Responsiveness in Low Orbits Using Electric Propulsion

Abstract

One promising option for space operational responsiveness is orbital maneuvering. In low orbit, a maneuverable spacecraft can provide valuable benefits such as better coverage properties, reduced revisit times, selectable targets, and local overflight times. Such maneuvers are not common due to the high cost of chemical propulsion. The more recent paradigm of operationally responsive space is to rapidly launch a small inexpensive asset and use it in a short disposable fashion. This concept relies on drastically reducing the cost of launch, yet it remains the most expensive piece, and so additional cost savings can be realized by minimizing the need for launches. Electric propulsion has been considered as an efficient alternative to chemical propulsion. With technological advances, electric propulsion can provide responsiveness in a timely propellant-efficient manner without requiring repeated launches to satisfy multiple missions. This study shows the control algorithm for a single low-Earth satellite equipped with the proper electric propulsion to overfly any target inside its coverage area in as little as 34 h for 1.8% of its propellant budget. A comprehensive survey to quantify global reach requirements is provided, and the optimal time and propellant solutions are explored. The results strongly support the argument that electric propulsion could be a key enabler in responsive operations.