Pictured is a Space Development Agency photo of the Thursday launch of 21 York Space Systems satellites aboard a SpaceX Falcon 9 rocket from Vandenberg Space Force Base, Calif.

A Tranche 1 (T1) launch from Vandenberg Space Force Base, Calif., for the Space Development Agency's (SDA) Proliferated Warfighter Space Architecture (PWSA) put 21 York Space Systems [YSS] Transport Layer communications satellites into low Earth orbit on Thursday aboard a SpaceX [SPCX] Falcon 9 rocket, the agency said. The satellites, among 63 on orbit in Tranche 1, "will enhance the tracking of advanced missile threats by providing secure, low-latency, beyond-line-of-sight tactical communication links, delivering a resilient, optically-connected network of integrated…