In April, the 78-year-old spoke at the National Press Club in Washington after the X-Conference, a convention of UFO researchers and activists.
"We are being visited," he said, according to the U.K.'s Guardian. "It is now time to put away this embargo of truth about the alien presence. I call upon our government to open up ... and become a part of this planetary community that is now trying to take our proper role as a space-faring civilization."
Buzz Aldrin, who made the first moon landing with Neil Armstrong, apparently claimed that he saw a UFO while on the Apollo 11 mission, according to a 2005 documentary for the Science Channel. But later, Aldrin would say his comments were taken out of context and the object he saw from the moon's surface was not unidentified at all.
In January, Skeptical Inquirer magazine published a story in which Aldrin repeated his denials and said the UFO was nothing more than a small panel that had connected parts of the spacecraft and was meant to detach itself as the spacecraft approached the moon.
Aldrins UFO allegations and denials only helped fuel conspiracy theorists on all sides, from those who believe in UFO's to those who think the whole moon landing program was a hoax.
Aldrin punched a leading Apollo skeptic in the face in 2002 after he confronted Aldrin and demanded he admit he never set foot on the moon.
But after returning to Earth, Aldrin did have a transformation of his own. He suffered from severe depression and alcoholism, both of which he wrote about extensively in his memoir, "Return to Earth." Those who know him say it wasn't so much the journey to the moon but the fame and glory in the aftermath that led to his troubles.
Apollo 15 astronaut James Irwin was so spiritually moved by traveling to the moon that he left NASA one year after his mission to form a religious organization, High Flight Foundation in Colorado Springs, Colo.
"I felt the power of God as I'd never felt it before," he said about the July 1971 experience. He was the lunar module pilot for the flight and explored the moon's surface for three days.
According to High Flight's Web site, the astronaut started the organization to encourage others to experience "the Highest Flight possible with God."
"Jesus walking on the earth is more important than man walking on the moon," it quotes Irwin as saying.
The group organizes religious retreats and trips to the Holy Land. Before his death in 1991, Irwin led expeditions to Turkey's Mount Ararat in search of evidence of Noah's Ark.
"The Earth reminded us of a Christmas tree ornament hanging in the blackness of space. As we got farther and farther away, it diminished in size. Finally, it shrank to the size of a marble, the most beautiful you can imagine," Irwin said. "That beautiful, warm, living object looked so fragile, so delicate, that if you touched it with a finger it would crumble and fall apart … seeing this has to change a man."
Other moonwalkers have expressed similar sentiments.
Speaking in Sington's documentary "In the Shadow of the Moon," astronaut Gene Cernan, who made the last moon landing in 1972, said he became a believer in the idea of a greater power after traveling to outer space.