Adaptation Rules Mars needs insects if human plan to colonise it
The goal for 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.
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, 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 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.
