Lighting Up Data Relay Networks

Building next-generation satellite data relay networks is and has been one of the more interesting problems facing commercial and government organizations alike. The sooner data moves off the satellite, the sooner it can be processed, analyzed, and acted upon. Within the civilian sector, the need for moving imagery and IoT data out of a store-and-forward model waiting for the next ground station pass to offload data into real-time network flow has long been desired, especially as optical and SAR constellations have emerged with commercial and government customers.  

On the government side, NASA is in the process of phasing out its legacy TDRS (Tracking and Data Relay Satellite) system. Existing missions such as the Hubble Space Telescope and the International Space Station will continue to operate on TDRS for the next decade or so, but new missions will go onto commercial services operated by Inmarsat, Kuiper, SES, SpaceX, Telesat, Viasat, and others, delivering a combination of connectivity options ranging from LEO to GEO and RF to optical.  

Optical as the primary means of moving data around in-orbit between satellites looks to be the future for a lot of reasons, including speeds between 10 Gbps to 1 Tbps, low-probability of intercept for security, and no pesky spectrum allocation requirements, unlike Ye Olde RF. By far the biggest government customer mover for optical communications is U.S. Space Force’s Space Development Agency (SDA) Hybrid Acquisition for Proliferated LEO (HALO) program.   

SDA has selected 19 “non-traditional” space companies to swim in the HALO pool, including some more traditional contractors like Airbus, SpaceX, and Tyvak Nano-Satellite Systems and newer ones including AST Space Mobile, Firefly, Kepler Communications, and Amazon’s Kuiper. Future prototype orders under HALO will consist of end-to-end mission demonstrations with the launch of a pair of satellites 12 to 18 months after award, so contractors will have to show they can build hardware and launch it in short order.  

Perhaps SDA’s most two useful functions have been to establish the Optical Communications Terminal (OCT) standard and letting vendors know that lots of terminals will be purchased to support plenty of satellites in the future as part of the JADC2 transport layer, with each satellite incorporating anywhere from three to five laser links. Mass production will help drive cost down and improve reliability, with increasing performance and lower mass and power consumption drive, the sort of healthy demand signaling that matches DoD needs to supplier planning and production investment.  

SDA’s success in establishing a transport layer standard with the appropriate hardware market should be replicated for the next big Space Force need, on-orbit servicing. Standards need to be set for refueling and other maintenance operations and propagated/adopted throughout industry with the necessary incentive funds to get everyone on board. Mobility and modularity should be the next development watchwords once Space Force and commercial industry move on from moving around bits in orbit to moving fuel and replacement hardware. 

You can hear more about the virtues of optical communication on January 30, 2025, at the “Can You Hear Me Now? The Future of High-Speed Optical Communications” session at SpaceCom in Orlando.   

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