L3Harris rendering of the SDA Tranche 3 Tracking Layer. Photo: L3Harris

Lockheed Martin, Rocket Lab USA, Northrop Grumman, and L3Harris Technologies are to build 72 satellites for Tranche 3 of the U.S. Space Force’s Space Development Agency’s (SDA) Tracking Layer under more than $3.5 billion in Other Transaction Authority (OTA) rapid prototyping contracts, SDA said on Friday.

For the Tracking Layer of Tranche 3, each of the four companies is to build 18 satellites under the firm fixed-price OTA awards. Lockheed Martin received $1.1 billion, L3Harris $843 million, Rocket Lab $805 million, and Northrop Grumman $764 million for the future work.

Lockheed Martin, L3Harris, and Northrop Grumman have received missile tracking awards in earlier tranches. While a newcomer to the Tracking Layer, Rocket Lab is on contract to build 18 SDA Tranche 2, Transport Layer-Beta satellites that are to transmit over Ultra High Frequency S-band. Lockheed Martin and Northrop Grumman are to build 72 satellites for the Beta effort, 36 by each company.

The Tracking Layer and communications Transport Layer are key parts of SDA’s future Proliferated Warfighter Space Architecture (PWSA) to feature optically linked, Low-Earth Orbit satellites to speed military actions.

Gurpartap “GP” Sandhoo, SDA’s acting director, said in a statement that the Tracking Layer of Tranche 3, “once integrated with the PWSA Transport Layer, will significantly increase the coverage and accuracy needed to close kill chains against advanced adversary threats.”

“The constellation will include a mix of missile warning and missile tracking, with half the constellation’s payloads supporting advanced missile defense missions to pace evolving threats,” he said. “The addition of these satellites will achieve near-continuous global coverage for missile warning and tracking, along with payloads capable of generating fire control quality tracks for missile defense.”

SDA had planned to launch once a month to get all 154 Tranche 1 satellites into orbit within a year — 126 for the Transport Layer and 28 for the Tracking Layer. The first Tranche 1 launches of 42 Transport Layer satellites by York Space Systems and Lockheed Martin were in September and October. Yet, November had no launches and SDA said that it expects to resume them early next year, as one vendor resolves software problems and as the agency looks for available launch pads and payload processing.

The fiscal year 2026 National Defense Authorization Act proposes a restoration of $500 million for Transport Layer satellites in Tranche 3 — funds that the Department of the Air Force zeroed in its budget request, as the department considers other communications options, including the National Reconnaissance Office-derived MILNET, which has SpaceX as a contractor.

This story was first published by Defense Daily