Apollo 6 was an unmanned test flight of the Saturn V rocket, which experienced multiple technical failures but ultimately paved the way for successful manned missions to the moon.
Vostok 3 Explained
Vostok 3 was a Soviet space mission that launched the first woman into space, Valentina Tereshkova, in 1963.
Mercury-Atlas 9 Explained
Mercury-Atlas 9 was the final manned space mission of NASA’s Mercury program, successfully orbiting the Earth and making John Glenn the first American to orbit the planet.