Buzz Aldrin while Command Module Pilot Michael Collins remained in lunar orbit. A Presbyterian elder, Aldrin became the first person to hold a religious ceremony on the Moon when he privately took communion. Upon leaving NASA in 1971, he became Commandant of the U.S. Air Force Test Pilot School. He retired from the Air Force in 1972, after 21 years of service. His autobiographies "Return to Earth," (1973) and "Magnificent Desolation" (2009), recount his struggles with clinical depression and alcoholism in the years after leaving NASA. He continued to advocate for space exploration, particularly a manned mission to Mars, and developed the
Neutral buoyancy simulation as a training aid post-mission evaluation of problems that he encountered during his Gemini IX-A EVA. NASA then modified the contract to include pre-mission training of Gemini XII astronaut, Buzz Aldrin. Astronaut Cernan also participated in this pre-mission training, as he was in a backup role to Aldrin as pilot of Gemini XII. Aldrin trained for the original Gemini XII EVA version which was then revised to eliminate the task of using a manned maneuvering unit. Aldrin returned to the McDonogh facility and trained for the final version of his EVA. NASA considered the flight EVA to be a total success, and Aldrin again