The U.S. Space Force has awarded SpaceX a new contract for the Space Data Network (SDN) Backbone program, the service’s Space Systems Command (SSC) announced May 26.

The $2.29 billion firm, fixed-price other transaction authority agreement will fund the buildout of a new proliferated satellite constellation in low Earth orbit (LEO), providing the Joint Force with high-capacity, low-latency data transport, with plans for a “fully operational prototype capability” by the end of 2027.

Formerly known as “Milnet,” the new constellation would build upon and alongside a separate constellation currently in development by the Space Development Agency (SDA) known as the Transport Layer. Fiscal 2027 budget documents show the Pentagon plans to zero out funding for the Transport Layer past its current contracts, and that the Space Force has earmarked $1.6 billion for the SDN to be funded via reconciliation.

“Current acquisition efforts between SDN Backbone and SDA’s Transport layer come together to evolve capabilities and build out the LEO portions of the SDN hybrid mesh data network,” SSC says in the release. “Together, these systems will form a unified and open architecture to provide critical data transport for current and future Department of [Defense] missions.”

The SpaceX contract was competitively awarded, SSC says. Pentagon officials have described the program as multi-vendor, even as SpaceX remains the sole known provider. The Space Force recently established an SDN consortium to team with industrial partners, with plans to expand the pool over this summer, the release said.