Astronaut Edgar Mitchell a Discussion with Art Bell

Mitchell's interests included consciousness and paranormal phenomena. On his way back to Earth during the Apollo 14 flight he had a powerful savikalpa samādhi experience, and he claimed to have conducted private ESP experiments with his friends on Earth. The results of these experiments were published in the Journal of Parapsychology in 1971. He retired from NASA and the U.S. Navy with the rank of captain in October 1972.[12] Immediately thereafter, he founded Edgar D. Mitchell & Associates of Monterey, California, a "commercial organization promoting ecologically-pure products and services designed to alleviate planetary problems."

After moving to Atherton, California, he became founding chairman of the Institute of Noetic Sciences (IONS) in Palo Alto, California in 1973 for the purpose of consciousness research and other "related phenomena".[24][17] "Science and religion have lived on opposite sides of the street now for hundreds of years," Mitchell said toward the end of his life. "So here we are, in the twenty-first century, trying to put two faces of reality—the existence face and the intelligence or conscious face—into the same understanding. Body and mind, physicality and consciousness belong to the same side of reality.[25]

Journalist Annie Jacobsen has asserted that Mitchell's Mind Science Institute (a Los Angeles, California-based organization ultimately subsumed by the Institute of Noetic Sciences) was employed by the Central Intelligence Agency (CIA) as a surreptitious conduit for payments to Andrija Puharich and Uri Geller while the latter was evaluated by an SRI International research group (led by Harold E. Puthoff and Russell Targ) in 1972.[26] In 1976, Mitchell attempted to secure additional funding for the SRI group's remote viewing research in a private meeting with then-Director of Central Intelligence George H. W. Bush, who knew Mitchell socially. Although Bush demurred (citing post-Watergate investigations of the intelligence community), he suggested the pursuit of military sponsorship, leading to the formation of the Stargate Project in 1978.[27]

From 1974 to 1978, he was president of the Palm Beach, Florida-based Edgar Mitchell Corporation. In 1975, he moved to nearby Lantana, Florida, where he resided for the rest of his life.[12] He co-founded the Association of Space Explorers in 1983 and later served as chairman of the Mitchell Communications Company.[17][28]

Mitchell's heretofore undisclosed experimentation with LSD was reported by writer David Jay Brown in The New Science of Psychedelics: At the Nexus of Culture, Consciousness, and Spirituality (2013). Although he favorably compared the sensations of the psychedelic experience to his time in zero gravity, it remains unclear if his use preceded or followed Apollo 14.[29]

In 1997, Mitchell was interviewed for NASA's oral history program.[17] In one excerpt from that, he talked about how he was drawn to the space program:[17]

After Kennedy announced the moon program, that's what I wanted, because it was the bear going over the mountain to see what he could see, and what could you learn, and I've been devoted to that, to exploration, education, and discovery. On June 29, 2011, the federal government of the United States filed a lawsuit against Mitchell in the United States district court in Miami, Florida after discovering that he placed a camera used on Apollo 14 for auction at the auction house Bonhams. The litigation requested the camera be returned to NASA. Mitchell's position was that NASA had given him the camera as a gift upon the completion of the Apollo 14 mission. Bonhams withdrew the camera from auction.[30] In October 2011, attorneys representing the government and Mitchell reached a settlement agreement, and Mitchell agreed to return the camera to NASA, which in turn would donate it for display at the National Air and Space Museum.[31] On September 20, 2012, Congress enacted H.R. 4158, confirming full ownership rights of artifacts to astronauts on Apollo (and Mercury and Gemini) space missions.