop” that is the holy grail of space-life-support research. Giacomelli and Wheeler have found that in such a system, 50 square meters of plant-growth space per astronaut (about 538 square feet, roughly the size of a standard American hotel room) could provide half that person’s daily calorie requirements (the remainder would come from stored food), plus 100 percent of his or her fresh water needs and about twice the oxygen.
NASA sponsorship for plant-research projects has fallen away recently, and the agency could face further changes as a new administrator steps in and an independent committee begins to review NASA’s human space-flight plans; but some researchers are securing other funding sources and looking at how their work could be applied to Earth-based agriculture. For example, Mitchell—whose initial goal was to design a self-sustaining, closed-loop system for future space colonies on the Moon and Mars—has started to work on a project that would harness a wide variety of the NASA researchers’ achievements, and it could have a significant impact on earthbound agriculture. He is working with a Purdue colleague, Gioia Massa, to harness “waste heat” from industrial sites to warm the soil in cold climates, making it possible to grow crops year-round (see drawing below). At the coal-fired power plant on the Purdue campus, the team’s test site, hot wastewater is a byproduct of electricity generation; Mitchell and Massa are working to channel that water through underground pipes beneath a farm site to heat the soil. The field will be covered with “high tunnels” (cheap, bottomless plastic greenhouses that cost only about 15 percent of the price of a commercial plastic greenhouse) to trap the heat. If all goes well (the team is in the process of securing funds to finish the project and expect to test it with fruits and vegetables this winter), the project could be expanded to future applications at sewage-treatment plants and landfills, where CO2 and methane are additional byproducts. At those sites, Mitchell says, “We could inject both the heat and the carbon dioxide into the high tunnels to stimulate crop growth” and generate electricity from the methane to power LED lighting. “We intend to use the loop-closure principles that we've learned working with NASA so that we can have affordable, local production of fruits and vegetables,” he says. “We could produce food locally [in the winter] in New York, Indiana, Minnesota—because waste is produced everywhere.”
It’s an exciting prospect, and it points to a common thread in all of the NASA-sponsored plant research: controlled environments. As Mitchell explains, “The reason plants are so much more productive in a greenhouse—or better yet in a growth chamber, or better still with hydroponics in the growth chamber—[is because in those environments] they come much closer to their genetic potential for productivity.” While some commercial growers do use controlled environments, it’s a relatively small industry in this country. “The USDA hasn't historically had areas that cover controlled-environment agriculture,” says Wheeler. “The field growers of corn and soybeans have been very efficient at lobbying their case. But if you add up the [whole] greenhouse industry, it’s not insignificant—they just haven’t been as effective in lobbying the USDA.”
There’s a possibility that this could all change if these researchers get together with others in the field of controlled-environment agriculture, particularly urban farmers. Strange as it sounds, it just may be that for the local-food movement, space really is the final frontier.