Researching Regolith for Plant Growth

For future Mars colonists to succeed, they must be able to grow at least some of their food. Researchers at Florida Tech are looking at how a variety of simulated Martian soil can support this necessity in preparation for an eventual stay on the Red Planet.

In a recent paper, the research team of ocean engineering and marine sciences associate professor Andrew Palmer,aeronautics assistant professor Brooke Wheeler, and Florida Tech alumni Ariana Eichler and Nathan Hadland, tested three simulants of Martian regolith, as the soil is known – JSC-MARS-1A, Mars Mojave and Mars Global Simulant (MGS). The initial results indicate that, contrary to previous research, not all three can support plant growth.

For example, MGS, widely considered to be among the most chemically and mineralogically accurate simulants available, was actually toxic to plants, despite various strategies to make it viable. Hadland discovered that the pH level of MGS was higher than other samples, which may have played a factor in the lack of growth. More importantly, the discovery that this simulant is unable to support plant growth suggests that our understanding of how to grow food on Mars is not as advanced as previously thought.

“When we look at these different simulants, which have unique problems associated with them and are different in their composition and mechanics, we can understand and develop strategies for mitigating their specific problems,” Hadland said. “That means when we arrive on Mars and encounter a certain problem, we have a strategy to mitigate it.”

By showing that these simulants are not facilitating plant growth as well as hoped, the findings will give current and future researchers a roadmap for testing other simulants for their ability to support plant growth, as well as help indicate what additional supplies must be transported to Mars for food production. For example, all of the simulants tested, like Mars itself, are largely devoid of nitrogen, a critical element for plant growth.

Palmer noted there are a variety of simulants made by companies and research groups, each with slightly different physical and chemical properties – much like the diverse regolith of the Martian surface. The team tested the ability of the three different simulants to support plant growth, and their findings will help us better understand the potential challenges of living on parts of Mars.

“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. Just like how I can pick up a pile of dirt at the beach and a pile of dirt in West Melbourne, those soil compositions can be drastically different,” Palmer said.

The research has provided the team with experience that will be helpful for future researchers and explorers of Mars.

“To find where the failures and shortcomings could be, it is so valuable to do that now,” Eichler said. “We want to make as many of those (discoveries) right now before we go, because once we go, we don’t want to make mistakes.”

The next step of the research will be handled by recent Astronaut Scholarship recipient Samantha Pryor, with Eichler graduating from Florida Tech in the summer and Hadland now a Ph.D. candidate at the University of Arizona. Pryor will be following up on Hadland’s discovery that the MGS is toxic, attempting to confirm if pH or some other factor is at play. Working with other students, she will also explore which nutrients, such as nitrogen, and how much of the nutrients need to be added to simulants to allow for plant growth. This will help determine if the nutrients are available on the Red Plant or will have to come from the Blue Planet (Earth).

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