NASA is learning the best way to grow food in space
“Our plants aren’t looking too good,” astronaut Scott Kelly tweeted from the International Space Station on December 27, 2015. He was right: The attached picture showed four baby zinnias bathed in magenta light. Three of the four leafy stalks were discolored and curling in on themselves. The station’s garden was struggling to recover from a mold problem. It’s an issue familiar to terrestrial gardeners. And while on Earth, the problem means a trip to the local nursery for replacements, in space you can’t do that.
The zinnias, brightly colored flowers in the daisy family, were part of an experiment called Veggie, whose ultimate mission is to provide crews with a long-term source of food. In prior tests, astronauts had successfully harvested lettuce. The zinnias had a longer growth period—60 to 80 days—and then would bloom, producing neon-hued blossoms that look like they belong in a psychedelic corsage. They were practice for something finickier and tastier than leafy greens: tomatoes. If station crews were ever going to grow something that intricate, they needed to figure out—among other things— how to vanquish mold.
Veggie is a relatively uncomplicated way for astronauts to develop their green thumbs. “It’s a very simple system,” says Gioia Massa, one of the project’s lead scientists. “It doesn’t control much at all.” Instead, the humans do.
Space gardening will be essential someday if space travelers are to go beyond low-Earth orbit or make more than a quick trip to the moon. They can’t carry on all the food they need, and the rations they do bring will lose nutrients. So astronauts will need a replenishable stash, with extra vitamins. They’ll also require ways to make more oxygen, recycle waste, and help them not miss home so much. Space gardens can, theoretically, help accomplish all of that.
Veggie and other systems aboard the space station are helping researchers figure out how radiation and lack of gravity affect plants, how much water is Goldilocks-good, and how to deal with deplorables like mold. Just as important, scientists are learning how much work astronauts have to put in, how much work they want to put in, and how plants nourish their brains as well as their bodies.
For all its potential importance, Veggie is pretty compact. It weighs 41 pounds, just a hair less than the station’s 44-pound coffeemaker. The top—an off-white rectangular box that houses the grow lights—resembles an old VCR. From this, a curtain of clear plastic hangs to encase the 1.7-square-foot planting surface. Astronauts preset how long the lights stay on each day; how brightly they emit red light to optimize photosynthesis, and blue light to control the plants’ form and function. They can also activate a built-in fan to adjust the humidity.
The most important part of Veggie, though, is the fragile bounty it is meant to cultivate. That begins as seeds encased in little Teflon-coated Kevlar pouches. The scientists call them plant pillows. “You can think of it like a grow bag,” Massa says of these packets stuffed with seeds, water wicks, fertilizer, and soil.
People have anticipated this scenario for more than a century. In 1880, science-fiction author Percy Greg wrote Across the Zodiac, a novel about an astronaut who traveled to Mars with plants to recycle waste. Fifteen years later, Konstantin Tsiolkovsky, a Russian rocket scientist, wrote Dreams of Earth and Sky, which laid out how space farers and flora could live together inside a closed system.
In the 1950s, green things burst from book covers and into the lab. NASA and the U.S. Air Force started growing algae to see if it could help with life support (turns out, it tasted bad, was full of indigestible cell walls, and had too much protein). Then, Soviet scientists experimented with nearly self-sufficient ecosystems in which humans survived on oxygen, water, and nutrition produced mostly within an enclosed habitat. In the longest run, a 180-day trial inside a facility called BIOS-3, an earthbound crew got 80 percent of its food from its own wheat and vegetables. Finally, in 1982, plants in space became a reality when Soviet cosmonauts grew Arabidopsis thaliana, a flowering species related to cabbage and mustard, to maturity aboard their Salyut 7 space station. The yield was too small to be a source of food.