It can take seven months – or more – to get to Mars. NASA can send supplies to the International Space Station if need be, but the same isn’t true of the distant planet. Instead, astronauts spending any time on Mars will have to rely on what’s known as in-situ resource utilization (ISRU) – using what’s around to replace objects brought from Earth. That includes food, which will eventually have to be grown there, to support any long-term residents. Instead of hauling bags of fertilizer in the spacecraft, researchers are trying to figure out how to make do with what’s on the ground, that is, Martian soil.
Thanks to NASA’s rovers and landers, scientists know about the pH and mineral makeup of the planet’s soil, which is known as regolith. Mars gets its red color from the oxidation of its rocks, regolith, and dust. Below the dust is the crust, which contains iron, magnesium, calcium, potassium, and more elements, according to NASA. But their presence isn’t enough to ensure plants can thrive there. The nutrients may not exist in a usable, or bioavailable, form. The levels of some may be toxic.
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Some studies have shown it’s theoretically possible to grow plants in replicated Martian soil, but there aren’t big enough samples of actual Martian regolith to be certain. Since there’s no way to do farming trials on Mars itself, scientists try to replicate conditions on Earth. Researchers at the Florida Institute of Technology recently tried to grow Arabidopsis thaliana, a weed, and Lactuca sativa, lettuce, in a trio of Martian Regolith Simulants. These simulants are mixtures of artificial and natural materials that mimic the basalt-like Martian surface. The scientists found that neither plant in the synthetic soil without the addition of supplemental nutrients.
“These findings underscore that ISRU food solutions are likely at a lower technological readiness level than previously thought,” the researchers wrote in the study, which will be published in Icarus. For example, it’s a mistake to assume the regolith is uniform over the entire planet. “Our strategy was, rather than saying this simulant grows plants so that means we can grow plants everywhere on Mars, we need to say that Mars is a diverse planet,” ocean engineering and marine sciences associate professor Andrew Palmer told Florida Tech News.
In another new study, also published in Icarus, researchers break down the preparation of five new types of Mars simulants. Laura Fackrell, a doctoral candidate at the University of Georgia in Athens, and her colleagues created the mixtures specifically formulated with characteristics of Martian regolith that might make it difficult to grow plants. TThe soil might have high salinity or a low level of organic matter. Such conditions might require future Mars residents to add other minerals and components to their gardens before planting. “Specific types of bacteria and fungi are known to be beneficial for plants and may be able to support them under stress conditions like we see on Mars,” Fackrell told TNW.
To test the mock Mars dirt, Fackrell tried growing several plants, including a moth bean. They hold up better with less water than other options she tried, “But they’re not necessarily super healthy,” Fackrell told Science News.
It will be years before humans reach Mars, but in the meantime, research into growing plants in difficult environments could translate to Earth, where temperatures are rising. Fackrell studied microbes that live in hot springs. “Anything we learn about farming on Mars could help with farming in challenging environments on Earth that help us build to a sustainable future,” she told Florida Tech News.