SDA opens contest for 54 ‘Tranche 3’ missile tracking satellites

Space Development Agency’s Tracking Layer will provide missile warning, tracking and fire control for missile defense against ballistic and hypersonic missiles. (Northrop Grumman graphic)

The Tranche 3 Tracking Layer birds — part of a larger planned constellation of hundreds of satellites in low Earth orbit to track not just ballistic but also hypersonic cruise missiles — would expand on the capabilities being provided by earlier design iterations under Tranche 1 and Tranche 2.

These include: “targeted technology enhancements, expanded coverage, increased integration, established calibration processes, and greater production efficiencies” that will be interoperable with the Transport Layer satellites and a common ground system, the agency elaborated.

The Tranche 3 missile tracking birds will be placed in six different orbital planes, carrying a mix of infrared sensors for missile warning, tracking and “defense” (i.e. sensors capable of providing precision coordinates for interceptor fire control).

According to the formal solicitation posted on SAM.gov, SDA is looking to make three awards for 18 satellites each. Further, to solicitation said the agency may decide to contract for more Tranche 3 Tracking Layer satellites at a future date. Interested vendors have until May 22 to respond.

The first Tranche 3 Tracking Layer satellites are expected to be launched in the fourth quarter of fiscal 2029, SDA said.

The request for industry bids for SDA’s Tracking Layer comes as the agency’s future is underneath a bit of a cloud.

The Defense Department in February launched a review of its performance and independent status. Further, as part of its fiscal year 2026 cost-cutting drill ordered by Defense Secretary Pete Hegseth, the Department of the Air Force now is weighing a plan to scrap further development of SDA’s other key constellation, the Transport Layer data relay satellites, and instead contracting with SpaceX for its Starlink internet communications service, sources previously told Breaking Defense.

SDA in July 2022 contracted with Northrop Grumman and L3Harris Technologies for a total of 28 Tranche 1 Tracking Layer birds now expected to begin launching later this summer. In January 2024, SDA awarded approximately $2.5 billion in total to teams led by L3Harris Technologies, Lockheed Martin and Sierra Space for Tranche 2, comprising 54 satellites, is expected to begin launching in 2026.