Human sewage combined with lunar or Martian regolith can provide the necessary nutrients to grow crops on the Moon and Mars, a new experiment has shown.
“In lunar and Martian outposts, organic waste will be key to generating healthy, productive soil,” study leader Harrison Coker of Texas A&M University said in a statement. “By weathering simulating soils from moon and March with organic waste streams, it was revealed that many essential plant nutrients can be harvested from surface minerals.”
If humans are going to make permanent bases on the moon or Mars, they need to learn live off the land — especially on Mars, where the travel time to Earth is too high and the cost of travel too high to rely on regular supplies, including fertiliser, from home.
Unfortunately, the dirt on the moon and Mars is currently not suitable for growing crops. Scientists refer to this dirt as “regolith” rather than soil because the regolith is inorganic, and while the regolith contains nutrients in minerals, those nutrients are locked up and are mostly unavailable to life as things stand.
So scientists have been looking for ways to make these nutrients available and transform the dead regolith into something closer to organic soil.
In the past, scientists have taken a variety of approaches to this problem, such as heat treatment, hydroponics, liquid salts (known as ionic liquids) and electro-deoxidation which on Earth are used to break down pollutants in wastewater. However, although they have met with varying levels of success, all of these methods have a common flaw: they require additional chemicals, energy and technology to be imported and to be constantly replenished with fresh nutrients, making them expensive processes.
So Coker and his team looked for another way to prepare soil for crops using in situ resource utilization. In other words, everything would already be at hand on the Moon or Mars, and none of the components of the process would need to be imported from Earth beyond the original technology.
The components are simply regolith and the human waste produced by the astronauts. Coker and Julie Howe, also from Texas A&M, teamed up with scientists at NASA’s Kennedy Space Center in Florida, where researchers are running a prototype of a bioregenerative life support system (BLiSS) called the Organic Processing Assembly (OPA).
OPA is a series of bioreactors and filters. Sewage is placed at one end, works its way through the system and comes out at the other end as a nutrient-rich drain with the toxins filtered out.
The experiments used simulated sewage along with simulated regoliths, one representing the Moon and the other Mars. Simulants must be used because we actually have no real Martian regolith on Earth, and the samples of lunar regolith we do have are rare and precious.
Coker’s team combined the effluent produced by OPA with the simulated regoliths and placed the two different solutions in a shaker for 24 hours, which acted to “weather” the regoliths.
They found that the mixtures resulted in the lunar regolith simulator desorbing (ie releasing) significant amounts of sulfur, as well as calcium and magnesium. The Mars simulant also produced these, in addition to sodium. These nutrients are then available for plants to feed on and grow.
Furthermore, one could see through a microscope that particles of simulant had been weathered in the shaker. The moon simulant particles had tiny pits on them, while the martian simulant particles were covered in nanoparticles. This type of weathering is a significant step towards becoming a more soil-like material.
Of course, plants need more varied nutrients than what was desorbed in this experiment; iron, zinc and copper are just some of the necessary nutrients that were missing.
In addition, the BLiSS technology is not yet fully effective, and the simulants used are only approximate to the real thing – real lunar and Martian regolith may react differently. So more experiments in this direction are needed.
But the research is already piling up: The new results are just the latest in a series exploring how resources on the Moon or Mars could be used to help astronauts live there.
In January 2025, for example, scientists revealed that crops grow better in fertilized lunar regolith rather than the Martian variety. The experiment used Milorganite, which is a brand of fertilizer made from heat-treated microbes that digest sewage. The Martian regolith did not fare so well in the tests, partly because it can be very dense and clay-like, which prevents oxygen from reaching plant roots.
Martian regolith also contains perchloratewhich is a strong oxidizing agent. Studies by researchers at Indian Space Research Organisation have explored how two bacteria, Sporosarcina pasteurii and Croococcidiopsiscould create a binder from their waste products that, when combined with guar gum, could bond particles of Martian regolith together to form a kind of brick-like material that could be used to build habitats. However, the toxicity of the perchlorate necessitated the researchers find more robust strains of the bacteria to resist the oxidizing effects.
The same researchers have also shown how Sporosarcina pasteurii can be used in a similar way to make brick-like materials on the moon. However, they showed that sintering a regolith mixture in a furnace produces stronger bricks than the bacteria – but such bricks are prone to cracking under lunar conditions. So their solution was to use Sporosarcina pasteurii-derived brick material as a sealant to fill any cracks in the sintered moonstones.
If we’re going to live on the moon or Mars, it will give a whole new meaning to the concept of living off the land, and eventually, hopefully, make our extraterrestrial outposts as self-sufficient as possible.
Coker’s team’s findings were published Jan. 7 in the journal ACS Earth and Space Chemistry.
