What was Buzz Aldrin's official Apollo 11 crew role?

Buzz Aldrin’s official Apollo 11 crew role was Lunar Module Pilot. He shared the lunar module Eagle with mission commander Neil Armstrong and helped operate it during humanity’s first crewed lunar landing.

Aldrin was responsible for systems, navigation, procedures, and communications associated with the lunar module. Although the title says “pilot,” Apollo mission commanders generally had final authority during critical flight decisions. Armstrong manually took over important portions of Eagle’s descent after the onboard guidance system aimed toward a boulder-strewn area, while Aldrin called out altitude, velocity, and computer data.

Aldrin and Armstrong landed on July 20, 1969, and conducted the first lunar surface excursion. Aldrin followed Armstrong down the ladder about 20 minutes later and spent approximately two hours outside Eagle. The third crew member, Michael Collins, was the Command Module Pilot and remained in lunar orbit aboard Columbia. Aldrin was therefore not the commander or command module pilot, and “Lunar Module Pilot” is the formal Apollo 11 assignment even though Armstrong performed much of the hands-on landing maneuver.