With the Artemis program returning humans to the moon in (hopefully) a few years, there will be considerable logistics to be addressed to keep such fragile beings alive in such a hostile environment.
Last but not least, the issue of food. The space agencies involved with the International Space Station are now very experienced in providing pre-packaged food, but there are benefits to having access to fresh food, including physical and mental health.
If lunar soil proved to be a suitable medium for growing fresh plants, 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 thale cress Arabidopsis thaliana.
“For future, longer space missions, we could use the moon as a hub or launch pad. It makes sense that we would want to use the soil we already have for growing plants,” says University of Florida horticultural scientist Rob Ferl.
“So what happens when you grow plants in lunar soil, something totally outside of a plant’s evolutionary experience? What would plants do in a moon greenhouse? Could we have moon farmers?”
Well, spoilers: lunar dirt, also known as lunar regolith, isn’t particularly good for growing plants. But this research is just a first step toward one day growing crops 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 valued.
Ferl and his colleagues, University of Florida horticultural scientist Anna-Lisa Paul and geologist Stephen Elardo, received a loan of just 12 grams of the precious material after three applications over 11 years.
This required a very small, very narrow experiment – a mini garden of Arabidopsis. They carefully divided their samples into 12 thimble-sized pots, each containing a nutrient solution and a few seeds.
Control groups of seeds were also planted in 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 ground simulation and a lunar simulation called JSC-1A. This is important as previous experiments have shown that plants can grow well in either type of simulant, but subtle differences could mean the reality is a different story.
Above: Plants growing in the three sets of lunar soil and soil simulant.
That seems to be the case. To the researchers’ surprise, almost all of the seeds planted in the lunar samples germinated, but this is where things took a turn. Instead of growing happily, the seedlings appeared smaller, slower growing, and much more varied in size than the plants grown in the lunar simulant.
When the team then extracted the plants to conduct genetic analysis, they found out why.
“On a genetic level, the plants pulled out the tools normally used to deal with stressors like salt and metals or oxidative stress, so we can conclude that the plants experience the lunar soil environment as stressful,” says Paul .
“Ultimately, we want to use the gene expression data to investigate how we can improve stress responses to a level where plants – particularly crops – are able to grow on lunar soil with very little impact on their health.”
The lunar samples used by the researchers were from three different locations on the moon, at different depths from the surface, collected by Apollo 11, 12 and 17.
Interestingly, this seemed to have an impact on how well the plants responded to the soil. Those planted in 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 solar wind, causing it to become damaged.
In contrast, seeds planted in less exposed soil performed significantly better, although the results were still not as good as plants grown in terrestrial volcanic ash. This information could help scientists figure out how best to grow plants on the moon and devise ways to make the lunar soil more hospitable to plants.
But we’re not that far yet. Further research to characterize and optimize lunar soil for plant growth needs to take place before we can consider using lunar soil for growing plants. 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 we asked ourselves this question for years: would plants grow in lunar soil,” said Ferl. “The answer, it turns out, is yes.”
The research was published in communication biology.