Stock photo illustrating a plant growing on the moon.
Scientists have grown plants in the soil from the moon, for the first time in human history and an important moment in lunar and space research.
In a new research paper published in the journal Communications Biology on May 12, 2022, scientists at the University of Florida showed that plants can successfully germinate and grow in lunar soil. Their study also looks at how plants respond biologically to the moon’s soil, also known as lunar regolith, which is radically different from the typical soil found on Earth.
This study is the first step towards growing plants for food and oxygen on the moon or during future space missions. Rather, this study comes when the Artemis program plans to bring people back to the moon.
“Artemis will require a better understanding of how to grow plants in space,” said Rob Fearl, one of the study’s authors and a prominent professor of horticultural science at the UF’s Institute of Food and Agricultural Sciences (UF / IFAS).
Anna-Lisa Paul, left, and Rob Fearl, working with lunar soils in their lab. Credit: UF / IFAS photo by Tyler Jones
Even in the early days of the lunar study, plants played an important role, said Anna-Lisa Paul, also one of the study’s authors and a professor of gardening at UF / IFAS.
“The plants helped to establish that soil samples brought from the moon did not contain pathogens or other unknown components that would harm terrestrial life, but these plants were only sprinkled with lunar regolith and were never actually grown there.” said Paul.
Paul and Fearl are internationally recognized experts in the study of plants in space. Through the UF Space Plants Lab, they sent experiments on space shuttles, to the International Space Station and on suborbital flights.
Anna-Lisa Paul is trying to moisten the lunar soil with a pipette. Scientists have found that soils repel water (they were hydrophobic), leading to the formation of grains on the surface. It is necessary to actively mix the material with water to break the hydrophobicity and to wet the soil evenly. Once moistened, lunar soils can be moistened by capillary action for plant culture. Credit: UF / IFAS photo by Tyler Jones
“For future longer space missions, we can use the moon as a center or launch site. “It makes sense to want to use the soil that’s already there to grow plants,” Ferll said. “So what happens when you grow plants in lunar soil, something that is completely beyond the evolutionary experience of the plant?” What would plants in a lunar greenhouse do? Can we have lunar farmers?
To begin answering these questions, Firl and Paul designed a deceptively simple experiment: plant seeds in lunar soil, add water, nutrients, and light, and record the results.
Arabidopsis plants 6 days after planting the seeds. The four wells on the left contain plants growing in lunar soil simulator JSC-1A. The three wells on the right contain plants growing in lunar soils collected during the Apollo 11, 12 and 17 missions. UF / IFAS photo by Tyler Jones. Credit: UF / IFAS photo by Tyler Jones
The complication: the scientists had only 12 grams – just a few teaspoons – of lunar soil to do this experiment. Borrowed from NASA, this soil was collected during the Apollo 11, 12 and 17 missions to the moon. Paul and Fearl have applied three times in 11 years for a chance to work with lunar regolith.
The small amount of soil, not to mention its incalculable historical and scientific significance, meant that Paul and Fearl had to design a small-scale, carefully choreographed experiment. To grow their little moon garden, the researchers used thimble-sized wells in plastic plates, which are commonly used to cultivate cells. Each well functioned like a pot. After filling each “pot” with approximately a gram of lunar soil, the scientists moistened the soil with a nutrient solution and added a few seeds of the Arabidopsis plant.
Arabidopsis is widely used in plant science because its genetic code is fully mapped. Growing Arabidopsis in lunar soil has allowed researchers to understand how soil affects plants, down to the level of gene expression.
Rob Fearl, left, and Anna-Lisa Paul watch the plates, part filled with lunar soil and part with control soils, now under LED lights for growth. At the time, scientists did not know if the seeds would even germinate in lunar soil. Credit: UF / IFAS photo by Tyler Jones
As comparison points, the researchers also planted Arabidopsis in JSC-1A, a terrestrial substance that mimics real lunar soil, as well as simulated Martian soils and terrestrial soils from extreme environments. Plants grown in these non-lunar soils were the control group of the experiment.
Prior to the experiment, researchers were unsure whether seeds planted in lunar soils would germinate. But almost everyone did.
“We were amazed. We didn’t anticipate that, “Paul said. “This told us that lunar soils do not interrupt the hormones and signals involved in plant germination.”
However, over time, researchers have observed differences between lunar plants and the control group. For example, some of the plants grown in lunar soils are smaller, slower, or more diverse than their counterparts.
These are all physical signs that plants are working to cope with the chemical and structural composition of the moon’s soil, Paul explained. This was further confirmed when the researchers analyzed the gene expression patterns of the plants.
“At the genetic level, plants take out tools that are commonly used to deal with stressors such as salt and metals or oxidative stress, so we can conclude that plants perceive the lunar soil environment as stressful,” Paul said. “Ultimately, we would like to use gene expression data to help tackle how we can improve stress responses to a level where plants – especially crops – can grow in lunar soil with very little impact on their health.
How plants respond to lunar soil may be related to where the soil is collected, said Ferl and Paul, who collaborated in the study with Stephen Ellardo, assistant professor of geology at UF.
For example, researchers have found that the plants with the most signs of stress are those grown in what lunar geologists call mature lunar soil. These mature soils are those exposed to a more cosmic wind that changes their composition. On the other hand, plants grown in relatively less mature soils do better.
Growing plants in lunar soils can also change the soils themselves, Elardo said.
“The moon is a very, very dry place. How will the minerals in the lunar soil react to the cultivation of a plant in them with the added water and nutrients? Will adding water make mineralogy more hospitable to plants? ”Elardo said.
Subsequent studies will be based on these and other issues. So far, scientists are celebrating that they have taken the first steps towards growing plants on the moon.
“We wanted to do this experiment because we’ve been asking ourselves this question for years: Will plants grow in lunar soil,” Fearl said. “It turns out the answer is yes.”
Reference: “Plants grown in Apollo’s lunar regolith present stress-related transcripts that inform the prospects of lunar research” by Anna-Lisa Paul, Stephen M. Ellardo and Robert Fearl, May 12, 2022, Communications Biology.DOI: 10.1038 / s0220- 03334-8
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