At the heart of humanity’s grand odyssey into the cosmos lies a problem that needs to be solved. The success of our final frontier journey — the reality of settling humans long-term on the moon, Mars, and beyond — hinges on our ability to cultivate our own sustainable sustenance.
Transforming harsh, disagreeable lunar and Martian soil into a nurturing medium suitable for terrestrial plants is no easy task. Yet, it’s one that has fascinated graduate students Jessica Atkin of Texas A&M University and Sara Oliveira Santos of Brown University. In late January 2024, the two revealed that they managed to grow chickpeas from simulated lunar regolith (a.k.a. material meant to mimic moondust) with the help of fungi and worm manure. While their findings were posted in the preprint server bioRxiv, their research supports other studies in the field that are trying to grow food in space.
Finding Plant Growth in Space
Unlike soil on Earth, lunar regolith, or rock and dust, lacks the necessary nutrients and structural integrity to support any growing flora. Not only that, said Atkin, moondust is chockfull of heavy metals and other toxins that would kill a seed or stunt a plant’s growth; the moon’s microgravity can also impair a plant’s ability to effectively take up nutrients and oxygen, causing what’s known as root zone hypoxia.
To combat this, Atkin and Oliveira Santos used techniques practiced on Earth to remediate damaged soil where crops won’t grow. One such tactic involves arbuscular mycorrhizal fungi (AMF), a microorganism inhabiting soil that forms mutually symbiotic relationships with select nearby plants — essentially, the friendly neighbor who takes helping out to a whole new level.
“The fungus is able to secrete a protein that surrounds the heavy metals so they are less available for uptake [by the plant],” says Atkin. “And if the heavy metals make it past that mechanism, then [the fungus] has another mechanism limiting access to penetrate the root. If they do penetrate the root, the fungus will gather the toxins in its own biomass or keep it in the root of the plant so it doesn’t get up to the seed.”
AMF can also help offset the less-than-stellar effects of radiation and microgravity on a growing plant. This is further aided by vermicompost, a natural fertilizer produced by red wiggler worms that chomp down on food waste and other organic material. It’s also packed with essential nutrients like nitrogen and phosphorus.
Read More: Scientists Create a Prototype Lunar Oxygen Plant
Fungus to the Rescue
Armed with fungus and worm poop, Atkin and Oliveira Santos tried their hand at growing chickpeas from moondust. Not only are the all-around favorite legumes high in protein, but they can form symbiotic relationships with multiple microorganisms, including AMF.
Into pots went chickpea seeds, AMF, vermicompost, and lunar regolith. Now, Atkin and Oliveira Santos couldn’t use real lunar regolith — there’s a limited supply of the real stuff obtained from past moon missions. They had to use a simulated alternative that sources from geological materials found on Earth, such as glass and minerals like olivine, plagioclase, and chromite.
“Lunar regolith simulant is 99 percent compositionally accurate to the different landing sites that [astronauts] took samples from in the Apollo and lunar missions,” says Atkin.
As the seedlings grew, some plants showed signs of stress characteristics at first and seemed to be struggling. But around week seven, the AMF’s magic kicked in.
Fledgling plants were still showing signs of stress but less so for the chickpeas inoculated with the helpful fungus. These plants had better chlorophyll levels compared to the non-inoculated plants; by week 10, they were flowering while their non-AMF counterparts were dying off.
While this research may sound like the first giant leap to whipping up space hummus with a side of pita, Atkin and Oliveira Santos haven’t tested whether their moondust-grown chickpeas are edible and safe to consume (i.e., containing no heavy metals).
“It’s going to take a little bit, it’s definitely not going to be fixed on the first planting,” says Atkin.
Read More: How Do Scientists Build the Best Diet for Astronauts?
Space Hummus and Beyond
In 2022, researchers at the University of Florida managed to grow Arabidopsis thaliana seeds — a small plant in the mustard greens family often considered a weed — from a few grams of actual lunar regolith collected during the Apollo 11, 12, and 17 missions from three different locations across the moon. The aim of the experiment, which was the first time scientists managed to nurture seeds in lunar soil, was to see how the plants responded, both physically and at a genetic level, to moondust.
One of the lead researchers, Anna-Lisa Paul, a space biologist and director of the University of Florida’s Interdisciplinary Center for Biotechnology Research, said the new findings with chickpeas were “a good solid piece of work” building nicely on the existing body of scientific research conducted in the last couple of decades by NASA and other scientists.
“It’s absolutely in the direction that I think we should all be going with respect to understanding what it takes to mitigate the toxic effects of true lunar regolith,” says Paul.
According to Paul, the next steps would be to see how this bioremediation technique holds up in true lunar regolith rather than simulated, something Atkin and Oliveira Santos are eager to test out if they can manage to secure more grant funding.
“There’s been no external funding for this [research], so what we’ve been able to analyze and how far we’ve been able to take this has been limited by that,” says Oliveira Santos. “Now, we’re really hoping that we will be able to get some NASA funding to really analyze and use more [lunar soil] replicants and do all these things.”
Oliveira Santos added the value of their research isn’t limited to the scope of sustainable space living for astronauts or future lunar (or even Martian) colonists. As climate change threatens ecology and agricultural growth, she and Atkin believe their research could lend to figuring out how to optimize bioremediation on Earth, to revitalize and protect vulnerable, arable land.
“I feel a lot of people look at this [research] and are like why are we looking at this, why are we thinking about the moon when we have so many problems on Earth,” says Oliveira Santos. “While we’re doing this for lunar regolith simulant, all these techniques and all these findings are applicable to Earth. All the things that we find will be able to help us here too.”
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