Neil Armstrong December 23, 1968, as Apollo 8 orbited the Moon. In a meeting that was not made public until the publication of Armstrong's biography in 2005, Slayton told him that although the planned crew was Commander Armstrong, Lunar Module Pilot Buzz Aldrin, and Command Module Pilot Michael Collins, he was offering Armstrong the chance to replace Aldrin with Jim Lovell. After thinking it over for a day, Armstrong told Slayton he would stick with Aldrin, as he had no difficulty working with him and thought Lovell deserved his own command. Replacing Aldrin with Lovell would have made Lovell the lunar module
Buzz Aldrin shot down two MiG-15 aircraft. After earning a Sc.D. degree in astronautics from the Massachusetts Institute of Technology, Aldrin was selected as a member of NASA's Astronaut Group 3, making him the first astronaut with a doctoral degree. His doctoral thesis was "Line-of-Sight Guidance Techniques for Manned Orbital Rendezvous", earning him the nickname "Dr. Rendezvous" from fellow astronauts. His first space flight was Gemini 12 during which he spent over five hours on extravehicular activity (EVA) outside the spacecraft. Aldrin set foot on the Moon at 03:15:16 on July 21, 1969 (UTC), nine minutes after Armstrong first touched the surface,