Applied Physics Laboratory
The Johns Hopkins University Applied Physics Laboratory is a not-for-profit, United States Navy-sponsored, university-affiliated research center in Howard County, Maryland, United States.
APL is affiliated with Johns Hopkins University and employs more than 8,800 people as of 2025. APL conducts research, engineering and analysis to address national security and scientific challenges faced by the United States and its allies. The Laboratory brings together technical expertise, longstanding experience and specialized facilities to support rapid prototyping and long-term research and development. APL works across a range of domains, contributing to both operational systems and foundational science and technology.
The Laboratory serves as a technical resource for every branch of the Department of Defense, the Intelligence Community, the Department of Homeland Security, NASA, and other government agencies, along with industry. APL has developed numerous systems and technologies in the areas of air and missile defense, surface and undersea naval warfare, computer security, and space science and spacecraft construction. The Lab's work spans 13 mission areas, including applications from undersea systems and cyber operations to biological sciences and space exploration. Multidisciplinary teams integrate domain expertise and systems engineering to support a range of government missions.
History
APL was established in 1942 during World War II under the Office of Scientific Research and Development's Section T as part of the government's effort to mobilize the nation's science and engineering expertise within its universities. Its founding director was Merle Anthony Tuve, who led Section T throughout the war.File:1942SilverSpringOffice.jpg|alt=The original APL facility on Georgia Avenue in Silver Spring, Maryland.|thumb|400x400px|The original APL facility on Georgia Avenue in Silver Spring, Maryland, where the Laboratory opened during World War II and operated in the early Cold War era.
Section T was created on Aug. 17, 1940. According to the official history of the Office of Scientific Research and Development, Scientists Against Time, APL was the name of Section T's main laboratory from 1942 onward, not the name of the organization overall. Section T's Applied Physics Laboratory succeeded in developing the variable-time proximity fuze, which played a significant role in the Allied victory. In response to the fuze's success, APL created the MK 57 gun in 1944.
Pleased with APL's work, the Navy tasked the Laboratory with the mission to find a way to negate guided missile threats. From then on, APL became heavily involved in air and missile defense research. Expected to disband at the end of the war, APL instead became deeply engaged in the development of guided missile technology for the Navy. At the government’s request, the University continued to maintain the Laboratory as a public service.
APL was originally located in Silver Spring, Maryland in a used-car garage at the Wolfe Building at 8621 Georgia Avenue. APL began moving to Laurel in 1954 with the construction of a $2 million building and a $700,000 wing expansion in 1956. The final staff transitioned to the new facility in 1975. Before moving to Laurel, APL also maintained the “Forest Grove Station,” north of Silver Spring on Georgia Avenue near today's Forest Glen Metro, which included a hypersonic wind tunnel. The Forest Grove Station was vacated and torn down in 1963, and flight simulations were moved to Laurel. In the 1960s, APL built two early and pioneering autonomous robots, or “mobile automatons,” called Ferdinand and the Johns Hopkins Beast.
The Laboratory's name comes from its origins in World War II, but APL's major strengths are systems engineering and prototyping solutions to complex national security and scientific challenges with technical expertise, research and development, and analysis. More than 80% the staff are technical professionals, including nearly 1,500 Ph.Ds., and a majority of staff have degrees in engineering, math, computer science, physics, biology or similar fields.
APL conducts programs in fundamental and applied research; exploratory and advanced development; test and evaluation; and systems engineering and integration. In addition to its sponsored work, APL maintains a robust internal research and development program that provides seed funding for exploration of innovative ideas and concepts to address the nation’s future challenges.
Wartime Contributions
During the 1950s and ‘60s, APL worked with the Navy on the Operation Bumblebee Program, which produced the RIM-2 Terrier, RIM-8 Talos, and RIM-24 Tartar surface-to-air missile systems. The follow-on Typhon missile project, based on improved Talos and Tartar missiles, was successful but was cancelled in 1963 because of high costs. It was eventually developed into the Standard Missile and the now well-known Aegis combat system, based on an improved Terrier.APL led the development of the transformational system needed to demonstrate ballistic missile defense from the sea. The resulting experiments proved that BMD technology could be integrated with a Navy weapon system to “hit a bullet with a bullet” in space from sea.
In 1990, APL contributed to Operation Desert Storm, including work in the Gulf Crisis Room and other efforts.
Notable Contributions
- Transit Navigation System : Developed the world’s first satellite-based navigation system, laying the groundwork for today’s GPS.
- Pershing : Developed and implemented a test and evaluation program for the Pershing missile systems for the U.S. Army. APL developed the Pershing Operational Test Program, provided technical support to the Pershing Operational Test Unit, identified problem areas and improved the performance and survivability of the Pershing systems.
- AMFAR : Created the Adaptive Modular Phased Array Radar, contributing foundational technology for modern phased-array radar systems.
- Exploiting Undersea Physics : Advanced sonar array capabilities that enabled long-range detection of threat submarines and informed stealth design for the Navy.
- SATRACK : Revolutionized ballistic missile testing by enabling high-precision tracking of missile trajectories using onboard instrumentation.
- Tomahawk : Developed guidance algorithms enabling autonomous navigation and precision targeting, making Tomahawk the world’s first long-range, precision-guided cruise missile.
- Cooperative Engagement Capability : Enabled networked air defense by allowing distributed sensors and weapons systems to operate as a unified force.
- Discovery Program Missions : Led pioneering low-cost planetary missions, including NEAR and MESSENGER, expanding NASA’s deep space exploration.
- Ballistic Missile Defense from the Sea : Developed sea-based missile defense capabilities, enabling naval platforms to detect, track and intercept ballistic missiles around the world.
- Double Asteroid Redirection Test : Led the first planetary defense test mission to deliberately alter the orbit of an asteroid through kinetic impact.
Campus
In 2021, APL opened an interdisciplinary research center, Building 201, with 263,000 square feet of space, a 200-person auditorium and more than 90,000 square feet of specialized laboratory space. The building also includes a four-story atrium, a STEM center and 100 huddle conference and auditorium breakout rooms. In 2025, the building was renamed the Ralph D. Semmel Center for Innovation in honor of APL’s eighth director, Ralph Semmel, who led the Laboratory from 2010 to 2025.
Education and internships
APL is also home to a Johns Hopkins Whiting School of Engineering part-time graduate program in engineering and applied sciences for APL staff members and the public, called Engineering for Professionals.Up to 75% of EP students now come from outside APL. The faculty includes scientists and engineers from APL and WSE; from regional aerospace, engineering and information technology companies; and government agencies. EP offers master’s degrees in 25 areas, 14 of which are based at APL and chaired by APL’s technical professional staff members. Courses are taught at seven locations in the Baltimore-Washington metropolitan area, including the APL Education Center.
APL's STEM Academy includes several programs that provide a pathway to science, technology, engineering and math careers for students in grades 3–12. APL’s core programs are designed to be complementary and are grounded in an integrated model that ensures children learn about what being a STEM professional means.
Programs include Maryland MESA, an after-school offering for students in grades 3-12; the STEM Academy, an after-school course program for middle and high school students in grades 8-12; APL's Student Program to Inspire, Relate and Enrich, which allows high school juniors and seniors to experience and explore STEM careers before college; and Pathways, APL’s college internship program.
Research
APL operates across 13 mission areas, encompassing disciplines such as undersea systems, space exploration, cybersecurity and biological sciences. Its teams apply systems engineering and technical expertise to support the development, testing and integration of technologies for national security and scientific research.The Laboratory works in coordination with government sponsors and industry partners to align research and development priorities with mission needs. Its efforts focus on transitioning technologies into operational use, supporting both prototype development and broader implementation by external organizations.
APL's portfolio includes longstanding areas of work such as air and missile defense and undersea warfare, as well as research addressing emerging domains and strategic priorities. These include autonomous systems, hypersonic systems, survivability and performance, artificial intelligence, assured autonomy, biomanufacturing and next-generation materials.