A greenhouse on the Moon, full of terrestrial vegetables to feed a human colony: science fiction has installed this dream in our imagination, which is a little closer today, after announcing the success of growing plants on lunar soil. Specifically, these are specimens of Arabidopsis thaliana –a plant similar to watercress, commonly known as a 'caterpillar'– which have germinated in samples collected during three NASA Apollo missions. The achievement is published this Thursday in the magazine Nature.
“The idea of a greenhouse on the Moon is the stuff that dreams of space exploration are made of. When civilizations move to settle somewhere, we humans always carry our agriculture with us. The ability to successfully take plants with us to the Moon is the way we will be able to grow food to stay there for a while without the need for resupply, also to purify the air by removing CO2 and produce drinking water," he said this week. At a press conference, space biologist and geneticist Robert Ferl, one of the researchers from the University of Florida involved in the experiment and awarded precisely this Wednesday with NASA Medal for Exceptional Public Service.
“Plants have always been part of the deep exploration agenda. Showing that plants can grow on lunar soil is a huge step," Ferl explained to the press. Researchers have found, however, that these plants grow more slowly and show more signs of stress when grown in lunar soil samples than in volcanic ash from Earth.
Ferl and his colleagues wanted to see if lunar soil could support plant life. For this they have cultivated specimens of arabidopsis thaliana, a small flowering plant, native to Eurasia and Africa. Scientists often use it in experiments because its complete genetic map was sequenced in the year 2000. In this case, they have grown it on 12 soil samples collected during the Apollo 11, 12 and 17 lunar missions (in 1969 and 1972).
The idea of a greenhouse on the Moon is the stuff that dreams of space exploration are made of
Robert Ferl — Biochemist and geneticist
The samples were collected in different soil layers during each mission, those from Apollo 11 had been exposed to the lunar surface for longer than those from Apollo 12 and Apollo 17, details the University of Florida in a statement.
The researchers examined whether the way these plants grow and adapt differed from those grown in 16 samples of volcanic ash from Earth. A volcanic ash – 'regolith', in geological jargon – that has a particle size and mineral composition similar to that of lunar soil.
The team discovered that, although the seedlings – the plant in its early stages of development – could grow in all soil conditions, in lunar soil they do so more slowly, taking longer to expand their leaves and putting out more stunted roots than those grown in lunar soil. volcanic ash.
Furthermore, while some plants grown in lunar regolith have a similar shape and color to those grown in volcanic ash, others grow stunted and contain dark, reddish pigments, characteristics that often indicate plant stress.
face the unknown
The researchers emphasized, at the press conference, the fact that we are dealing with the study of terrestrial living beings reacting to an environment that they had never faced, throughout their evolution as a species. Molecular biologist and geneticist Anna-Lisa Paul, another of the University of Florida researchers, used the toolbox metaphor to explain what plants were up against: “By looking at the tools needed to do a job, we can deduce what kind of job it is."
In this case, the 'tools' that selected those plants to cope with an unknown environment were certain genes; specifically, the activation of certain genes. Genetic analysis of three smaller, darker plants revealed that they expressed more than a thousand genes, mostly related to stress, at different levels than those grown in ash.
In addition, the researchers found that the plants grown in the Apollo 11 samples did not grow as well as those grown in the Apollo 12 and 17 samples and expressed a greater number of genes at different levels than those grown in volcanic ash.
Plants grown in the Apollo 11, 12 and 17 samples expressed 465, 265 and 113 genes at different levels, respectively. 71% of these genes were associated with stress caused by salts, metals and reactive oxygen-containing molecules.
The results indicate that although lunar soil can be used to grow plants, it does not support plant growth as well as volcanic ash, especially if it has been more exposed to the Moon's surface. The researchers speculate that cosmic ray and solar wind damage to the lunar soil, as well as the presence of small iron particles in the soil, could induce stress responses in plants and impair their development.
The authors conclude that the findings published Thursday show the need for more research on the interactions between plants and lunar soil for plant life to grow more efficiently.