Beyond M&Ms, space espresso and astronaut ice cream, a lot of work remains when it comes to securing nutrition in space. Knowing how to cultivate, culture and cycle consumable nutrients will be necessary for humans to successfully settle deep space. And it might be helpful for feeding hungry mouths on our home planet, too.
As our planetary next-door neighbor, farming on Mars seems like a natural starting point to investigate. However, such lofty field goals are not without their obstacles. Many resource-finding challenges are in store for future Terran transplants, including locating water and nutrients, removing toxins and, perhaps most ironically, finding room to grow. On Earth and off it, one of the biggest obstacles to farming is space itself.
On Earth, the traditional method for tackling lack of space is to build terraced farms. More recently, Closed Environment Agriculture (CEA) has taken root. In 2018, Aerofarms in New Jersey claimed to grow 2 million pounds of greens annually without sun or soil in a vertically stacked system, as CNN reports. Water usage in that vertical farming project, housed in an old steel mill, was reportedly 95% less than conventional, ground-based Earth farming.
Vertical farming is a great example of technology transfer, from up to down in this case. NASA started growing plants in space without soil or water in 1997. Starting from either cuttings or seeds, plants engineered to grow rapidly are misted with liquid nutrients. Plants grown by aeroculture appear to take up more nutrients. Without gravity to hold them down, they also grow faster — in the case of tomato plants, more than twice as fast. Small, inflatable aeroponic food systems can grow more than 1,000 bunches of vegetables in less than a month, as NASA reports.
Farming microbes might also be a necessary way to bulk up the nutritional and caloric content of space diets for every life form on a Mars mission. People aren’t the only ones who munch on microbes for their health. Plants, do, too! Adding microbes is a critical step toward making Martian regolith — a term used to describe sterile material — into a plant-friendly growth medium, as Utah State University notes. But before we add nutrients to non-living Mars dust, turn it into soil and start farming on Mars, we’ll need to make sure we remove the poison.
The Poison and the (Microscopic) Cure
That poison comes in the form of chlorine atoms connected to four oxygen atoms, a.k.a. perchlorates. These compounds are produced by living organisms as well as inorganic processes. On Earth, they are found in many places, including the groundwater near NASA JPL. On Mars, the Curiosity Rover picked them up, literally, while looking for signs of organic life in the regolith, according to NASA.
With some tinkering, perchlorates can be turned into explosives, fertilizer or fireworks, according to the U.S. Food and Drug Administration. But on their own, perchlorates are highly toxic to people.
Perchlorates in the regolith are by no means an intractable farming problem — quite the opposite. In space, wasting is not an option. Perchlorates could be used to feed microbes or power rocket engines and mining equipment. Future Martian farmers don’t necessarily need to eliminate the perchlorates; they just need to collect and extract them. Plus, if perchlorates are fed to microbes, they’ll produce a super-helpful compound for humans living in space: oxygen.
To Farm or Terraform
None of these methods for farming on Mars rise to the level of “terraforming” Mars: making it similar to Earth. Transformation on that scale could only occur if the entire planet were shielded from the solar wind. Allowing Mars’ atmosphere to grow, the air pressure to rise and water to remain on the surface in liquid form would require a magnetic field on the scale of our own magnetosphere. According to Phys.org, NASA computer modeling indicates that, with a truly enormous shield in place — plus several hundred million years of waiting — the planet would warm, the polar caps would melt, and the atmosphere would grow enough for terraforming Mars to take place en masse.
Fortunately, our efforts at space agriculture and settlement need not wait that long. Farming in enclosed environments, on Earth and in space, has been happening successfully for decades. The options for us to begin the process in deep space include sending food-growing systems in advance of the mission and finding ways to use the resources available once we arrive. Given how many calories humans require, we probably need to use both strategies at once.
Today’s Martian regolith needs a little love to become soil, but as ScienceNews points out, with the help of multivitamins, minerals, microbes, perchlorates removal, air pressure and radiation shielding, that may not remain true for long. Human mastery of genetics is growing. It is increasingly possible for us to engineer life forms — such as those living on the outside of the International Space Station — that find the current surface of Mars appealing. Even without terraforming Mars, we might be able to raise plants that will, with the right encouragement, take root in the new earth.
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