When the Artemis program returns humans to the Moon in (hopefully) a few years, there is a lot of logistics that must be addressed to keep such fragile creatures alive in such a hostile environment.
Not least the food issue. Space agencies involved in the International Space Station have, to date, a great deal of experience providing prepackaged provisions, but there are advantages to accessing fresh food, including physical and mental health.
If the lunar soil proves to be a convenient medium for growing fresh crops, that would be amazing. So a team of scientists used a few precious grams of actual moon samples collected during the Apollo missions to try to grow plants — specifically, cress, or Arabidopsis thaliana.
“For longer future space missions, we might use the Moon as a hub or launch pad. It makes sense that we’d like to use the soil that already exists to grow plants,” says horticulturist Rob Ferrell of the University of Florida.
“So, what happens when you grow plants in lunar soil, which is something completely outside the plant’s evolutionary experience? What are the plants going to do in a lunar greenhouse? Can we have lunar farmers?”
Well, spoiler: Moon dust, also known as lunar regolith, isn’t terribly good at growing plants. But this research is just the first step toward one day growing plants on the moon in an exciting science fiction future.
The current amount of lunar sample material here on Earth is very small, and therefore valuable and highly valuable.
Ferrell, colleagues, and fellow University of Florida horticulturist Anna Lisa Ball and geologist Stephen Ellardo were given a loan of just 12 grams of the valuables, after three requests made over 11 years.
This entailed a very small and very narrow experiment – a small garden of Arabidopsis. They carefully divided their samples to distribute them among 12 thimble-sized containers, to each of which a nutrient solution and a few seeds were added.
Control groups from seeds were also planted in terrestrial soils from harsh environments, and simulated soils (a ground material used to simulate the properties of extraterrestrial soils).
For the experiment, the team used a Martian 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 simulations, but subtle differences could mean the real thing is a different story.
Above: Plants growing in the three groups of lunar soils and mimic soils.
This appears to be the case indeed. To the researchers’ surprise, nearly all of the seeds planted in the moon samples sprouted, but this is where things take a turn. Instead of merrily growing, the seedlings appeared smaller, slower growing, and varying in size much more than plants grown in the lunar simulation.
When the team extracted the plants for genetic analysis, they discovered why.
“At the genetic level, the plants were extracting tools typically used to deal with stressors, such as salt, minerals or oxidative stress, so we can conclude that the plants perceive the lunar soil environment as stressful,” Ball says.
“Ultimately, we would like to use gene expression data to help address how we can improve stress responses to the level where plants – especially crops – are able to thrive in lunar soil with very little impact on their health.
The lunar samples the researchers used came from three different locations on the moon, at different layers of depth from the surface, collected by the Apollo 11, 12 and 17 missions.
In , this appeared to have an effect on how well plants respond to the soil. Those planted in soil closer to the surface, from Apollo 11, fared worse; Until one plant died. This is the lunar regolith most exposed to cosmic rays and the solar wind that damages it.
By contrast, seeds grown in less exposed soil fare significantly better, although the results were still not as good as plants grown in ground volcanic ash. This information could help scientists discover how best to grow plants on the Moon, as well as develop ways to make lunar soil more suitable for plants.
We haven’t gotten there yet, though. More research will need to be done into characterizing lunar soils and improving them for plant growth before we can consider using lunar soils to grow crops. But scientists now 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’ve been asking this question: Will plants grow in lunar soil,” Ferrell said. “The answer, it turns out, is yes.”
The search was published in Communication biology.