A pair of agricultural scientists has successfully cultivated chickpeas in “lunar soil” in a recent study. The cultivation did not occur directly on the surface of the Moon or in lunar dust, but it represents a step forward for future lunar bases to become self-sufficient.
The research, led by Jessica Atkin of Texas A&M University and Sara Oliveira Pedro dos Santos, a Ph.D. student at Brown University, is still awaiting peer review but is already available for preprint on biorxiv. In the study, agricultural scientists used a simulation of lunar dust along with mycorrhizae and vermicompost to ensure the successful cultivation of chickpeas.
Cultivation is essential for space expansion
Growing one’s own food is a crucial requirement for the success of colonies on other worlds, and transporting Earth soil for this purpose can be prohibitively expensive. Consequently, developing cultivation techniques with extraterrestrial soil may be the optimal solution.
In the case of the Moon, there is no soil as we know it, and regolith is expected to be the primary medium for future colonies to cultivate. Thanks to the Apollo missions, we understand the composition of lunar dust and even have samples. While these samples do not offer ideal conditions for cultivation, researchers suggest that using terrestrial fungi and worm humus can resolve this issue.
Creating an ideal environment in lunar soil
Regolith primarily presents two problems that make it non-cultivable on its own: the presence of harmful toxins and a lack of essential nutrients. To address this, scientists used mycorrhizae to capture heavy metals from lunar soil and prevent them from reaching the plants, and worm humus to provide nutrients.
To avoid depleting the available Apollo mission samples, lunar regolith brought by them was replicated as faithfully as possible, distributed in pots containing between 25 and 100% lunar dust mixed with vermicompost. Half of the crops were protected with fungi, while the others had to fend off toxins on their own.
- Plants not inoculated with fungi began to die in the 10th week of the study.
- Those containing mycorrhizae but were in pots with 100% regolith died in the 2nd week.
- Those with up to 75% lunar soil and fungi showed better performance despite signs of chlorophyll deficiency.
Chickpeas and other crops
The choice of chickpeas was due to their richness in proteins and micronutrients, in addition to being vegetables, enabling a symbiotic relationship with fungi. Although the study did not consider lunar radiation and gravity, data collected by Chang’e 4 indicates that lunar low gravity may even favor the growth of terrestrial plants.
Further observations are still necessary to determine if the plants will yield chickpeas and if they can be consumed by humans. If successful, scientists may extend the research to other crops.
Not the first Attempt
In addition to the recent success in growing chickpeas in lunar soil, it’s worth noting that this endeavor isn’t the first attempt at cultivating plants beyond Earth’s atmosphere. The Vegetable Production System, known as Veggie, stands as a pioneering space garden situated on the space station. Veggie’s primary objective is to facilitate NASA’s exploration of plant growth in microgravity, providing fresh food for astronauts and contributing to their overall well-being during their missions in space.
The Veggie garden, approximately the size of a carry-on piece of luggage, typically accommodates six plants. Each plant is housed in a “pillow” filled with a clay-based growth medium and fertilizer. These pillows play a crucial role in maintaining a healthy balance of water, nutrients, and air around the plant roots, preventing issues like drowning or air engulfment, which can occur due to the unique fluid dynamics in microgravity environments.
In the absence of gravitational forces, plants rely on alternative environmental factors, such as light, to guide their growth. A bank of light-emitting diodes (LEDs) positioned above the plants emits a spectrum of light tailored to support optimal plant growth. The Veggie chamber often emanates a magenta-pink glow since plants reflect a significant amount of green light and utilize more red and blue wavelengths.
Veggie has achieved notable success, cultivating various plants, including three types of lettuce, Chinese cabbage, mizuna mustard, red Russian kale, and even zinnia flowers. Astronaut Scott Kelly notably enjoyed the zinnia flowers, picking a bouquet and capturing photographs of them floating in the cupola against the Earth’s backdrop. Some of the cultivated plants were harvested and consumed by the crew, with remaining samples sent back to Earth for analysis. Despite concerns about harmful microbes on the produce, no contamination has been detected thus far, ensuring that the food grown in Veggie remains safe and enjoyable for the spacefaring crew.