Mars might need insects if humans get there – 12/03/2023 – Science

Initially it was just a flower, but Texas A&M University student Emmanuel Mendoza worked hard to help it bloom. When the five-petaled structure burst from his collection of English pea plants in late October, and then more flowers and even pea pods appeared, he too could see, a little better, what it all could mean for a future on another world far away from Earth.

Those weren’t just any plants. Some were grown in soil meant to mimic Mars’ inhospitable regolith, the mix of grainy rocks and eroded minerals that covers the planet’s surface. To this simulated regolith, Mendoza added a fertilizer called frass — the residue left after black soldier fly larvae finish eating and digesting. Essentially, insect dung.

Mendoza and his collaborators’ goal was to investigate whether frass and the insects that create it could one day help astronauts grow food and manage waste on Mars.

Black soldier fly larvae could consume astronauts’ organic waste and process it into frass, which in turn could serve as fertilizer to stimulate plant growth in alien soil. Humans could eat the plants and even food made from the larvae, producing more waste for the cycle to continue.

While this is possibly not the final way astronauts will grow food on Mars, they will have to grow food. “We can’t take everything with us,” said Lisa Carnell, director of NASA’s Biological and Physical Sciences Division.

Gardening, however, doesn’t just require a piece of land, a little water, a ray of sunshine. It requires very lively ingredients: insects, like black soldier flies, and the microorganisms that keep these ecological systems alive. operation.

A trip to Mars for a long-term stay, then, will not only involve humans. It will also involve baggage that most people don’t think about when they imagine brave explorers setting foot on new worlds.

Space travelers haven’t gone very far for very long.

“These days, when you go to space, it’s more like going on an extended camping trip,” said Scott Parazynski, a former NASA astronaut who spent nearly two months in space. Astronauts carry freeze-dried food (and flavor enhancers like hot sauce). If they are on the International Space Station (ISS), they may have the opportunity to look at, but rarely consume, fresh vegetables from an experimental garden.

“It’s very different from the kitchen downstairs and the spice rack,” Parazynski said.

To remain on the surface of Mars for a long time, however, astronauts will not be able to rely on their space pantries. They’ll have to turn to Martian gardens, which will need a little help — perhaps from black soldier fly larvae and their excretions.

“They are very voracious,” said Hellen Elissen, a researcher at Wageningen University and Research in the Netherlands. “They’ll eat almost anything.” And, if they are well fed, they will produce a lot of frass.

In the last 5 or 10 years, scientists have started using frass — rich in nitrogen, potassium, phosphorus and bacteria — as a fertilizer. The material still contains chitin, from insect bodies, and residual organic matter.

Elissen recently published a review article on how frass affects plants and soil, and one of her main conclusions was that the value of insect waste matches the value of their food. Gram? The frass suffers. Give the larvae more energetic food scraps? Bingo.

“You know what they say about you being what you eat?” she asked. “The same goes for larvae.”

Jeffery Tomberlin, professor of entomology at Texas A&M University, knows this all too well after 25 years of studying black soldier flies. And he recruited others to his cause.

Graduate student Noah Lemke, for example, arrived at Texas A&M to research the reproductive behavior of these flies. Through a university program that allows graduate students to recruit undergraduates for specific projects, he met Mendoza, an aerospace engineering student who had tried growing radishes in simulated Martian soil in high school.

“The title of his project was ‘Black soldier flies can feed the world, but we need more of them,'” recalls Mendoza, who imagined that perhaps they could help feed another world. “I thought, ‘Well, what’s to stop me from using this as a catalyst to develop my interest in space farming?'”

Soon the idea of ​​setting up a complete system came. The larvae could eat the astronauts’ food waste and produce frass to fertilize the bad alien soil, which could produce food plants. Then, the larvae themselves could be ground into a protein source, which the astronauts — or the animals they might carry — could consume.

“You have this system where humans feed the flies, which feed the plants and animals. And ultimately the plants and animals feed the humans,” Mendoza said.

They decided to test frass’s fertilizing capabilities on English peas, planted in simulated Martian soil.

Initially, Tomberlin was skeptical.

“When they came to me and said, ‘Hey, we want to get Martian soil,’ I thought, ‘Where do you get Martian soil?'” Tomberlin said. “They said, ‘Oh no, we have a supplier.’

It was Martian Garden, a company based in Texas.

With simulated regolith in hand, they mixed the frass with simulated Martian soil in different proportions to see how the peas reacted. In an initial experiment, these combinations ranged from zero frass and all regolith to all frass and no regolith, covering intermediate percentages.

They then compared the growth of these plants with that of vegetation surrounded by plant soil for consumption, also fertilized with various proportions of frass. After this test, the researchers narrowed the range, experimenting with phrase percentages from 0 to 50.

“Peas behave similarly in both Martian soil and potting mix,” Lemke said, at least if the conditions are right.

“Too much frass is detrimental to the health of the plant,” Lemke said. Plants receive many nutrients. Too little frass and they don’t get enough nitrogen, which is also not conducive to germination. The ideal amount was “about 10%, and that seems to work well,” Lemke said. The microbes that mix with the frass also seem to help, as does crushing the regolith — a pestle-like task — so that it can better absorb water.

Mendoza recently presented the results of the experiment at the Entomological Society of America conference. Now, he hopes to use his engineering background to begin work on a physical system that could actually be used in space exploration, keeping insects contained and productive away from their Earthly home.

The trio’s research builds on work that NASA and other groups have been doing for years, including studies on how the space environment affects insects, microbes and other living things. “Tardigrades, nematodes, fruit flies, yeast fungi,” Carnell said. “We look at everything.”

In the food field, researchers have done some combining of flora and fauna. Interstellar Lab in Florida is a finalist in NASA’s Deep Space Food Challenge, working on a self-sufficient plant and mushroom growing system that includes insects. In it, insects live separately from plants, but produce carbon dioxide for their consumption. “We’re looking at how to bring in the right microbes so we can create a much more robust soil mix,” Carnell said.

A recent study by scientists at China Agricultural University in the journal Communications Biology showed that three types of bacteria mixed together, released into simulated lunar soil, helped plants grow larger and greener by converting phosphorus trapped in the soil into the type that plants could consume.

But the presence of these microbes, Carnell continued, raises other questions, such as how these little companions might change in space or on the surface of another world, and also how they will affect astronauts’ microbiomes.

On Earth, homebound researchers have used simulated Martian soil, as Mendoza did, to learn about crop growth on an extraterrestrial world.

A new set of research recommendations for NASA’s Biological and Physical Sciences Division has made room for more projects like these over the next ten years.

Within these recommendations, the agency is considering a campaign called BLiSS: Bioregenerative Life Support Systems, with the goal of building and understanding “systems that would provide high-quality food, renew air and water, process waste, and enable the creation of sustainable space environments for long periods of time independent of Earth”.

The soldier fly system, says Carnell, fits this idea well. “It consumes waste, it can produce fertilizer, it’s bringing so many benefits,” she said. Not to mention that astronauts could eat insect larvae for a hearty dinner — or a post-microgravity protein shake.

Eating peas fertilized by fly larvae is one thing, but eating the insect babies themselves may be harder for astronauts to swallow. “As long as the nutrition is there, they’ll probably make it work somehow,” Parazynski said, “but I wouldn’t want to be the first to get that meal.”