Key Takeaways:

  • The scientists recognised the agglutinates as one of the potential reasons for lack of growth by the seedlings in the Apollo soil compared to the terrestrial soil, and also for the difference in growth patterns between the three lunar samples.
  • This is the way that the regolith changes, through bombardment of the Moon’s surface by cosmic radiation, solar wind and minuscule meteorites, also known as space weathering.
  • This is an important conclusion, because it demonstrates that plants could be grown in lunar habitats using the regolith as a resource.

What do you need to make your garden grow? As well as plenty of sunshine alternating with gentle showers of rain – and busy bees and butterflies to pollinate the plants – you need good, rich soil to provide essential minerals. But imagine you had no rich soil, or showers of rain, or bees and butterflies. And the sunshine was either too harsh and direct or absent – causing freezing temperatures. 

Could plants grow in such an environment – and, if so, which ones? This is the question that colonists on the Moon (and Mars) would have to tackle if (or when) human exploration of our planetary neighbours goes ahead. Now a new study, published in Communications Biology, has started to provide answers. 

Image of Arabidopsis thaliana.
Arabidopsis thaliana on Earth. wikipedia, CC BY-SA

The researchers behind the study cultivated the fast-growing plant Arabidopsis thaliana in samples of lunar regolith (soil) brought back from three different places on the Moon by the Apollo astronauts. 

Dry and barren soil

This is not the first time that attempts have been made to grow plants in lunar regolith though, but it is the first to demonstrate why they don’t thrive.

The lunar regolith is very different from terrestrial soils. For a start, it doesn’t contain organic matter (worms, bacteria, decaying plant matter) that is characteristic of soil on Earth. Neither does it have an inherent water content. 

But it is composed of the same minerals as terrestrial soils, so assuming that the lack of water, sunlight and air is ameliorated by cultivating plants inside a lunar habitat, then the regolith could have the potential to grow plants.

The research showed that this is indeed the case. Seeds of A. thaliana germinated at the same rate in Apollo material as they did in the terrestrial soil. But while the plants in the terrestrial soil went on to develop root stocks and put out leaves, the Apollo seedlings were stunted and had poor root growth. 

The main thrust of the research was to examine plants at the genetic level. This allowed the scientists to recognise which specific environmental factors evoked the strongest genetic responses to stress. They found that most of the stress reaction in all the Apollo seedlings came from salts, metal and oxygen that is highly reactive (the last two of which are not common in terrestrial soil) in the lunar samples. 

Image of the plants grown in the experiment.
Experimental results, with different wells for each soil. Paul et al., CC BY-SA

The three Apollo samples were affected to different extents, with the Apollo 11 samples being the slowest to grow. Given that the chemical and mineralogical composition of the three Apollo soils were fairly similar to each other, and to the terrestrial sample, the researchers suspected that nutrients weren’t the only force at play. 

The terrestrial soil, called JSC-1A, was not a regular soil. It was a mixture of minerals prepared specifically to simulate the lunar surface, and contained no organic matter. 

The starting material was basalt, just as in lunar regolith. The terrestrial version also contained natural volcanic glass as an analogue for the “glassy agglutinates” – small mineral fragments mixed with melted glass – that are abundant in lunar regolith. 

The scientists recognised the agglutinates as one of the potential reasons for lack of growth by the seedlings in the Apollo soil compared to the terrestrial soil, and also for the difference in growth patterns between the three lunar samples. 

Agglutinates are a common feature of the lunar surface. Ironically, they are formed by a process referred to as “lunar gardening”. This is the way that the regolith changes, through bombardment of the Moon’s surface by cosmic radiation, solar wind and minuscule meteorites, also known as space weathering. 

Because there is no atmosphere to slow down the tiny meteorites hitting the surface, they impact at high velocity, causing melting and then quenching (rapid cooling) at the impact site. 

Gradually, small aggregates of minerals build up, held together by glass. They also contain tiny particles of iron metal (nanophase iron) formed by the space weathering process. 

It is this iron that is the biggest difference between the glassy agglutinates in the Apollo samples and the natural volcanic glass in the terrestrial sample. This was also the most probable cause of the metal-associated stress recognised in the plant’s genetic profiles.

So the presence of agglutinates in the lunar substrates caused the Apollo seedlings to struggle compared with the seedlings grown in JSC-1A, particularly the Apollo-11 ones. The abundance of agglutinates in a lunar regolith sample depends on the length of time that the material has been exposed on the surface, which is referred to as the “maturity” of a lunar soil.

Very mature soils have been on the surface for a long time. They are found in places where regolith has not been disturbed by more recent impact events that created craters, whereas immature soils (from below the surface) occur around fresh craters and on steep crater slopes. 

The three Apollo samples had different maturities, with the Apollo 11 material being the most mature. It contained the most nanophase iron and exhibited the highest metal-associated stress markers in its genetic profile.

The importance of young soil

The study concludes that the more mature regolith was a less effective substrate for growing seedlings than the less mature soil. This is an important conclusion, because it demonstrates that plants could be grown in lunar habitats using the regolith as a resource. But that the location of the habitat should be guided by the maturity of the soil.

And a last thought: it struck me that the findings could also apply to some of the impoverished regions of our world. I don’t want to rehearse the old argument of “Why spend all this money on space research when it could be better spent on schools and hospitals?”. That would be the subject of a different article. 

But are there technology developments that arise from this research that could be applicable on Earth? Could what has been learned about stress-related genetic changes be used to develop more drought-resistant crops? Or plants that could tolerate higher levels of metals?

It would be a great achievement if making plants grow on the Moon was instrumental in helping gardens to grow greener on Earth.

Contributor

Recently Published

Key Takeaway: Scientists have discovered that some organelles function perfectly without a membrane, introducing a new class called biomolecular condensates. These membraneless organelles create unique biochemical compartments within cells, attracting specific proteins and RNA molecules. Currently, scientists have identified around 30 different types of biomolecular condensates, compared to just over a dozen traditional, membrane-bound organelles. […]
Key Takeaway: Memory research has long explored the reasons behind forgetting, with the “forgetting curve” illustrating that people lose details of new information quickly after learning it. Memory formation involves strengthening synapses, making the memory more resilient. Memory is also adaptive, constantly evolving to handle new information. This adaptability is vital for navigating minor changes […]

Top Picks

Key Takeaway: Alice Walton, a Walmart heiress, has a $1.5 billion philanthropic footprint, including a $390 million donation in 2023 to support the Alice L Walton School of Medicine. However, her philanthropic efforts raise questions about the societal costs of billionaire giving and the genuineness of her contributions. The broader social and economic costs of […]
Key Takeaway: CubeSats, affordable, lightweight satellites, are revolutionizing space exploration by focusing on single scientific goals like observing asteroids or tracking water on the Moon. They travel as secondary payloads, minimizing space debris and accelerating discovery. CubeSats are also unlocking mysteries of distant worlds, paving the way for humanity’s dreams of becoming a multiplanetary species. […]
Key Takeaway: The fascination with fear is deeply rooted in human evolution, with emotions playing a critical role in survival. Controlled fear experiences, such as watching horror movies or navigating a haunted house, offer a safe way to engage with this powerful emotion. Exposure to intense fear reduces anxiety levels afterward, leaving people feeling more […]
Key Takeaway: Daron Acemoglu, Simon Johnson, and James Robinson were awarded the 2024 Nobel Memorial Prize in economics for their book Why Nations Fail, which argued that countries succeed when they adopt inclusive institutions like democracy, while extractive institutions stifle growth by concentrating power and wealth in elites. However, their theory has faced criticism for […]
Key Takeaway: In a world filled with crises, existential anxiety is a growing concern. This anxiety often manifests as mental distress, with the brain responding with stress hormones. Doomscrolling, a cycle of anxiety, can intensify feelings of helplessness and vulnerability to conspiracy theories. To manage this, stress-reduction exercises, emotional and social connections, and problem-solving can […]

Trending

I highly recommend reading the McKinsey Global Institute’s new report, “Reskilling China: Transforming The World’s Largest Workforce Into Lifelong Learners”, which focuses on the country’s biggest employment challenge, re-training its workforce and the adoption of practices such as lifelong learning to address the growing digital transformation of its productive fabric. How to transform the country […]

Join our Newsletter

Get our monthly recap with the latest news, articles and resources.

Login

Welcome to Empirics

We are glad you have decided to join our mission of gathering the collective knowledge of Asia!
Join Empirics