Implications of different plant cultivation techniques for food production in space based on experiments in EDEN ISS
The EDEN ISS greenhouse is a space-analogue test facility near the German Neumayer III station in Antarctica. The facility is part of the project of the same name and was designed and built since 2015 and eventually deployed in Antarctica in January 2018. The first operational phase of the greenhouse started on February the 7th and continued until the 20th of November 2018. The purpose of the facility is to enable multidisciplinary research on topics related to future plant cultivation on human space exploration missions. Research on food quality and safety, plant health monitoring, microbiology, system validation, human factors and horticultural sciences was conducted. Part of the latter was an experiment to compare different plant cultivation techniques for lettuce and tomato plants. For lettuce two different harvest methods were applied, either batch harvesting of the fully grown lettuce heads or spread harvesting of mature leaves while leaving the plant alive to allow regrowth. The dwarf tomato plants were cultivated for three different durations. The short growth cycle ended right after the first set of fruits were harvested. The plants were then terminated and new plants sown. The longest duration cultivation involved several pruning events were old stems and leaves were removed from the plants allowing regrowth of new shoots. This paper compares the impact of the different cultivation techniques on the biomass output, the required crewtime and the required energy. The results show that depending on whether the goal is to optimize for highest biomass production, lowest energy demand or lowest crewtime demand some cultivation techniques are more favorable than others.