In-Orbit Experiment Design for Monitoring Bio-Based Materials in Space

Kurzfassung

Bio-based materials have the potential to reduce the environmental impact of spacecraft structures, but their behaviour under long-term exposure to the space environment remains insufficiently characterised. This thesis develops an in-orbit experiment to monitor the response of bio-based materials under low-Earth-orbit conditions. A 3U CubeSat is designed to expose twelve samples of Scots pine,birch, balsa, and poplar for about 10 months following deployment from the International Space Station. The experiment combines repeated visual inspection and temperature measurements using four internal cameras, four 30 mm deployable mirrors at a 40 degree angle, and forty-eight Type T thermocouples. The CubeSat architecture is developed at system level and assessed through structural and thermal analyses. The structural analysis gives positive margins of safety for all evaluated launch-load cases, with a lowest metallic margin of 1.03, a lowest wood margin of 0.94, and a first natural frequency of 888.74 Hz. The thermal analysis shows material-dependent temperature behaviour, with balsa experiencing the largest temperature variations. The change in optical properties between beginning-of-life and end-of-life conditions increases maximum wood-panel temperatures by up to 30 C and decreases minimum temperatures by up to 18 C, while internal temperatures increase by 2-4 C. These differences are detectable with the selected thermocouples. A physical engineering model further confirms that the selected mirror geometry allows the complete height of the material samples on all four lateral faces to be imaged. The work does not qualify a specific bio-based material for use in space. Instead, it defines and assesses an experimental architecture for obtaining time-dependent in-orbit measurements that can be compared with ground testing and numerical predictions, providing a basis for the further evaluation of bio-based materials for spacecraft applications.