It can take seven months – or more – to get to Mars. NASA can send supplies to the International Space Station if necessary, but the same cannot be said for the distant planet. Instead, astronauts spending any time on Mars will have to rely on what’s known as in situ resource use (ISRU) – using what’s around to replace objects brought in from the sea. Earth. This includes food, which will eventually need to be grown there, to support long-term residents. Instead of carrying bags of fertilizer on the spacecraft, the researchers are trying to figure out how to cope with what is on the ground, that is, Martian soil.
Thanks to NASA rovers and landers, scientists know the pH and mineral composition of the planet’s soil, known as regolith. Mars gets its red color from the oxidation of its rocks, regolith and dust. Underneath the dust is the crust, which contains iron, magnesium, calcium, potassium and other elements, according to NASA. But their presence is not enough to guarantee that the plants thrive there. Nutrients may not exist in a usable or bioavailable form. The levels of some can be toxic.
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Some studies have shown that it is theoretically possible to grow plants in replicated Martian soil, but there are not enough samples of actual Martian regolith to be sure. Since there is no way to do agricultural trials on Mars itself, scientists are trying to replicate the conditions on Earth. Researchers at the Florida Institute of Technology recently attempted to cultivate Arabidopsis thaliana, a weed, and Lactuca sativa, lettuce, in a trio of Martian regolith simulants. These simulants are blends of man-made and natural materials that mimic the Martian basalt-like surface. Scientists have found that no plant in synthetic soil without the addition of additional nutrients.
“These results 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 is a mistake to assume that regolith is uniform across the planet. “Our strategy was, rather than saying that this simulant grows plants so that we can grow plants all over Mars, we have to say that Mars is a diverse planet,” said Andrew Palmer, associate professor of ocean engineering and in Marine Sciences at Florida Tech News.
In another new study, also published in Icarus, researchers break down the readiness of five new types of Mars simulants. Laura Fackrell, a doctoral student at the University of Georgia in Athens, and her colleagues created the mixtures specifically formulated with the characteristics of Martian regolith that could make growing plants difficult. Soil can have high salinity or a low level of organic matter. Such conditions could force future residents of Mars to add other minerals and components to their gardens before planting. “Specific types of bacteria and fungi are known to be beneficial to plants and may be able to support them under stressful conditions like we see on Mars,” Fackrell told TNW.
To test for fake Mars dirt, Fackrell tried growing several plants, including a butterfly bean. They hold up better with less water than the other options she tried, “but they’re not necessarily very healthy,” Fackrell told Science News.
It will be years before humans reach Mars, but in the meantime research on growing plants in harsh environments could translate to Earth, where temperatures are rising. Fackrell studied the microbes that live in hot springs. “Everything we learn about farming on Mars could help farming in harsh environments on Earth that help us build a sustainable future,” she told Florida Tech News.
For more information on Mars, find out how there was once a salt lake on the Red Planet and how a study revealed lakes below the surface of Mars.