Like Apollo 10 which preceded it, the three-person crew selected for Apollo 11 consisted entirely of spaceflight veterans from the two-person Gemini spacecraft program that encompassed ten crewed flights prior to Apollo. The six goals of Gemini were to develop and conduct: 1. Long duration spaceflight needed for lunar missions, 2. Proficiency in rendezvous and docking using multiple spacecraft, 3. Controlling Earth re-entry trajectory, 4. Techniques for extra-vehicular activity (i.e. spacewalks), 5. Proficiency of astronauts and ground crews, and 6. Scientific experiments.