Defining Space Security: Concepts, Evolution, and Contemporary Boundaries

As reliance on outer space deepens, the concept of space security has become central to debates over military stability, economic resilience, environmental sustainability, and global governance. Despite its insreased salience, space security remains inconsistently defined across academic, policy, and legal communities. This article addresses that gap by clarifying what space security is, how the concept has evolved, and why definitional precision matters. It first situates space security within broader understandings of security, then reviews prominent definitions and their underlying emphases. Building on these perspectives, the article advances a consolidated definition of space security as the safe, reliable, and sustainable access to and use of outer space and its resources in the face of both human-made and natural threats. The article further introduces three interrelated dimensions of space security: security in space, from space, and to space, and traces the evolution of the concept from Cold War strategic rivalry to the contemporary NewSpace era. By clarifying the conceptual boundaries of space security, the article provides a foundation for more coherent analysis, policy design, and governance in an increasingly crowded and contested space environment.