Is this the first step towards terraforming other planets?

For the first time ever, scientists have sprouted plants from lunar soil. Image credit: Tyler Jones/UF/IFAS

Due to dramatic changes in Earth’s climate and the depletion of natural resources, the thought of modifying the environment of a different planet to make it habitable for human life has recently been at the center of attention. While terraforming a whole planet would take a very long time and wouldn’t even be possible with present-day technology, scientists at the University of Florida have made a breakthrough discovery that could be the first step towards just that – making another planet habitable.

For the first time ever, Anna-Lisa Paul, Stephen M. Elardo, and Robert Ferl were able to grow plants in lunar soil collected during the Apollo missions decades ago. The team published their findings in the journal Communications Biology.

It took them 15 years to convince NASA to send them samples of lunar soil. Image credit: Tyler Jones/UF/IFAS

The researchers have been requesting lunar samples from NASA for 15 years, having already succeeded in growing plants in samples imitating lunar soil. But because there aren’t a lot of lunar soil samples on Earth, NASA has repeatedly turned them down.

Nevertheless, after the scientists have developed a method that requires only 1 gram of soil sample per plant, the American space agency finally granted their request at the end of 2020. The move may also have to do with NASA’s Artemis program, launched in 2018, which aims to land humans on the Moon again.

“This research is critical to NASA’s long-term human exploration goals as we’ll need to use resources found on the Moon and Mars to develop food sources for future astronauts living and operating in deep space,” said NASA Administrator Bill Nelson. “This fundamental plant growth research is also a key example of how NASA is working to unlock agricultural innovations that could help us understand how plants might overcome stressful conditions in food-scarce areas here on Earth.”

Anna-Lisa Paul and her team received 12 grams of lunar soil that were collected during the Apollo 11, 12 and 17 missions between 1969 and 1972. The soil of the Moon, which is composed of rock fragments, mono-mineralic fragments, and various kinds of glasses, has been thoroughly studied since astronauts first brought samples to Earth after the first successful Moon landing in 1969. However, it’s been unknown if plants could grow in this regolith that differs greatly from the soil of the Earth. Until now.

The researchers used Arabidopsis thaliana seeds as their test subjects. Image credit: Tyler Jones/UF/IFAS

For the experiment, the research team filled small plastic wells with a gram of lunar soil, and placed Arabidopsis thaliana seeds into the Moon regolith. They also added some water and a nutrient solution to the soil each day. To see how lunar soil performs against other kinds of soils, the scientists created a control group, by planting seeds in Earth soil, volcanic ash, and in a synthetic substance that simulates lunar soil.

The scientists chose Arabidopsis thaliana as their test subject because it grows very easily, and it’s also one of the most studied plants in the world. More commonly known as thale cress, this small flowering plant native to Eurasia and Africa is actually edible, and it’s a relative of mustard greens and broccoli. But more importantly, due to being a model organism for plant biology research, its genetic code has been mapped, which allowed the scientists to examine how the alien soil would affect the plants gene expression. Also, Arabidopsis thaliana has a previous space history, since it was grown on board the International Space Station as well.

The results were actually so promising that they even left the researchers surprised. After two days, all the seeds germinated, even though they didn’t anticipate every one of them to sprout.

“After two days, they started to sprout!” said Anna-Lisa Paul, first author on the paper, and professor of horticultural sciences at the University of Florida. “Everything sprouted. I can’t tell you how astonished we were! Every plant – whether in a lunar sample or in a control – looked the same up until about day six.”

After 2 days, every seed have sprouted. Image credit: Tyler Jones/UF/IFAS

Even though the sprouts started out well, the ones planted in lunar soil began to show signs of struggle, and it became clear that they grew much differently than the ones in the control group. Their growth was much slower and their roots became stunted, in addition to a reddish pigmentation on the leaves, which is a sign of stress.

Just before the plants started to flower, the team harvested the plants, ground them up, and began studying their DNA. This showed that the plants were indeed affected by the alien soil, and reacted similarly to those that had been grown in other hostile environments.

Interestingly, there was also a difference in the growth of the sprouts depending on which lunar sample they were planted in. The reason behind this is that the samples collected during the Apollo 11 mission were more exposed to the harsh space environment than the Apollo 12 and 17 samples.

The plants that grew from lunar soil showed signs of stress. Image credit: Tyler Jones/UF/IFAS

While the “space plants” didn’t prove to be as robust as the ones planted in Earth soil, this experiment has exceeded all expectations, and opens the door to potentially growing plants on the Moon one day. It also provides many opportunities for scientists to expand our knowledge about space exploration.

The researchers want to conduct a series of follow-up studies next, to understand how growing plants in the Moon’s environment could actually alter its soil.