[LUM#18] From the Sea to the Moon
Enjoying cod aioli with a view of Lake Félicité… A scene straight out of a science fiction novel that could one day become a reality thanks to the work of Cyrille Przybyla. His mission: to develop a self-sustaining closed-loop aquaculture system to increase food security on Earth—even if it means reaching for the moon.
In 2015, astronauts on the International Space Station tasted the first lettuce grown in space (Sciences et avenir, March 6, 2020). Since then, radishes, wheat, and even chili peppers have taken root at an altitude of over 400 kilometers. A luxury when most of the food available on board is irradiated, freeze-dried, or canned, but not enough to satisfy hunger either, especially with future missions to the Moon on the horizon.
So how can we ensure these astronauts get their share of protein—especially animal protein—vitamins, and omega-3s? Thanks to fish! Except that, barring a miraculous catch, there’s little chance of spotting a fish in the Sea of Serenity. It is to address this lunar challenge that Cyrille Przybyla, a marine biologist at the Ifremer L-3AS laboratory, a member of the Marbec* laboratory, and a specialist in integrated multi-trophic aquaculture (IMTA), has taken his hands out of the water and reached toward the sky. “I work on Earth. My goal is to successfully raise fish in a closed-loop system by integrating multiple organisms—hence the term ‘multi-trophic.’ It’s somewhat similar to the principle of a permaculture garden.”
Everything changes
In this closed, controlled system, “nothing is lost, nothing is created, everything is transformed” — as Lavoisier might have said once again. “The key word here is circularity,” explains the biologist. “Everything the fish excrete in solid and liquid form must be recoverable and usable by having it converted by other organisms. " Thus, sea worms or sea cucumbers will be used to break down the fish feces while also serving as a potential food source for the fish. "
The CO₂ released by the fish, like the ammonia produced by their digestive system, can serve as a basis for microalgae cultivation. “These microalgae, in addition to purifying the water in the tanks, can be incorporated into feed, thereby avoiding the need to catch wild fish to feed farmed fish. And we’re the first to do this,” continues Cyrille Przybyla. In short, it’s a win-win system on every front: water savings, reuse of biologically valuable compounds, preservation of biodiversity, and, finally, increased global food security.
Land-based food
“The FAO (Food and Agriculture Organization) is very interested in this biologically self-sustaining system, which could therefore serve as an excellent source of nutrition in geographically isolated areas or in poor and extreme environments. ” And what could be more extreme than the Moon? Vibrations, hypergravity, microgravity, radiation… It’s a whole range of tests that the researcher—who also holds a university diploma in celestial mechanics and is a graduate of the International Space University—had to set up to test, as part of the Lunar Hatch project, the resilience of fish in space. Or rather, fish eggs, “because what’s expensive in space is weight, and you can fit 200 eggs into a small 10x10 cm cube, whereas it would take over 1 m³ to send 200 adult fish.”
This small cube in question is a CubeSat developed in collaboration with the Montpellier University Space Center (CSUM), with whom the biologist is working to conduct these launch simulation tests. “We exposed sea bass eggs to the same vibrations as those experienced by Soyuz for ten minutes, then brought them back to Palavas to study the rest of the embryogenesis. A total of 162 eggs hatched, which is the same result as in our test group, so this first step has been validated,” explains Cyrille Przybyla.
Aim for the Moon
To test resistance to hypergravity—that is, acceleration ranging from 1G to 5G— the European Space Agency funded the rental of a centrifuge and a microgravity simulator. “We based our tests on the acceleration curve of a Soyuz launch and found no impact on the hatching rate of the eggs. ” While radiation tests conducted in collaboration with the Institute for Radiation Protection and Nuclear Safety (IRSN) are still underway at the Cadarache Atomic Energy Commission, the initial results are encouraging there as well, but new questions arise at every stage. “We’re able to hatch these eggs, but are our fish born stressed? Does radiation cause DNA damage? In short, are the tiny larvae we’re bringing into the world viable in a lunar environment?” wonders the biologist.
These are all questions he will need to answer before 2032, the scheduled date of the European Space Agency’s next biomission, which will carry nearly 2 tons of biological experiments to the Moon—among them, perhaps, our 200 little “fishonauts.” In the meantime, Cyrille Przybyla has flown to Florida for two months at NASA’s invitation. A crowning achievement for someone who admits to having “always had this idea in mind. I’ve combined my passion for space exploration with a conviction and expertise drawn from 20 years of research on fish production systems in controlled environments. It is by confronting the extreme constraints of space that we will overcome challenges on Earth.”
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