Pointing budget and radiation analysis for CubeSat missions

The growing reliance on the CubeSat standard for complex scientific and commercial applications demands rigorous analyses to validate mission reliability under stringent environmental and operational constraints. This dissertation addresses two critical aspects of space systems engineering, i.e. environmental radiation survivability and attitude pointing performance, by analyzing two Low Earth Orbit Sun-Synchronous CubeSat missions: the CubeSat Solar Polarimeter (CUSP) and the Bi-directional IoT Satellite Service (BISS), that are both part of the ASI-funded ALCOR programme. The first part of the study focuses on the CUSP mission in the framework of phase B, characterizing the space radiation environment through the SPENVIS software in compliance with ECSS standards. The analysis investigates the Single Event Effects (SEEs), specifically evaluating the Single Event Latchup (SEL) risk profile for the payload’s MAROC2 integrated circuit. The second part transitions to the pointing domain of the BISS mission during its C-D design phases, moving past preliminary spreadsheet-based Root-Sum-Square (RSS) estimations toward a high-fidelity dynamic approach. Utilizing the ESA Pointing Error Engineering Tool (PEET), a stochastic model is implemented to propagate time-constant misalignments and frequency-dependent random processes through the spacecraft’s transfer functions and closed-loop architecture. Environmental disturbance torques, dominated by atmospheric aerodynamic drag at a worst-case altitude of 450 km, are modeled alongside sensor noise contributions from a fused Wahba’s problem solution and gyroscope data. The resulting dynamic budget validates compliance with the mission’s 5 degrees pointing requirement across all operational, fallback, and eclipse scenarios at a 99.7% confidence level, further demonstrating that equipment noise and assembly biases act as the primary performance drivers.