SDA's Tranche 0 satellites enable first ever Link 16 space to ground transmission

SDA's Tranche 0 satellites enable first ever Link 16 space to ground transmission
by Clarence Oxford
Los Angeles CA (SPX) Dec 05, 2023

The Space Development Agency (SDA), a key player in the United States Department of Defense's strategic initiatives, recently announced a significant milestone in space communication technology. In a series of demonstrations held from November 21-27, 2023, the SDA successfully executed the first-ever network entry using the Link 16 system from low Earth orbit (LEO) to a series of terrestrial receivers.

This technological breakthrough involved a series of active and passive network entries, precise synchronization, and the transmission of multiple tactical messages. These operations were conducted using L-band radios aboard the Tranche 0 (T0) Transport Layer satellites and were directed towards a ground test site within the territory of a Five Eyes partner nation.

The significance of this accomplishment extends beyond the immediate demonstration. It marks a crucial advancement for the Proliferated Warfighter Space Architecture's (PWSA) Tranche 0 and highlights a novel capability for warfighter support.

This development is especially pivotal for the Department of Defense's Joint All Domain Command and Control (JADC2) initiative, aiming to globally connect sensors to warfighting platforms. The PWSA Transport Layer, forming the backbone of JADC2 in space, is now set to deliver tactical messages, including in beyond-line-of-sight scenarios, using Link 16 radios aboard space vehicles.

SDA's director, Derek Tournear, underscored the importance of this achievement: "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."

Link 16, a tactical datalink communication system, is extensively used by the United States, NATO, and coalition forces to transmit and exchange real-time situational awareness data among network participants. For the initial demonstration, the SDA utilized three T0 Transport Layer satellites provided by York Space Systems, Denver, following their launches in 2023. The 46th Test Squadron, 96th Test Wing at Eglin Air Force Base, Florida, spearheaded the ground operations for these tests.

A significant aspect of this demonstration was its rapid initiation, commencing within 10 hours of receiving approval from an allied nation, following a waiver issued by the National Telecommunications and Information Administration (NTIA) in line with the International Telecommunication Union process. This waiver was critical for transmitting from space to ground and included provisions for future tests over international waters.

Due to current Federal Aviation Administration (FAA) restrictions preventing the broadcasting of Link 16 from space into the U.S. National Airspace System, the SDA coordinated with the NTIA to obtain a waiver for transmissions to a Five Eyes nation and over international waters, aligning with established PWSA mission criteria.

While Link 16 has been a staple aboard aircraft used by the U.S. military and allied partners for years, the full operationalization of PWSA necessitates establishing bi-directional communication from space to ground. These tests, conducted first with an international partner and then over international waters, reflect a compromise and underscore the SDA's ongoing efforts to test over U.S. airspace to fully demonstrate the capabilities of the PWSA.

Tranche 0, termed the warfighter immersion tranche, is pivotal in demonstrating the feasibility of a proliferated architecture in terms of cost, schedule, and scalability. It is essential for beyond-line-of-sight targeting and advanced missile detection and tracking. The SDA launched the first batch of 10 satellites in April 2023 and another 13 in September 2023, with a third launch planned soon. Upon completion, the Tranche 0 constellation will comprise 28 satellites, forming a resilient network in LEO.

Looking ahead, SDA plans to deploy the first operational generation of the PWSA, Tranche 1, starting in late 2024. This tranche will include an expanded constellation of 126 Transport Layer satellites, 35 Tracking satellites, and 12 tactical demonstration satellites.

These operations will be managed by SDA's innovative space operations centers, heavily influenced by commercial space operations models. This step represents a fresh chapter in space-based military communication, promising enhanced connectivity and tactical capabilities for the U.S. and its allies.