CubeSat missions face stringent constraints on power, volume, and mass, often compounded by limited budgets and small teams whose expertise evolves from concept through launch. Accurately predicting MARMOTSat’s behavior under both launch level vibrations and in orbit thermal loads,including the resulting thermoelastic deformations,is therefore essential to ensure mission success. This thesis develops detailed finite element (FE) models to evaluate MARMOT- Sat’s structural, thermal, and coupled thermoelastic performance. In the structural study, modal analyses are performed in a stowed configuration (solar panels folded and antennas removed) using the Lanczos eigenvalue extraction method. Thermal simulations model MARMOTSat’s LEO orbit, incorporating solar flux, Earth infrared radiation, and internal heat dissipation.