When the Artemis program returns humans to the Moon in (hopefully) a few years, there will be considerable logistics to sort out to keep such fragile beings alive in such a hostile environment.
The question of food is not the least. Space agencies involved with the International Space Station are now very experienced in providing pre-packaged provisions, but there are benefits to having access to fresh food, including for physical and mental health.
If the lunar soil were to prove a favorable medium for the cultivation of new crops, it would be incredible. Thus, a team of scientists used a few precious grams of real lunar samples collected during the Apollo missions to try to grow plants – in particular, the watercress of Thale, or Arabidopsis thaliana.
“For future, longer space missions, we could use the Moon as a hub or as a launch pad. It makes sense that we want to use the soil that’s already there to grow plants,” says horticultural scientist Rob Ferl from the University of Florida.
“So what happens when you grow plants in lunar soil, something that’s 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 at growing plants. But this research is just the first step towards one day growing plants on the Moon in an exciting sci-fi future.
The current amount of lunar samples here on Earth is quite small, and therefore valuable and highly prized.
Ferl and his colleagues, University of Florida horticultural scientist Anna-Lisa Paul and geologist Stephen Elardo, secured a loan of just 12 grams of the precious object, after three requests made over 11 years.
It required a very small, very tight experiment – a mini-garden of Arabidopsis. They carefully divided their samples into 12 thimble-sized jars, to each of which were added a nutrient solution and some seeds.
Seed control groups were also planted in terrestrial soils from extreme environments and soil simulants (terrestrial material used to simulate the properties of extraterrestrial soils).
For the experiment, the team used a Martian ground simulator and a lunar simulator named JSC-1A. This is important, as previous experiments have shown that plants can grow well in both types of simulant, but subtle differences could mean the reality is a different story.
Above: Plants growing in the three Lunar Soil sets and the Soil Simulator.
This indeed appears to be the case. To the surprise of the researchers, almost all the seeds planted in the lunar samples germinated, but that’s when things changed. Instead of growing happily, the seedlings appeared to be smaller, slower growing, and much more variable in size than plants grown in the lunar simulant.
When the team then extracted the plants for genetic analysis, they discovered why.
“At the genetic level, plants were releasing the tools typically 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.” , said Paul.
“Ultimately, we’d like to use gene expression data to help determine how we can improve stress responses to the level where plants – especially crops – are able to grow in lunar soil with very little stress. impact on their health.
The lunar samples used by the researchers came from three different locations on the Moon, at different surface depth layers, collected by the Apollo 11, 12 and 17 missions.
Interestingly, this seems to have an effect on how plants react to soil. Those planted in the ground closest to the surface, from Apollo 11, fared less well; one plant even died. It is the layer of lunar regolith most exposed to cosmic rays and the solar wind that damages it.
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 the best way to grow plants on the Moon, as well as develop ways to make the lunar soil more hospitable to plants.
We’re not there yet, however. Further research into characterizing and optimizing lunar soil for plant growth will need to take place before we can consider using lunar soil to grow crops. But now scientists at least have a better understanding of what they’re working with and what the next steps should be.
“We wanted to do this experiment because for years we had this question: would plants grow in lunar soil,” Ferl said. “The answer, it turns out, is yes.”
The research has been published in Communications Biology.