Until recently, those wanting to escape the effects of terrestrial light pollution could leave cities and travel to the countryside to observe the night sky. But increasingly there is nowhere, and therefore no way, to escape the pollution from the thousands of satellites being launched each year. ‘Mega-constellations’ composed of thousands or even tens of thousands of satellites are designed to provide low-cost, low-latency, high-bandwidth Internet around the world. This chapter outlines how the application of the ‘consumer electronic product model’ to satellites could lead to multiple tragedies of the commons, from the loss of access to certain orbits because of space debris, to changes to the chemistry of Earth’s upper atmosphere, to increased dangers on Earth’s surface from re-entered satellite components. Mega-constellations require a shift in perspectives and policies. Instead of looking at single satellites, we need to evaluate systems of thousands of satellites, launched by multiple states and companies, all operating within a shared ecosystem.

The rapid development of mega-constellations raises difficult issues of international law, including liability for collisions involving satellites. Establishing ‘causation’ – that the actions of one satellite operator caused a specific collision with another space object and resulted in damage – could be a challenge, especially in the context of knock-on collisions where debris from an initial collision later collides with one or more spacecraft, including satellites. A further challenge is determining, in the absence of binding international rules on the design and operation of satellites, what is ‘reasonable’ behaviour and therefore what constitutes ‘negligence’. This chapter also addresses the interference to astronomy that is increasingly resulting from light and radio spectrum pollution from satellites. A full interpretation of the Outer Space Treaty leads to the conclusion that states are already required to take certain steps, including conducting an environmental impact assessment, before licensing mega-constellations, because of the obligation of ‘due regard to the corresponding interests of all other States Parties to the Treaty’.