That’s one small plant stem, one enormous advance for plant science. The first seedlings ever seeded in lunar dirt have sprouted in a tiny, lab-grown garden. This little crop, seeded in Apollo mission samples, gives astronauts optimism that they would be able to cultivate their own food on the moon someday.
Plants planted in lunar dirt, on the other hand, developed more slowly and scrawnier than those grown in volcanic material from Earth, according to a study published in Communications Biology. This conclusion implies that farming on the moon would require far more than a green thumb.
“Ah! It’s really cool!” said astrobotanist Richard Barker of the University of Wisconsin–Madison about the experiment. “Botanists have been curious in what would happen if you cultivated plants in these materials ever since they came back,” adds Barker, who was not involved in the study. “But everyone knows those delicate samples… are priceless, which is why [NASA] was hesitant to disclose them.”
NASA’s impending intentions to return men to the moon as part of its Artemis program have provided a new incentive to investigate that valuable dirt and investigate how lunar resources could support long-term missions.
Nothing really compares to the first time we observed the seedlings emerging in the lunar regolith. It was an emotional experience to be able to state that we were observing the very first terrestrial organisms to grow on extraterrestrial elements. And it was amazing.
Anna-Lisa Paul
The regolith, or moon soil, is a gardener’s greatest nightmare. This thin powder of razor-sharp particles contains metallic iron rather than oxidized iron, which plants prefer. It’s also littered with microscopic glass shards created by space debris crashing into the moon. It lacks nitrogen, phosphorus, and other nutrients that plants require for growth. So, despite the fact that scientists have gotten very adept at persuading plants to grow in artificial moon dust composed of earthly materials, no one knew whether newborn plants could put down their fragile roots in the actual thing.
A trio of researchers from the University of Florida in Gainesville conducted experiments with thale cress to find out (Arabidopsis thaliana). This well-studied plant is in the same family as mustards and can grow in just a tiny clod of material. That was key because the researchers had only a little bit of the moon to go around.
The seeds were sown in little pots containing about a gram of earth each. Four pots were filled with Apollo 11 samples, four more with Apollo 12 samples, and four more with Apollo 17 dirt. Another 16 pots were filled with earthly volcanic material, which had previously been used to simulate moon dirt in previous tests. All were produced in the lab under LED lights and were irrigated with a nutrition broth.
“Nothing really compares to the first time we observed the seedlings emerging in the lunar regolith,” says plant molecular scientist Anna-Lisa Paul. “It was an emotional experience to be able to state that we were observing the very first terrestrial organisms to grow on extraterrestrial elements. And it was amazing. Just amazing.”
Plants grew in all of the lunar dirt pots, but none grew as well as those grown in earthly soil. “The healthiest ones were simply smaller,” Paul explains. The sickest moon-grown plants were small and had purplish pigmentation, indicating plant stress. Plants growing in Apollo 11 samples, which had spent the greatest time on the lunar surface, were the most stunted.
Paul and his colleagues also examined the genes of Eden, their miniature alien. “By looking at what genes are turned on and off in response to a stress, you can see what tools plants are drawing out of their metabolic toolbox to deal with that stress,” she explains. All plants grown in moon dirt pulled out genetic tools typically seen in plants struggling with stress from salt, metals or reactive oxygen species.
The genetic profile of Apollo 11 seedlings was the most severely stressed, providing fresh indication that regolith exposed to the lunar surface for a longer period of time — and so littered with more impact glass and metallic iron — is more harmful to plants.
Future space explorers could choose a suitable location for their lunar dwelling. Perhaps lunar dirt could be manipulated in some way to make it more hospitable to plants. Plants could also be genetically modified to feel more at home in foreign soil. “We can also select plants that perform better,” Paul says. “Perhaps spinach plants, which are extremely salt-tolerant, would thrive in lunar regolith.”
Barker isn’t scared of the hurdles that this maiden try at lunar gardening promises. “Many, many steps and pieces of technology must be developed before humanity can truly engage in lunar agriculture,” he explains. “However, having this specific dataset is really crucial for those of us who believe it is both possible and important.”
