The Mercury Seven were the first group of American astronauts selected for NASA's Project Mercury, the nation's first human spaceflight program. They were chosen from a pool of over 500 military test pilots in 1959.

Here are the seven astronauts:

* Alan Shepard (1923-1998): First American in space (suborbital flight, 1961)

* Gus Grissom (1926-1967): Second American in space (suborbital flight, 1961); tragically died in the Apollo 1 fire

* John Glenn (1921-2016): First American to orbit Earth (1962)

* Scott Carpenter (1925-2013): Second American to orbit Earth (1962)

* Wally Schirra (1923-2007): Third American to orbit Earth (1962)

* Gordon Cooper (1927-2004): Last American to fly a solo space mission (1963)

* Deke Slayton (1924-1993): Originally selected as a pilot, but was grounded due to a heart condition; became NASA's first director of flight crew operations

The Mercury Seven were national heroes and became symbols of the American space race against the Soviet Union. Their achievements paved the way for future space exploration, including the Gemini and Apollo programs that ultimately landed a man on the moon.