Multiple Quantum Well Retromodulators for Spacecraft - To - Spacecraft Laser Interrogation

This paper describes a novel concept for laser-based interrogation, communication, and navigation between multiple spacecraft platforms using a gimbaled laser source on a pursuer spacecraft and a target board populated with retromodulators (modulating retroreflectors) integrated on a host spacecraft. The combined laser source and retroreflectors can provide centimeter-level relative positioning between each vehicle, as well as spacecraft-tospacecraft laser communication via semiconductor-based Multiple Quantum Well retromodulators. Additionally, strategies are developed for utilizing the target board retromodulator array to provide relative attitude between each vehicle. In this scenario, each reflector has its own unique modulating code sequence, allowing the returned signals to be discriminated and processed by the pursuer spacecraft to determine the relative orientation. Based on additional attitude sensing capability, three classes of host spacecraft are considered: fully-cooperative, partiallycooperative, and non-cooperative. Numerical simulations using a five-sensor target board demonstrate the potential of the concept, and preliminary test results demonstrate reflector discrimination capability.