Captured by a fish-eye lens view, Apollo 14 astronauts Alan B. Shepard, foreground, and Edgar D. Mitchell work in a lunar module simulator at the Kennedy Space Center in Florida in 1970. (AFP/AFP/Getty Images)

Edgar D. Mitchell, an astronaut who was spiritually transformed by his journey to the moon in 1971 and who devoted much of the rest of his life to exploring esoteric realms of science, psychic phenomena and the existence of extraterrestrial beings, died Feb. 4 at a hospice in West Palm Beach, Fla. He was 85.

A daughter, Kimberly Mitchell, confirmed his death to the Palm Beach Post. The cause was not immediately known.

Mr. Mitchell was the lunar module pilot aboard Apollo 14, which took off from Florida’s Cape Canaveral on Jan. 31, 1971. Veteran astronaut Alan B. Shepard was the mission commander, and Stuart A. Roosa was pilot of the command module.

Shepard and Mr. Mitchell spent 33 hours on the moon, including more than nine hours outside the lunar module. They conducted scientific experiments and brought back about 100 pounds of moon rocks and other lunar materials. Shepard pulled out a 6-iron and made three golf shots.

Mr. Mitchell used a color camera to record some of their exploits, among them a striking image of Shepard standing alongside an American flag.

Astronaut Edgar D. Mitchell in 2007. (Henny Ray Abrams/ASSOCIATED PRESS)

During the nine-day spaceflight, Mr. Mitchell surreptitiously carried out experiments in extrasensory perception. Fewer than 10 percent of the experiments succeeded, but he considered the number statistically significant, and when he returned to Earth, he knew that his life was forever changed.

“The experience I had on the flight was akin to a religious experience,” Mr. Mitchell told People magazine in 1974. “It was euphoric, one of those rare moments in life when you seemed to be able to reach out and touch the universe, when you had an intuitive flash about the real meaning of truth.”

As one of only 12 men to set foot on the moon, Mr. Mitchell realized that he had a special perspective on the world, and he spent the rest of his life trying to understand the full meaning of that experience.

For two years, he didn’t shave the beard that had begun to sprout as he stood on the moon. The stoic Texas-born test pilot and Navy veteran, who had a doctorate from MIT, turned his life upside down as he embarked on a decades-long quest to reconcile the contradictory worlds of science and metaphysics, interstellar exploration and personal growth.

He underwent hypnosis and deep-relaxation techniques to try to recapture the emotions he felt in the Apollo 14 capsule during the three-day return flight from the moon.

“What I experienced during that three-day trip home was nothing short of an overwhelming sense of universal connectedness,” he wrote in a 1996 memoir, “The Way of the Explorer.”

Within a year of the moon mission, Mr. Mitchell retired from NASA and the Navy and began to investigate such fields as acupuncture, astrology, telekinesis, Gestalt therapy, fire-walking and healing techniques. He founded a group called the Institute of Noetic Sciences, which sought to blend science with consciousness-raising, and in 1974, he published the book “Psychic Exploration: A Challenge for Science.”

Edgar D. Mitchell, in background, stands on the moon during the February 1971 Apollo 14 mission. Mission Cmdr. Alan Shepard is in the foreground. (STF/AFP/Getty Images)

“There’s a very large proportion of people who think I’m totally crazy,” Mr. Mitchell said in 1988. “I’m sorry they have such tunnel vision about what the nature of reality is.”

Over time, Mr. Mitchell became something of an odd man out among astronauts, some of whom would not comment publicly about him.

Mr. Mitchell occasionally noted that he grew up near Roswell, N.M., where many people believe that an alien spacecraft crashed in 1947. He said he had never seen a UFO, but he was outspoken in his belief that aliens had probably visited Earth and that the government covered up the evidence.

“Dr. Mitchell is a great American,” a NASA spokesman said, “but we do not share his opinions on this issue.”

Edgar Dean Mitchell was born Sept. 17, 1930, in Hereford, Tex., into a ranching family. During the Depression, he moved to Artesia, N.M. While walking to school near Roswell, he would pass the home of Robert H. Goddard, whose early experiments in rocketry helped propel the country into space.

Mr. Mitchell spent many days on horseback and learned to fly when he was 13. After graduating in 1952 from what is now Carnegie Mellon University, in Pittsburgh, he joined the Navy and became a pilot.

He served in the Korean War and later said he trained as a test pilot under Chuck Yeager, the first person to fly faster the speed of sound.

Mr. Mitchell received a second bachelor’s degree in aeronautical engineering in 1961 from the Naval Postgraduate School in Monterey, Calif., and then a doctorate in aeronautics and astronautics from the Massachusetts Institute of Technology in 1964. He joined NASA’s astronaut corps in 1966.

In 1970, one year before Mr. Mitchell went into space, he worked in the lunar module simulator at the Johnson Space Center in Houston during the Apollo 13 mission. An on-board explosion nearly caused the spacecraft to be lost as it approached the moon. With the lives of three fellow astronauts at stake, he devised procedures to help the crippled space capsule return to Earth. Later that year, he received the Presidential Medal of Freedom.

In 1975, Mr. Mitchell settled in Palm Beach County, Fla., where he lived the rest of his life. He had a tempestuous personal life that included protracted legal battles, three divorces and a paternity suit.

“It was the White House one day, some yoga guru the next,” his second wife, Anita Mitchell, said in 1988. “Cary Grant would call one day, and then we’d have a bunch of Sufi dancers whirling in our living room. Uri Geller would come by and bend some metal. I must have met all the nuts, flakes and fruits in the whole granola box.”

Mr. Mitchell’s first two marriages, to the former Louise Randall and Anita Rettig, ended in divorce. In the mid-1980s, he was ordered to pay $1,200 a month in child support to Sheilah Ann Ledbetter, a former Playboy playmate who had filed the paternity suit. She and Mr. Mitchell were married in 1989 and later divorced.

Their son, Adam Mitchell, died in 2010 at age 26.

Survivors include two daughters from his first marriage; three stepchildren from his second marriage, whom Mr. Mitchell adopted; and several grandchildren.

In 2011, Mr. Mitchell was sued by NASA when he sought to sell a film camera from Apollo 14 at auction. He said the camera would have been left on the moon had he not brought it back. In a settlement, he agreed to donate it to the National Air and Space Museum in Washington.

In person, Mr. Mitchell could be physically imposing, intellectually intense, and alternately compelling and confounding. He was health-conscious but a heavy smoker, a scientist who maintained that he had been cured of kidney cancer by a psychic he never met in person.

Anita Mitchell, his former wife, said in 1988, “He’s the damnedest study of the human psyche you’ll ever come across.”