Only a dozen men have walked on the surface of the moon, and this Saturday marks the 50th anniversary of the groundbreaking Apollo 11 moon landing mission.
Of the 12 Americans who have set foot on the moon, only four are still alive.
From Apollo 11, the first lunar mission on July 20, 1969, Neil Armstrong and Buzz Aldrin took that giant leap for mankind.
Armstrong, an astronaut and aeronautical engineer, retired from NASA in 1971, and served as a corporate spokesperson for several businesses. Though he had a reputation for being reclusive, Armstrong spoke at public events, hosted a science series and taught college.
Armstrong died in 2012 at age 82.
Aldrin, who piloted the Apollo 11 mission, was the second man on the moon. He kept a higher public profile as an outspoken advocate for space exploration, including a manned mission to Mars.
Aldrin was a popular guest on the talk show circuit and even appeared on "Dancing with the Stars" in 2010.
He became the oldest person to reach the South Pole at 86 years old in 2016, where he said he had a near-death experience.
At 89 years old, Aldrin now makes his home in Florida.
Pete Conrad became the third person to walk on the moon in November 1969 as part of the Apollo 12 mission.
He retired from NASA in 1973 and worked in business. Conrad died in a motorcycle accident in California in 1999. He was 69.
Conrad’s Apollo 12 crewmate Alan Bean became the fourth man on the moon. He eventually logged 1,600 hours in space, serving in missions to Skylab and taking part in the Apollo-Soyuz Test Project.
After retiring from NASA in 1981, he became a painter, incorporating pieces from his spacesuit patches in his paintings.
Bean died in Texas in May 2018. He was 86.
Alan Shepard walked on the moon in February 1971 as a part of the Apollo 14 mission. He retired from NASA in 1974 and went on to work in banking and real estate, serve on nonprofit boards and found what would later become the Astronaut Scholarship Foundation.
He died of leukemia in 1998 at age 74.
Shepard’s crewmate on Apollo 14 Edgar Mitchell became the sixth man to walk on the moon. After retiring from NASA in 1972, he helped found the Institute of Noetic Sciences, a nonprofit organization in California that researches ESP and other psychic phenomena.
Mitchell died in Florida in 2016 at age 85.
Apollo 15 astronaut David Scott walked on the moon in both July and August 1971, but most notably became the first man to drive on the moon during the same mission.
After retiring from NASA in 1977, he became a writer and consultant for books and documentaries about its space program.
He now lives in Los Angeles, California.
James Irwin, who embarked on the same mission, became the eighth person to walk on the moon. He retired from NASA in 1972 and founded the High Flight Foundation, a Christian religious outreach organization.
Irwin died of a heart attack in 1991 at age 61, which made him the first of the moon men to die.
In April 1972, John Young became the ninth person to walk on the moon on the Apollo 16 mission. He later flew missions on the Space Shuttle Columbia and spent more than 40 years with NASA before retiring in 2004.
Young died in January 2018 at 87 years old.
Charles Duke became the 10th man on the moon during the same Apollo 16 mission. He retired from NASA in 1975 and became active in prison ministry.
Now at 83 years old, Duke lives in Texas and serves as chairman of the board of the Astronaut Scholarship Foundation.
In December 1972, Eugene Cernan took his moon walk during the Apollo 17 mission. Not only was Cernan the 11th man on the list; his are the last footprints to be left on the surface of the moon.
He retired from NASA in 1976 and worked in private industry and occasionally served as the commentator for "Good Morning America."
Cernan died in Texas in January 2017. He was 82.
The most recent living man to take steps on the moon was Harrison Schmitt, who was a geologist on the same Apollo 17 mission.
Schmitt retired from NASA in 1975 and went on to represent New Mexico in the U.S. Senate as a Republican for one term, starting the following year. He also taught at the university level and served as a business consultant.
At 84 years old, Schmitt now lives in New Mexico.