Neil Armstrong stepped into history on July 20, 1969, leaving the first human footprint on the surface of the moon.
Neil Armstrong sits inside the lunar module after his historic walk on the surface of the moon.
"That's one small step for man, one giant leap for mankind," Armstrong is famously quoted as saying after walking on the moon, but in interviews he claimed that he meant to say "one small step for a man."
Apollo 11 astronaut Buzz Aldrin stands on the moon next to the lunar module "Eagle" on July 20, 1969.
Neil Armstrong can be seen taking the picture in the reflection on the helmet.
A young Buzz Aldrin poses in a NASA photograph at left. At right, Aldrin speaks in London in 2016.
Aldrin, now 86, was medically evacuated from the South Pole in December 2016 after suffering symptoms of altitude sickness, but quickly recovered.
Alan Bean and Charles Conrad
Apollo 12 Astronaut Alan L. Bean holds a container filled with lunar soil during a moonwalk with Charles Conrad, Jr., in Nov.1969.
Conrad, who took this picture, is reflected in Bean's helmet visor.
Charles "Pete" Conrad, the third man to walk on the moon, poses at left in 1965 photo before his first space flight aboard Gemini 5. Conrad died after a motorcycle accident in Ojai, California, in 1999. He was 69.
Apollo 12 lunar module pilot Alan Bean poses in 1969 at right. Bean resigned from NASA in June 1981 to devote his time to painting.
Edgar Mitchell and Alan Shepard
Astronaut Edgar D. Mitchell, lunar module pilot, left, conducts a seismic experiment during the first Apollo 14 moonwalk with Alan Shepard on Feb. 5, 1971.
The photograph was captured by an automatic camera mounted on a vehicle the mission used to haul equipment.
The crew of the Apollo 14 lunar landing mission, from left, Stuart A. Roosa, commander Alan B. Shepard Jr., and lunar module pilot Edgar D. Mitchell. Roosa remained in orbit while the other two landed on the moon.
Mitchell died at 85, in Florida, in early 2016. After NASA, Mitchell devoted his life to exploring the mind, physics and unexplained phenomena such as psychics and aliens.
Shepard died in 1988. Before walking on the moon, Shepard became the first American in space with a suborbital flight in 1961.
James Irwin and David Scott
Astronaut James B. Irwin, lunar module pilot, gives a military salute to David Scott, taking the picture, while standing beside the U.S. flag during the Apollo 15 mission on Aug. 1, 1971.
The lunar module Falcon stands at center. Hadley Delta in the background rises approximately some 13,000 feet above the plain.
Apollo 15 astronauts James Irwin, left, and David Scott sample rocks in the Mojave Desert during a field trip in which they used a lunar rover simulator to explore a lava flow at the base of the Sierra Nevadas in California on April 29, 1971.
Irwin resigned from NASA and the Air Force in July 1972 to form a religious organization, High Flight Foundation, in Colorado Springs. He died in 1991.
A personal watch that David Scott wore while walking on the moon sold for a whopping $1.625 million at auction in 2015. He is only one of three astronauts who have flown both earth orbital and lunar Apollo missions.
Charles Duke and John Young
Astronaut Charles Duke collects lunar samples during the first Apollo 16 moonwalk on April 21, 1972.
Astronaut John W. Young captured the image as Duke stood at the rim of Plum crater.
The Apollo 16 crew relaxes during water egress training in the Gulf of Mexico on Feb. 5, 1972.
From left, Thomas K. Mattingly II, John W. Young, and Charles M. Duke. Mattingly remained in orbit while Young and Duke landed on the moon.
At 36, Charles Duke was the youngest man to walk on the moon.
John Young was the commander for the space shuttle fleet's inaugural flight in 1981.
Harrison Schmitt and Eugene Cernan
Astronaut Harrison H. Schmitt stands next to a huge, split lunar boulder during the third Apollo 17 moonwalk with astronaut Eugene Cernan in Dec. 1972.
NASA astronauts Eugene Cernan, left, and Harrison "Jack" Schmitt pose aboard the Apollo 17 spacecraft during the final lunar landing mission in Dec. 1972.
Schmitt was the first person initially trained as a scientist to walk on the moon. Originally a geologist, he was selected by NASA in June 1965 along with a group of other scientist-astronauts - the first group not to be test pilots.
Apollo 17 mission commander Eugene Cernan holds the lower corner of the U.S. flag during the mission's first moonwalk on Dec. 12, 1972.
Cernan, the last man on the moon, traced his only child's initials in the dust before climbing the ladder of the lunar module the last time. He died on Jan. 16, 2017, in Texas.
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