Deke Slayton was an American astronaut and one of the original Mercury Seven astronauts selected by NASA in 1959. Born on March 1, 1924, in Wisconsin, he served as a pilot in the U.S. Army Air Forces during World War II and later became a test pilot. Slayton was known for his calm demeanor and technical expertise. After being grounded due to a heart condition, Slayton transitioned to management roles within NASA. He played a key part in the Apollo program and later served as the director of flight crew operations. Slayton flew in space for the first time on the Apollo-Soyuz Test Project in 1975.