DARPA OTTER: Air-Breathing Electric Propulsion and the Strategic Race to Control Very Low Earth Orbit

Introduction: Strategic Context — Opening a New Operational Regime Very Low Earth Orbit (VLEO), generally defined as the orbital region below approximately 450 kilometers and extending in some mission concepts to around 90 kilometers, is attracting renewed military and commercial interest. Operating closer to Earth can improve the spatial resolution of optical and radar sensors,…