It’s history: plants have grown on lunar soil

Making the Moon greener is possible. Or at least, considered. Research shows that while growing plants in lunar soil is more difficult, it is a technique that works. We just need to better understand what makes this growth difficult.

Taking humans and allowing them to survive off Earth is already a very complicated thing. But also bringing organisms capable of withstanding the very hostile environment outside our planet is also a real challenge.

A big step forward has just been taken with a study published in Nature Communications Biology this May 12, 2022. The authors have achieved a feat: growing plants in lunar soil, a first. Clarification: they did not go for a ride on the Moon for a little gardening session. They used several samples collected during the Apollo 11, 12 and 17 missions to use as soil to see if plants could grow there.

We have shown that terrestrial plants can grow in several regoliths (the loose rock that covers the surface NdR) lunarsalutes the main author Anna-Lisa Paul. But it is difficult !»

12 grams of rocks for 12 plantations

The University of Florida biotech researcher specializes in plants in space. She even runs a laboratory dedicated to this question, the Space Plants Lab, which notably sent plantations to the International Space Station to control their growth. Here, with her team, she made a dozen small jars of different samples, each the size of a thimble, plus a reference sample from terrestrial volcanic rock.

A lunar regolith simulant modified to mimic material found on the Moon. The study has some limitations here because it is unclear whether the samples are representative of the Moon, and how much they have been altered by radiation or meteor impacts. In addition, they were distributed sparingly and the team obtained only 12 grams of rocks in total!

On the 16th day, plant growth in the simulant on the left, and the lunar soil on the right
On the 16th day, plant growth in the simulant on the left, and the lunar soil on the right. Source – Study

Lunar regolith is very different from what we have on Earthsays Stephen Elardo, one of the authors of the study. Its composition is not the same, it is much less hospitable, and it has been subjected to much more radiation. It’s not really the kind of soil we’re going to use to grow tomatoes! »

But here, they didn’t want to grow tomatoes, but Arabettes des dames. A plant present almost everywhere in Europe and in Asia, in particular at the edge of the roads like any weed. ” This choice seemed obvious to ussays one of the authors, Robert Ferl, because this plant has the advantage of being extremely well known. Its entire genome is decrypted by thousands of laboratories all over the world so we have a huge database. She even grew in the ISS! Another significant advantage: it is quite small and will therefore be able to feel comfortable in the pots of just over a centimeter in diameter used for the experiment. Once the seeds were sown, the scientists took care of them like any gardener, giving them water and light.

Positive but fragile results

The constraints to grow it in the lunar soil were still numerous, and the researchers did not necessarily leave triumphant. But after long months of gardening, it is clear that the lunar soil can indeed accommodate plants. “ All our plantations workedsmiles Anna-Lisa Paul. All the samples did give rise to plants that grew, but not all of them were very robust.»

At first, everything went well, the seeds germinated well. But after a few months, while the Arabidus sown in the simulant formed beautiful leaves, those of the other samples were much smaller, even almost dead. ” Plants took longer to grow, and showed signs of poor health, recognizes Anna-Lisa Paul. The environment in which they had grown up was not optimal.»

Anna-Lisa Paul and Robert Ferl in their laboratory
Anna-Lisa Paul and Robert Ferl in their laboratory. Source – Study

To find out for sure, they analyzed the plants at the genetic level, to see what made them react the way they did. Their verdict: the presence of salt or metals that oxidize them and prevent them from unfolding properly. Despite everything, for Robert Ferl, it’s a success: ” If nothing had pushed, we would have been at an impasse. But a positive result, even mixed, opens up new possibilities, it shows that we are going in the right direction.It is now a question of determining exactly what prevents plants from being healthy on the Moon in order to be able to correct the defects and test with other organisms, perhaps more resistant to the very inhospitable conditions of our satellite.

For the authors, succeeding in bringing agriculture into space is a necessary step if humanity wants to establish itself in the more or less long term on other stars. Be careful, terraforming fantasies are still quite distant, and this study only marks a first step. But researchers are now wondering what impact these plants might have on the very arid lunar regolith. Could the arrival of water and nutrients make the Moon less hostile?

Look at the world from space

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