The renewal of the human spirit for space exploration has many competitors, both government and private institutions, funding space programs, backed by the latest technology and innovation, with a vision to return humans to space and establish colonies on Moon and Mars. Agricultural innovation plays a major role in this regard. How far are we from having plants grown in a non-viable environment such as the Lunar surface?
The Earth’s ecosystem comprises the ideal factors required to sustain all life including that of plants. This includes the environmental factors in the hydrosphere, lithosphere, atmosphere, and biosphere. Water stands out as the most vital but having a soil composition and an atmosphere with climatic and weather variations that can retain and circulate the water establishing an interconnected network between the biotic and abiotic factors across the planetary body with an ideal gravity is necessary as well. In the absence of such conditions sustaining life is a challenge but a challenge to be solved, nonetheless.
The lunar environment does not meet these conditions in the least with a gravity measuring 1/6th of that of Earth’s that is not capable of sustaining a proper atmosphere and as a result, the lunar surface is constantly bombarded with harmful solar radiation and meteorites of a wide range in size. Consequently, the lunar surface is stratified, and a layer of soil covers the surface called the Regolith. Its chemical composition is composed of the major elements like oxygen, silicon, Aluminium, calcium, iron, magnesium, and titanium and minor elements like manganese, sodium, potassium, and phosphorous.
In comparison to terrestrial soil, it lacks carbonates, any form of organic matter, or hydrous minerals in other words no water but observations carried out by Deep Impact spacecraft in 2010 were successful in detecting trace amounts of water on the lunar surface, especially in the polar regions, which is believed to be endogenous due to solar winds, which are mostly protons, interacting with oxygen in the soil and exogenous from comets and asteroids harboring water ice.
A recent study carried out by Dr. Robert Ferl and Dr. Anna-Lisa Paul of the Space Plants lab at the University of Florida was focused on the feasibility of growing plants in lunar soil. They had chosen, Arabidopsis thaliana, a plant that is native to Eurasia and Africa and widely used in research in plant biology. It was planted in lunar soil samples collected during the Apollo 11, 12, and 17 missions, and in addition, in a control sample containing volcanic ash, the lunar simulant, from Earth. Nutrient solutions were added to each daily.
They were surprised to find sprouts from each sample on the second day after planting them and that they were like those grown in the volcanic ash but from day six onwards, they started to observe clear differences with that of the control sample. They displayed stunted root and leaf growth and reddish pigmentation. This was a result of stress growth resulting from a lack of nutrients or due to the presence of too much salt or heavy metals in the soil which was justified through RNA sequencing.
Finally, what does this imply? This is not a mere discovery but a door opener for future research on space agriculture, and horticulture which will bring us evermore closer to establishing colonies outside the home planet. The time has come when one’s imagination of a human settlement surrounded by plants whether it may be on the Lunar or Martian surface becomes a reality.
Written by Savindu Weerathunga
- Microsoft PowerPoint – Lunar_Soil_Physical_Properties.ppt (usra.edu)
- Scientists Grow Plants in Lunar Soil. (2022, May 13). Nasa.Gov. https://www.nasa.gov/feature/biological-physical/scientists-grow-plants-in-soil-from-the-moon
- Korotev, R. L. (2022). The Chemical Composition of Lunar Soil. Http://Eps.Wustl.Edu/. https://sites.wustl.edu/meteoritesite/items/the-chemical-composition-of-lunar-soil/
- It’s Official: Water Found on the Moon | Solar System Exploration Research Virtual Institute (nasa.gov)
- Paul, AL., Elardo, S.M. & Ferl, R. Plants grown in Apollo lunar regolith present stress-associated transcriptomes that inform prospects for lunar exploration. Commun Biol 5, 382 (2022). https://doi.org/10.1038/s42003-022-03334-8
- Slyuta, E.. (2014). Physical and mechanical properties of the lunar soil (a review). Solar System Research. 48. 330-353. 10.1134/S0038094614050050.