L3Harris Technologies has completed the preliminary design review for 18 missile-tracking satellites that will form part of the Space Development Agency (SDA)’s Tranche 3 Tracking Layer.
The review confirms the baseline design for L3Harris’ contribution to the program, covering the satellites, ground systems, communications, networking, and infrared payloads.
SDA’s Tracking Layer is intended to provide warning, tracking, and eventually fire-control-quality data against conventional and advanced missile threats, including hypersonic weapons.
Once deployed, the satellites are expected to provide near-continuous global missile warning and tracking as part of the SDA’s Proliferated Warfighter Space Architecture (PWSA).
The architecture uses large numbers of satellites in low Earth orbit that can share data through a low-latency communications network.
Tranche 3 Expands SDA’s Missile Tracking
L3Harris’ latest milestone comes as the SDA builds out a much larger Tranche 3 constellation.
In December 2025, the SDA awarded four agreements worth about $3.5 billion to Lockheed Martin, Rocket Lab, Northrop Grumman, and L3Harris for 72 Tracking Layer satellites. Each company is responsible for 18 spacecraft, with launches planned for fiscal 2029.
The SDA had originally planned to deploy at least 54 satellites equipped with infrared sensors across six orbital planes. The agency said the satellites would expand coverage and integrate with the PWSA’s Transport Layer to provide low-latency data to users on the ground and in the field.
The program has since expanded further through an accelerated missile-defense effort. In July 2026, the SDA awarded two agreements worth about $1.75 billion for 36 additional Tranche 3 satellites across four orbital planes.
L3Harris is also part of that effort. In July, the company received a separate award to produce 18 Accelerated Missile Defense Tranche 3 satellites for the US Space Force’s missile defense architecture.
