Robert Lusser (1900 - 1969) was a German engineer and aircraft designer. He is remembered both for several designs significant during World War II, and for his theoretical study of the reliability of complex systems.
Like many important German engineers, Lusser was brought to the United States after the end of World War II. There, he worked for the Navy, the Jet Propulsion Laboratory, and in 1953, re-joined von Braun's rocketry team at Huntsville, Alabama. During his six years there, he formalised his theories of reliability, which focus on the contribution that the reliability of each part makes to the reliability of an overall system. This is now known as Lusser's Law. Based on these calculations, he was to pronounce that von Braun's ambitions of reaching the Moon and Mars were doomed to failure because of the complexity of the spacecraft required.