Design of the Nutrient Delivery System for the EDEN NEXT Gen Greenhouse Module

Kurzfassung

Completely regenerative life support systems are essential to the long-term exploration of far-off locations in space. The shift from physico-chemical to bio-regenerative life support systems has the potential to be a major step towards that goal. The cultivation of plants as part of such a system not only provides life support functions and fulfills the dietary needs of the crew, but it also favorably affects human psychology. To maximize these benefits, a potential greenhouse module needs to provide a completely controlled environment for the plants. In this thesis, the Nutrient Delivery System, which is responsible for the root environment for a greenhouse module on the Moon, is designed. The result is an aeroponic cultivation system supplying two different nutrient solutions of independent compositions to a total growth area of 30.8 m². The distribution can be adapted depending on the respective share of plant species. The important parameters to enable a favorable root environment for plants including the necessary technological capabilities are discussed. For the aeroponic system, diaphragm pumps are chosen that operate at a pressure between 7.6 and 10 bar. They are supported by accumulator tanks reducing pressure spikes and the required number of pump cycles, thus increasing pump lifetime. To provide the optimal root conditions with a minimum of required crew time, the electrical conductivity and the pH are measured and adjusted automatically. Two 550 l tanks are used to store premixed nutrient solutions and are refilled automatically from storage containers. Microbes in the nutrient solution are eliminated by an ozone concentration of 1-3\,mg l. The System is designed to operate autonomously for one month at a time. A preliminary selection of components results in acquisition costs of roughly 32000€, a mass of around 612 kg and a power consumption of 650 W. The design decisions and key parameters established in this thesis provide a foundation for the execution of the project and its potential far-reaching benefits. As such, the nutrient delivery system design presented here may play a small part in helping to establish self-sufficient settlements in outer space.