If you’re like me and struggle to keep an indoor plant alive, the thought of growing plants in moon soil seems out of this world.
A team of scientists from the University of Florida have shown it can be done, by successfully growing the plant Arabidopsis thaliana in soil samples collected during the Apollo 11, 12 and 17 lunar missions. Arabidopsis thaliana, also known as thale cress, is a small flowering plant belonging to the Brassicaceae family (which includes mustard, cabbage and radish), and is a valuable plant used in numerous plant experiments.
Plants are essential in our ambitions for extended space exploration. As model organisms, they provide insight into space-related phenomena such as gravity and radiation but plants also provide necessary components for human habitation, such as food, oxygen, water recycling, and carbon dioxide sequestration.
While previous extra-terrestrial plant experiments have relied on hydroponic setups, this experiment used lunar soils to understand how plants might grow on the moon’s surface. The researchers also used a sample of compositionally similar lunar soil simulant made from volcanic ash from Earth as a control. The Apollo mission soils each had their own characteristics: samples from Apollo 11 had been exposed to lunar surfaces for longer than those from missions Apollo 12 or 17, as samples were collected from different soil layers during each mission.
So, how did the moon garden grow?
Results were mixed. All samples germinated normally 48–60 hours after planting, with lunar seedlings showing normal stems and cotyledons (the first leaves that emerge from the seed). From day six, researchers found stunted roots in the lunar samples compared to the volcanic ash plants. From day eight aerial growth (above the ground) became slower and more variable: the lunar plants took longer to develop leaves, and also grew smaller leaves in comparison to the Earthly controls. Plants grown in the Apollo 12 and 17 samples did better than those grown in Apollo 11 soil.
A genetic analysis of the least healthy-looking lunar plants found that over 1,000 stress-related genes were expressed at different levels to the volcanic ash plants. The Apollo 11 plants also expressed more genes differently compared to the Apollo 12 and 17 samples. Of these genes, 71% were associated with stress caused by salts, metals and reactive oxygen-containing molecules. Researchers think this may be due to the increased cosmic rays and solar wind that may have damaged the lunar soils.
While the plants flourished less, the experiment proved that lunar soil can support plant life; an important step in our understanding of the Moon. Unfortunately, as at time of publication, researchers had no comment on moon-cress flavour or recipes.