Happy Sixth Birthday to the U.S. Space Force!

The U.S. Space Force (USSF) turns six years old today. The youngest branch of the U.S. military was established on December 20, 2019, with the passage of the John S. McCain National Defense Authorization Act. Here are a few things to know about the newest U.S. military service.  

Space force was created to address the growing importance of space to both national security and everyday life. Just as the U.S. Marine Corps is part of the Department of the Navy, space force is organized under the Department of the Air Force. The new service’s ties to the air force are understandable. It was created by merging twenty-three different air force units, and Air Force General John W. “Jay” Raymond was named its first chief of space operations. In 2022, another air force veteran, General B. Chance Saltzman, succeeded Raymond as chief of space operations. The air force’s influence over the USSF will likely continue for some time—it handles much of the space force’s logistics work.   

Space force’s mission is to “secure our nation’s interests in, from, and to space.” Its specific responsibilities include operating missile detection networks and the Geographic Positioning System (GPS) constellation—the set of satellites that your smartphone, among other applications, uses to pinpoint your location. The USSF also monitors both intentional and unintended threats (e.g., “space junk”) to the more than 7,500 satellites active in space—more than two-thirds of which U.S. owners operate. And it works to enhance U.S. space strategy, including for commercial uses of space, and the international rules governing space.   

In just a few years, space force has built itself up rapidly. Key milestones include the stand-up of U.S. Space Command in 2019 as a unified combatant command partner; the establishment of Combat Forces Command, Space Systems Command, and Space Training and Readiness Command. The service has fielded its first doctrines, operational concepts, and service-specific personnel system, while building a cadre of space professionals focused exclusively on the space domain. 

Members of space force are called “guardians.” Space force’s motto is Semper Supra, or “Always Above.” As space force hits its sixth birthday, it has approximately 9,670 uniformed guardians with an authorized end-strength of 9,800 this fiscal year. To put that number in perspective, the next smallest service, the coast guard, has 40,590 active-duty service members. Space force’s relatively small size is intentional; the hope is that staying small will enable it to remain agile. So don’t expect the space force to ever rival the size of the air force (330,000 active-duty personnel), let alone the army (445,500 active-duty personnel).  

Because it is a new service, all mid- and senior-level officers in space force began their military careers in another service. Space force does not have a university to call its own as four of the other five military services do. Space force began its first consolidated officer training course last fall. Run out of Peterson Space Force Base in Colorado Springs, Colorado, the course provides twelve months of skills-training on critical space-related technologies, operations management, satellite deployment, and other topics so that space-force officers have a shared baseline understanding of their operations. The first class graduated this past September. Chief of Space Operations General Chance Saltzman delivered the graduation remarks. In a separate innovation, space force is partnering with Johns Hopkins University to create a postgraduate school for its officers rather than establish its own war college as the army, navy, and air force have.  

Although space force is the first independent service of its kind in U.S. history, it isn’t the U.S. military’s first space-centered program. Shortly after World War II ended, the Army Air Forces (the predecessor of the U.S. Air Force) turned its attention and funding to satellite and rocket technology. In 1985, the Defense Department organized U.S. Space Command, which was charged with planning military operations in the domain of space. In 2002, Space Command was absorbed into U.S. Strategic Command. It was reactivated as a distinct combatant command in 2019 and now works closely with space force. Meanwhile, U.S. military leaders and policymakers debated the need for an independent branch for space for years before President Donald Trump pushed for the USSF’s establishment.  

Space force stands separate from NASA, the United States’ civilian space agency. The two, however, are frequent collaborators. The first uniformed guardian went into space last year and returned this March after his six-month mission as part of the NASA SpaceX Crew-9 mission to the International Space Station. Space force and NASA also share information on near-earth objects to help inform efforts to construct a planetary defense strategy against asteroids. USSF also cooperates with international partners, such as Japan and Norway. 

In 2023, space force published a white paper titled “Competitive Endurance: A Proposed Theory of Success for the U.S. Space Force.” The document warns: 

The increasingly contested operational environment in space threatens the satellites the Joint Force depends on. Equally alarming, our pacing challenge, China, has invested heavily in developing its own military space capabilities. The resulting space-enabled kill web provides them with a long-range precision strike capability that can hold our land, sea, and air forces at risk before we are close enough to project combat power. To protect our joint force the U.S. must be ready to prevent any strategic rival from effectively employing space or counterspace capabilities in a conflict.  

To that end, space force argues for a policy of “competitive endurance” in which U.S. “adversaries must never be desperate enough or emboldened enough to pursue destructive combat operations in space.” Rather than seeking short-term dominance or episodic advantage, competitive endurance emphasizes the ability to outlast competitors over time by maintaining credible capabilities, resilient architectures, disciplined escalation control, and sustained partnerships with allies, industry, and other services. It is meant to recognize that success in space is measured not only by prevailing in conflict, but by preventing conflict and preserving the space environment on which all nations depend. 

Last month, space force released Space Force Vector 2025, a guiding framework for the service on key initiatives and concepts. In its conclusion, General Saltzman writes: 

The Space Force must recognize that we cannot take our old structures and processes, rename them, and expect different outcomes. Since we know we need new outcomes, we must invest our time, energy, and effort into developing and optimizing new structures and processes to achieve them. We need these new concepts to become the warfighting service that our Nation needs.  

Just last week, Major General Stephen Purdy, one of space force’s most influential acquisition leaders, sat down on the Space News show to discuss the conclusions of Vector 2025 and how the space force has been innovating itself in 2025.  

Colonel Corey Trusty, a space force officer spending a year as a visiting military fellow in CFR’s David Rockefeller Studies Program, recommended readings for those wanting to learn more about the space force. Here are his suggestions:  

U.S. Space Force, Spacepower: Doctrine for Space Forces (2020). This foundational doctrinal document articulates how the Space Force thinks about the space domain, its missions, and its role in joint warfighting. It is essential reading for understanding how concepts like deterrence, space control, and competitive endurance are operationalized. 

Bleddyn E. Bowen, War in Space: Strategy, Spacepower, Geopolitics (2020). Bowen provides a rigorous strategic framework for understanding space as a domain of competition and conflict. His analysis is particularly useful for policymakers and military professionals seeking to understand escalation dynamics, restraint, and the geopolitical implications of space power. 

Everett C. Dolman, Astropolitik: Classical Geopolitics in the Space Age (2002). While written before the creation of the Space Force, Dolman’s work remains influential in shaping debates about space strategy, control, and competition. Reading it alongside contemporary Space Force doctrine highlights both continuity and evolution in U.S. thinking about space power. 

Leland Melvin, Chasing Space: An Astronaut’s Story of Grit, Grace, and Second Chances (2017). A deeply human account of perseverance, adaptability, and authentic leadership. Melvin’s journey—from segregated Virginia to the NFL and ultimately to space—underscores the importance of resilience, identity, and purpose in elite institutions. His story reinforces that leadership is not about fitting a mold, but about bringing your whole self to the mission and using success as a platform to inspire and lift others. 

The space force also maintains a “Leadership Library,”Chief Master Seargent John Bentivegna stood up in March, to suggest books for guardians and prospective guardians. Among the suggested books are Alan Shepard and Deke Slayton’s Moon Shot: The Inside Story of America’s Race to the Moon; Daniel Kahneman’s Thinking, Fast and Slow; and Art Kleiner’s The Age of Heretics.  

The National Museum of the United States Air Force in Dayton, Ohio, has a free exhibit on the USSF. The exhibit showcases some of the most important rockets and spacecraft developed over the past decades and the stories of America’s brave astronauts who paved the way for space operations to become such an important part of the U.S. military. The Smithsonian National Air and Space Museum in Washington, DC, also has an impressive set of exhibits showing the historical progression of spaceflight as the United States sent rockets, then humans, and then satellites into space. 

The growing military and commercial role of space means that the importance of space force will only increase in the future. So Happy Birthday to the U.S. military’s youngest branch, and a tip of the cap to all new and incoming guardians of the U.S. Space Force for their service. Semper supra!