The "Mercury Seven" refers to the group of seven astronauts selected by NASA in 1959 for the Mercury program, the United States' first human spaceflight program. The members included Alan Shepard, John Glenn, Gus Grissom, Scott Carpenter, Wally Schirra, Gordon Cooper, and Deke Slayton. They were chosen for their exceptional skills and backgrounds, which included military test pilots and engineers. These astronauts played a crucial role in advancing human space exploration. Their missions, such as Freedom 7 and Friendship 7, helped gather valuable data about space travel and laid the groundwork for future programs, including the Gemini and Apollo missions.