NASA/JPL-Caltech · Public domain

Theodore von Kármán turned aerodynamics into a precise science, working out how airflow behaves as it crosses from subsonic into supersonic and hypersonic speeds — theory that underpinned the jet and rocket age. The boundary of space itself is named the Kármán line in his honor. The Hungarian-born engineer later helped found what became NASA's Jet Propulsion Laboratory after emigrating to the United States.