USSF-51

USSF-51 is an American National Security Space Launch Mission under the vision of United States Space Force. The launch is significant as it is the Last launch for United Launch Alliance's Atlas V rocket for National Security Mission. After reaching orbit Three Satellite are deployed named USA-396, USA-397 and USA-398. In October 2025, one more satellite is deployed named USA-566 and after that deployed more satellite USA-567, 568 and 569.

Overview

USSF had assigned USSF-106 Mission to ULA in 2020. At the time it was planned to be the first National Security Mission on Vulcan Centaur but after reassignment to an Atlas V, USSF-106 become the first National Security Mission on Vulcan Centaur.
This mission is also last use of Russian RD-180 engine on US National Security Missions which is used on ULA's Atlas V rocket and is replaced with American made BE-4 engines, two of them is used on ULA's Vulcan Centaur rocket starting with USSF-106 Mission in August 2025.