Space systems provide vital services for many critical industries on Earth, including global communications, geolocation, imagery, and precision timing, as well as non-satellite applications such as space exploration and human habitation and settlement. The space environment is one of the most naturally hostile environments known to humankind, constantly facing threats such as electromagnetic radiation and space debris. In addition, the malicious threat environment is becoming increasingly adverse with an ongoing rise in cyber and electromagnetic attacks against space infrastructure, both terrestrial and deployed. Compounding the issues above, space systems are also known to have extensive and vulnerable international supply chains, with the space segment notably lacking inherent access to redundancy or maintenance options. Adding to the complexities of resilient space systems design, the space environment is becoming increasingly congested and contested with a burgeoning second space race that is seeing the rapid deployment of space systems containing a vast array of new technologies and, hence, vulnerabilities.

The combined effect of an increasingly hostile threat environment with increasingly vulnerable space systems necessitates that space technologies are built to be resilient-by-design. This requires the development of a pragmatic resilience assessment framework that can be utilised by space systems security professionals to assess the resilience of their system to any given adversity and shed light on any weaknesses in the space system design. The research project described in this dissertation details the development of a foundational space systems security ontology to guide future research and development, as well as a space system resilience assessment framework for determining the high-level resilience status of any given space system to any given adversity. This includes the space system’s ability to anticipate, react to, survive, recover from, and adapt to adverse events whilst maintaining control and sustaining core operations and services in a degraded state.

This research dissertation presents the space systems resilience assessment framework, which consists of seven individual novel academic contributions to the contemporary field of space systems security and resilience:

1. Comprehensive evaluation of space systems security literature;
2. Space systems security definition;
3. Space systems security knowledge domain;
4. Space systems resilience taxonomy;
5. Space systems resilience definition;
6. Space systems resilience model (including a phasal cycle and temporal chart); and
7. Space system resilience assessment framework.

This thesis outlines a mixed methodology to achieve the above outcomes, utilising both quantitative and qualitative approaches. The research involves conducting a three-phase Delphi study of two dozen space security experts across ten countries using online surveys and an expert focus group. The outcomes of the Delphi study are then experimentally tested using the case study methodology. In the methodology, three cyber-physical case studies are utilised to evaluate the effectiveness of the final framework against real-world space systems, using data collected through interviews with practicing space systems security managers. A cyber-physical terrorist threat model is used alongside the Lockheed Martin Cyber Kill Chain model to generate a theoretical adverse event that exploits the identified vulnerabilities in the real-world systems to finally test the high-level resilience of each space system using the new framework.

The final outcome of this body of research is an experimentally evaluated space system resilience assessment framework for assessing the high-level resilience status of any given space system to any given threat. This includes definitions and taxonomies for space systems security and resilience, a comprehensive space systems security knowledge domain, and a complete phasal and temporal resilience model.