by More than 50 years after astronauts brought the last moon rock samples to Earth, scientists have successfully grown plants in lunar soil from three Apollo missions for the first time.
all the Moon– soil plants grew slowly and relatively poorly, but those grown in samples more exposed to the lunar surface tended to perform worst, and genetic analysis showed changes indicative of stress. Poor growth may be cause for concern: As NASA prepares to send astronauts back to the moon via the moon Artemis program – and eventually even to Mars – to grow food on alien soil during long missions is becoming increasingly important.
“The ability to successfully take plants to the moon is… how we will grow our own food [and] how we’re going to stay there for a while without supplies,” Robert Ferl, a professor of horticultural science at the University of Florida and author of the study, told a virtual press conference on Wednesday (May 11) that growing plants on the moon has other potential uses. could have, including purifying air, removing carbon dioxide that people exhale, and producing clean water.
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For this study, the researchers used samples of lunar soil, called regolith, taken during Apollo 11, 12 and 17between 1969 and 1972. In all three samples, they grew a common lab sample, a small plant called thale cress (Arabidopsis thaliana† By comparison, the scientists also grew the thale cress in a type of soil made from volcanic ash found on Earth, called JSC-1A by NASA, intended to simulate lunar soil, which is powdery and full of abrasive glass fragments.
“The fragments are actually quite sharp and angular,” Stephen Elardo, a geologist at the University of Florida and an author of the study, told the news conference. The lunar floor also contains bits of metallic iron, and the glass fragments trap gas pockets, which volcanic ash doesn’t fully replicate.
The researchers were able to grow Arabidopsis in all three samples. The plants fared worst in the Apollo 11 soil, which was the most “mature,” meaning the soil was most exposed to the lunar surface. (Because the moon has no protective atmosphere like) Soils, the surface is ravaged by meteorites, the fragments of atoms that scientists call cosmic rays and the constant stream of charged particles flowing from the sun.) The plants grew better in the Apollo 12 sample, which was less mature, and in the Apollo 17 sample, which was the least mature.
All the plants grown in the lab-created volcanic ash grew remarkably faster and taller than all the plants in the lunar soils.
In addition, a genetic analysis of the plants revealed that compared to the plants grown in volcanic ash, those grown in lunar soil expressed many genes related to salt, metal-associated and oxidative stress.
The Apollo 11 plants expressed changes in 465 genes, while Apollo 12 plants expressed 265 genes at different rates and Apollo 17 plants 113. Most of these changes were stress-related. When they grouped the plants by appearance, they found that plants that looked the worst — small and a reddish-black color — also had the most genetic changes related to stress.
The results suggest that soil exposed more to the lunar surface is worse for plants, possibly due to changes caused by exposure to cosmic rays and the solar wind, the researchers wrote. If true, the researchers argued, soil from younger parts of the moon could be more effective at growing healthy plants. While even the healthiest of these plants would be stunted and slow-growing, the food they produce wouldn’t necessarily be harmful, yet could be nutritious. In fact, many types of dark pigmented products, such as cranberries and blueberries, are valued for their antioxidants produced in response to oxidative stress.
Eating plants grown in this way on lunar soil is “probably not a threat to humans,” Anna-Lisa Paul, a horticultural scientist at the University of Florida, said during the news conference. “It’s hard to say, but it’s more likely that the chemicals plants produce in response to stress are also substances that help human stress as well.” She said future research would be needed to explore how the lunar soil may affect the nutritional content and quality of foods grown in this soil.
It’s also clear from this research, the scientists said, that simulated lunar soil is not an effective substitute for the real thing in an experiment like this, despite some similarities. Growing plants in lunar soil permanently changes its chemistry, which is why an experiment like this has never been done before with the “precious natural treasures” that are the Apollo samples, Paul said. But the exact chemistry of lunar soil is unique and can provide scientists with insights that simulated soil never could.
“The devil is in the details,” Elardo said. “And the plants worry about the details.”
The investigation was: published on May 12 in the journal Communications Biology.
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