"[a][15] Apollo 11 effectively proved U.S. victory in the Space Race to demonstrate spaceflight superiority, by fulfilling a national goal proposed in 1961 by President John F. Kennedy, "before this decade is out, of landing a man on the Moon and returning him safely to the Earth.

[19] President Dwight D. Eisenhower responded to the Sputnik challenge by creating the National Aeronautics and Space Administration (NASA), and initiating Project Mercury,[20] which aimed to launch a man into Earth orbit.

[62] For Apollo 11, the CAPCOMs were: Charles Duke, Ronald Evans, Bruce McCandless II, James Lovell, William Anders, Ken Mattingly, Fred Haise, Don L. Lind, Owen K. Garriott and Harrison Schmitt.

"[116] As the descent began, Armstrong and Aldrin found themselves passing landmarks on the surface two or three seconds early, and reported that they were "long"; they would land miles west of their target point.

[117][118] Five minutes into the descent burn, and 6,000 feet (1,800 m) above the surface of the Moon, the LM guidance computer (LGC) distracted the crew with the first of several unexpected 1201 and 1202 program alarms.

Inside Mission Control Center, computer engineer Jack Garman told Guidance Officer Steve Bales it was safe to continue the descent, and this was relayed to the crew.

[122][123] Software engineer Don Eyles concluded in a 2005 Guidance and Control Conference paper that the problem was due to a hardware design bug previously seen during testing of the first uncrewed LM in Apollo 5.

[10] Armstrong acknowledged Aldrin's completion of the post-landing checklist with "Engine arm is off", before responding to the CAPCOM, Charles Duke, with the words, "Houston, Tranquility Base here.

At this time NASA was still fighting a lawsuit brought by atheist Madalyn Murray O'Hair (who had objected to the Apollo 8 crew reading from the Book of Genesis) demanding that their astronauts refrain from broadcasting religious activities while in space.

Climbing down the nine-rung ladder, Armstrong pulled a D-ring to deploy the modular equipment stowage assembly (MESA) folded against Eagle's side and activate the TV camera.

[144] Copies of this video in broadcast format were saved and are widely available, but recordings of the original slow scan source transmission from the lunar surface were likely destroyed during routine magnetic tape re-use at NASA.

One explanation for the absence may be that his accent caused him to slur the words "for a" together; another is the intermittent nature of the audio and video links to Earth, partly because of storms near Parkes Observatory.

[161] While on the surface, Armstrong uncovered a plaque mounted on the LM ladder, bearing two drawings of Earth (of the Western and Eastern Hemispheres), an inscription, and signatures of the astronauts and President Nixon.

[158] In a 2010 interview, Armstrong explained that NASA limited the first moonwalk's time and distance because there was no empirical proof of how much cooling water the astronauts' PLSS backpacks would consume to handle their body heat generation while working on the Moon.

[166][167] According to the plan, Mission Control would "close down communications" with the LM, and a clergyman would "commend their souls to the deepest of the deep" in a public ritual likened to burial at sea.

[167] The script for the speech does not make reference to Collins; as he remained onboard Columbia in orbit around the Moon, it was expected that he would be able to return the module to Earth in the event of a mission failure.

[174] Roughly two hours later, at 17:54:00 UTC, the Apollo 11 crew on the surface safely lifted off in Eagle's ascent stage to rejoin Collins aboard Columbia in lunar orbit.

[177] In the 48 minutes of each orbit when he was out of radio contact with the Earth while Columbia passed round the far side of the Moon, the feeling he reported was not fear or loneliness, but rather "awareness, anticipation, satisfaction, confidence, almost exultation".

On his first orbits on the back side of the Moon, Collins performed maintenance activities such as dumping excess water produced by the fuel cells and preparing the cabin for Armstrong and Aldrin to return.

A regular repair was not possible in the available time but the station director, Charles Force, had his ten-year-old son Greg use his small hands to reach into the housing and pack it with grease.

[189] A presidential party consisting of Nixon, Borman, Secretary of State William P. Rogers and National Security Advisor Henry Kissinger flew to Johnston Atoll on Air Force One, then to the command ship USS Arlington in Marine One.

Poor visibility which could make locating the capsule difficult, and strong upper-level winds which "would have ripped their parachutes to shreds" according to Brandli, posed a serious threat to the safety of the mission.

[219] Stops on the tour in order were: Mexico City, Bogota, Buenos Aires, Rio de Janeiro, Las Palmas in the Canary Islands, Madrid, Paris, Amsterdam, Brussels, Oslo, Cologne, Berlin, London, Rome, Belgrade, Ankara, Kinshasa, Tehran, Mumbai, Dhaka, Bangkok, Darwin, Sydney, Guam, Seoul, Tokyo and Honolulu.

[223] While most people celebrated the accomplishment, disenfranchised Americans saw it as a symbol of the divide in America, evidenced by protesters led by Ralph Abernathy outside of Kennedy Space Center the day before Apollo 11 launched.

[240] Columbia was moved in 2017 to the NASM Mary Baker Engen Restoration Hangar at the Steven F. Udvar-Hazy Center in Chantilly, Virginia, to be readied for a four-city tour titled Destination Moon: The Apollo 11 Mission.

[242] For 40 years Armstrong's and Aldrin's space suits were displayed in the museum's Apollo to the Moon exhibit,[243] until it permanently closed on December 3, 2018, to be replaced by a new gallery which was scheduled to open in 2022.

The rice-sized particles were four small pieces of Moon soil weighing about 50 mg and were enveloped in a clear acrylic button about as big as a United States half-dollar coin.

[268] In July 2010, air-to-ground voice recordings and film footage shot in Mission Control during the Apollo 11 powered descent and landing was re-synchronized and released for the first time.

[273][274] A group of British scientists interviewed as part of the anniversary events reflected on the significance of the Moon landing: It was carried out in a technically brilliant way with risks taken ... that would be inconceivable in the risk-averse world of today ...

[281] On July 19, 2019, the Google Doodle paid tribute to the Apollo 11 Moon Landing, complete with a link to an animated YouTube video with voiceover by astronaut Michael Collins.