We examine ways to enhance cybersecurity in spacecraft operations by analyzing and reducing the attack surface of flight software. We advocate for reducing complexity in the software archtecture and adopting more secure architectural principles to mitigate vulnerabilities and make spacecraft more resilient against cyber attacks. Utilizing a systematic approach, we focus on the real-time operating system (RTOS) and operating system abstraction layer (OSAL) as key areas of scrutiny and development of mitigations. This study's findings suggest strategies for simplifying abstractions to make them more secure, addressing implementation issues, and providing supporting evidence for moving to a more resilient architectural approach.