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
Buzz Aldrin (CMP) and Aldrin as Lunar Module Pilot (LMP). Their assignment as the backup crew of Apollo 9 was officially announced on November 20, 1967. Due to design and manufacturing delays in the lunar module (LM), Apollo 8 and Apollo 9 swapped prime and backup crews, and Armstrong's crew became the backup for Apollo 8. Under the normal crew rotation scheme, Armstrong was then expected to command Apollo 11. Michael Collins, the CMP on the Apollo 8 prime crew, experienced trouble with his legs that doctors diagnosed as a requiring surgery. Lovell took his place on the Apollo 8 crew. When