(CNN) — For the first time in history, scientists grew plants on lunar substrate using samples collected during the Apollo missions to the Moon. It is the first time that plants have sprouted and grown on Earth in the soil of another celestial body.
The study could lay the groundwork for growing plants that supply oxygen and food on the Moon, a timely consideration as the program NASA’s Artemis it seeks to host the first woman and first person of color at the lunar south pole later this decade.
But the experiments also reveal how stressful it is for plants to grow in lunar regolith that is so different from natural habitats on Earth.
A study detailing the plant experiment was published Thursday in the academic journal Communications Biology.
Different types of plants, including food crops, have flown on the space shuttle and the International Space Station. Plant samples have even been used to show that lunar samples are not harmful to life on Earth.
(From left) Study co-authors Anna-Lisa Paul and Rob Ferl of the University of Florida Institute for Food and Agricultural Sciences work with lunar substrates.
“The plants helped establish that the soil samples brought back from the Moon harbored no pathogens or other unknown components that could harm terrestrial life, but those plants were just dusted with lunar regolith and never actually grown on it,” she said. study co-author Anna-Lisa Paul, a research professor of horticultural sciences at the Institute of Food and Agricultural Sciences at the University of Florida.
Paul and study co-author Rob Ferl, Distinguished Professor of Horticultural Sciences at the UF Institute of Food and Agricultural Sciences, wanted to go a step further and see if the seeds would grow in lunar soil.
“For future longer space missions, we could use the Moon as a hub or launch pad,” Ferl said in a statement. “So what happens when you grow plants on lunar soil, something that is totally outside of a plant’s evolutionary experience? What would plants do in a lunar greenhouse? Could we have lunar farmers?”
historical samples
This is an experiment that has been a long time in the making: 15 years have passed since the researchers made their first proposal and request for lunar samples. The request was granted 18 months ago.
The research team asked NASA for 4 grams of lunar material collected during the Apollo 17 mission. Ryan Zeigler, NASA’s Apollo Sample Curator, saw the scientific value of providing more than different Apollo missions. He sent them a total of 12 grams (2.7 teaspoons) of lunar samples collected on the Apollo 11, 12, and 17 missions.
“That made a big difference, as it allowed us to delve deeper into the science and into the effects of lunar regolith on plants than we otherwise would have been able to,” Paul said.
(From left) Ferl and Paul grew the seeds under LED lights set to optimal wavelengths for photosynthetic plant growth.
The researchers used thimble-sized plates as pots. Normally these plastic trays are used to grow cells.
The scientists filled each well with a gram of lunar soil, added nutrients and water, and introduced a few seeds of Arabidopsis thaliana, or field cress, a small flowering plant native to Eurasia and Africa.
Arabidopsis thaliana plants, commonly known as garden cress, are shown sprouting from the lunar substrate.
Cress is an attractive specimen for researchers because it is well studied and its genetic code has already been mapped, allowing researchers to study how foreign soil affected the plant’s gene expression. In addition, the plant has already been to space aboard the shuttle and the space station, providing the team with space data for comparison.
Arabidopsis seeds were also planted in a synthetic substance that simulates lunar soil, as well as volcanic ash and other substrates from extreme environments.
To the surprise of the researchers, almost all the seeds planted in the dark lunar soil sprouted and began to grow.
“We hadn’t anticipated it,” Paul said. “That told us that the lunar substrates did not disrupt the hormones and signals involved in plant germination.”
hostile ground
However, the Arabidopsis shoots showed signs of difficulty as they adapted to the lunar soil.
Seedlings were smaller, grew more slowly, and varied in size compared to plants grown on terrestrial substrates. The roots were stunted. And the plants took longer to have expanded leaves than Arabidopsis plants grown in volcanic ash. Some of the plants in lunar substrate showed reddish-black pigments in their leaves, an outward sign of stress.
At the genetic level, three of the smaller, darker plants expressed more than 1,000 genes largely related to stress.
“At the genetic level, the plants were putting out the tools typically used to cope with stressors, such as salt and metals or oxidative stress, so we can infer that the lunar soil environment is perceived by plants as stressful.” Paul said.
“Ultimately, we’d like to use gene expression data to help address how we can enhance stress responses to the level where plants, particularly crops, are able to grow on lunar soil with very little impact on the environment.” your health”.
On day 16, there were clear physical differences between plants grown in volcanic ash (left) and those grown in lunar soil (right).
The Arabidopsis plants that had the most difficulty were grown in mature lunar soil, and turned purple in response to oxidative stress. These substrate samples collected during the Apollo 11 mission were more exposed to the harsh space environment, and the plants grown on the Apollo 12 and 17 samples seemed to perform better.
The lunar surface, regularly bombarded by cosmic rays and the solar wind, also includes iron particles and small glass fragments. All of these elements could harm plant growth.
“Even plants that seemed healthy were struggling to stay healthy,” Paul said. “They grew on the lunar regolith, but they had to deal with it on a metabolic level to maintain that kind of health.”
space greenhouses
The researchers want to conduct follow-up studies to understand how growing plants in the lunar environment might actually alter the lunar substrate.
“The Moon is a very, very dry place,” said study co-author Stephen Elardo, an assistant professor of geology at the University of Florida. “How will the lunar soil minerals respond to having a plant grown on them, with the added water and nutrients? Will the addition of water make the mineralogy more plant friendly?”
On the Moon, these plants could extract resources from the lunar soil, such as metallic iron, and make them available in other, more useful forms.
The experimental plants were placed in flasks for genetic analysis.
Further research could also help determine the most efficient way to grow plants on lunar soil and help them avoid stressors identified during the study. Furthermore, the team wanted to get a clear understanding of the nutritional value of these plants, and whether this is affected by the substrate.
Although cress is edible, it is not palatable, nor is it considered a food crop. But it belongs to the same plant family as broccoli, collard greens, turnips, and cauliflower.
Sharmila Bhattacharya, NASA’s chief scientist for astrobionics, called the plant growth discovery “pretty exciting” and said the study presents many follow-up opportunities for scientists. Bhattacharya was not involved in this study.
“We need to figure out how to make plants grow even better on this regolith substrate,” Bhattacharya wrote in an email. “For example, do we need to add other components to help the plants, and if so, what are they? Are there other plants that are better suited to these regolith substrates, and if so, what traits make them more resistant to these substrates?” environments?” he said.
“That’s the exciting thing about science; each new finding leads to more unique and transformative results in the future, which we can then use to help improve the sustainability of our future space exploration missions!”
Scientists see their experiment as a positive outcome for what may be possible as humans push the limits of space exploration.
“It’s surprising that the plant continues to grow in this harsh environment,” Elardo said. “She’s stressed, but she doesn’t die.”
“When humans move as civilizations to stay somewhere, we always take our agriculture with us,” Ferl said. “The idea of bringing lunar soil into a lunar greenhouse is what exploration dreams are made of.”