SpaceX successfully launched 21 satellites on September 10 (2025), from the Vandenberg Space Force Base, California. The satellites are sent to the low Earth orbit (LEO), and this has marked the start of the US military’s new encrypted space-based communications network, which is led by the Space Development Agency (SDA).
The mission was the first Tranche-1 Transport Layer launch, which will eventually form a constellation of 126 satellites. The Falcon 9’s first stage completed its sixth flight and safely landed on the SpaceX droneship in the Pacific Ocean about 8.5 minutes after liftoff.
Payload and Contractors
The payload consisted of 21 satellites manufactured by York Space Systems. To complete the Tranche-1 constellation, Lockheed Martin and Northrop Grumman have also been contracted, each tasked with building 42 satellites.
While SpaceX confirmed the deployment into orbit, the exact timing of satellite separation was not disclosed.
The Transport layer network
The satellites are part of the Proliferated Warfighter Space Architecture (PWSA), a large-scale project by the SDA, which is now integrated into the US Space Force. Established in 2019, the SDA aims to quickly develop and deploy advanced defence capabilities in space.
The Transport Layer of the PWSA will serve as a secure relay system, enabling encrypted global communications for US forces beyond line-of-sight. Once completed, this layer will include 126 interconnected satellites using laser-based communication links.
From Tranche 0 to Tranche 1
Before this operational launch, the SDA had tested nearly two dozen demonstration satellites between 2023 and 2024 under Tranche 0. The new Tranche 1 represents the first full-scale deployment, signalling a shift from experimental systems to operational military infrastructure.
In addition to communications, the full PWSA architecture will also feature tracking and navigation satellites, creating a resilient and secure multi-layered defence network in space.
