🌱 Human waste to fertilize lunar and Martian soil

Feeding astronauts on Mars without relying on supplies from Earth is a major challenge. A surprising avenue is emerging, however: transforming sterile soil into fertile land thanks... to human waste.

To establish permanent bases on the Moon or Mars, self-sufficiency is essential. The journeys are long and costly, making the importation of fertilizer impractical. The soil of these celestial bodies, called regolith, is inorganic and does not support plant growth without modification.


Scientists have explored a method using local resources. They combined effluents from simulated human waste with lunar and Martian regolith simulants. This mixture was stirred to replicate a weathering process, simulating the natural conditions that could occur in space.

The results show that this approach releases nutrients like sulfur, calcium, and magnesium from the lunar simulant, and adds sodium for the Martian one. These elements become accessible to plants, a step towards creating an organic soil. Microscopic observation reveals altered particles, with small cavities on the lunar simulant and nanoparticles on the Martian one.

But obstacles remain. Some essential nutrients, like iron or zinc, were not released. Furthermore, the simulants are not identical to real regolith, and the waste treatment technology needs to be optimized.

Other studies complement this picture. For instance, research has shown that plants can grow in fertilized lunar regolith. Also, bacteria could help build habitats by binding regolith particles, although toxins like perchlorates pose problems.

These advances pave the way for more self-sufficient space colonies. By recycling waste to nourish crops, astronauts could reduce their dependence on Earth's resources, making long-term exploration more viable.

The nature of extraterrestrial regolith

Regolith is the layer of dust and rocks that covers the surface of bodies like the Moon or Mars. Unlike Earth's soil, it is inorganic and therefore contains no organic matter or readily available nutrients for plants. This absence makes plant growth impossible without intervention.

On Earth, soil forms thanks to biological and climatic processes that release minerals. In space, regolith remains frozen, with its nutrients trapped in mineral structures. This explains why astronauts cannot simply sow seeds and hope for a harvest.

Understanding regolith helps design agricultural systems suited to space environments, taking into account the specific limitations of each celestial body.