The Space Development Agency (SDA) has successfully demonstrated the first-ever Link 16 network entry through space to ground connection from LEO to a series of receivers using terrestrial radios during three demonstrations held November 21-27, 2023.
Operators working with SDA conducted both passive and active network entry, obtained fine synchronization, and transmitted multiple tactical messages from satellites using L-band radios aboard Tranche 0 (T0) Transport Layer satellites to a ground test site located within the territory of a Five Eyes partner nation.
This success represents a major milestone for T0 of the Proliferated Warfighter Space Architecture (PWSA) and demonstration of a significant new capability for the warfighter. This accomplishment also reflects a leap ahead in the Department of Defense-wide Joint All Domain Command and Control (JADC2) effort, connecting available sensors to available warfighting platforms globally.
The PWSA Transport Layer is the backbone of JADC2 in space and will enable delivery of tactical messages, including beyond-line-of-sight scenarios, using Link 16 radios aboard space vehicles.
Link 16 is a tactical datalink communication system used by the United States, NATO, and coalition forces to transmit and exchange real-time situational awareness data among all network participants. For the initial Link 16 demonstration, SDA used three T0 Transport Layer satellites provided by York Space Systems, Denver, from both of the 2023 T0 launches. The 46th Test Squadron, 96th Test Wing, headquartered at Eglin Air Force Base, Florida, served as the lead developmental test organization for ground operations.
The demonstration leveraged prior fixed-site risk reduction testing at the 46th Test Squadron Datalinks Test Lab and with York Space Systems. The tests began within 10 hours of receiving approval from an allied nation after the National Telecommunications and Information Administration issued a waiver, in accordance with the International Telecommunication Union process, to transmit from space to ground.
The waiver also includes permission to conduct future tests over international waters. Due to current Federal Aviation Administration restrictions that prevent broadcasting Link 16 from space into the U.S. National Airspace System, SDA coordinated with the NTIA to obtain a waiver to transmit to a Five Eyes nation and over international water to meet established PWSA mission criteria.
While the U.S. military and allied partners have used Link 16 aboard aircraft for years, a fully operational PWSA will require the ability to establish bi-directional communication from space to ground. Testing Link 16 from space, first with an international partner and then over international water, represents a compromise position and SDA’s requirement remains to test over U.S. air space to demonstrate the feasibility of the PWSA and its ability to deliver fire control information to the warfighter over existing tactical data networks.
Tranche 0, the warfighter immersion tranche, demonstrates the feasibility of a proliferated architecture in cost, schedule, and scalability toward necessary performance for beyond-line-ofsight targeting and advanced missile detection and tracking.
SDA launched the first 10 satellites in April of 2023 and the next 13 in September of 2023. A third launch carrying the final T0 space vehicles is scheduled for the near future. Once completed, the Tranche 0 constellation will consist of 28 satellites – 19 Transport and eight Tracking satellites, plus one ground-based testbed satellite – forming a resilient constellation in LEO.
SDA plans to field the first operational generation of the PWSA, Tranche 1, beginning in late 2024. Tranche 1 will include 126 Transport Layer satellites, 35 Tracking satellites, and 12 tactical demonstration satellites (called T1DES). Tranche 1 will be operated by SDA’s groundbreaking space operations centers based heavily on commercial space operations models.
“I can’t underscore enough the significance of this technical achievement as we demonstrate the feasibility of the Proliferated Warfighter Space Architecture and its ability to deliver space-based capabilities to the warfighter over existing tactical data links. This is not only the first time Link 16 has been broadcast from space, but the beginning of turning the world’s finest warfighting force into a truly connected beyond line-of-sight joint force.” — Derek Tournear, Director, SDA
