As humans expand space exploration farther from Earth, the ability to grow a supplemental food crop is a solution to the challenge of long-duration missions into deep space. The packaged diet currently used by crews in low-Earth orbit works well and has supported an uninterrupted human presence in space since Nov. 2, 2000; however, it relies on frequent resupply missions. During a two- or three-year mission to Mars, the vitamins and quality of packaged food would degrade over time. Supplementation with fresh, edible crops will provide necessary nutrients while also enhancing dietary variety. Anecdotal evidence also supports the potential for psychological benefits for astronauts, rooted in the enjoyment of eating and caring for plants.
•The Vegetable Production System (Veggie) is a plant growth unit on the International Space Station. • The Veggie concept is a simple, low-power system to grow fresh, nutritious food for our astronauts to supplement their diet and use as a tool to support relaxation and recreation.
• There are two Veggie units aboard the station, along with a more sophisticated growth chamber, the Advanced Plant Habitat.
• Earlier versions of the Veggie hardware were tested at NASA’s Kennedy Space Center.
• The Veggie hardware and the VEG-01 experiment flew to the space station as commercial cargo, part of NASA’s Commercial Resupply Services SpaceX CRS-3 mission that launched from Kennedy Space Center on April 18, 2014.
• Astronauts Rick Mastracchio and Steve Swanson installed Veggie in the Columbus Laboratory Module on May 7, 2014.
•Veggie runs on about 70 watts for the lights, fans and control electronics.
•Veggie utilizes passive wicking to provide water to the plants as they grow.
• Currently, the seeds are glued into wicks, which are white flaps emerging from the top of a plant pillow.
• The glue actually is guar gum, a water-soluble natural polymer made from legumes called guar beans. This is what secures the seeds in place. Check your ice cream – you may find guar gum as a thickening agent.
• Plant pillows are Teflon-coated black Kevlar with a Nomex bottom, which contains the growth media (calcined clay – often used to condition baseball infields), controlled release fertilizer and water (injected through a quick-disconnect valve).
• Each plant pillow receives two or three seeds as a hedge against germination failure.
• Future plans are to have seeds embedded in a tape or film, which would allow seeds and pillows to fly independently. The space station could have a seed bank and a plant pillow bank, which would allow crews to decide what to grow.
• The plant experiment starts by placing the root mat on the Veggie baseplate, then the plant pillows are bungeed in place on top of the root mat. Water is injected into the plant pillow, then water is injected into the root mat. The wicks carry the water to the seeds, which are glued in, and the combination of water and light trigger germination. Seeds are oriented so that the plant grows up and the roots grow down into the plant pillow.
• As part of each plant experiment in Veggie, researchers at Kennedy grow crops on the ground in sync with the orbital experiments as a control group.
• Growing plants in microgravity is complicated by the fluid physics and lack of convective flow.
Plants need oxygen and carbon dioxide, and the roots need water and oxygen at the same time. Too much water stresses plants like a flood, and too little is like a drought. Veggie has a fan system, which draws in cabin air for the growing plants to ensure they don’t end up in a diffusion controlled bubble of humidity and oxygen.
• As a good practice and precaution, the Veggie team also developed a produce-sanitizing step for leafy greens utilizing food-safe, citric acid-based wipes that are used to sanitize the fresh produce and also clean the Veggie units.
• NASA is building up the ingredients for a pick-and-eat salad; or rather, a pick, sanitize and eat salad since there is no way to cook on the station yet.
• Astronauts have grown eight different types of leafy greens in Veggie for the astronauts to eat. Overall, 15 different types of plants have grown in space in Veggie. Researchers at Kennedy Space Center have tested more than 100 crops on the ground.
• Including experiments by teams of student citizen scientists working in partnership with the Veggie team via the Fairchild Tropical Botanic Garden’s Growing Beyond Earth Project challenge, more than 200 crops have been tested for potential use in space