Killers from Space - 1954

Killers from Space (also known as The Man Who Saved the Earth) is a 1954 American independent science fiction film produced and directed by W. Lee Wilder, and starring Peter Graves, Barbara Bestar, Frank Gerstle, James Seay, and Steve Pendleton. Shot in black-and-white, the film originated as a commissioned screenplay from Wilder's son Myles Wilder and their regular collaborator William Raynor.
Dr. Douglas Martin is a nuclear scientist working on atomic bomb tests. While collecting aerial data on a United States Air Force (USAF) atomic blast at Soledad Flats, the pilot loses control of their aircraft and they crash. Dr Martin appears to have survived, unhurt, walking back to the air base with no memory of what happened. On his chest is a strange scar that was not there before the crash.