Mercury-Redstone was a suborbital spaceflight program developed by NASA in the early 1960s. It was designed to launch the first American astronauts into space as part of the Mercury program. The rocket used was the Redstone, which was a modified version of the Army's Redstone ballistic missile. The first successful crewed flight of the Mercury-Redstone program was Freedom 7, launched on May 5, 1961, with astronaut Alan Shepard aboard. This mission marked the United States' entry into the space race, demonstrating the capability to send humans into space and safely return them to Earth.