Emmanuel Mendoza, Junior Aerospace Engineer, is Growing Pea Plants from Simulated Martian Soil and Fertilizer from Black Soldier Fly Flass (aka poop) to Help Astronauts Grow Food and Manage Waste on Mars
By New York Times, Sarah Scoles
At first it was just one flower, but Emmanuel Mendoza, an undergraduate student at Texas A&M University, had worked hard to help it bloom. When this five-petaled thing burst forth from his English pea plant collection in late October, and then more flowers and even pea pods followed, he could also see, a little better, the future it might foretell on another world millions of miles from Earth.
These weren’t just any pea plants. Some were grown in soil meant to mimic Mars’s inhospitable regolith, the mixture of grainy, eroded rocks and minerals that covers the planet’s surface. To that simulated regolith, Mr. Mendoza had added fertilizer called frass — the waste left after black soldier fly larvae are finished eating and digesting. Essentially, bug manure.
The goal for Mr. Mendoza and his collaborators was to investigate whether frass and the bugs that created it might someday help astronauts grow food and manage waste on Mars. Black soldier fly larvae could consume astronauts’ organic waste and process it into frass, which could be used as fertilizer to coax plants out of alien soil. Humans could eat the plants, and even food made from the larvae, producing more waste for the cycle to continue.
While that might not ultimately be the way astronauts grow food on Mars, they will have to grow food. “We can’t take everything with us,” said Lisa Carnell, director for NASA’s Biological and Physical Sciences Division.
But gardening doesn’t just require a plot of land, a bit of water, a beam of sunlight. It also requires very animate ingredients: the insects, like black soldier flies, and microorganisms that keep these ecological systems in working order. A trip to Mars for a long-term stay, then, won’t just involve humans. It will also involve creeping, crawling carry-ons most people don’t think about when they envision brave explorers stepping foot on new worlds.
Space travelers haven’t yet gone very far for very long.
“Currently, when you’re going into space, it’s more like going on a prolonged camping trip,” said Scott Parazynski, a former NASA astronaut who spent nearly two months in space. Astronauts bring freeze-dried food (and flavor enhancers like hot sauce). If they’re on the International Space Station, they might get to look at, but rarely consume, fresh greens from an experimental lettuce plot.
“It’s a far cry from the kitchen downstairs and the spice rack,” Dr. Parazynski said.
To stay for an extended time on the surface of Mars, though, astronauts won’t be able to rely on their space pantries. They’ll need Martian gardens. And Martian gardens will need a little help — maybe from black soldier fly larvae and their excretions.
“They’re very voracious eaters,” said Hellen Elissen, a researcher at Wageningen University and Research in the Netherlands. “They eat almost anything.” And if you feed them well, they’ll make a lot of frass.
In the past five or 10 years scientists have started to use that frass — rich in nitrogen, potassium, phosphorous and also bacteria — as fertilizer. The material also contains chitin, from the insects’ bodies, and leftover organic matter. Dr. Elissen recently published a review article about how frass affects plants and soil, and one of her main takeaways was that the value of the insects’ waste coincides with the value of their food. Grass? Frass suffers. Give the larvae higher-energy food scraps? Jackpot.
“You know what they say about you are what you eat?” she said. “The same goes for larvae.”
Jeffery Tomberlin, an entomology professor at Texas A&M University, knows this well after 25 years of studying black soldier flies. And he’s recruited others to his cause. A graduate student, Noah Lemke, for instance, arrived at Texas A&M to research black soldier flies’ reproductive behavior. Through the university’s Aggie Research Program, which lets graduate students recruit undergraduates for specific projects, he met Mr. Mendoza, an aerospace engineering major who had tried to grow radishes in simulated Martian soil in high school.
“His project header was ‘Black soldier flies can feed the world, but we need more of them,’” Mr. Mendoza said. Mr. Mendoza thought maybe the flies could, instead, help feed another world.
“I thought, ‘Well, what’s to stop me from using this as a catalyst to develop my interest in space agriculture?’” he said.
Soon the idea for a whole system came together. The larvae could eat astronauts’ food waste and produce frass to fertilize bad alien soil, which could then produce food plants. Then the larvae themselves could be ground into a protein source, which astronauts — or animals they might bring along — could consume. “You have this system where humans are feeding the flies, the flies are feeding the plants and animals, the plants and animals are feeding the humans,” Mr. Mendoza said.