The lunar surface is covered with dead volcanoes, impact craters, and lava flows, shining bright nightly in brilliant grayscale. Besides the oceans of water found on our blue planet, the moon lacks plant growth, which is integral for human life to flourish on other worlds.
Using samples of rock and dust that cover the hard rock surface (regolith) collected during the Apollo 11, 12, and 17 missions as substrates to grow plants, University of Florida scientists report the germination and development of a terrestrial plant these mixtures of moon material—albeit with much difficulty.
The findings, “Plants grown in Apollo lunar regolith present stress-associated transcriptomes that inform prospects for lunar exploration,” is published in the Nature journal Communications Biology, show that plants, in this case, Arabidopsis thaliana, grown on lunar regolith were slow to develop and displayed severe stress. Lead author Anna-Lisa Paul, director of the Interdisciplinary Center for Biotechnology Research, said that understanding the adaptation in the plant’s patterns of gene expression and metabolism to grow in this new and novel material will support future exploration of taking plants off the planet.
Author Stephen M. Elardo, assistant professor of Geological Sciences, thinks that the primary reason the plants grown on lunar regolith showed such stress-related responses is that lunar regolith is quite different from the terrestrial substrates would typically grow. The moon is very poor in water, carbon, nitrogen, and phosphorous, and lunar soils don’t have many of the nutrients needed to support plant growth.
Additionally, the physical characteristics of lunar regolith are not particularly hospitable. The lunar regolith is very fine-grained and powdery, and the fragments are quite sharp and angular. “Apollo regolith is quite abrasive,” said Elardo. “[Lunar regolith] got onto the door seals of the Apollo missions. It abraded space suits. It’s not something you’d want to breathe in—it would damage your lungs. You wouldn’t want to put it in your garden to grow your tomatoes.”
Lunar regolith mineralogy is also quite different than terrestrial soils. There are lots of tiny glass fragments containing gases and metallic iron in the lunar regolith. “These are properties that plants did not evolve to grow successfully in and presented a lot of challenges to the plants,” said Distinguished Professor Robert Ferl, a horticultural sciences professor in UF’s Institute of Food and Agricultural Sciences. “Going forward, we really need to explore what properties of the soil are driving these stress-related responses in plants.”
The biggest questions are why we would be interested in growing plants in lunar soil. Ferl says that we need to think about the fundamental principles for living off the earth’s surface. When humans move as civilizations, and not just to explore for a couple of days, we take our agriculture with us, which is critical to creating long-term habitats on the moon.
“The ability to take plants with us successfully to the moon is how we will grow our own food, stay there for a while without resupply, purify air and takeaway CO2, and produce clean water,” said Ferl. “We can do plant growth hydroponically, but the idea of bringing lunar soil into a lunar green house is the stuff of exploration dreams. Plants have always been part of the deep exploration agenda. Showing that plants will grow in lunar soil is actually a huge step in that direction in being able to establish ourselves in lunar colonies.”