Duckweed: A Tiny Aquatic Plant with Enormous Potential for Bioregenerative Life Support Systems

Self-sufficiency of space life support systems is crucial for long-duration exploration missions. NASA’s Technology Roadmap states that this will be achieved through resource recovery, system closure, high-reliability, autonomous control, and minimal use of expendables. Regenerative space life support will undoubtedly require food production to recover nutrients and close the carbon loop. Biological plant based systems also provide multiple life support functions such as CO2 removal, oxygen production, water recovery, and waste recycling. Technologies that both treat waste and produce food with minimal resources (such as energy and water) enable sustainable agriculture on Earth, benefiting populations in water and nutrient scarce regions. Duckweed (Lemna minor) is a tiny flowering plant with enormous potential for bioregenerative space life support. This small angiosperm is gaining global recognition as a powerful and ecologically friendly means of absorbing nutrients and other pollutants from wastewater. In addition, duckweed has a very high protein content and very little fibrous material, making it a 100% edible food supplement for diets lacking in protein. This review explores the capacity of Duckweed to provide a food supplement for a spacecraft crew that is high in protein, while recycling nutrients from human metabolic waste, removing and reducing CO2 from the cabin air, providing oxygen, and purifying metabolic waste water for drinking (ridding of the need to process brine). The review also presents challenges in the safe implementation of a duckweed wastewater treatment and food production system with recommendations for possible solutions and future research.