Editing Neil Armstrong (section)

=== Apollo program ===
On January 27, 1967—the day of the [[Apollo 1 fire]]—Armstrong was in Washington, D.C., with Cooper, Gordon, Lovell and [[Scott Carpenter]] for the signing of the United Nations [[Outer Space Treaty]]. The astronauts chatted with the assembled dignitaries until 18:45, when Carpenter went to the airport, and the others returned to the Georgetown Inn, where they each found messages to phone the MSC. During these calls, they learned of the deaths of [[Gus Grissom]], [[Ed White (astronaut)|Ed White]] and [[Roger B. Chaffee|Roger Chaffee]] in the fire. Armstrong and the group spent the rest of the night drinking scotch and discussing what had happened.{{sfn|Lovell|Kluger|2000|pp=24–25}}

On April 5, 1967, the same day the Apollo{{nbsp}}1 investigation released its final report, Armstrong and 17 other astronauts gathered for a meeting with Slayton. The first thing Slayton said was, "The guys who are going to fly the first lunar missions are the guys in this room."{{sfn|Cernan|Davis|1999|p=165}} According to Cernan, only Armstrong showed no reaction to the statement. To Armstrong it came as no surprise—the room was full of veterans of Project Gemini, the only people who could fly the lunar missions. Slayton talked about the planned missions and named Armstrong to the backup crew for [[Apollo 9]], which at that stage was planned as a [[medium Earth orbit]] test of the combined [[lunar module]] and [[command and service module]].{{sfn|Hansen|2005|pp=312–313}}

The crew was officially assigned on November 20, 1967.{{sfn|Brooks et al.|2009|p=374}} For crewmates, Armstrong was assigned Lovell and Aldrin, from Gemini 12. After design and manufacturing delays of the lunar module (LM), [[Apollo 8]] and{{nbsp}}9 swapped prime and backup crews. Based on the normal crew rotation, Armstrong would command Apollo 11,{{sfn|Hansen|2005|pp=312–313}} with one change: Collins on the Apollo{{nbsp}}8 crew began experiencing trouble with his legs. Doctors diagnosed the problem as a bony growth between his fifth and sixth vertebrae, requiring surgery.{{sfn|Collins|2001|pp=288–289}} Lovell took his place on the Apollo{{nbsp}}8 crew, and, when Collins recovered, he joined Armstrong's crew.{{sfn|Cunningham|2010|p=109}}

[[File:Apollo 11 LLRV 1.jpg|thumb|left|Armstrong descends to the ground on a parachute after ejecting from [[Lunar Landing Research Vehicle]] 1.|alt=An indistinct photo of a smoke trail rising from an area of orange fire in a recently harvested field. A white and orange parachute is recovering a human figure above and to the right of the fire.]]To give the astronauts practice piloting the LM on its descent, NASA commissioned [[Bell Aircraft]] to build two [[Lunar Landing Research Vehicle]]s (LLRV), later augmented with three Lunar Landing Training Vehicles (LLTV). Nicknamed the "Flying Bedsteads", they simulated the Moon's one-sixth gravity using a [[turbofan]] engine to support five-sixths of the craft's weight. On May 6, 1968, {{convert|100|feet|m|0}} above the ground, Armstrong's controls started to degrade and the LLRV began [[aircraft principal axes|rolling]].{{sfn|Hansen|2005|p=330}} He ejected safely before the vehicle struck the ground and burst into flames. Later analysis suggested that if he had ejected half a second later, his parachute would not have opened in time. His only injury was from biting his tongue. The LLRV was completely destroyed.{{sfn|Kraft|2001|p=312}} Even though he was nearly killed, Armstrong maintained that without the LLRV and LLTV, the lunar landings would not have been successful, as they gave commanders essential experience in piloting the lunar landing craft.{{sfn|Hansen|2005|p=334}}

In addition to the LLRV training, NASA began lunar landing simulator training after Apollo 10 was completed. Aldrin and Armstrong trained for a variety of scenarios that could develop during a real lunar landing.{{sfn|Chaikin|1994|p=171}} They also received briefings from geologists at NASA.{{sfn|Chaikin|1994|p=179}}

==== Apollo 11 ====
{{Main|Apollo 11}}
[[File:Ap11-s69-31740.jpg|thumb|alt=Three astronauts in white space suits. They are holding their helmets. All are light-skinned. Armstrong is smiling widely and wears his hair parted to the right. Collins has dark hair and looks the most serious. Aldrin's hair is very short. Behind them is a large photo of the Moon.|The [[Apollo 11]] crew: Armstrong, [[Michael Collins (astronaut)|Michael Collins]], and [[Buzz Aldrin]].]]
After Armstrong served as backup commander for Apollo{{nbsp}}8, Slayton offered him the post of commander of Apollo 11 on December 23, 1968, as Apollo{{nbsp}}8 orbited the Moon.{{sfn|Nelson|2009|p=17}} According to Armstrong's 2005 biography, Slayton told him that although the planned crew was Commander Armstrong, Lunar Module Pilot Buzz Aldrin, and Command Module Pilot Michael Collins, he was offering Armstrong the chance to replace Aldrin with Jim Lovell. After thinking it over for a day, Armstrong told Slayton he would stick with Aldrin, as he had no difficulty working with him and thought Lovell deserved his own command. Replacing Aldrin with Lovell would have made Lovell the lunar module pilot, unofficially the lowest ranked member, and Armstrong could not justify placing Lovell, the commander of Gemini 12, in the number{{nbsp}}3 position of the crew.{{sfn|Hansen|2005|p=338}} The crew of Apollo 11 was assigned on January 9, 1969, as Armstrong, Collins, and Aldrin, with Lovell, Anders, and [[Fred Haise]] as the backup crew.{{sfn|Collins|2001|pp=312–313}}

According to [[Chris Kraft]], a March 1969 meeting among Slayton, George Low, [[Bob Gilruth]], and Kraft determined that Armstrong would be the first person on the Moon, in part because NASA management saw him as a person who did not have a large ego. A press conference on April 14, 1969, gave the design of the LM cabin as the reason for Armstrong's being first; the hatch opened inwards and to the right, making it difficult for the LM pilot, on the right-hand side, to exit first. At the time of their meeting, the four men did not know about the hatch consideration. The first knowledge of the meeting outside the small group came when Kraft wrote his book.{{sfn|Kraft|2001|pp=323–324}}{{sfn|Hansen|2005|pp=365–373}} Methods of circumventing this difficulty existed, but it is not known if these were considered at the time. Slayton added, "Secondly, just on a pure protocol basis, I figured the commander ought to be the first guy out{{nbsp}}... I changed it as soon as I found they had the time line that showed that. Bob Gilruth approved my decision."{{sfn|Cortright|1975|p=160}}

==== Voyage to the Moon ====
A [[Saturn V]] rocket launched Apollo 11 from [[Kennedy Space Center Launch Complex 39A|Launch Complex 39A]] at the [[Kennedy Space Center]] on July 16, 1969, at 13:32:00 [[Coordinated Universal Time|UTC]] (09:32:00 EDT local time).{{sfn|Orloff|2000|p=92}} Armstrong's wife Janet and two sons watched from a yacht moored on the [[Banana River]].{{sfn|Hansen|2005|p=2}} During the launch, Armstrong's heart rate peaked at 110{{nbsp}}beats per minute.{{sfn|Hansen|2005|p=410}} He found the first stage the loudest, much noisier than the Gemini{{nbsp}}8 Titan II launch. The Apollo command module was relatively roomy compared with the Gemini spacecraft. None of the Apollo 11 crew suffered [[space sickness]], as some members of previous crews had. Armstrong was especially glad about this, as he had been prone to [[motion sickness]] as a child and could experience [[nausea]] after long periods of [[aerobatics]].{{sfn|Hansen|2005|pp=411–412}}

[[File:Neil Armstrong.jpg|thumb|left|alt=Armstrong smiling in his space suit with the helmet off. He wears a headset and his eyes look slightly watery.|Armstrong in the lunar module after the completion of the [[extravehicular activity|EVA]]]]
Apollo 11's objective was to land safely on the Moon, rather than to touch down at a precise location. Three minutes into the lunar descent, Armstrong noted that craters were passing about two seconds too early, which meant the [[Lunar Module Eagle|Lunar Module ''Eagle'']] would probably touch down several miles (kilometres) beyond the planned landing zone.{{sfn|Smith|2005|p=11}} As the ''Eagle''{{'}}s landing [[radar]] acquired the surface, several computer error alarms sounded. The first was a code [[Jack Garman#1202|1202]] alarm, and even with their extensive training, neither Armstrong nor Aldrin knew what this code meant. They promptly received word from CAPCOM [[Charles Duke]] in Houston that the alarms were not a concern; the 1202 and 1201 alarms were caused by executive overflows in the [[Apollo Guidance Computer|lunar module guidance computer]]. In 2007, Aldrin said the overflows were caused by his own counter-checklist choice of leaving the docking radar on during the landing process, causing the computer to process unnecessary radar data. When it did not have enough time to execute all tasks, the computer dropped the lower-priority ones, triggering the alarms. Aldrin said he decided to leave the radar on in case an abort was necessary when re-docking with the Apollo command module; he did not realize it would cause the processing overflows.{{sfn|Hansen|2005|pp=459–465}}
[[File:AP11 FINAL APPROACH.ogv|thumb|Armstrong lands the [[Lunar Module Eagle|Lunar Module ''Eagle'']] on the Moon, July 20, 1969.]]
When Armstrong noticed they were heading toward a landing area that seemed unsafe, he took manual control of the LM and attempted to find a safer area. This took longer than expected, and longer than most simulations had taken.{{sfn|Chaikin|1994|p=199}} For this reason, Mission Control was concerned that the LM was running low on fuel.{{sfn|Chaikin|1994|p=198}} On landing, Aldrin and Armstrong believed they had 40{{nbsp}}seconds of fuel left, including the 20{{nbsp}}seconds' worth which had to be saved in the event of an abort.{{sfn|Chaikin|1994|p=200}} During training, Armstrong had, on several occasions, landed with fewer than 15{{nbsp}}seconds of fuel; he was also confident the LM could survive a fall of up to {{convert|50|ft|m}}. Post-mission analysis showed that at touchdown there were 45 to 50{{nbsp}}seconds of propellant burn time left.{{sfn|Manned Spacecraft Center|1969|pp=9-23–9-24}}

The landing on the surface of the Moon occurred several seconds after 20:17:40 UTC on July 20, 1969.<ref>{{cite web |last=Jones |first=Eric M. |title=The First Lunar Landing, time 109:45:40 |url=http://www.history.nasa.gov/alsj/a11/a11.landing.html |website=Apollo 11 Surface Journal |publisher=NASA |access-date=March 4, 2018 |url-status=dead |archive-url=https://web.archive.org/web/20171225232200/https://history.nasa.gov/alsj/a11/a11.landing.html |archive-date=December 25, 2017 }} That was the time of probe contact; the exact time of landing is difficult to determine, because Armstrong said the landing was "very gentle" and "It was hard to tell when we were on."</ref> One of three {{convert|67|in|cm|adj=on}} probes attached to three of the LM's four legs made contact with the surface, a panel light in the LM illuminated, and Aldrin called out, "Contact light." Armstrong shut the engine off and said, "Shutdown." As the LM settled onto the surface, Aldrin said, "Okay, engine stop"; then they both called out some post-landing checklist items. After a 10-second pause, Duke acknowledged the landing with, "We copy you down, ''Eagle''." Armstrong confirmed the landing to Mission Control and the world with the words, "Houston, [[Tranquility Base]] here. The ''Eagle'' has landed." Aldrin and Armstrong celebrated with a brisk handshake and pat on the back. They then returned to the checklist of contingency tasks, should an emergency liftoff become necessary.<ref>{{cite web |last=Jones |first=Eric M. |title=The First Lunar Landing, time 1:02:45 |url=http://www.history.nasa.gov/alsj/a11/a11.landing.html |access-date=November 30, 2007 |website=Apollo 11 Surface Journal |publisher=NASA |date=September 15, 2017 |url-status=dead |archive-url=https://web.archive.org/web/20171225232200/https://history.nasa.gov/alsj/a11/a11.landing.html |archive-date=December 25, 2017 }}</ref><ref>{{cite web |last=Jones |first=Eric M. |title=Mission Transcripts, Apollo 11 AS11 PA0.pdf |url=https://www.jsc.nasa.gov/history/mission_trans/AS11_PAO.PDF |access-date=November 30, 2007 |website=Apollo 11 Surface Journal |publisher=NASA |archive-url=https://web.archive.org/web/20080917232517/http://www.jsc.nasa.gov/history/mission_trans/AS11_PAO.PDF |archive-date=September 17, 2008 |url-status=dead}}</ref><ref>{{cite web |last=Jones |first=Eric M. |title=Apollo 11 Mission Commentary 7-20-69 CDT 15:15 – GET 102:43 – TAPE 307/1 |url=https://history.nasa.gov/alsj/a11/a11transcript_pao.htm |url-status=dead |archive-url=https://web.archive.org/web/20171108072819/https://history.nasa.gov/alsj/a11/a11transcript_pao.htm |archive-date=November 8, 2017 |website=Apollo 11 Surface Journal |publisher=NASA}}</ref> After Armstrong confirmed touch down, Duke re-acknowledged, adding a comment about the flight crew's relief: "Roger, Tranquility. We copy you on the ground. You got a bunch of guys about to turn blue. We're breathing again. Thanks a lot."{{sfn|Chaikin|1994|p=200}} During the landing, Armstrong's heart rate ranged from 100 to 150{{nbsp}}beats per minute.{{sfn|Manned Spacecraft Center|1969|p=12-1}}

==== First Moon walk ====
{{See also|Apollo 11#Lunar surface operations}}
[[File:Apollo 11 Landing - first steps on the moon.ogv|thumb|right|Armstrong describes the lunar surface.]]
{{Listen
| filename     = Frase de Neil Armstrong.ogg
| title        = "That's one small step for [a] man, one giant leap for mankind"
| description  = 
| format       = [[Ogg]]
}}
The flight plan called for a crew rest period before leaving the module, but Armstrong asked for this to be moved to earlier in the evening, [[Central Time Zone (North America)|Houston time]]. When he and Aldrin were ready to go outside, ''Eagle'' was depressurized, the hatch was opened, and Armstrong made his way down the ladder.{{sfn|Cortright|1975|p=215}} At the bottom of the ladder, while standing on a [[Apollo Lunar Module|Lunar Module]] landing pad, Armstrong said, "I'm going to step off the LM now". He turned and set his left boot on the lunar surface at 02:56 [[UTC]] July 21, 1969,{{sfn|Harland|1999|p=23}} then said, "That's one small step for [a] man, one giant leap for mankind."<ref name="Snopes">{{cite web |last1=Mikkelson |first1=Barbara |first2=David |last2=Mikkelson |title=One Small Misstep: Neil Armstrong's First Words on the Moon |date=October 2006 |website=Snopes.com |url=http://www.snopes.com/quotes/onesmall.asp |access-date=September 19, 2009}}</ref> The exact time of Armstrong's first step on the Moon is unclear.<ref>{{cite web | last=Stern | first=Jacob | title=One Small Controversy About Neil Armstrong's Giant Leap | website=[[The Atlantic]] | date=July 23, 2019 | url=https://www.theatlantic.com/science/archive/2019/07/tiny-imprecision-heart-apollo-11/594556/ | access-date=July 25, 2019 | quote=When he tried to match the air-to-ground transcript to an audiovisual recording, he found that the transcript was behind—and that one of the records had to be wrong about the time of Armstrong's first step.}}</ref>

Armstrong prepared his famous [[epigram]] on his own.<ref name="Plimpton" /> In a post-flight press conference, he said that he chose the words "just prior to leaving the LM."<ref>{{cite web |title=Apollo 11 Post Flight Press Conference, 16 September 1969 |url=https://history.nasa.gov/ap11ann/FirstLunarLanding/ch-7.html |publisher=NASA |access-date=July 24, 2015 |quote=Yes, I did think about it. It was not extemporaneous, neither was it planned. It evolved during the conduct of the flight and I decided what the words would be while we were on the lunar surface just prior to leaving the LM. |url-status=live |archive-url=https://web.archive.org/web/20151016015011/http://history.nasa.gov/ap11ann/FirstLunarLanding/ch-7.html |archive-date=October 16, 2015}}</ref> In a 1983 interview in ''[[Esquire (magazine)|Esquire]]'' magazine, he explained to [[George Plimpton]]: "I always knew there was a good chance of being able to return to Earth, but I thought the chances of a successful touch down on the moon surface were about even money—fifty–fifty{{nbsp}}... Most people don't realize how difficult the mission was. So it didn't seem to me there was much point in thinking of something to say if we'd have to abort landing."<ref name="Plimpton">{{cite magazine |last=Plimpton |first=George |author-link=George Plimpton |title=Neil Armstrong's Famous First Words |magazine=[[Esquire (magazine)|Esquire]] |date=December 1983 |pages=113–118}}</ref> In 2012, his brother Dean Armstrong said that Neil showed him a draft of the line months before the launch.<ref>{{cite news |last1=Gray |first1=Richard |title=Neil Armstrong's family reveal origins of 'one small step' line |url=https://www.telegraph.co.uk/news/science/space/9770712/Neil-Armstrongs-family-reveal-origins-of-one-small-step-line.html |access-date=July 24, 2015 |newspaper=[[The Daily Telegraph]] |date=December 30, 2012 |url-status=live |archive-url=https://web.archive.org/web/20150701041241/http://www.telegraph.co.uk/news/science/space/9770712/Neil-Armstrongs-family-reveal-origins-of-one-small-step-line.html |archive-date=July 1, 2015}}</ref> Historian [[Andrew Chaikin]], who interviewed Armstrong in 1988 for his book ''[[A Man on the Moon]]'', disputed that Armstrong claimed to have conceived the line during the mission.<ref>{{cite web |last1=Chaikin |first1=Andrew |title=Neil Armstrong Didn't Lie About 'One Small Step' Moon Speech, Historian Says |url=http://www.space.com/19136-neil-armstrong-moon-speech-truth.html |website=[[Space.com]] |access-date=July 24, 2015 |date=January 4, 2013 |url-status=live |archive-url=https://web.archive.org/web/20150724160705/http://www.space.com/19136-neil-armstrong-moon-speech-truth.html |archive-date=July 24, 2015 |publisher=Purch}}</ref>

Recordings of Armstrong's transmission do not provide evidence for the indefinite article "a" before "man", though NASA and Armstrong insisted for years that static obscured it. Armstrong stated he would never make such a mistake, but after repeated listenings to recordings, he eventually conceded he must have dropped the "a".<ref name="Snopes" /> He later said he "would hope that history would grant me leeway for dropping the syllable and understand that it was certainly intended, even if it was not said—although it might actually have been".{{sfn|Nickell|2008|p=175}} There have since been claims and counter-claims about whether acoustic analysis of the recording reveals the presence of the missing "a";<ref name="Snopes" /><ref>{{cite news |last=Goddard |first=Jacqui |title=One small word is one giant sigh of relief for Armstrong |newspaper=[[The Times]] |location=London |date=October 2, 2006 |url=https://www.thetimes.com/uk/science/article/one-small-word-is-one-giant-sigh-of-relief-for-armstrong-8ffrjd0s6wz |access-date=December 31, 2012 |url-access=subscription}}</ref> [[Peter Shann Ford]], an Australian computer programmer, conducted a digital audio analysis and claims that Armstrong did say "a man", but the "a" was inaudible due to the limitations of communications technology of the time.<ref name="Snopes" /><ref>{{cite web |last=Ford |first=Peter Shann |title=Electronic Evidence and Physiological Reasoning Identifying the Elusive Vowel "a" in Neil Armstrong's Statement on First Stepping onto the Lunar Surface |website=collectSPACE|date=September 17, 2006 |url=http://www.collectspace.com/news/news-100306a.html |access-date=August 28, 2007 |url-status=live |archive-url=https://web.archive.org/web/20070927015424/http://www.collectspace.com/news/news-100306a.html |archive-date=September 27, 2007}}</ref><ref>{{cite news |title=Software Finds Missing 'a' in Armstrong's Moon Quote |publisher=[[CNN]] |date=October 1, 2006 |url=http://www.cnn.com/2006/US/09/30/moon.quote.ap/index.html |archive-url=https://web.archive.org/web/20061004151135/http://www.cnn.com/2006/US/09/30/moon.quote.ap/index.html |archive-date=October 4, 2006 |agency=Associated Press}}</ref> Ford and [[James R. Hansen]], Armstrong's authorized biographer, presented these findings to Armstrong and NASA representatives, who conducted their own analysis.<ref>{{cite web|last=Smith |first=Veronica |agency=Agence France-Presse |title=Armstrong's Moon landing speech rewritten |magazine=[[Cosmos (Australian magazine)|Cosmos]] |date=October 2, 2006 |url=http://www.cosmosmagazine.com/node/717 |access-date=August 29, 2007 |archive-url=https://web.archive.org/web/20070831202457/http://www.cosmosmagazine.com/node/717 |archive-date=August 31, 2007}}</ref> Armstrong found Ford's analysis "persuasive".<ref>{{cite news |last=Carreau |first=Mark |title=High-tech analysis may rewrite space history |newspaper=[[Houston Chronicle]] |date=September 29, 2006 |url=http://www.chron.com/disp/story.mpl/front/4225505.html |access-date=September 30, 2006 |url-status=live |archive-url=https://web.archive.org/web/20061004192255/http://www.chron.com/disp/story.mpl/front/4225505.html |archive-date=October 4, 2006}}</ref><ref>{{cite news | title=Hear what Neil Armstrong really said on the moon | last=Carreau | first=Mark |newspaper=Houston Chronicle | date=September 30, 2006 | url=https://www.chron.com/news/nation-world/article/Hear-what-Neil-Armstrong-really-said-on-the-moon-1862496.php | access-date=July 25, 2019}}</ref> Linguists [[David Beaver]] and [[Mark Liberman]] wrote of their skepticism of Ford's claims on the blog [[Language Log]].<ref>[[Language Log]]s:
* {{cite web |first=David |last=Beaver |author-link=David Beaver |website=Language Log |url=http://itre.cis.upenn.edu/%7Emyl/languagelog/archives/003630.html |publisher=University of Pennsylvania |access-date=February 28, 2018 |title=One small step backwards |url-status=live |archive-url=https://web.archive.org/web/20171108072803/http://itre.cis.upenn.edu/%7Emyl/languagelog/archives/003630.html |archive-date=November 8, 2017 |ref=none}} (including audio)
* {{cite web |first=Mark |last=Liberman |author-link=Mark Liberman |website=Language Log |url=http://itre.cis.upenn.edu/%7Emyl/languagelog/archives/003632.html |title=One 75-millisecond step before a "man" |publisher=University of Pennsylvania |access-date=February 28, 2018 |url-status=live |archive-url=https://web.archive.org/web/20171108072810/http://itre.cis.upenn.edu/%7Emyl/languagelog/archives/003632.html |archive-date=November 8, 2017 |ref=none}}
* {{cite web |first=David |last=Beaver |author-link=David Beaver |website=Language Log |url=http://itre.cis.upenn.edu/~myl/languagelog/archives/003634.html |title=Armstrong's abbreviated article: the smoking gun? |publisher=University of Pennsylvania |access-date=February 28, 2018 |url-status=live |archive-url=https://web.archive.org/web/20171108072811/http://itre.cis.upenn.edu/~myl/languagelog/archives/003634.html |archive-date=November 8, 2017|ref=none}}
* {{cite web |first=David |last=Beaver |author-link=David Beaver |website=Language Log |url=http://itre.cis.upenn.edu/%7Emyl/languagelog/archives/003635.html |title=Armstrong's abbreviated article: notes from the expert |publisher=University of Pennsylvania |access-date=February 28, 2018 |url-status=live |archive-url=https://web.archive.org/web/20171108072827/http://itre.cis.upenn.edu/%7Emyl/languagelog/archives/003635.html |archive-date=November 8, 2017|ref=none}}
* {{cite web |first=David |last=Beaver |author-link=David Beaver |website=Language Log |url=http://itre.cis.upenn.edu/~myl/languagelog/archives/003639.html |title=First Korean on the moon! |publisher=University of Pennsylvania |access-date=February 28, 2018 |url-status=live |archive-url=https://web.archive.org/web/20171108072825/http://itre.cis.upenn.edu/~myl/languagelog/archives/003639.html |archive-date=November 8, 2017|ref=none}}
* {{cite web |first=Mark |last=Liberman |author-link=Mark Liberman |website=Language Log |url=http://itre.cis.upenn.edu/~myl/languagelog/archives/003645.html |title=What Neil Armstrong said |publisher=University of Pennsylvania |access-date=February 28, 2018 |url-status=live |archive-url=https://web.archive.org/web/20171108072829/http://itre.cis.upenn.edu/~myl/languagelog/archives/003645.html |archive-date=November 8, 2017|ref=none}}</ref> A 2016 peer-reviewed study again concluded Armstrong had included the article.<ref>{{Cite journal |last1=Baese-Berk |first1=M. M. |last2=Dilley |first2=L. C. |last3=Schmidt |first3=S. |last4=Morrill |first4=T. H. |last5=Pitt |first5=M. A. |year=2016 |title=Revisiting Neil Armstrong's Moon-Landing Quote: Implications for Speech Perception, Function Word Reduction, and Acoustic Ambiguity |journal=PLOS ONE |volume=11 |number=9 |pages=1–11 |doi=10.1371/journal.pone.0155975 |pmid=27603209 |pmc=5014323 |bibcode=2016PLoSO..1155975B|doi-access=free  |issn = 1932-6203}}</ref> NASA's transcript continues to show the "a" in parentheses.<ref>{{cite web |last=Jones |first=Eric M. |title=One Small Step, time 109:24:23 |url=http://www.hq.nasa.gov/office/pao/History/alsj/a11/a11.step.html |access-date=December 18, 2012 |website=Apollo 11 Surface Journal |publisher=NASA |url-status=live |archive-url=https://web.archive.org/web/20130102060848/http://www.hq.nasa.gov/office/pao/History/alsj/a11/a11.step.html |archive-date=January 2, 2013}}</ref>

When Armstrong made his proclamation, [[Voice of America]] was rebroadcast live by the [[BBC]] and many other stations worldwide. An estimated 530{{nbsp}}million people viewed the event,<ref>{{cite web |url=https://www.nasa.gov/mission_pages/apollo/missions/apollo11.html |title=Apollo 11 Mission Overview |publisher=NASA |access-date=March 4, 2018 |url-status=live |archive-url=https://web.archive.org/web/20180209204039/https://www.nasa.gov/mission_pages/apollo/missions/apollo11.html |archive-date=February 9, 2018 |date=April 17, 2015}}</ref> 20 percent out of a world population of approximately 3.6{{nbsp}}billion.<ref>{{cite news |last=Stuckey |first=Alex |date=October 29, 2018 |title='Giant leap' for space collectibles: Neil Armstrong's personal collection goes on auction block |url=https://www.chron.com/news/nation-world/article/Giant-leap-for-space-collectibles-Neil-13345916.php |newspaper=Houston Chronicle |agency=Associated Press |access-date=May 26, 2019}}</ref><ref>{{cite web |url=https://esa.un.org/unpd/wpp/DVD/Files/1_Indicators%20(Standard)/EXCEL_FILES/1_Population/WPP2017_POP_F01_1_TOTAL_POPULATION_BOTH_SEXES.xlsx |publisher=United Nations Population Division |title=Total Population—Both Sexes |access-date=April 7, 2018 |format=xlsx |url-status=dead |archive-url=https://web.archive.org/web/20170730155936/https://esa.un.org/unpd/wpp/DVD/Files/1_Indicators%20(Standard)/EXCEL_FILES/1_Population/WPP2017_POP_F01_1_TOTAL_POPULATION_BOTH_SEXES.xlsx |archive-date=July 30, 2017}}</ref>{{nbsp}}

{{Quote box
| quote = Q: Did you misspeak?

A: There isn't any way of knowing.

Q: Several sources say you did.

A: I mean, there isn't any way of ''my'' knowing. When I listen to the tape, I can't hear the 'a', but that doesn't mean it wasn't there, because that was the fastest VOX ever built. There was no mike-switch — it was a [[Voice-operated switch|voice-operated key or VOX]]. In a helmet you find you lose a lot of syllables. Sometimes a short syllable like 'a' might not be transmitted. However, when I listen to it, I can't hear it. But the 'a' is implied, so I'm happy if they just put it in parentheses.
| source = ''[[Omni (magazine)|Omni]]'', June 1982, p. 126
}}

[[File:As11-40-5886.jpg|thumb|left|Armstrong on the Moon|alt=A grainy picture from behind of a human figure in white space suit and backpack standing in front of the Lunar Module on the surface of the Moon. A landing leg is visible and the U.S. flag on the descent stage.]]
About 19{{nbsp}}minutes after Armstrong's first step, Aldrin joined him on the surface, becoming the second human to walk on the Moon. They began their tasks of investigating how easily a person could operate on the lunar surface. Armstrong unveiled a plaque commemorating the flight, and with Aldrin, [[Flag planting|planted]] the [[Lunar Flag Assembly|flag of the United States]]. Although Armstrong had wanted the flag to be draped on the flagpole,{{sfn|Chaikin|2007|p=212}} it was decided to use a metal rod to hold it horizontally.{{sfn|Johnson|2008|p=60}} However, the rod did not fully extend, leaving the flag with a slightly wavy appearance, as if there were a breeze.{{sfn|Hansen|2012|pp=503–504}} Shortly after the flag planting, President [[Richard Nixon]] spoke to them by telephone from his office. He spoke for about a minute, after which Armstrong responded for about thirty seconds.{{sfn|Hansen|2005|pp=505–506}} In the Apollo 11 photographic record, there are only five images of Armstrong partly shown or reflected. The mission was planned to the minute, with the majority of photographic tasks performed by Armstrong with the single [[Hasselblad]] camera.<ref>{{cite web |url=http://next.nasa.gov/alsj/a11/a11.5886.html |archive-url=https://web.archive.org/web/20110728042723/http://next.nasa.gov/alsj/a11/a11.5886.html |archive-date=July 28, 2011 |date=July 28, 2011 |title=AS11-40-5886 |last1=Jones |first1=Eric M. |website=Apollo 11 Lunar Surface Journal |publisher=NASA |url-status=dead |access-date=May 13, 2011}}</ref>

After helping to set up the [[Apollo Lunar Surface Experiments Package|Early Apollo Scientific Experiment Package]], Armstrong went for a walk to what is now known as East Crater, {{convert|65|yd|m}} east of the LM, the greatest distance traveled from the LM on the mission. His final task was to remind Aldrin to leave a small package of memorial items to Soviet [[List of cosmonauts|cosmonauts]] [[Yuri Gagarin]] and [[Vladimir Komarov]], and Apollo{{nbsp}}1 astronauts Grissom, White and Chaffee.<ref>{{cite web |last1=Jones |first1=Eric M. |last2=Glover |first2=Ken |title=EASEP Deployment and Closeout |url=http://www.hq.nasa.gov/alsj/a11/a11.clsout.html |website=Apollo 11 Lunar Surface Journal |publisher=NASA |access-date=March 28, 2014 |at=111:36:38 |year=1995 |url-status=live |archive-url=https://web.archive.org/web/20140225025455/http://www.hq.nasa.gov/alsj/a11/a11.clsout.html |archive-date=February 25, 2014}}</ref> The Apollo 11 EVA lasted two and a half hours.<ref name="ApolloSum" /> Each of the subsequent five landings was allotted a progressively longer EVA period; the crew of [[Apollo 17]] spent over 22{{nbsp}}hours exploring the lunar surface.<ref name="ApolloSum">{{cite web |title=Summary Data on Apollo Missions |publisher=NASA |url=https://history.nasa.gov/SP-4214/app5.html |access-date=May 20, 2011 |url-status=dead |archive-url=https://web.archive.org/web/20120117134054/http://history.nasa.gov/SP-4214/app5.html |archive-date=January 17, 2012}}</ref> In a 2010 interview, Armstrong explained that NASA limited their Moon walk because they were unsure how the [[space suit]]s would cope with the Moon's extremely high temperature.<ref>{{cite web |url=http://www.space.com/10469-neil-armstrong-explains-famous-apollo-11-moonwalk.html |title=Neil Armstrong Explains His Famous Apollo 11 Moonwalk |website=Space.com |date=December 10, 2010 |access-date=October 14, 2013 |url-status=live |archive-url=https://web.archive.org/web/20130802234446/http://www.space.com/10469-neil-armstrong-explains-famous-apollo-11-moonwalk.html |archive-date=August 2, 2013}}</ref>

==== Return to Earth ====
[[File:President Nixon welcomes the Apollo 11 astronauts aboard the U.S.S. Hornet.jpg|thumb|alt=The three crew members smiling at the President through the glass window of their metal quarantine chamber. Below the window is the Presidential Seal, and above it is stenciled on a wooden board "HORNET + 3". President Nixon is standing at a microphone, also smiling. He has dark crinkly hair and a light gray suit.|The Apollo 11 crew and President [[Richard Nixon]] during the post-mission quarantine period]]
After they re-entered the LM, the hatch was closed and sealed. While preparing for liftoff, Armstrong and Aldrin discovered that, in their bulky space suits, they had broken the ignition switch for the ascent engine; using part of a pen, they pushed in the circuit breaker to start the launch sequence.{{sfn|Hansen|2005|pp=489–490}} The ''Eagle'' then continued to its rendezvous in lunar orbit, where it docked with ''[[Command module Columbia|Columbia]]'', the command and service module. The three astronauts returned to Earth and splashed down in the Pacific Ocean, to be picked up by the {{USS|Hornet|CV-12|6}}.<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1969-059A |title=Apollo 11 Command and Service Module (CSM) |publisher=NASA |access-date=August 26, 2012 }}</ref>

After being released from an 18-day quarantine to ensure that they had not picked up any infections or diseases from the Moon, the crew was feted across the United States and around the world as part of a 38-day "Giant Leap" tour.<ref>{{cite news |url=https://www.newspapers.com/clip/27494178/the_logan_daily_news/ |title=Apollo 11 Crew Starts World Tour |agency=Associated Press |date=September 29, 1969 |page=1 |location=Logan, Ohio |newspaper=Logan Daily News |via=Newspapers.com}}</ref> [[File:Apollo 11 ticker tape parade 1.jpg|thumb|New York City ticker tape parade, August 13, 1969]]
The tour began on August 13, when the three astronauts spoke and rode in [[ticker-tape parade]]s in their honor in New York and Chicago, with an estimated six million attendees.<ref name="LADinner">{{cite web |last=Nixon|first=Richard|title=Remarks at a Dinner in Los Angeles Honoring the Apollo 11 Astronauts |url=https://www.presidency.ucsb.edu/documents/remarks-dinner-los-angeles-honoring-the-apollo-11-astronauts |website=The American Presidency Project|editor-last=Peters |editor-first=Gerhard |editor2-last=Woolley |editor2-first=John T.|publisher=University of California, Santa Barbara |access-date=July 20, 2019 |date=August 13, 1969}}</ref><ref>{{cite news|url=https://www.newspapers.com/clip/27531303/the_evening_sun/|title=President Offers Toast to 'Three Brave Men'|newspaper=The Evening Sun|date=August 14, 1969|page=1|location=Baltimore, Maryland|via=Newspapers.com|agency=Associated Press}}</ref> On the same evening an official [[state dinner]] was held in Los Angeles to celebrate the flight, attended by members of Congress, 44{{nbsp}}governors, the [[Chief Justice of the United States]], and ambassadors from 83{{nbsp}}nations. President Nixon and Vice President Agnew presented each astronaut with a [[Presidential Medal of Freedom]].<ref name="LADinner" /><ref>{{cite news|url=https://www.newspapers.com/clip/27531557/the_honolulu_advertiser/|title=Astronauts Awed by the Acclaim|newspaper=The Honolulu Advertiser|page=1|date=August 14, 1969|last1=Smith|first1=Merriman|agency=United Press International|via=Newspapers.com}}</ref>

After the tour Armstrong took part in [[Bob Hope]]'s 1969 [[USO]] show, primarily to Vietnam.{{sfn|Hansen|2005|p=580}} In May 1970, Armstrong traveled to the Soviet Union to present a talk at the 13th annual conference of the International [[Committee on Space Research]]; after arriving in [[Leningrad]] from Poland, he traveled to Moscow where he met [[Premier of the Soviet Union|Premier]] [[Alexei Kosygin]]. Armstrong was the first westerner to see the supersonic [[Tupolev Tu-144]] and was given a tour of the [[Yuri Gagarin Cosmonaut Training Center]], which he described as "a bit Victorian in nature".{{sfn|Hansen|2005|p=583}} At the end of the day, he was surprised to view a delayed video of the launch of [[Soyuz 9]] as it had not occurred to Armstrong that the mission was taking place, even though Valentina Tereshkova had been his host and her husband, [[Andriyan Nikolayev]], was on board.{{sfn|Hansen|2005|pp=582–584}}