Entwurf einer Steuerelektronik für die Nährstofflösungsbehandlung in einer planetaren Treibhausanwendung

Abstract

Following the EDEN ISS mission, DLR is advancing the development of the (nearly) closed-loop greenhouse system for the upcoming EDEN LUNA mission, scheduled to occur in the LUNA analog environment in Cologne from 2026 onwards. The primary focus of the EDEN LUNA development is to enhance the automation of operations, aiming to save valuable crew time. Furthermore, new components are being tested with a focus on suitability for the space environment. The targeted advancements necessitate the creation of a new controller module for the Nutrient Delivery System (NDS), which is responsible for conditioning and supplying the greenhouse plants with nutrient solution. Throughout the design process of the module, several secondary considerations, such as cost-efficiency and streamlined design iteration, are being addressed. To accommodate these factors, a modular design approach known as snippet-based design has been adopted, enabling a flexible and adaptable system architecture that supports circuit level modularity and enables rapid future customization. Initiating the development process detailed in this work, an analysis of potential failure modes (FMEA) within the controller module is conducted, serving as a foundation for establishing monitoring requirements for critical components. The implementation arising from these requirements, utilizing the snippet-based design process in KiCAD, is explored at both the circuit and module levels through the example of the stepper driver circuit, which is crucial for operating the NDS dosing pumps. By using the snippet-based design approach, it was possible to avoid the need for fully new development of every functional building block, and instead rely on already tested modules from the DLR's own library. Considering the suitability for space applications, the selection of new active components (e.g. integrated circuits) was based on publicly available radiation test results. In cases where such results were unavailable, the modular design approach allowed for independent testing and irradiation using a Co60 source. The corresponding test results indicated that the chosen stepper driver components remained undamaged during irradiation, supporting the design decisions that led to the printed circuit module presented in this thesis.