As there’s no plant life on the moon, you might wonder whether it’s possible to grow anything there at all. In this post, we’re going to take a look at a couple of experiments related to plants on the moon: growing plants in a lunar lander, and growing plants in lunar soil.
As plants need air, we can’t grow plants in the open on the moon’s surface, regardless of the quality of the soil. However, in 2019, there was an effort to grow plants in a vessel on the surface of the moon: the Chang’e 4 lunar lander.
Because the moon rotates to face Earth as it orbits, we always see the same side of the moon from Earth. This is the ‘near side’, whereas the side we can’t see from Earth is called the ‘far side’ or ‘dark side’.
It’s worth noting that the dark side isn’t actually much darker than the near side. Like the side we can see, the far side has phases when it’s lit up by the sun. If it’s a new moon on the near side, it’s a full moon on the far side. However, the far side doesn’t benefit from the reflected light of the Earth during lunar night.
Chang’e 4, an uncrewed probe launched by China, was the first spacecraft to land safely on the far side of the moon. It contained the Lunar Micro Ecosystem, a cylindrical container with a diameter of 16cm and a length of 18cm. Inside this container were water, soil, air, yeast, plant seeds and fruit fly eggs, along with cameras to monitor the experiment’s progress.
The lander reached the moon’s surface on 3 January 2019, and the seeds were watered. Images taken on 7 January 2019 showed that cotton seeds had sprouted inside the Lunar Micro Ecosystem: the first plants to grow on the moon. The hope was that the fly eggs would hatch and the flies, plants and yeast would all help to sustain each other in a miniature ecosystem.
Unfortunately, the Lunar Micro Ecosystem experiment was cut short. On 16 January 2019, less than a fortnight after landing, temperatures plummeted in the lunar night, and Chang’e 4’s equipment could not keep the ecosystem’s temperature controlled. The temperature inside the ecosystem fell to -52°C, freezing the contents. It wasn’t the desired end to the experiment, but the fact remained that seeds had successfully sprouted in the high-radiation, low-gravity environment of the moon.
The Chang’e 4 cotton seeds sprouted in soil brought from Earth. Can you grow plants in moon soil, though?
In early 2022, scientists at the University of Florida grew plants in soil samples from the moon. The plant they chose for their experiment was Arabidopsis thaliana, also called thale cress.
Arabidopsis thaliana is a small and quick-growing plant, and it’s often used in experiments. In 1982 it became the first species of plant ever to flower in space, aboard the Soviet space station Salyut 7, and it has also been grown on the International Space Station.
The samples of lunar soil used in this experiment came from the Apollo 12, Apollo 13 and Apollo 17 missions, which took place between 1969 and 1972. The experiment took place on Earth, where lunar soil is a scarce resource, so each Arabidopsis seed was planted in just a gram of soil.
The seeds were watered and given a daily nutrient solution. After two days, to the great excitement of the researchers, the plants started to sprout.
The plants struggled in the lunar soil. They were smaller and slower-growing than the control plants of the same species grown in NASA’s JSC-1A, a soil created on Earth using volcanic ash with the goal of mimicking soil from the moon. The plants grown in true lunar soil had stunted roots, and some of them were discoloured.
However, it’s exciting that the plants did still grow even in the moon’s inorganic soil, which had never before housed plant life. Although the moon’s lack of atmosphere makes it inhospitable to life, it’s still possible for plants to survive in its soil with some help.
In future experiments, it might be interesting to see whether plants growing in lunar soil might make the soil more habitable for later plant generations.
The scientists behind this experiment were Anna-Lisa Paul, Stephen M Elardo and Robert Ferl of the University of Florida. Their full scientific article about their discoveries, ‘Plants grown in Apollo lunar regolith present stress-associated transcriptomes that inform prospects for lunar exploration’, is available online.
There are many challenges to growing plants on the moon, such as the lack of atmosphere and the extreme temperatures. On the moon’s equator, temperatures can swing from 120°C in the daytime to -130°C at night, and it gets even colder at the poles. In addition, the nights on the moon are very long; every month, most parts of the moon will spend two weeks at a time without any sunlight.
Because of these obstacles, we’re unlikely to see greenery springing up on the moon’s surface any time soon. Plants on the moon need to be grown in enclosed, temperature-controlled environments where they can be supplied with air and light, and these environments must remain powered for long periods without access to solar energy.
However, Chang’e 4 has shown that, at least in theory, it is possible to grow plants on the moon in a sealed environment. The University of Florida’s experiments with lunar soil, meanwhile, have shown it might be possible to gather soil from the moon to grow plants in, rather than needing to import soil all the way from Earth.
These steps are small, but they’re significant. With each astrobotany experiment, humanity learns more about off-world plant growth. We can’t wait to see what we discover next.
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For more about growing plants in space, return to our AstroPlant page.