# Cyber Resilience Limitations in Space Systems Design Process: Insights from Space Designers
## 4 Results and Findings
### Engineering Methodologies and Practices  
The interview focused on three critical areas of cyber resilience in space engineering. Firstly, we inquired about the most effective engineering methodologies employed by the participants for designing, developing, and deploying critical systems--this question aimed to gather insights into the best practices and approaches used in the industry. Secondly, we explored how cybersecurity and resilience considerations are incorporated into the engineering design process. This line of questioning sought to understand the extent  
Figure 3: Major themes from thematic analysis of interview data. to which these crucial aspects are integrated into the design phase. Lastly, we asked participants about specific design principles or practices that they believe can enhance cyber resilience in systems engineering. By addressing these three areas, we aimed to gain a comprehensive understanding of cyber resilience in space systems design and identify potential strategies for improvement. As we thematically analysed the results (Figure 3), it became apparent that experts overwhelmingly preferred MBSE and Agile engineering approaches. The expert found Model-Based Systems Engineering (MBSE) the most reliable engineering approach for cyber resilience. They expressed the synergies between Model-Based Systems Engineering (MBSE) and Agile methodologies, which, combined, offer a powerful approach for developing complex systems with enhanced flexibility [26; 93; 94]. MBSE provides a structured, model-centric framework for capturing system requirements, behaviour, and architecture [95], whereas Agile practices enable iterative development, rapid adaptation to change, and continuous feedback. The experts highlighted the need to integrate these two approaches for a dynamic and responsive development process that leverages both benefits. This synergy can create high-quality, customer-centric systems that evolve and adapt to changing needs [94]. According to a systems engineer interviewed for this study _\"Model-Based Systems Engineering (MBSE), Concurrent Engineering, and Rapid Prototyping are all effective methodologies for the development of space systems. However, MBSE, in particular, stands out due to its comprehensive system modelling capabilities, which are especially critical given the complexity of my work and the high cost of errors in space missions\"_. Another central theme during the interviews was \"Principles-Based Standards vs. Compliance and Late Security Incorporation\". The \"Principles-Based Standards\" offer a flexible approach to cybersecurity and cyber resilience by focusing on the desired outcomes rather than strict compliance adherence [96]. The experts stressed the flexibility of the \"Principles-Based Standards\" with a warning that it can lead to inconsistent implementation and potential security gaps if not properly guided. However, compliance-based approaches provide clear checkboxes but may also foster a false sense of security, and support is needed to adapt to growing threats in the space domain. The need for increased stress on cyberworthiness [97] during the initial engineering stages was also recognised as a theme. Experts emphasised the need to integrate security measures from the outset rather than as an afterthought. Furthermore, embracing zero-trust architecture (ZTA) and security by design principles were presented as essential strategies for achieving cyber resilience in complex space engineering projects. The two approaches ultimately advocate for a \"never trust, always verify\" [98] mindset throughout the design and development phases to ensure overall security posture and resilience against cyber threats [99]. The further themes were \"Cyber Consideration Frequency and Cybersecurity Inclusion,\" where experts highlighted the need for proactive inclusion of security measures throughout the engineering process, which is critical for developing resilient systems.