In (hopefully) a few years'' time, the Artemis program will return humans to the Moon. There are several steps to be taken to keep such fragile individuals alive in such a hostile environment.
Not least, is food. By now, the space providers at the International Space Station are very experienced in providing pre-packed provisions, but there are benefits to having access to fresh food, including to physical and mental health.
If lunar soil were to be a strong means of growing fresh crops, it would be amazing. So, a team of scientists used a few precious grams of lunar samples collected during the Apollo missions to try to grow plants specifically, the thale cress or Arabidopsis thaliana.
"For future and longer space missions, we may use the Moon as a hub or launching pad. It makes sense that we would like to use the soil that''s already there to grow plants," says horticulturalist Rob Ferl of the University of Florida.
"So, what happens when you grow plants on lunar soil, something that is completely outside of a plant''s evolutionary experience?" What would plants do in a lunar greenhouse? Could we have lunar farmers?
Well, spoiler: Moon dirt, also known as the lunar regolith, isn''t hugely successful at plant cultivation. However, this research is just a first step towards one day cultivating plants on the Moon in a bright future.
The actual amount of lunar sample material here on Earth is quite small, and thus important and highly prized.
After three applications poured over 11 years, Ferl and his colleagues, horticultural scientist Anna-Lisa Paul, and geologist Stephen Elardo, were granted a loan of just 12 grams of precious stuff.
A very small, very tight experiment required a mini-garden of Arabidopsis. They carefully divided their samples to be divided between 12 thimble-sized pots, each of which was added a nutrition supplement and a few seeds.
A total of eight seeds were harvested on terrestrial soil from harsh environments, as well as soil simulants (a terrestrial material used to simulate the properties of extraterrestrial soils).
The team used a Mars soil simulant and a lunar simulant named JSC-1A. This is crucial because previous experiments have shown that plants can grow well in both types of simulant, but subtle differences may mean the real thing is a different story.
Communications Biology, 2022 (Paul et al., Paul & al., Communications Biology)
Above:Plants are growing in three sections of lunar soil and the soil simulant.
It appears to be that almost all the lunar samples planted were sprouted, but that''s where things took a turn. Instead of growing muggyly, the seeds seemed to be smaller, slower-growing, and much larger than the ones grown in the lunar simulant.
The researchers then determined the plants for a genetic analysis to determine why.
"At the genetic level, the plants were removing the tools used to deal with stressors, such as salt and metals or oxidative stress, so we can make certain that the plants perceive the lunar soil environment as turbulent," Paul writes.
"We would aim to use gene expression information to help us understand how we can alleviate stress responses to the level in which plants, particularly crops, are capable to grow in lunar soil with very little impact on their health."
The lunar samples used by the researchers were found in three different locations on the Moon, at different depths from the surface, which were then collected by Apollo missions 11, 12 and 17.
This appeared to have an impact on how well the plants responded to the soil. Those planted in the soil closest to the surface, from Apollo 11, improved; one plant died. This is the layer of lunar regolith that is most exposed to cosmic rays and the solar wind, which causes it to collapse.
The seeds harvested in less exposed soil were significantly better, although the results were still poor as those of terrestrial volcanic ash. This information could help scientists identify how best to grow plants on the Moon, as well as to make the lunar soil more hospitable to plants.
Further research will need to be done in order to understand what they''re working with and what they''ll do next.
"We wanted to do this experiment because, for years, we were asking 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.