Electro-optical-based relative navigation for close-proximity operations

In the next years, CubeSats and SmallSats are expected to play an increasing role for activities like repair or maintenance of active spacecraft, assembly of orbital structures, disposal of non-functional satellites, and outer-space exploration. Despite their differences, these scenarios require a spacecraft to safely maneuver in proximity of a space target, e.g., for monitoring, rendezvous, and landing purposes. Consequently, its navigation system must provide robust and accurate relative state estimates. This relative navigation task requires advanced algorithmic solutions to process data collected by Electro-Optical (EO) sensors in real time, which clearly poses strict constraints especially to small platforms. Keeping this aspect into account, this chapter aims to provide fundamentals on the design of a relative navigation architecture based on EO sensors, providing a classification of technological and algorithmic solutions while highlighting their main advantages and drawbacks.