The objective is to design an optical terminal adapted to future inter satellite link requirements for GNSS. In contrast to telecommunication links, the driving requirements are not high bandwidth, but high reliability, low cost, highest possible jamming resistance, small size, mass and power. The intersatellite link architecture shall be suitable to maintain the autonomous operation of the GNSS constellation. Additional benefits like satellite ranging and time and frequency transfer shall also be considered.

Communication links between GNSS satellites are required if the constellation shall operate for an extended time without ground contact. Under such circumstances, jamming resistance is considered a critical requirement and optical links can provide the ultimate protection from ground-to-space jamming. At the same time, low cost, high reliability and small size, mass and power are important to be implemented on a GNSS constellation. The activity shall review the requirements on intersatellite links based on the GNSS architecture. It shall design the optimal laser linked GNSS constellation, elaborate an advanced preliminary design of the complete terminal, proceed with the component selection, and derive the path to reduce the cost of building and qualifying such laser terminals providing the detailed roadmap for its development toward TRL 9 readiness.