Measurement of methane concentrations in the stratosphere is important for increasing understanding of the atmosphere’s impact on the climate. However, existing measurement methods are often expensive and technically complex. The MIRAGE project aims to develop a more cost-effective method for measuring methane using an NDIR sensor, an infrared gas sensor that measures methane concentration through light absorption, in a stratospheric balloon experiment. For the sensor to function under the extreme environmental conditions present in the stratosphere, an experimental module capable of maintaining stable pressure and temperature conditions is required.

The purpose of this thesis was to develop, dimension and assemble an experimental module with an associated pressure chamber for stratospheric measurements. The work included both the design of custom-developed components and the integration of commercial standard components into a functioning system. The work was conducted through document studies, concept generation and concept selection using Pugh’s concept selection method, CAD modelling, and analysis of simulation data in the form of FEA and CFD results. The design was developed iteratively in collaboration with the MIRAGE team and evaluated against requirements concerning, among other things, weight, sealing, structural strength, and integration.

The study resulted in an experimental module with a rectangular pressure chamber, where the selected design was assessed to provide good conditions for stable operation of the NDIR sensor and to enable the integration of the experiment’s different subsystems within the given constraints. The work shows that it is possible to develop a compact and functional experimental module for use in stratospheric environments, but that further verification through practical testing is required to fully ensure the performance of the design.