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.
In the 2015 blockbuster movie "The Martian," Mark Watney (Matt Damon) is famously depicted planting potatoes in a makeshift greenhouse after getting stranded on Mars during an epic storm that forced the rest of his crew to abandon their mission. Using vacuum-packed potatoes from the mission's base, Watney planted them using the planet's "soil," produced water from chemical reactions and fertilized his burgeoning potato crop with the crew's freeze-dried poop.
It seems like a pretty straightforward method of cultivating plants on Mars - but deceptively so.
"It's nowhere near that easy," Ralph Fritsche, senior project manager for food production at NASA's Kennedy Space Center, told Seeker.
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.
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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.
"Elon Musk has presented the world with a challenge," said Daniel Batcheldor, professor of physics and space sciences at the Florida Institute of Technology and project lead for the Buzz Aldrin Space Institute. "Right now, we know that we cannot deliver the mass needed to the surface of Mars purely from stuff sent from Earth. We have to create a sustainable colony on Mars that is not dependent on resupplies from Earth."
Whether we're thinking about setting up our first Mars colony or supporting a small team of NASA astronauts, researchers are currently developing novel strategies for growing plants beyond Earth.
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.
"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."
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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.