When U.S. astronauts landed on the moon in 1969, they brought back lunar soil that was just used to grow plants – an experiment that might lead to greenhouses on the moon, according to NASA.
“They would have to have a greenhouse just like a human would have to have a greenhouse because that there’s no atmosphere on the surface of the Moon,” said Anna-Lisa Paul, a professor in Horticultural Sciences at the University of Florida who worked on the experiment. “So all of the plant growth would be being carried on in some kind of greenhouse or other sort of enclosed habitat along with its attending humans.”
For more, stream KCBS Radio now.
In addition to lunar soil collected during Apollo 11’s trip to the moon, Paul and a team of scientists were able to grow Arabidopsis thaliana plants, in lunar soil called regolith collected during the Apollo 12 trip in late 1969 and the Apollo 17 trip in 1972. The study was part of the Apollo Next Generation Sample Analysis Program.
“It was pretty hard to get those,” said Paul of the lunar soil samples. “You have to remember, they’re a national treasure, they are completely irreplaceable in their original form.”
Paul explained that each trip brought back regolith from a different part of the Moon.
“The regolith from the Apollo 11 site, for instance, was more mature,” she said. “That means it has been exposed to the cosmic wind for longer.” Regolith from the Apollo 17 trip was collected after it got caught underneath the bumper of the lunar rover, Paul added.
Each of the samples was basaltic, similar to lava. For the experiment, scientists grew another control group of plants in volcanic ash. As for the lunar samples, only a gram of regolith was allotted for each plant. The lunar soil, water and seeds were placed on trays located in a clean room. A nutrient solution was added daily.
“We put the regolith inside these little pots and then planted seeds on top of them, watered them from below and: instant lunar garden,” said Paul.
She and her team were surprised how fast the plants in lunar regolith sprouted.
“After two days, they started to sprout!” said Anna-Lisa Paul, who is also a professor in Horticultural Sciences at the University of Florida, and who is first author on the paper. “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.”
While they grew, plants in the lunar soil did not look as healthy as the Arabidopsis thaliana growing in volcanic ash.
“The roots that were growing in the regolith were kind of scrunched up,” Paul said. She explained that the plants reacted to the low-nutrient lunar soil as if they were going through “salt stress” or “metal stress” in Earth soil with an excess of certain elements. Some had stunted leaves and other had a reddish color.
“So that was an interesting insight, that they were changing the way they express their genes to adapt to that new and novel environment,” said Paul.
Just before the plants started to flower – around 20 days into the experiment – the research team ground up the pants to study their RNA, a transcription of genes coded in DNA. This part of the project confirmed that the plants in lunar soil were under stress. However, they did grow.
“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.”
According to NASA, the research “opens the door” to one day growing plants on the Moon in greenhouses.
“Not only is it pleasing for us to have plants around us, especially as we venture to new destinations in space, but they could provide supplemental nutrition to our diets and enable future human exploration,” said Sharmila Bhattacharya, program scientist with NASA’s Biological and Physical Sciences (BPS) Division.
In fact, the Arabidopsis thaliana plants used for the experiment are related to vegetables such as broccoli. However, Paul said her crew wasn’t tempted to snack on them.
“Think about it: they’re a very small and very precious resource that we wanted to save to do the biochemical analyses,” she said.
“People have eaten them before, but it's not exactly something that would be good in a salad.”
In the future, Paul hopes to replicate the experiment and possibly engineer plants that fare better in lunar soil.
“So instead of putting their energy into the stress response, they put that energy into making more broccoli,” she said.