Imagine a future where astronauts cultivate lush gardens on the Moon or Mars, sustaining themselves with fresh produce grown in the most unlikely of places. Sounds like science fiction? It’s closer to reality than you might think. Inspired by the bleak agricultural scenes in the film Interstellar, Northern Arizona University doctoral candidate Laura Lee has embarked on a groundbreaking project to explore how we might transform barren extraterrestrial soils into fertile grounds for crops. But here’s where it gets controversial: her research suggests that fungi, fertilizer, and even human waste could be the keys to making this vision a reality.
At the heart of Lee’s work is the challenge of enriching the outer layers of planetary bodies—known as regolith—to support plant life. On 16 December 2025, at AGU’s Annual Meeting, Lee will unveil findings (https://agu.confex.com/agu/agu25/meetingapp.cgi/Paper/1899927) that highlight the potential of unconventional amendments like fungi, urea-based fertilizers, and biosolids (yes, poop) to help crops like corn thrive on the Moon and Mars. But is this approach practical, ethical, or even safe?
The Essential Ingredients for Life
Plants require 17 specific elements to survive and flourish. Carbon, hydrogen, and oxygen form cellulose, the backbone of cell walls, while nitrogen fuels vibrant green leaves and phosphorus strengthens roots. Other nutrients like iron and potassium are equally vital. However, the regolith on the Moon and Mars lacks many of these essentials. For instance, lunar regolith is nearly devoid of carbon and nitrogen, and its phosphorus is in a form plants can’t use, according to space biologist Jess Atkin of Texas A&M University.
Transporting Earth soil to space is prohibitively expensive due to the high cost of launching mass. As planetary geochemist Steve Elardo of the University of Florida puts it, ‘If you can avoid bringing all that up, it’s super advantageous.’ Instead, Lee and her colleagues are exploring lighter, more sustainable solutions, such as microbes and human waste, which astronauts will naturally produce during long-duration missions.
Simulating Extraterrestrial Soils
Studying real lunar or Martian regolith is challenging due to limited samples. The Apollo missions returned 382 kilograms of lunar material, while the Chang’e and Luna missions added just 4 kilograms. As a result, researchers like Lee rely on simulants—synthetic materials that mimic extraterrestrial regolith. For her experiments, Lee used simulants from Space Resource Technologies, one representing lunar highlands and the other approximating Martian regolith based on data from the Curiosity rover.
To address the lack of nitrogen in these simulants, Lee tested two nitrogen-rich amendments: a synthetic urea-based fertilizer commonly used by gardeners and Milorganite, a biosolid made from treated human waste produced in Milwaukee, Wisconsin. Milorganite not only provides essential nutrients but also mimics a resource astronauts will always have on hand—their own waste. ‘When they’re adding human waste, the best thing they’re doing is adding organic matter,’ explains Atkin, which can help bind regolith particles together.
The Role of Fungi in Space Farming
Lee also investigated the impact of arbuscular mycorrhizae, a symbiotic relationship between fungi and plant roots. These microscopic fungi extend the root zone, enhancing stability and nutrient uptake. In exchange, the plant provides carbon to the fungi. Lee’s experiments revealed that plants grown with fungi and Milorganite in lunar simulant showed higher chlorophyll levels and healthier growth compared to those without fungi. Even in Martian simulant, the addition of fungi improved plant survival and biomass production.
Ethical Dilemmas and Future Challenges
While the results are promising, they raise ethical questions. ‘There is a huge ethical question about bringing microorganisms to extraterrestrial places,’ Lee notes. Yet, astronauts will inevitably introduce microbes via their own microbiomes, and 96 bags of human waste already sit on the Moon’s surface from the Apollo missions. Additionally, experiments with real lunar regolith have shown that while plants can grow, they often struggle due to the regolith’s sharp, shard-like grains and incompatible chemistry.
And this is the part most people miss: Simulants, though useful for research, don’t perfectly replicate the complex chemistry of extraterrestrial regolith. As Elardo points out, simulants are often designed for engineering purposes, not biological studies. Still, Lee’s work opens exciting possibilities, such as using fungi to enhance nutrient uptake in challenging environments.
A Thought-Provoking Question for You
As we venture further into space, should we prioritize practical solutions like using human waste and fungi, even if they come with ethical and scientific uncertainties? Or should we tread more cautiously, risking delays in establishing sustainable extraterrestrial settlements? Share your thoughts in the comments—let’s spark a conversation about the future of space farming!
