There have been increasing calls in transition research for a global view of sustainability challenges. We argue that this focus should be expanded from a concentration on the Earth's surface and stratosphere to include outer space. The substantial growth of the space sector over the past decade has seen huge increases in the number of rocket launches, the diversity of actors, and the availability of new essential services that depend on space-based infrastructure. In particular, the rise of satellite-based infrastructure could drive the need for inter-related multi-system transitions across a wide range of Earth-bound sectors. These developments, however, cause diverse new sustainability pressures, such as atmospheric pollution, increased energy consumption, and the accumulation of space debris. To address these challenges, this article proposes earth-space sustainability as a new frontier for sustainability transition research, requiring the expansion of conceptual and analytical tools at the interface of transition and global governance research.