Interspacecraft optical communication and navigation using modulating retroreflectors

A novel concept is described for optical interrogation, communication, and navigation between pursuer and target spacecraft platforms. The technique uses a gimbaled laser source on the pursuer spacecraft and an array of eight solid-state, multiple quantum, well modulating retroreflectors on the target spacecraft. The sensor system provides high-bandwidth optical communication, centimeter-level relative positioning, and arc-minute-level relative orientation of the target platform with minimal sacrifice in target size, weight, and power. To accomplish the relative navigation, each target retroreflected signal is modulated with a unique code sequence, allowing for individual discrimination of the returned composite signal from a single photodetector on the pursuer platform. Experimental results using a dual-platform, multi-degree-of-freedom robotics testbed provide verification and demonstration of the concept, highlighting its potential for applications such as interspacecraft rendezvous and capture, long-baseline space interferometry, and formation flying.