Given the increasing dependence on satellites for military applications, the spectrum of associated threats, notably satellite cyberattacks, is expanding. Incidents of satellite hacking, particularly those highlighted during the Ukrainian conflict, have underscored the latent vulnerabilities in satellite communication and intensified the requirement for enhanced satellite security. Therefore, safeguarding the flight software and addressing the classification of software errors are pivotal. This study proposes methods for appraising the safety of aerospace software within the defense domain, drawing upon NASA's software safety standard, NASA-STD-8739.8B. By integrating this standard, this study aims to formulate strategies to augment the reliability and robustness of space-based defense systems. Within this framework, the focus is on applying NASA-STD-8739.8B software threat analysis to NextSat-1, undertaking initiatives for the classification of software errors, and ensuring quality and safety during the development and management phases of NextSat-1’s flight software. Amid the steadily increasing landscape of space cyber threats, this study aims to establish a precedent for protecting future aerospace technologies and is anticipated to significantly contribute to enhancing satellite security and system resilience.