# Space Development Agency The **Space Development Agency** (SDA) was created on March 12, 2019 by Under Secretary of Defense Mike Griffin to build military satellites the way the commercial sector does: many small, cheap spacecraft, bought in fixed two-year "tranches," instead of a few exquisite ones. It moved into the [[U.S. Space Force]] in October 2022. Its product is the **Proliferated Warfighter Space Architecture (PWSA)**, a low-Earth-orbit mesh built in two main layers: - a **Transport Layer** of data-relay satellites that move targeting data between forces; - a **Tracking Layer** that detects and tracks ballistic and hypersonic missiles. The architecture overlaps with the [[MILNET]] constellation, and the agency is a major customer of [[SpaceX]] and its [[SpaceX Starshield]] line. ## Leadership Derek Tournear built the agency and led it from 2019. He left in September 2025 for academia. His deputy, Gurpartap "GP" Sandhoo, served as acting director and was named director in May 2026, also taking the portfolio acquisition executive role for missile warning and tracking. ## The promise versus the pace The tranche model is the agency's whole argument, and 2025–26 tested it. - **The first launches.** The first 42 Tranche 1 satellites launched in September and October 2025. Hardware and software problems then forced a months-long "strategic pause." The agency had to learn to manage the satellites as a network rather than as individual spacecraft. - **The second batch.** Twenty-one more satellites launched on July 16, 2026. That left 63 of 154 Tranche 1 satellites in orbit by mid-September. - **The slip.** Completion slipped from summer 2026 to spring 2027. The on-orbit mesh demonstration moved from September to the end of the year. Optical terminals and focal-plane arrays remain the bottlenecks. ## Golden Dome The tracking layer is written into the [[Golden Dome]] executive order as a core element of the missile shield. In July 2026 SDA awarded **$1.75 billion** for 36 Tranche 3 missile-tracking satellites: $955 million to [[L3Harris]] and $798 million to Sierra Space, due for launch by 2028. The agency's schedule is now the shield's schedule. If Golden Dome's space layer is late, it will be late here first. ## See Also - [[Golden Dome]] · [[Space Systems Command]] · [[U.S. Space Force]] - [[MILNET]] · [[SpaceX Starshield]] · [[SpaceX Contracts]] - [[L3Harris]] · [[Rocket Lab]] · [[Lanteris Space Systems]]