Earth's orbits are polluted by more than 100 million debris objects that pose a collision threat to satellites and other spacecraft. The risk of perturbing highly valuable space-based services critical to life on Earth, such as weather monitoring and disaster management, is making debris mitigation an urgent policy challenge. This book provides the latest findings from the OECD project on the economics of space sustainability, which aims to improve decision makers’ understanding of the societal value of space infrastructure and costs of space debris. It provides comprehensive evidence on the growth of space debris, presents methods to evaluate and quantify the value of the satellites at risk and discusses ways to ensure a more sustainable use of the orbital environment. It notably includes case studies from Italy, Japan and Korea on the socio-economic value of different types of space infrastructure and discusses the feasibility and optimal design of fiscal measures and voluntary environmental rating schemes to change operator behaviour. This work is informed by contributions from researchers worldwide involved in the OECD project.