Gus Grissom was an American astronaut and test pilot, a key figure in the early days of the U.S. space program. He was one of the original seven Mercury Seven astronauts selected by NASA in 1959. Grissom is best known for being the second American to fly in space, after Alan Shepard. His mission, Project Mercury-Redstone 3, was aborted due to a launch pad fire, and he later served as the commander of the Apollo 1 mission, which ended in a tragic fire during a pre-flight test. Grissom died in this accident along with his crewmates Edward White and Roger Chaffee.