When the Artemis program returns humans to the Moon (hopefully) in a few years, there will be considerable logistics that will need to be addressed to keep such fragile beings alive in such a harsh environment.
No less important is the issue of food. The space agencies involved in the International Space Station already have a lot of experience in providing pre-packaged provisions, but having access to fresh food has advantages, including for physical and mental health.
If lunar soil were to prove to be a conducive medium for growing fresh crops, that would be amazing. So a team of scientists used a few precious grams of actual lunar samples collected during the Apollo missions to try to grow plants, specifically, thale cress, or Arabidopsis thaliana.
“For future longer space missions, we may use the Moon as a hub or launch pad. It makes sense that we would want to use the soil that is already there to grow plants,” says horticulturist scientist Rob Ferl of the University of Florida.
“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?”
Well, spoiler: lunar soil, also known as lunar regolith, isn’t very good for growing plants. But this research is just a first step toward growing plants one day on the Moon in an exciting sci-fi future.
The current amount of lunar sample material here on Earth is quite small and therefore valuable and highly prized.
Ferl and her colleagues, University of Florida horticultural scientist Anna-Lisa Paul and geologist Stephen Elardo, were granted a loan of just 12 grams of the precious material, after three requests over 11 years.
This required a very small and very tight experiment: a mini garden of Arabidopsis. They carefully divided their samples into 12 thimble-sized pots, to each of which was added a nutrient solution and some seeds.
Control groups of seeds were also planted in terrestrial soil from extreme environments and soil simulants (a terrestrial material used to simulate the properties of extraterrestrial soils).
For the experiment, the team used a Mars soil simulator and a lunar simulator called JSC-1A. This is important because previous experiments have shown that plants can grow well in both types of simulators, but subtle differences could mean that reality is a different story.
Above: Plants growing in the three lunar soil sets and the soil simulator.
That seems to be the case. To the researchers’ surprise, almost all of the seeds planted in the lunar samples sprouted, but that’s where things changed. Instead of growing merrily, the seedlings seemed to be smaller, slower-growing, and much more varied in size than the plants growing in the lunar simulator.
When the team extracted the plants for genetic analysis, they discovered why.
“At the genetic level, plants were putting out the tools normally used to deal with stressors, such as salt and metals or oxidative stress, so we can infer that plants perceive the lunar soil environment as stressful.” Paul says.
“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, can grow in lunar soil with very little impact on their health.” “.
The lunar samples used by the researchers came from three different locations on the Moon, at different depth layers from the surface, collected by the Apollo 11, 12 and 17 missions.
Interestingly, this seemed to have an effect on how well the plants responded to the soil. Those planted on the ground closest to the surface, from Apollo 11, fared worse; one plant even died. This is the layer of lunar regolith most exposed to cosmic rays and the solar wind, which damages it.
In contrast, seeds planted in less exposed soils fared markedly better, although the results were not as good as those of plants grown in terrestrial volcanic ash. This information could help scientists figure out the best way to grow plants on the Moon, as well as develop ways to make lunar soil more hospitable to plants.
However, we are not there yet. More research will need to be done to characterize and optimize lunar soil for plant growth before we can consider using lunar soil for farming. But now scientists at least have a clearer understanding of what they are working with and what the next steps should be.
“We wanted to do this experiment because, for years, we asked ourselves this question: Would plants grow on lunar soil?” Ferl said. “Turns out the answer is yes.”
The research has been published in Communications Biology.