Edge computing is an emerging paradigm aiding responsiveness, reliability, and scalability of terrestrial computing and sensing networks like cellular and IoT. However, edge computing is largely unexplored in high-datarate nanosatellite constellations. Cubesats are small, energy-limited sensors separated from the cloud by hundreds of kilometers of atmosphere and space. As they proliferate, centralized architectures impede advanced applications. In this work, we define and characterize Orbital Edge Computing. We describe power and software optimizations for the orbital edge, and we use formation flying to parallelize computation in space.