The Mercury and Gemini programs enabled the operational testing of the various technological engineering systems developed for the implementation of the Apollo space program.
Mercury Program (1958–1963)
1. The first American manned space program, launched in response to the Soviet lead in space exploration.
2. Its primary objective was to send a man into space and bring him back safely.
3. It used extremely simple and robust single-seat capsules.
4. Six manned missions were carried out between 1961 and 1963.
5. Alan Shepard became the first American in space; John Glenn became the first American to orbit the Earth.
6. Gemini Program (1965–1966)
7. A vital transitional program leading toward Apollo.
8. Two-man capsules with longer-duration missions (up to 14 days).
9. Mastery of orbital rendezvous and docking techniques.
10. The first American extravehicular activities (spacewalks).
11. Validation of the key techniques required for a lunar landing.