[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 reality thanks to the work of Cyrille Przybyla. His mission: to develop a self-sufficient 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. This is a luxury when most of the food available on board is irradiated, freeze-dried, or canned, but it is not enough to satisfy hunger, especially in view of future missions to the Moon.
So how can these astronauts be provided with their required intake of protein, particularly animal protein, vitamins, and omega-3 fatty acids? Through fish! However, unless there is a miraculous catch, there is little chance of seeing any fish in the Sea of Serenity. It was to address this lunar problem that Cyrille Przybyla, a marine biologist at the Ifremer L-3AS laboratory, member of the Marbec* laboratory and specialist in integrated multi-trophic aquaculture (IMTA), took his hands out of the water and raised them to the sky. "I work on land. My goal is to successfully raise fish in a closed circuit by integrating several organisms, hence the term multi-trophic. It's a bit like the principle of a permaculture vegetable garden."
Everything changes
In this closed and controlled circuit, "nothing is lost, nothing is created, everything is transformed, " Lavoisier could have declared a second time. "The key word here is circularity," explains the biologist. " Everything that is emitted by fish in solid and liquid form must be recovered and valorized by converting it through other organisms. " Thus, worms or sea cucumbers will be used to break down fish feces while providing a potential source of food for the fish.
The CO₂ released by the fish, like the ammonia released by their digestive system, can be used as a basis for growing microalgae. "These microalgae, in addition to purifying the water in the ponds, can be used in feed, thereby avoiding the need to catch wild fish to feed farmed fish. And we are the first to do this," continues Cyrille Przybyla. In short, it's a win-win system on all fronts: water savings, reuse of molecules with high biological value, preservation of biodiversity, and finally, increased global food security.
Terrestrial food
"The FAO (Food and Agriculture Organization) is very interested in this biologically autonomous system, which could be 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... The researcher, who also holds a university diploma in celestial mechanics and is a graduate of the International Space University, had to set up a whole range of tests to assess the resistance of fish in space as part of the Lunar Hatch project. Or rather fish eggs, "because what is expensive in space is weight, and you can put 200 eggs in a small 10/10 cm cube, whereas it would take more than 1 m3 to send 200 adult fish."
This small cube is a CubeSat developed in collaboration with the Montpellier University Space Center (CSUM), with whom the biologist is working to carry out these takeoff simulation tests. "We exposed sea bass eggs to the same vibration as 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 our test group, so this first stage has been validated," says Cyrille Przybyla.
Aim for the Moon
To test resistance to hypergravity, in other words acceleration from 1G to 5G, the European Space Agency financed the rental of a centrifuge and a microgravity simulator. "We based our tests on the Soyuz takeoff acceleration curve and found no impact on egg hatching rates. " While radiation tests conducted in collaboration with the Institute for Radiation Protection and Nuclear Safety (IRSN) are still ongoing at the Cadarache Atomic Energy Commission, the initial results are also encouraging, but new questions arise at each new stage. "We are able to hatch these eggs, but are our fish born stressed? Does radiation cause DNA damage? In short, are the tiny larvae we bring into the world viable in a lunar environment?" wonders the biologist.
These are all questions that will need to be answered 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, including, perhaps, our 200 little "fishonauts." In the meantime, Cyrille Przybyla has flown to Florida for two months at the invitation of NASA. This is a crowning achievement for someone who admits to having "always had this idea in mind. I have combined my passion for space exploration with the conviction and expertise gained from 20 years of research into fish production systems in controlled environments. It is by confronting the extreme constraints of space that we will meet the challenges on Earth."
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