Tranche 0 refers to the first deployment of LEO satellites by the Space Development Agency (SDA) for the DoD, as a demonstrator for later tranches as the Proliferated Warfighter Space Architecture (PWSA).
The SDA’s objective with Tranche 0 is to establish an initial architecture by deploying a set of satellites in LEO. This is essentially a test layer, aiming to demonstrate capabilities, validate concepts, and establish a foundational architecture that future tranches can build upon.
Tranche 0 is expected to comprise two types of satellite constellations: the Transport Layer (T-Layer) and the Tracking Layer.
The Transport Layer is meant to demonstrate low-latency data relay and multi-phenology/On orbit sensor fusion. FSO via Laser Communication Terminals (LCT) as well as Ka-band & L-Band Link 16 & Integrated Broadcast Service (IBS) communications are used.
The Tracking Layer is focused on missile warning and tracking. These satellites are equipped with wide-field-of-view infrared sensors to detect and track advanced missile threats including beyond line of sight targeting.
In addition, a third layer of tactical demonstration satellites (T1DES) is expected for Furter tranches, which will have UHF and S-band communications payloads for providing mobile wireless services. These payloads are currently used in geostationary satellites but are new to LEO usage.
Contracts and Awards
The SDA has awarded contracts to multiple companies to manufacture satellites for Tranche 0. The aim was to have a mix of vendors to encourage competition and foster innovation, as well as to deter single points of failure.
The initial launch of 10 Tranche 0 satellites occurred April 2nd 2023 via SpaceX Falcon 9 rockets, with a second launch in September 2023. Follow on tranches expected in roughly two year increments.