Carbonaceous asteroids as a means of space agriculture

The chemistry and mineralogy of carbonaceous chondrite meteorites and asteroids Bennu and Ryugu were evaluated for their potential as media for space‐based agriculture. Sustained human presence in space will require growing plants for food and recycling of air and water. The organic‐bearing serpentine and smectite, and associated minerals in asteroid regolith, contain essential plant nutrients such as N, P, K, Ca, Mg, and S, and show promise to support agricultural applications. Key challenges include high Mg/Ca ratios, heavy metal toxicity, and poor regolith structure. Terrestrial serpentine soil studies suggest microbial remediation techniques could be applied to detoxify asteroid simulants. Asteroid‐derived char offers promise for both heavy metal detoxification and use as an amendment; however, methods for removing the contaminated char are nonexistent and require development. Liming practices proven effective in low‐calcium terrestrial soils could improve levels of organic carbon, nitrogen, and phosphorous, which are vital for plant growth. Incorporating higher plants would not only improve nutrition for astronauts but also provide biomass to improve soil structure. All necessary plant nutrients can be sourced from asteroids, and surface boulders may be the first real foray in mining for space agriculture. Microbial and mycoremediation show both promise and limitations. Fungi and bacteria can immobilize, transform, or extract heavy metals while converting organics into bioavailable forms, reducing toxicity and improving plant growth. However, these approaches are not permanent, as metal can be re‐released. Significant scientific investment is required to scale the techniques, manage metal‐laden biomass, and ensure microbial survival in the enclosed life support environment.