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SDA Releases Solicitation for T2TL Alpha Layer

By Rachel Jewett | June 30, 2023

      The transport layer in the Space Development Agency’s National Defense Space Architecture (NDSA). Photo: SDA

      The Space Development Agency (SDA) issued a solicitation for 100 satellites for its Proliferated Warfighter Space Architecture (PWSA) on June 28. The SDA is looking for industry proposals for 100 “Alpha” satellites that will be part of the Tranche 2 Transport Layer (T2TL).

      The PWSA is a proliferated constellation architecture for beyond line of sight targeting and advanced missile detection and tracking, consisting of a Tracking Layer and Transport Layer. The SDA has said the Tranche 2 Transport Layer will provide “global communications access and deliver persistent regional encrypted connectivity in support of warfighter missions around the globe.”

      The SDA described the Alpha constellation as two sub-constellations: Alpha-Low, with four lowly inclined orbital planes of 19 space vehicles; and Alpha-High, with six highly inclined orbital planes of four space vehicles. 

      Baseline payloads and subsystems on all T2TL satellites include three optical communication terminals, Ka-band payload, subsystems for networking and data routing and navigation, and an S-band backup. 

      Specifically on the Alpha satellites, the SDA is looking for a fourth optical communications terminal, a Link-16 payload, battle management, command, control, and communications (BMC3) module, and global navigation satellite systems (GNSS) situational awareness (SA) capability within the navigation subsystem. 

      Industry proposals are accepted until July 28. At Space Symposium in April, SDA Director Derek Tournear said two vendors will likely be selected for Alpha satellites

      The Tranche 2 Transport Layer satellites will be similar to those currently under development for the Tranche 1 Transport Layer, with tech enhancements. T2TL is set to start launching in September 2026. 

      York Space Systems, Lockheed Martin, and Northrop Grumman are building 42 satellites each for the 126-satellite Tranche 1 Transport Layer, under contracts worth a combined $1.8 billion