For the first time in history, researchers have used a small sample of lunar regolith to sprout seeds. The results can tell us much about feeding humanity throughout the solar system.
The Moon would be a harsh environment to live in. It has no weather and no liquid water. With no atmosphere to keep things stable, lunar temperatures can range from 224 degrees Fahrenheit (107 degrees Celsius) during the day to -228 degrees Fahrenheit (-144 degrees Celsius) at night. Furthermore, the land is not ideal for agriculture. Buzz Aldrin once referred to lunar regolith, which is similar to soil, as “talcum powder-like dust.” Researchers who have studied lunar soil samples have described it as glassy, metallic, and rich in minerals that do not exist on Earth.
That’s why it is so impressive that, for the first time, scientists have successfully grown plants using lunar soil gathered from previous missions to the Moon.
The feat was recently documented in a study published in the journal Communications Biology. The experiment has been in the works for over a decade, according to study author Rob Ferl, a professor of horticultural sciences at the University of Florida, but researchers only carried it out last year. “Something like this takes tons of planning,” he says, because Moon soil is a limited resource that is difficult to obtain once depleted. In a pot about the size of a thimble, the team had only a few teaspoons to work with.
Lunar vs. terrestrial soil
According to Ferl, in the years leading up to the experiment, researchers collected soils from Earth that were as close to the composition of lunar soil as possible. They used soil from terrestrial craters, as well as a “lunar simulate soil” known as JSC1A, an industrial mixture of chemicals designed to mimic the Moon’s soil conditions. He claims that getting everything just right ahead of time was critical to optimizing growing conditions when it came time to plant in real lunar soil.
Because there is no lunar atmosphere, outdoor agriculture is impossible, so researchers created a laboratory environment on the Moon instead. “Given conditions on the Moon, you can’t just throw seeds out on the surface and ask them to grow,” says Ferl.
He claims that lunar soil differs from that found on Earth due to the harsh solar wind and cosmic rays. Researchers discovered that the soil’s jagged edges and metallic minerals created suboptimal conditions for growing the Arabidopsis plant, a small flowering weed native to Europe and Asia. They chose this variety because, unlike most other plants, its genes have already been mapped, which makes studying the species’ gene expression as part of the experiment easier.
What happened to the plants? The team discovered that plants grown in lunar soil struggled physically and biologically when compared to control plants grown in terrestrial soil. “Plants grown in lunar soil tended to be smaller and they contained purplish pigments that were indications of stress. They also expressed genes typical of plants grown in marginal conditions like salty soils and soils with high metal content,” Ferl says.
But, as Ferl points out, the plants grew, which is significant. Clive Neal, a Notre Dame researcher who specializes in lunar exploration, agrees. According to him, this was an excellent first experiment that tested the “validity of using lunar regolith” to grow this novel set of Moon plants.
“The really intriguing thing is the results suggest mature regolith inhibits plant growth,” says Neal. The maturity of lunar soil is based on its exposure to solar winds and other inhospitable aspects the lunar surface. Researchers can pinpoint the soil’s maturity based on the size of granules as well as gases implanted in soil particles. But Neal says that there’s still a lot we don’t know. “We need more regolith returned from the Moon of varying degrees of maturity [to further study it],” he says.
Although this research is still in its early stages, Ferl is excited about where it may lead researchers in the future. He believes that this is about far more than just lunar soil. It is about determining how plants can function as a support system on other planets, just as they do on Earth.“What are the limits of our collective biology’s ability to live somewhere else in the solar system?” he asks.
There’s also a more pragmatic angle: Ferl and his team want to figure out how to produce enough food for humans to stay on the Moon and Mars for longer periods of time. And if plants can act as a support system elsewhere in the solar system, humans can provide their own food rather than relying on what they can bring with them.
For Ferl and his colleagues, this research is about more than just growing lunar plants in a lab — it’s about surviving and thriving in a world other than our own.