Critical dependencies on space-based infrastructure have grown dramatically in recent decades, and now extend to small states and the global economy as a whole. However, as geopolitical rivalries re-emerge in more traditional domains of interstate conflict, the prospects for future stability in space appear increasingly dim. While the consequences of a great-power clash in space could be ruinous, a shared understanding of the perils involved has yet to take hold. Strategic interaction along the final frontier is set to enter a period of considerable danger. Among the various environments into which humans have expanded their economic, military, and scientific activities, outer space is easily the most unwelcoming and inhospitable. Impossible to access except through massive expenditures of energy per unit of mass to be placed into orbit, and utterly hostile to human life as well as to many types of man-made machinery, the maintenance of a permanent presence outside Earth’s protective atmosphere remains a highly ambitious undertaking. Despite various complications, however, this presence – which, in most cases, has entailed the placement of unmanned artificial satellites in earth-centric orbits – has become an essential pillar of the global economic and security systems in the late 20th and early 21st centuries. From highly specialized scientific and commercial services to everyday applications of information technology (IT), space-based infrastructures now form part of the life-support system of a civilization that has tied its economic well-being and, indeed, its very survival to global connectivity.