During World War II, what field of research did Edwin Hubble work in?

During World War II, Edwin Hubble worked in ballistics research. He served as a civilian at the U.S. Army's Aberdeen Proving Ground in Maryland, where he became chief of the External Ballistics Branch of the Ballistic Research Laboratory.

His work focused on how bombs, rockets, and projectiles moved through the air. Hubble helped improve experimental methods and developed instruments, including a high-speed clock camera that recorded the flight characteristics of bombs and low-velocity projectiles. Such measurements helped researchers improve weapon design and accuracy.

This wartime role was a major departure from Hubble's better-known career in observational astronomy. He did not primarily work in nuclear physics, radar, or rocket propulsion. His ballistics research earned him the Legion of Merit in 1946, recognizing his contribution to the military effectiveness of bombs and projectiles.