If humans have any chance at all of living on the Moon or colonizing other planets, we’ve got to first find a way to grow food in those alien environments. The first stumbling block to accomplishing this is soil, arguably one of the most important elements to growing healthy crops. Recently, scientists have had some success with two different techniques, one hydroponic based and the other using bacteria to unlock nutrients in moon soil.
The soil on the Moon, known as regolith, is very different than what’s found on Earth. For starters, Lunar soil, known as “regolith,” contains no organic matter because it is not formed through biologic or chemical means as terrestrial soils are. Instead, lunar soil is primarily the result of mechanical weathering. Over billions of years, continual meteoric impacts and bombardment by solar and interstellar charged atomic particles ground the basaltic and anorthositic rock – the regolith of the Moon – into the progressively finer lunar soil.
There are also two profound differences in the chemistry of lunar regolith and dirt from terrestrial materials here on Earth. The first is that the Moon is very dry. As a result, those minerals with water as part of their structure (mineral hydration) such as clay, mica, and amphiboles are absent from the Moon’s surface. The second difference is that lunar regolith and crust are chemically reduced, rather than being significantly oxidized like the Earth’s crust.
Previous experiments using lunar samples returned to Earth show that plants can grow in lunar soil but they aren’t exactly healthy. A lack of nitrogen compounds and the tendency of lunar soil to become tightly compacted when wet makes it a challenge for plants to take root and flourish.
One new technique tackling this problem comes from the European Space Agency (ESA) and Norwegian lunar agriculture company Solsys Mining. According to a statement from the ESA, researchers have devised a way to grow plants hydroponically in nutrient-rich water instead of soil by extracting essential minerals from the regolith.
In theory, the regolith would be passed through a sorter to extract and process valuable mineral nutrients, which would then be dissolved in water and fed into a hydroponic greenhouse where plants grow vertically on the moon’s surface. The Solsys Mining team has already had success growing beans using simulated lunar regolith.
Another promising solution comes from researchers at the China Agricultural University in Beijing who found some success treating lunar soil with three species of bacteria. The action of the bacteria, the researchers said, made the soil more acidic. This resulting low pH environment caused insoluble phosphate-containing minerals to dissolve and release the phosphorus in them, increasing phosphorus availability for the plants. The researchers tested other bacteria as well, but those did not produce the same beneficial effects.
Yitong Xia, lead author of the study, points out that the soil treatment technique has benefits over hydroponic methods. Importantly, it does not require horticultural soil and equipment, or soil substitutes like hydrogels, all which would be very expensive to transport to the moon and maintain.
NASA does not have an exact timeline for establishing a human outpost on the Moon but it is part of its long-term plan that will eventually help send a crewed mission to Mars, aka the “Moon to Mars” plan. Being able to grow food in an alien environment will be even more important for humans exploring Mars as the distance from Earth is even greater. The average distance between the Earth and the Moon is 238,855 miles, versus the approximately 235 million miles to Mars. (Sources: Space, NASA, Gizmodo, ESA)
