Bio
BioRalph Semmel is APL director emeritus and served as the eighth director of the Laboratory from 2010 to 2025.
Semmel oversaw the Laboratory as it developed a broad array of game-changing science and technology innovations for the nation across domains such as air and missile defense, cyber, multi-service strategic deterrence, artificial intelligence and autonomy, hypersonics, C4ISR, undersea systems, space science and engineering, biology, biothreat defense, special operations, human-machine teaming, brain-computer interfaces, specialized microelectronics, and materials science. Semmel also deepened ties between APL and the rest of Johns Hopkins, resulting in increased collaboration and innovative research breakthroughs. Moreover, he led APL in developing a sharply focused centennial vision dedicated to creating defining innovations and an agile strategic plan that enabled the Lab to tackle the most critical challenges facing our nation.
During his tenure as Director, APL delivered numerous critical national security capabilities that have ensured our forces remain the most capable in the world. These include revolutionary technologies for ballistic and cruise missile defense that are in operational use today across the globe; breakthroughs in cyber operations, data fusion, and machine learning that have greatly accelerated intelligence and information sharing capabilities throughout the government; AI and autonomy advances that have transformed and enabled unmanned Navy and Air Force systems; cutting-edge undersea warfare innovations that have been deployed to provide our forces with key advantages; and technical, analytical, and operational contributions that have ensured the reliability of current and future Navy and Air Force strategic weapon systems.
The Laboratory also created many groundbreaking space science and technology innovations for NASA during this time. The New Horizons spacecraft accomplished its historic 2015 flyby of the dwarf planet Pluto and, later, a Kuiper Belt object, revealing exciting insights into both previously unexplored bodies, while Parker Solar Probe, launched in 2018, fulfilled a nearly 50-year-old dream of sending a spacecraft to the Sun to explore solar processes and the origins of space weather. APL also envisioned, built, and operated the Double Asteroid Redirection Test (DART), which, in 2022, demonstrated how we might defend our planet from incoming asteroids to save life on Earth. And the Laboratory’s revolutionary Dragonfly mission, scheduled to launch in 2028, will send a first-of-its-kind nuclear-powered octocopter to explore the surface of the ocean world Titan, Saturn’s largest moon, to help us understand the origins of life on our planet and across the universe.
During Semmel’s career, he led and served on a variety of noteworthy federal government science and technology boards, panels, and committees that guided national security research strategies. He has been a member of the Defense Science Board and the U.S. Strategic Command Strategic Advisory Group, and is currently a member of the Council on Foreign Relations. He also serves on a variety of boards of organizations that are focused on the national good and are complementary to APL.
Among his many leadership roles at APL prior to his appointment as director, Semmel served as the founding head of APL’s Applied Information Sciences Department, assistant head of the Power Projection Systems Department, deputy director of the Research and Technology Development Center, and business area executive for both Infocentric Operations and Science and Technology. He also chaired three professional graduate programs for JHU’s Whiting School of Engineering and has an appointment of professor in the Department of Computer Science. Before joining APL in 1986, Semmel held leadership and technical positions with Wang Laboratories, MITRE Corporation, and the U.S. Army.
Semmel is a West Point graduate with master’s degrees in computer science and systems management and a Ph.D. in computer science.
