This dissertation explores the design, testing, and implementation of cutting-edge spaceborne instrumentation through the investigation of three distinct projects: SPARCS, STRUVE, and EXCITE. The SPARCS astrophysics project focuses on the development of a thermal vacuum chamber for testing contamination-sensitive hardware, alongside the design of ground support equipment (GSE) tailored to SPARCS' performance requirements. STRUVE, a heliophysics CubeSat mission concept, is examined for its mechanical and thermal design strategies, as well as thermal sensitivity studies crucial for mission success. The EXCITE project, an infrared spectrometer balloon-based astrophysics mission, is analyzed for its opto-mechanical design and comprehensive coefficient of thermal expansion (CTE) stress analysis. Throughout the dissertation, each project's challenges, innovations, and solutions are meticulously documented, providing insights into the intricacies and demands of space instrumentation design and testing. The introduction sets the stage by contextualizing the significance of spaceborne instrumentation projects and outlining the scope of the dissertation. The chapters present detailed examinations of SPARCS, STRUVE, and EXCITE, and discuss the engineering complexities and advancements achieved in each project. In conclusion, the dissertation reflects on the lessons learned, implications for future space missions, and the broader impact of SPARCS, STRUVE, and EXCITE on the field of spaceborne instrumentation. This research contributes to the ongoing discourse surrounding space technology innovation and underscores the importance of interdisciplinary collaboration in pushing the boundaries of space exploration.