CI Asteroid Regolith as an in Situ Plant Growth Medium for Space Crop Production

Abstract

Human expansion into the solar system is currently at the forefront of space research. For our astronauts to survive, they will need to be fed a healthy and nutritious diet on a consistent basis. Right now, our current method of feeding astronauts consists of resupplied prepackaged food from Earth, which is unsustainable for long-term missions. Using planetary resources via in situ resource utilization to grow crops is the next step toward sustainability in space. Asteroids are an abundant space resource and should not be overlooked when considering crewed missions. In particular, the primordial CI carbonaceous asteroids are of interest because the regolith is suggested to contain soluble elemental nutrients, such as phosphorous and potassium, that crops can use for growth and development. We present a study on the ability of CI carbonaceous asteroid regolith simulant to sustain plant growth of lettuce (Latuca sativa), radishes (Raphanus sativus), and peppers (Capsicum annuum). We tested growing the selected crops in increasing mixtures of simulant and peat moss. The results showed that each species reacted differently to each treatment and that the radishes were more affected by the treatments. Subsequent analysis showed that the simulant contains small amounts of plant-usable nutrients, despite its high pH, low cation exchange capacity, and classification as a silt-based soil. Our results indicate that the simulant is prone to compaction and crusting, leading to drought stress on the crops. Further investigations are needed to determine mitigation strategies to make CI asteroid regolith a more conducive soil.