Vulcan | SDA Tranche 1 Tracking Layer D

Vulcan Rocket Set to Launch SDA Tranche 1 Tracking Layer D Mission

On June 30, 2026, the skies above Cape Canaveral Space Force Station in Florida will witness the launch of United Launch Alliance's (ULA) Vulcan rocket, carrying the Space Development Agency's (SDA) Tranche 1 Tracking Layer D payload. This mission marks a pivotal step in bolstering the United States' missile defense capabilities, deploying satellites designed to detect and track advanced threats in real time.

At the heart of the mission are the objectives of the Proliferated Warfighter Space Architecture (PWSA) Tranche 1 Tracking Layer constellation. This network aims to provide global indications, warnings, tracking, and targeting of sophisticated missile threats, including hypersonic systems that travel at speeds exceeding Mach 5 and can maneuver unpredictably. The Tracking Layer D satellites, part of a series of five similar missions, feature advanced infrared sensors and optical communications systems. These payloads enable persistent surveillance from low Earth orbit (LEO), allowing for rapid data relay to ground stations and integrated defense networks. Unlike traditional geostationary satellites, which offer limited coverage, this proliferated constellation—comprising hundreds of small, cost-effective satellites—ensures resilient, redundant monitoring. This design mitigates risks from anti-satellite weapons by distributing capabilities across numerous nodes, enhancing survivability in contested space environments.

The Vulcan rocket itself represents a leap forward in launch vehicle technology. Developed by ULA as a successor to the Atlas V and Delta IV, Vulcan incorporates a modular design with a first stage powered by two BE-4 engines from Blue Origin, fueled by liquid natural gas (LNG) and liquid oxygen. This methane-based propulsion offers higher efficiency and lower costs compared to traditional kerosene systems, with the BE-4 providing approximately 550,000 pounds of thrust per engine. The upper stage, Centaur V, uses two RL10 engines for precise orbital insertion, capable of delivering payloads up to 27,200 kilograms to LEO. Vulcan's fairing options range from 5.4 to 7 meters in diameter, accommodating diverse payloads like the SDA satellites. Technical innovations include reusable engine components and advanced avionics for autonomous flight termination, reducing operational risks and environmental impact through cleaner propellants.

Vulcan's performance history, though nascent, builds on ULA's legacy of reliability. Its inaugural flight in January 2024 successfully deployed the Peregrine lunar lander, demonstrating the rocket's precision and