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Food in Space!

Q&A with Mike Dixon

Text by Everett DeJong

What would it take to grow food on a space station, the surface of the moon, or even Mars? What are the technological and biological challenges to providing future generations of off-world explorers with a reliable source of nutrition? Will there be extra-terrestrial landscape architects? Maybe that’s getting ahead of ourselves, but it’s not outside the realm of possibility. In some part, thanks to the work of Professor Mike Dixon, Director of the University of Guelph’s Controlled Environment Systems Research Facility. Ground’s Everett DeJong sat down to ask him about that work.

Lettuce growing under red LEDs. IMAGE/ Michael Stasiak

Everett DeJong: I understand from what you’re doing that you are attempting to grow food in outer space. Do I have that right?

Mike Dixon: Well, we’re aiming for that. If you think about it, food determines how far from the Earth we can go and how long we can stay. It’s the fundamental top-of-the-heap in life support requirements for human space exploration, and plants for food are a logical option because they give us oxygen, clean up the water, scrub our CO2, and we can eat them.

Rendering of explorers on a Mars landscape. IMAGE/ Michael Stasiak

EDJ: So what are you doing at the University of Guelph?

MD: The program started in 1994/1995, when we got the first grant funding for projects that had space in the subtitle. We were looking at how to develop environment control requirements for harsh environments like space. The vacuum pressure and gravity are issues we can’t investigate easily on Earth. The radiation challenge is another one that needs the real thing—beyond our atmosphere—to truly investigate the reaction of plant genetics, human genetics, and even the radiation challenges. We couldn’t do some of those, but the pressure piqued our interest way back, and we got major funding from the federal and provincial governments to answer a pretty simple question: how low can you take the pressure and still have plants providing all the functions of human life support—food, oxygen, water, CO2 scrubbing, et cetera? If the answer was you need full atmosphere (21 kilopascals of oxygen, 78 of nitrogen, and a whole bunch of other things), when you go to the vacuum of the moon or the almost vacuum of Mars, it wouldn’t work. Human space exploration, as we can currently conceive of, would have been impossible. The mass and energy cost of going into space with a structure that will contain full Earth atmosphere in a vacuum outside is just prohibitive. So, we built hypobaric chambers that allowed us to drop the pressure incrementally, change the atmosphere composition, and answer that question. Happily for us, and for human space exploration, plants can handle down to a 10th of Earth’s atmospheric pressure and a third of the oxygen. Oxygen is the main limiting variable pressure. Plants are relatively impervious to dramatic changes in atmospheric pressure, and they deal with hydrostatic pressures internally.

Neutron Star Interior Composition Explorer on the outside of the International Space Station. IMAGE/ NASA

EDJ: We can grow plants in space.

MD: If you have the right controlled environment. And that’s what our program is all about. What is the recipe for light quality and quantity, CO2, temperature, humidity, nutrients, water, and pressure. 

Lettuce seedling growing in Grodan rockwool. IMAGE/ Michael Stasiak

EDJ: And you’re replicating that in a lab?

MD: Yeah. We have some pretty unique controlled environment facilities here with sealed chambers where we can monitor how plants respond physiologically.

EDJ: What is the number one thing you have learned over those 20 years?

MD: We never expected plants would be as tough as they are under the hypobaric conditions we were imposing on them. It’s a great relief and a bit of a surprise that plants can handle down to as low as one tenth of Earth’s atmosphere. Humans and insects (which we need for pollination) can’t, and we’ve done some work on that. They’re going to be far more limiting on the environment control recipe than plants. Plants will acclimatize to almost anything within almost an order of magnitude range of variability of most of those environment variables, except temperature.

Growing media testing with red leaf lettuce. IMAGE/ Michael Stasiak

Turfgrass in a PS1000 precision growth chamber. IMAGE/ Michael Stasiak

EDJ: When you say plants, are you talking strictly vegetables?

MD: Edibles, food plants. I attempted many years ago to have roses selected as a candidate crop plant and it was rejected because the mass and energy cost of growing a plant you can’t eat is not worth it. We can’t afford that. So roses are out for now.

Interior of a container farm. IMAGE/ Michael Stasiak

Hybrid corn ready for harvest and analysis. IMAGE/ Michael Stasiak

EDJ: This research is not just happening at the University of Guelph, you collaborate with several international organizations or countries.

MD: We have long-term collaborations with NASA, the European Space Agency, the Canadian Space Agency, and the German Space Agency. I have a student there now on an internship, and we’ve had personnel exchanges with NASA. I spent a sabbatical year there. My colleague Tom Graham spent three years there on a fellowship. So, we have a lot of collaborations and interchange. But the program in Guelph, by virtue of the unique infrastructure of the chamber technology we developed here, has risen to the top. And we are among the world’s leading research venues now in developing technologies and doing research to grow plants in harsh environments.

Pepper plant growing under blue LEDs. IMAGE/ Michael Stasiak

EDJ: Typically, when we think of vegetables or plants, there’s soil, sunlight, and many natural occurrences taking place. I’m assuming there is no soil in the lab, so maybe describe what’s happening in the lab. What’s physically happening in there?

MD: In our program, we generally use a hydroponic nutrient film technique with very small amounts of rooting medium. We sometimes have a little plug of rock wool or something. But the plants are generally in a nutrient film technique (NFT), an approach where you wash water over the roots on a continuous, recirculating basis. Developing the sensors and the technology to do this reliably is one of our big challenges. We have used various substrates such as glass beads, rock wool, and even peat and conventional growing media, but they tend to mess things up because they fall apart and get stuck in the pumps—they’re not the most successful in a recirculating system. Remember, when you go into space, you have to understand you can’t throw anything away. There’s no such thing as “garbage” anymore. You must make a valiant effort at recycling everything. We can’t do that very well here on Earth yet. And one of the big challenges is recycling the nutrient solution. You can’t throw water away. It’s a valuable resource in space. So, just developing the technologies to recycle everything, the sensors that reliably help you recycle all of the carbon, oxygen, and water, is an enormous technical challenge. But the benefits that creates for us in what we’ll call terrestrial agrifood are equally as enormous.

CESRF small hypobaric chambers IMAGE/ Per Aage Lysaa

A gold leaf designed to evaluate heat transfer under microgravity. IMAGE/ Jamie Lawson

EDJ: When we say “space,” I’m assuming space stations?

MD: Well, microgravity is a technical challenge we’re actually ignoring. We’ve done some work with NASA: we collaborated and sent seeds to the space station in our Tomatosphere project and distributed them to primary and secondary schools across Canada for the last 22 years. But the microgravity technical challenge is one I don’t really care about much because, when you think about it, and looking at the prospect of human space exploration, we have low-Earth orbit where the station is, we have the moon, and Mars. But at least there’s an up and down when you’re on a terrestrial, lunar, or Martian surface. The applications of microgravity requirements is just low-Earth orbit, a few hundred kilometres away, or possibly a transit mission—six or seven months on the way to Mars. That’s with current propulsion technology. We’ll get better. We’ll get faster. So those are the only applications where food production might be considered. And you don’t need to do it in low-Earth orbit because you can resupply it from Florida at infinitum. For a six or seven-month trip to Mars, I can carry enough bacon and Kraft Dinner to handle that, so that’s not a big challenge either. It’s when you get on the surface of especially Mars and propose long-term exploration agendas where you’re searching for life.

And, by the way, we’re going to find life, or at least the fossils of some microbial life on Mars. You heard it here first. We will absolutely find some vestiges of a life form on that planet, because it was very much like Earth in its early stages. It cooled off, lost its molten core, lost its atmosphere, and got kind of chilly but, for a time there, there was liquid water on the surface. All the conditions, all the chemistry, were exactly the same as it was on Earth when life evolved here. So I’m pretty confident we’ll find, in the rock bottom of a frozen Martian lake, some form of life.

Hoop houses in the Kuwait desert. IMAGE/ Michael Stasiak

EDJ: I understand some researchers have taken some... I’m not sure if you use the term “soil” on the moon?

It’s called lunar regolith, because it’s not earth. Those are close colleagues of ours at the University of Florida, and they’re seasoned veterans in space exploration, plant science. They’ve done a lot of experiments on the space station. We’re currently collaborating with them in a very huge proposal to NASA for a lander experiment on the moon that will include a system we designed here in Canada in collaboration with the Canadensys Aerospace. We’ve designed a miniature lunar greenhouse, a controlled environment that will grow barley. And you, you of all people, know why.

Red leaf lettuce grown under white, red, and blue LEDs. IMAGE/ Michael Stasiak

EDJ: Single malts are appreciated. 

MD: We’ll learn about the fate of that multimillion-dollar proposal to put a lander on the surface of the moon and then investigate the challenge of growing food under those conditions which are really cold or really hot, depending on if you’re in the sun or not. And the radiation challenge is one of the first questions we’ll ask of the plant, and the plant genetics. What do we have to do, if anything, to mitigate that as we go forward

Rendering of a greenhouse on the moon. IMAGES/ Michael Stasiak

EDJ: “How extreme and to what extent can we grow food?” Is that the lesson learned to be brought back to Earth?

MD: Well, I’ve been talking like everything is going into space. We don’t very often get a mission to go to space. Canada doesn’t have a launch facility. That being the case, even though a lot of the research is directly or indirectly related to solving a problem dealing with the challenge of growing plants in the harsh environment of outer space, or lunar or Martian surface, when you apply this to Earth, we find some very significant harsh environments here on Earth. And this is Canada. If you’re going to grow a plant in Canada for six or seven months of the year, you’d have to use a very sophisticated, controlled environment. I submit that the challenge of a snowbank in Yellowknife in February is not much worse or better than the surface of the moon or Mars. And the technical solution is almost identical. So, all the technical solutions to growing plants under strange conditions for lunar and Martian applications have equal application here on Earth, in harsh environments like Canada’s North, where we have a food security issue, or the deserts of the Middle East. We’ve collaborated with Middle Eastern countries, Kuwait in particular, on developing adaptations of these technologies for the desert climate where they have a food security issues, too.

Mohammed Albaho from the Kuwait Institute for Scientific Research inspecting lettuce growing in a modular plant production system. IMAGE/ Michael Stasiak

EDJ: Have you done any studies in Canada’s far North?

MD: We’ve collaborated with the government of the Northwest Territories, FedNor, ComDev (Canadian aerospace company), and the Aurora Research Institute. We published a feasibility study a number of years ago, it’s on the Aurora Research Institute website, called “AgNorth.” In that study, we assessed the technical and economic feasibility of growing a select handful of high-end crops like strawberries, cherry tomatoes, and other perishables that are routinely shipped from Mexico, offsetting the import requirement. We learned with the five or six different high-end commodities we chose to evaluate that you can actually do it and make a buck in the harsh Canadian north. Now, you can’t do that with things like potatoes and staple crops, as the mass-energy cost would be excessive. But we could certainly make an effort to offset the nutritional food requirements for our cousins in the North and offset their requirements for subsidy. 

A prototype high-powered and water-cooled LED array developed by Intravision Canada. IMAGE/ Michael Stasiak

EDJ: Knowing the food security issues we have, and climate change, it sounds like, based on your research, there is some hope in this.

MD: Absolutely. And the advent of the more recent upbeat in vertical farming technology, really high density controlled environment food production technologies in all the research projects we’ve attempted and proposed over the 30 years. The rationale for deploying these solutions in harsh environments in our North has always been at the back of our minds, and is now more front-of-mind because of federal and provincial programs requiring specifically those kinds of solutions. The whole vertical farming industry now has created a technological boom in LED lighting and environmental control technology that is adaptable to small, tight, highly controlled spaces. We’ve got to get away from growing lettuce, though. Lettuce isn’t going to save anybody, and it’s not even food until you add the ranch dressing. So we’re working on more protein-based crops.

Large scale plant production system concept. IMAGE/ Intravision Canada

EDJ: How healthy will humans be eating vegetables in a controlled environment such as the ones you’re describing? Have you done tests on humans eating food grown in those environments?

MD: I’m not allowed to test humans without special permission. But we evaluate the effect of our environment control recipes. We test the results on plant physiology, and their nutritional composition. So our objective has been to produce a predictable and systematic profile of nutritional compounds in all of the 30 or 40 different crops that have currently been selected for human space exploration. We don’t work on all of them, but we take a cross-section of a few of them, and the objective is to generate a standardized profile of nutritional compounds. We’re taking exactly the same lessons learned in trying to achieve that in food crops for the last 30 years in Guelph and exploiting the same technology in the phytopharmaceutical industry sector. With recent changes to legislation in Canada related to cannabis, that’s an obvious candidate for standardizing the profile of medicinal compounds and possibly propel it to be accepted as a relatively conventional pharmaceutical commodity. It can’t be now, because it’s so variable. We’re just scratching the surface of the requirements needed to produce a standardized medicine from that plant.

Cannabis plant IMAGE/ Vivo Cannabis Inc.

Soybeans growing in a hypobaric chamber. IMAGE/ Michael Stasiak

EDJ: Are there any benefits or liabilities to controlled environments when it comes to climate change?

MD: You eliminate climate as an obstacle if you go into a fully controlled environment. The challenge there, of course, is economic. And there’s a lot of energy going into food production-controlled environments. So recycling is at the fundamental core of all of the research activity. You just can’t throw anything away. You can’t say that enough to our students.

Astronaut David Saint-Jacques holding tomato seeds for the Tomatosphere™ school outreach program. IMAGE/ NASA

Astronaut Chris Hadfield with a batch of tomato seeds destined for the Tomatosphere™ school outreach program. IMAGE/ NASA

EDJ: How do we take your research and apply it to the landscape architecture profession?

MD: Landscape architecture is encroaching on interior spaces more and more. You can’t go to a shopping mall without seeing some deployment of plant systems that require horticultural maintenance. The province of landscape architects and horticultural managers. Many years ago, among the first projects in our program was the biological filter of a vertical wall. You suck all the air through the wall, dissolve the volatile organic compounds that we associate with poor quality indoor air, and present them to the microbes in the root zone in order to convert to CO2 and water in a conventional way. This isn’t exactly revolutionary science, since it’s how the planet works. The biofilter consumes the volatiles we associate with polluted air, indoor spaces, sick building syndrome, etc. And that project evolved and became commercialized locally at Nedlaw Living Walls. So I still collaborate with the proponents of, shall we say, interior landscape architecture.

Dr. Cara Wehkamp preparing tomato plants for hypobaric plant research. IMAGE/ CESRF

EDJ: How did you get into this? 

MD: I got lucky and established a network of collaborators, friends, and drinking partners over the years. That pulls and pushes you with bright ideas. And I work with a very talented team. We’re internationally renowned for our expertise in high fidelity controlled environment and are deferred to by space agencies.

I was always interested in automating data acquisition because I’m basically lazy. The technical side, the computer automation and increasing the fidelity and robustness of sensor technology for measuring plant environment-interaction became my focus. That attracted the attention of the space agency when it was formed here in Canada. And it grew from there.

I’m a Trekkie, like most of us of my age, and the interest in space is an undeniable hook. I talked to a group of ten-year-olds in an auditorium in Alberta and I said the Canadian horticultural mission specialist on the first trip to Mars is in grade three today. You could hear a pin drop. It is a shameless recruiting approach. And that’s our Tomatosphere™ outreach project, where we send these seeds into space, bring them back, and ship them out to students. I think we’ve gone past 4 million student engagements in that project now since the year 2000, when Canadian astronaut Marc Garneau took our first bag of seeds up to space. I keep in fairly close contact with Tomatosphere co-founder and retired Canadian astronaut Dr. Bob Thirsk. And I’ve continued to work with Chris Hadfield on a number of other things: innovations and initiatives he’s engaged with still to do with going to the moon and growing food for humans.

Prototype LED system for small plant testing. IMAGE/ Michael Stasiak

BIO/ Everett DeJong is an Entrepreneur, Master of Landscape Architecture student at the University of Guelph, and Ground editorial board member. He’s fascinated by growth.