Securing space domain awareness overview: decisions in the nick of time

Space domain awareness (SDA) has evolved in parallel with the growing recognition of space as a domain. It has not developed in isolation; the inexorable presence of cyberspace and electromagnetic spectrum domains further complexifies it. SDA is not only about improving global awareness of space itself; it ultimately guides all decision-making made in it. This review traces the evolution and characteristics of the space domain, the architecture and operational principles of SDA, and the interplay with cyber and spectrum capabilities. It focuses on securing the end-to-end decision chain and highlights how architectural choices, scaling, and integration between physical and non-physical domains influence the resilience of SDA. Emphasis is also placed on forward-looking initiatives, both technical and non technical, that aim to safeguard data, operations and their timing; the linchpin of SDA.