Society’s dependence on space infrastructure is at a critical juncture. Public and private actors worldwide are planning to launch tens of thousands of satellites into Earth’s orbit in the next five years. This will greatly expand and enrich the use of space resources, but it will also result in more crowded orbits and greater risk of damage from satellite collision and space debris. As satellite launches continue to multiply and concerns grow, the long-term sustainability of space-based infrastructure on orbit and beyond is set to emerge as an increasingly important space policy issue of the 21st century. This publication takes stock of the growing socio-economic dependence of our modern societies on space assets, and the general threats to space-based infrastructure from debris in particular. Notably, it provides fresh insights into the value of space-based infrastructure and the potential costs generated by space debris, drawing on new academic research developed especially for the OECD project on the economics of space sustainability.