Vulcan | SDA Tranche 2 Transport Layer B

Vulcan Rocket Launches SDA Tranche 2 Transport Layer B Mission

On September 30, 2026, the United Launch Alliance's (ULA) Vulcan rocket lifted off from Cape Canaveral Space Force Station, carrying a classified payload for the Space Development Agency's (SDA) Tranche 2 Transport Layer B mission. This launch marks a pivotal step in bolstering the United States' space-based communication infrastructure, amid growing demands for resilient, low-latency data networks in an increasingly contested orbital environment.

The mission's objectives center on enhancing the SDA's Proliferated Warfighter Space Architecture (PWSA), a constellation designed to provide secure, high-bandwidth data transport for military operations. Tranche 2, building on the foundational Tranche 0 and 1 layers, aims to deploy hundreds of satellites in low Earth orbit (LEO) to create a mesh network capable of relaying tactical data, including missile tracking, targeting information, and command-and-control signals. While specifics remain classified, the Transport Layer B satellites are engineered for optical inter-satellite links, enabling rapid data transfer without reliance on vulnerable ground stations. Payload capabilities include advanced encryption for jam-resistant communications and integration with other PWSA elements like the Tracking Layer for hypersonic threat detection. This setup promises to reduce latency to milliseconds, a critical edge in modern warfare where real-time intelligence can determine outcomes.

At the heart of the launch is the Vulcan rocket, ULA's next-generation heavy-lift vehicle designed to succeed the aging Atlas V and Delta IV fleets. Standing approximately 202 feet tall with a diameter of 17.7 feet, Vulcan features a two-stage configuration powered by Blue Origin's BE-4 engines in the first stage—each producing 550,000 pounds of thrust using liquid oxygen and liquefied natural gas. The upper Centaur V stage, equipped with Aerojet Rocketdyne's RL10 engines, provides precise orbital insertion. Vulcan's modular design allows for up to six GEM 63XL solid rocket boosters, enabling a payload capacity of up to 59,500 pounds to low Earth orbit or 33,000 pounds to geostationary transfer orbit. This flexibility, combined with its reusable engine aspirations (though not yet implemented), positions Vulcan as a cost-effective alternative to competitors like SpaceX's Falcon 9, with per-launch costs targeted below $100 million.

Vulcan's performance history has been marked by steady progress since its inaugural Certification-1 flight in January 2024,