A NASA astronaut has begun setting up a new horticultural project on the International Space Station that will compare two different LED light recipes for growing dwarf tomatoes aboard the craft.
The experiment marks the first time that the ISS crew has used the onboard Veggie facility for tomatoes, although it recently picked them from a separate growth chamber called XROOTs.
Veggie is is the oldest of at least three LED-lit horticultural chambers on the craft. It is an open chamber from which astronauts can snip or pick produce. It germinates plants in pillows which sometimes contain a soil substrate and also contain water and fertilizer. Water can be applied manually via a syringe, or through a mechanical system called PONDS (Passive Orbital Nutrient Delivery System).
NASA has used Veggie since 2014 to grow greens such as romaine lettuce, zinnia flowers, mizuna, pak choi, and others in four different stages. Late last week, flight engineer Nicole Mann began preparing Veggie for the fifth stage — Red Robin dwarf tomatoes — NASA reported on its ISS blog. In NASA parlance, the tomatoes represent Veg-05.
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“The research of Veg-05 expands crop variety to dwarf tomatoes and focuses on the impact of light quality and fertilizer on fruit production, microbial food safety, nutritional value, taste acceptability by the crew, and the overall behavioral health benefits of having plants and fresh food in space,” NASA explains on a separate informational web page.
“Flight definition testing has assessed different red-to-blue light recipes and fertilizer formulations for optimum growth of these crops on the ground,” it noted. “Two light treatments with different red-to-blue ratios are tested for each crop on the ISS. This investigation is expected to help define light colors, levels, and horticultural best practices to achieve high yields of safe, nutritious leafy greens and tomatoes to supplement a space diet of pre-packaged food. A duplicate ground-study provides a comparison to the plants grown on the ISS to determine the effects of spaceflight.”
NASA did not provide details on the light recipes. It is carrying out the same growth experiments on the ground.
NASA grows food and other crops on the ISS to better understand how to grow food that can sustain humans in future space endeavors, and also to gain insights for optimizing plant growth — including the lighting aspect — on Earth. In Veg-05 it is also examining possible psychological benefits of tending plants onboard for astronauts.
Unlike Veggie, the recently installed XROOTS (eXposed Root On-Orbit Test System) applies only hydroponics and aeroponics methods. NASA believes that XROOTS might scale up better than Veggie and take up less space per yield.
A third system, APH (Advanced Plant Habitat), is a completely enclosed chamber using LED lights, a clay substrate, cameras, and about 180 sensors to monitor growth; it communicates the data to Kennedy Space Center, where a team can operate APH remotely. It has a much wider spectrum of LED lights than does Veggie, including red, green, blue, white, far red, and infrared. Whereas astronauts eat the yields of Veggie, they freeze or chemically fix APH harvest — such as cabbage and thale cress — before sending it back to land for analysis.
In another project last year, ISS astronauts were growing thale cress in petri dishes under LED lights, freeze drying the thale cress after 10 to 12 days before returning it to Earth to help learn more about early stage plant growth and RNA.
A Japanese team onboard the ISS has also experimented with growing basil under “just regular lighting” — not using LEDs.
MARK HALPER is a contributing editor for LEDs Magazine, and an energy, technology, and business journalist ([email protected]).
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