{{Short description|United States Space Force National security Mission}} {{Use American English|date=July 2020}} {{Use dmy dates|date=July 2020}} {{Infobox spaceflight | auto = all | name = USSF-51 | image = 250px | image_caption = USSF-51 Launch | insignia = | mission_type = | operator = USSF | COSPAR_ID = | SATCAT = | mission_duration = | spacecraft_type = | manufacturer = | dry_mass = | launch_mass = | dimensions = | power = | launch_date = 30 July 2024 10:45 UTC | launch_rocket = Atlas V 551 (AV-101) | launch_site = Cape Canaveral, SLC-41 | launch_contractor = United Launch Alliance | disposal_type = | deactivated = | decay_date = | orbit_epoch = | orbit_reference = Geocentric orbit | orbit_regime = Geosynchronous orbit | orbit_periapsis = | orbit_apoapsis = | orbit_inclination = | orbit_period = | orbit_slot = | apsis = gee | programme = USSF Launch | previous_mission = USSF-62 | next_mission = USSF-106 }}
'''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.<ref>{{Cite web |title=USSF-51 (USA-396 to 398) {{!}} Atlas V 551 {{!}} Next Spaceflight |url=https://nextspaceflight.com/launches/details/5055/ |access-date=2025-10-16 |website=nextspaceflight.com |language=en}}</ref><ref>{{Cite web |last=Davenport |first=Justin |date=2024-07-29 |title=Atlas V successfully launched its last ever national security mission |url=https://www.nasaspaceflight.com/2024/07/ussf-51/ |access-date=2025-10-16 |website=NASASpaceFlight.com |language=en-US}}</ref><ref>{{Cite web |title=ULA launches Atlas 5 rocket on the company's 100th national security mission – Spaceflight Now |url=https://spaceflightnow.com/2024/07/29/live-coverage-ula-to-launch-atlas-5-rocket-on-the-companys-100th-national-security-mission/ |access-date=2025-10-16 |language=en-US}}</ref><ref>{{Cite web |first=Mike |last=Wall |date=2024-07-29 |title=Atlas V rocket launches its final national security mission for US military (video) |url=https://www.space.com/atlas-v-final-national-security-launch-ussf-51- |access-date=2025-10-16 |website=Space |language=en}}</ref><ref>{{Cite web |title=Atlas V USSF-51 |url=https://www.ulalaunch.com/missions/archived-launched/atlas-v-ussf-51 |access-date=2025-10-16 |website=www.ulalaunch.com}}</ref><ref>{{Cite web |last=ULA |title=United Launch Alliance Successfully Launches 100th National Security Mission |url=https://newsroom.ulalaunch.com/releases/united-launch-alliance-successfully-launches-100th-national-security-mission |access-date=2025-10-16 |website=newsroom.ulalaunch.com |language=en}}</ref><ref>{{Cite web |title=USA 396, 397, 398 (USSF 51) |url=https://space.skyrocket.de/doc_sdat/usa-396.htm |access-date=2025-10-16 |website=Gunter's Space Page |language=en}}</ref><ref>{{Cite web |title=USSF-51 (USA-396 to 398) {{!}} Atlas V 551 {{!}} Next Spaceflight |url=https://nextspaceflight.com/launches/details/5055/ |access-date=2025-10-17 |website=nextspaceflight.com |language=en}}</ref>
==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.<ref name="NSSL-FY20">{{cite web |url=https://www.af.mil/News/Article-Display/Article/2305576/space-force-awards-national-security-space-launch-phase-2-launch-service-contra/ |publisher=U.S. Air Force |access-date=11 June 2023 |title=FY20 NSS Missions|date=August 7, 2020 }}</ref>
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.<ref name=sn20140917>{{cite news|last1=Ferster|first1=Warren|title=ULA To Invest in Blue Origin Engine as RD-180 Replacement |url=http://www.spacenews.com/article/launch-report/41901ula-to-invest-in-blue-origin-engine-as-rd-180-replacement|archive-url=https://archive.today/20140918114236/http://www.spacenews.com/article/launch-report/41901ula-to-invest-in-blue-origin-engine-as-rd-180-replacement|url-status=dead|archive-date=September 18, 2014|date=September 17, 2014|publisher=SpaceNews|access-date=September 19, 2014}}</ref>
==See also== {{Portal|Spaceflight}} *List of USA satellites *List of USSF launches *National Security Space Launch
== References == {{Reflist}}
{{Orbital launches in 2024}} {{Portal bar|Spaceflight}}
Category:Spacecraft launched in 2024 Category:United States Space Force satellites Category:July 2024 in the United States Category:2024 in Florida
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