Is Sustainable Extraterrestrial Farming on Mars Possible?

The movies make it look easy, but to grow food on Mars we'll have to create the soil from scratch and build our own mini-biosphere.

Landing humans on Mars would be a momentous event in human history. To live beyond Earth's biosphere is a dream to many, but establishing a sustainable presence on the Red Planet will require mastering its environment. We would need to devise ways of producing food where none exists, because depending on supplies from Earth would neither be sustainable or practical.

NASA plans to send astronauts to Mars by the 2030s, and Elon Musk's SpaceX has proposed an aggressive Mars colonization effort based on the Interplanetary Transport System (ITS). But while SpaceX may have the expertise to transport people to Mars, there is no consideration as to how they might stay there and "live off the land" to produce food.

Considering that it would cost an estimated $1 billion per person per year just to send food from Earth to Mars, it quickly becomes clear that we need another plan for feeding future Mars explorers.

Fritsche and his NASA colleague Trent Smith have teamed up with scientists at the Buzz Aldrin Space Institute to investigate how we might really grow food on Mars. Though using astronauts' physical waste for fertilizer might play a role, everything from toxin removal to "designer bacteria" will be needed to create a Martian version of the soil that we take for granted here on Earth.

The lettuce that was only grown in Mars only simulant (without added nutrients) produced only small leaves in the lab (FIT/Buzz Aldrin Space Institute)

There shouldn't be any organic matter in Mars regolith" — powdered rock on the planet's surface from eons of meteorite impacts — "and, in order to recycle the nutrients, you need to have decomposers to break down what's there to make it available, in the right form, for plants to use," said assistant professor Brooke Wheeler, of Florida Tech's College of Aeronautics.

"That would be one potential strategy of making a colony more sustainable to recycle waste, whether that's human waste or leftover food for composting, or any other [organic] waste products to help build that into the design of the habitat."

Wheeler and her colleague Drew Palmer, an assistant professor of biological sciences at Florida Tech, are using a Mars regolith simulant in hopes of investigating how we might use native resources when we eventually land a human mission on Mars.

The simulant, which is essentially powdered volcanic rock from Hawaii, contains none of the nutrients necessary for plants to grow, but it's the closest thing we have to approximating Martian regolith.

But it doesn't stop there. As Mars doesn't have the soil microbes that form the backbone of the vital cycles that drive Earth's biosphere, we will need to introduce the bacteria and strategic plant life to the Martian regolith to ensure the plants receive the necessary nutrients.

Lettuce grown in Mars simulant with added nutrients produced healthy leaves (FIT/Buzz Aldrin Space Institute)

The raw material behind these cycles is fertilizer, so when planning Mars agriculture, we need to consider how that will be sourced. Will it be shipped from Earth? Or will it be produced on site to reduce cost and the dependence on Earth?

The challenges of producing food on Mars are rich and varied, but one of the biggest benefits of physically growing plants on Mars would be a psychological one. As the project lead for the International Space Station's "Veggie" experiment — which uses hydroponics to supply plants with the necessary water and nutrients in a microgravity environment Trent Smith realized that the astronauts on the orbiting outpost took great joy in growing plants on an otherwise sterile environment away from home.

"Because they're on the space station, in a really hostile environment, with all these wires and cables and metal and plastic... when they have these little growing plants that they care for, it's their little piece of home, their little piece of nature," Smith remarked. "When we go to Mars, this is going to become really important."

"Initially, as we go for months at a time, we might just do hydroponic farming… hydroponics are incredibly efficient," Smith noted. "But if you're going for an extended amount of time, then it makes sense to switch over to a regolith-farming system. You'll have these two different ways to grow plants for food."

Whichever way you look at it, we will need to use our technological prowess to re-learn how to farm in an inhospitable environment.

"It will basically be like going back to an early agrarian society, when we were learning how to farm the earth," said Batcheldor. "But instead of using fertile soil, we've basically got to make the soil on Mars."

"Establishing a permanent colony on Mars is going to be the ultimate act of sustainability for humanity," he added.

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