Studies have shown crops can grow in simulated Martian regolith. But that faux material, which is similar to soil, lacks the toxic perchlorates that makes plant growth in real Red Planet regolith virtually impossible. New research involving Florida Tech is examining how to make the soil on Mars useful for farming.
Andrew Palmer, co-investigator and ocean engineering and marine sciences associate professor, along with Anca Delgado, principal investigator and faculty member at Arizona State University’s Biodesign Swette Center for Environmental Biotechnology, and researchers from the University of Arizona and Arizona State University, are participating in the study, “EFRI ELiS: Bioweathering Dynamics and Ecophysiology of Microbially Catalyzed Soil Genesis of Martian Regolith.” This National Science Foundation and NASA-funded project will use microorganisms from bacteria to remove perchlorates from Martian soil simulants and produce soil organic matter containing organic carbon and inorganic nutrients.
Martian regolith contains high concentrations of toxic perchlorate salts that will impede plant cultivation in soil, jeopardizing food security and potentially causing health problems for humans, including cancer. Researchers will look at different bacterial populations and how well they are able to process and break down the perchlorates, as well as what kind of materials they produce when they do. They’ll also look at different temperatures and moisture conditions, as well as in the presence or absence of oxygen. Students in the Palmer Lab will receive the simulants after this process, try to replicate it, and then test how well the perchlorate-free regolith is able to grow plants.
A challenge the researchers face is how they remove the toxic salts, as well as if they can remove all of them. Palmer cautioned that the possibility that removing the perchlorates does not necessarily mean the regolith is ready for farming.
“You can’t make the cure worse than the disease, so we have to be ending up with regolith on the other side that’s better than when we started,” Palmer said. “We can’t trade perchlorates for some other toxic accumulating compound. Just because we’re removing the perchlorates doesn’t necessarily mean that we’re going to make the regolith better for plants. We might just make it not toxic anymore. How much does it improve is really what we’re trying to figure out.”
Even without perchlorates, there are significant challenges to growing crops in Martian soil. While researchers have grown plants in simulated regolith, the regolith is not good for plant growth, as in addition to a lot of salts, it has a high pH and is very fine, which means it can ‘cement’ when wet, suffocating plant roots.
Being able to grow in the soil instead of using hydroponics could also provide a more efficient, cost-effective solution.
“There is always the option of hydroponic growth of food crops, but with a significant distance to Mars and the lack of readily available water, we need a different kind of plan,” said ASU’s Delgado. “If there is a possibility to grow plants directly in the soil, there are benefits in terms of water utilization and resources to get supplies to Mars.”
Some of the microbial solutions the team is proposing could also help with studies of soils on Earth.
“The best soils for agriculture on earth, they were taken up decades ago, and so now we’re trying to farm on new land that’s not really meant for agriculture, if you think about it,” Palmer said. “So, as we think about ways to convert it into better soil, I think this research helps teach us how to do that, but it also inspires.”
The research will also allow Florida Tech students to get hands-on space agriculture experience.
“We’re going to be training the grad students and the undergraduates who are going to be the researchers who take on those new challenges, so I think one of our most important products are going to be the students we train,” Palmer said. “We’ll deliver Mars soil, but we also deliver, I think, a future group of researchers.”