Unlike the future Gene Roddenberry depicted in Star Trek, we don’t have replicators to deal with space-faring food needs. (Yet?) So, food must be either taken to space or grown there.
“The ability for us to grow fresh food in space is an essential part of the solution to the challenges for NASA’s long-duration human exploration of the moon and beyond,” says Murat Kacira, director of the University of Arizona’s Controlled Environment Agriculture Center, in his July 24 presentation at the “Training the Next Generation of Space Farmers” webinar, part of the SpaceAg Conversations series put on by Agritecture.
Considerations of space ag
Kacira told webinar participants about what it takes to grow fresh produce in space.
“When we consider space exploration, the resources are limited,” he says.
These limitations present unique challenges. At the most basic, any food-growing system, what Kacira calls a bioregenerative life support system, has to work without external inputs. Everything including air, water, nutrients and waste products must be reliably recycled into the system.
“A truly closed bioregenerative life support system must handle feedback loops, for instance, like one crop failing or an unexpected microbial outbreak, or hardware system issues without collapsing,” he adds.
Kacira explains different types of technologies to meet these challenges are being explored, including different types of controlled environment agricultural systems and creating planting substrate in space.
These systems will need to produce a wide variety of crops as well. He reports that NASA has been focusing on mostly “pick-and-eat” produce crops that require minimal harvesting, cleaning or preparation needs. Experiments have involved a lot of leafy greens such as kale, lettuce, wasabi, bok choy, mustard greens, but also fruit and vegetables such as strawberries, radish, peppers and even sweetpotatoes.
Space agriculture systems not only need to provide for the dietary needs of astronauts, but also their psychological well-being. NASA cites four considerations — nutrition, menu fatigue, behavior health and systems resiliency — that would drive the number of crops that would be needed. Based on experience and experiments at the International Space Station, it recommends:
- At least 15 different crops to address nutritional needs
- At least three colors, three textures and four different flavor types to help address menu fatigue
- At least three different growth habits (e.g. leafy, vining, flowering, etc.) in crops with varied appearances, smell, feel and care needs to help with behavior health
- At least three different crop plant families (e.g. nightshades, cruciferous vegetables, etc.) to help address the system’s resiliency to disease, poor germination or other production issues
Greenhouses for the Moon and Mars
Kacira talks specifically about the Mars Lunar Greenhouse Prototype project that the University of Arizona’s Controlled Environment Agriculture Center has been working on since 2004.
Earlier iterations of the greenhouse prototype were built with the assumption that the greenhouses would be buried under the Moon’s fine, dusty surface layer (regolith) to prevent exposure to radiation and potential damage from meteorites. The current version, however, is built with a lunar or Martian surface habitat in mind.
Kacira describes the current MLGH prototype as “a robotic machine growing crops. It’s a collapsible and expandable system with rings, with low weight materials used in the making of the system. It’s like an NFT system, but modular and lightweight. The crop production unit is recycling the nutrients and water resources for plant production.”
He also explains to The Packer that the cylindrical shape of the current prototype would both make the system more practical to fit into a rocket for transport to the moon.
“We also considered hub-and-spoke type of habitat designs where cylindrical shape would be more desirable for habitat expansion purposes.”
The system has been designed through experiments run at the Amundsen-Scott South Pole Station and aims to provide both food and oxygen but also remove carbon dioxide from a lunar or Martian habitat installation.
Kacira says they have worked with lettuce varieties, kale, spinach, bok choy, chard, strawberries and sweetpotatoes. He adds they, and NASA, focus on dwarf varieties to optimize space, reduce resource demand and ease harvesting.
Space agriculture above, CEA below
Kacira spoke at length about how the needs and considerations of space agriculture look an awful lot like terrestrial controlled environment agriculture. That shouldn’t be a surprise, however, because many tools and systems used in CEA down here were innovated for space agriculture first.
“If you look at some of the sensors used, climate control systems, LED lighting, other technologies — they had been initiated for space research, and we are translating that to earth-based controlled environment agriculture systems,” he says. On the example of LED lighting, he points out that there was a 10-to-15-year lag between its development for space purposes and its availability to other industries.
One area where Kacira is hopeful is that space agriculture can benefit from innovations happening in earth-side CEA.
“When you consider controlled environment agriculture systems on earth, a majority of the varieties we are using are suited for field agriculture,” he notes. “But we are now seeing new varieties that are bred for the controlled environment agriculture setting, so I would love to see that innovation and improvements in terms of plant genetics as well, because we can only do so much with the physics of the system.”
Traits that would be especially important for space agriculture would be resource efficiency, maintaining yield and quality while under low-light settings and resiliency, he says.
But it is not only in the tangible innovations that space agriculture and terrestrial CEA are intertwined. Kacira notes that the education, skill sets and interests needed in CEA — “understanding plant needs, environmental demands, technologies out there to grow crops, understanding space challenges, plant physiology, systems thinking, data and automation integration” — are needed in space agriculture as well.
“Considering the education and training needed, especially with our young generation, we need a variety of skill sets, and controlled environment agriculture is one of them,” he says.
