Beaconless Pointing for Deep-Space Optical Communication

Abstract

Free space optical communication is of interest to NASA as a complement to existing radio frequency communication methods. The potential for an increase in science data return capability over current radio-frequency communications is the primary objective. Deep space optical communication requires laser beam pointing accuracy on the order of a few microradians. The laser beam pointing approach discussed here operates without the aid of a terrestrial uplink beacon. Precision pointing is obtained from an on-board star tracker in combination with inertial rate sensors and an outgoing beam reference vector. The beaconless optical pointing system presented in this work is the current approach for the Integrated Radio and Optical Communication (iROC) project.

Optical Wireless Communications: Illuminating the Path for Cooper's Law

“…Non-linear symbol detection techniques based on the outputs of array elements are examined in [316]. An effective beaconless pointing and tracking approach-deployed onboard the Integrated Radio and Optical Communication (iROC) project-utilizes an on-board star tracker in conjunction with high rate inertial reference unit and an outgoing beam reference vector in order to track and correct the satellite attitude in the orbit [317].…”

Deep Space Relay Terminals for Mars Superior Conjunction

“…The present deep space optical communication architecture planned for Mars provides a beacon to space terminals, to assist the spacecraft with acquisition of the forward link, and to overcome spacecraft attitude disturbances 31 . This is not the only possibility; other architectures 32 avoid the need for the beacon, but may involve extra expense for equipment to orient the optical terminal very precisely. However, if a beaconless architecture proved to be advantageous, obviously the illumination intensity constraint could be relaxed, allowing an opportunity to choose a smaller relay terminal if desired, with concomitant lower data rate capacity.…”