View source for Astronomy:Apollo program

{{Short description|1961–1972 American crewed lunar exploration program}}
{{Infobox space program
| name            = Apollo program
| image           = [[File:Apollo program.svg|frameless|upright]]
| alt             = The letter "A" printed with a depiction of a trans-lunar trajectory streaking across; the Moon and Earth are depicted on opposite sides of the "A", with Apollo's face outlined on the Moon
| country         = United States
| organization    = [[Organization:NASA|NASA]]
| purpose         = Crewed lunar landing
| cost            = {{Unbulleted list
  | $25.4 billion (1973)<ref name="ApolloCost" />
  | ${{format price|{{Inflation|US|25400000000|1972|r=3}}}} ({{Inflation/year|US}}){{Inflation/fn|US}}
  }}
| status          = Completed
| duration        = 1961–1972
| firstflight     = {{Unbulleted list
  | [[Engineering:Saturn I SA-1|SA-1]]
  | {{Start date|1961|10|27}}
  }}
| firstcrewed     = {{Unbulleted list
  | [[Engineering:Apollo 7|Apollo 7]]
  | {{Start date|1968|10|11}}
  }}
| lastflight      = {{Unbulleted list
  | [[Engineering:Apollo 17|Apollo 17]]
  | {{Start date|1972|12|19}}
  }}
| successes       = 32
| failures        = 2 ([[Engineering:Apollo 1|Apollo 1]] and [[Engineering:Apollo 13|13]])
| partialfailures = 1 ([[Engineering:Apollo 6|Apollo 6]])
| launchsite      = {{Unbulleted list
  | Cape Kennedy
  | Kennedy Space Center
  | White Sands
  }}
| crewvehicle     = {{Hlist|[[Engineering:Apollo command and service module|Apollo CSM]]|[[Engineering:Apollo Lunar Module|Apollo LM]]}}
| launcher        = {{Hlist|[[Engineering:Little Joe II|Little Joe II]]|[[Astronomy:Saturn I|Saturn I]]|[[Astronomy:Saturn IB|Saturn IB]]|[[Engineering:Saturn V|Saturn V]]}}
}}
{{United States space program sidebar}}

The '''Apollo program''', also known as '''Project Apollo''', was the United States [[Astronomy:Human spaceflight|human spaceflight]] program carried out by the [[Organization:NASA|National Aeronautics and Space Administration]] (NASA), which succeeded in preparing and [[Astronomy:Moon landing|landing]] the first men<ref>{{cite web | url=https://www.nasa.gov/history/july-20-1969-one-giant-leap-for-mankind/ | title=July 20, 1969: One Giant Leap for Mankind - NASA | date=July 20, 2019 }}</ref> on the Moon from [[Engineering:Apollo 7|1968]] to [[Engineering:Apollo 17|1972]]. It was first conceived in 1960 during President Dwight D. Eisenhower's administration as a three-person spacecraft to follow the one-person [[Astronomy:Project Mercury|Project Mercury]], which put the first Americans in space. Apollo was later dedicated to President [[Biography:John F. Kennedy|John F. Kennedy]]'s national goal for the 1960s of "landing a man on the Moon and returning him safely to the Earth" in an address to Congress on May 25, 1961. It was the third US human spaceflight program to fly, preceded by the two-person [[Astronomy:Project Gemini|Project Gemini]] conceived in 1961 to extend spaceflight capability in support of Apollo.

Kennedy's goal was accomplished on the [[Engineering:Apollo 11|Apollo 11]] mission when astronauts Neil Armstrong and [[Biography:Buzz Aldrin|Buzz Aldrin]] landed their [[Engineering:Apollo Lunar Module|Apollo Lunar Module]] (LM) on July 20, 1969, and walked on the lunar surface, while Michael Collins remained in [[Astronomy:Lunar orbit|lunar orbit]] in the [[Engineering:Apollo command and service module|command and service module]] (CSM), and all three landed safely on Earth in the Pacific Ocean on July 24. Five subsequent Apollo missions also landed [[Astronaut|astronaut]]s on the Moon, the last, [[Engineering:Apollo 17|Apollo 17]], in December 1972. In these six spaceflights, [[Astronomy:List of Apollo astronauts#Apollo astronauts who walked on the Moon|twelve people walked on the Moon]].

[[File:Aldrin Apollo 11 original.jpg|thumb|Buzz Aldrin (pictured) walked on the Moon with Neil Armstrong, on Apollo 11, July 20–21, 1969.|alt=Astronaut Buzz Aldrin, standing on the Moon]]
[[File:NASA-Apollo8-Dec24-Earthrise.jpg|alt=|thumb|''Earthrise'', the iconic 1968 image from Apollo 8 taken by astronaut William Anders]]

Apollo ran from 1961 to 1972, with the first crewed flight in 1968. It encountered a major setback in 1967 when an [[Engineering:Apollo 1|Apollo 1]] cabin fire killed the entire crew during a prelaunch test. After the first successful landing, sufficient flight hardware remained for nine follow-on landings with a plan for extended lunar [[Astronomy:Geology of the Moon|geological]] and [[Physics:Astrophysics|astrophysical]] exploration. Budget cuts forced the cancellation of three of these. Five of the remaining six missions achieved successful landings, but the [[Engineering:Apollo 13|Apollo 13]] landing was prevented by an oxygen tank explosion in transit to the Moon, crippling the CSM. The crew barely returned to Earth safely by using the lunar module as a "lifeboat" on the return journey. Apollo used the [[Engineering:Saturn (rocket family)|Saturn family of rockets]] as launch vehicles, which were also used for an [[Astronomy:Apollo Applications Program|Apollo Applications Program]], which consisted of [[Engineering:Skylab|Skylab]], a space station that supported three crewed missions in 1973–1974, and the [[Engineering:Apollo–Soyuz|Apollo–Soyuz]] Test Project, a joint {{wipe|United States}}-[[Place:Soviet Union|Soviet Union]] [[Astronomy:Low Earth orbit|low Earth orbit]] mission in 1975.

Apollo set several major human spaceflight milestones. It stands alone in sending crewed missions beyond [[Astronomy:Low Earth orbit|low Earth orbit]]. [[Engineering:Apollo 8|Apollo 8]] was the first crewed spacecraft to orbit another celestial body, and Apollo 11 was the first crewed spacecraft to land humans on one.

Overall, the Apollo program returned {{convert|842|lb|kg}} of lunar rocks and soil to Earth, greatly contributing to the understanding of the Moon's composition and geological history. The program laid the foundation for NASA's subsequent human spaceflight capability and funded construction of its [[Organization:Johnson Space Center|Johnson Space Center]] and Kennedy Space Center. Apollo also spurred advances in many areas of technology incidental to rocketry and human spaceflight, including [[Engineering:Avionics|avionics]], telecommunications, and computers.

==Name==
The program was named after [[Unsolved:Apollo|Apollo]], the Greek god of light, music, and the Sun, by NASA manager [[Biography:Abe Silverstein|Abe Silverstein]], who later said, "I was naming the spacecraft like I'd name my baby."<ref>Murray & Cox 1989, p. 55</ref> Silverstein chose the name at home one evening, early in 1960, because he felt "Apollo riding his chariot across the Sun was appropriate to the grand scale of the proposed program".<ref name="pressrelease">{{cite press release |title=Release 69-36 |date=July 14, 1969 |publisher= [[Organization:Glenn Research Center|Lewis Research Center]] |url=http://www.nasa.gov/centers/glenn/about/history/apollo_press_release.html |location=Cleveland, OH |access-date=June 21, 2012}}</ref>

The context of this was that the program focused at its beginning mainly on developing an advanced crewed spacecraft, the [[Engineering:Apollo command and service module|Apollo command and service module]], succeeding the Mercury program. A lunar landing became the focus of the program only in 1961.<ref name="Nast 2013 t554">{{cite magazine |title=Project Olympus (1962) |magazine=WIRED |date=2013-09-02 |url=https://www.wired.com/2013/09/project-olympus-1962/ |access-date=2023-10-12}}</ref> Thereafter [[Astronomy:Project Gemini|Project Gemini]] instead followed the Mercury program to test and study advanced crewed spaceflight technology.

==Background==
===Origin and spacecraft feasibility studies===
{{main|Astronomy:Apollo spacecraft feasibility study}}

The Apollo program was conceived during the Eisenhower administration in early 1960, as a follow-up to Project Mercury. While the Mercury [[Engineering:Space capsule|capsule]] could support only one astronaut on a limited Earth orbital mission, Apollo would carry three. Possible missions included ferrying crews to a space station, [[Astronomy:Circumlunar trajectory|circumlunar flight]]s, and eventual crewed [[Astronomy:Moon landing|lunar landing]]s.

In July 1960, NASA Deputy Administrator Hugh L. Dryden announced the Apollo program to industry representatives at a series of [[Engineering:Space Task Group|Space Task Group]] conferences. Preliminary specifications were laid out for a spacecraft with a ''mission module'' cabin separate from the ''command module'' (piloting and reentry cabin), and a ''propulsion and equipment module''. On August 30, a feasibility study competition was announced, and on October 25, three study contracts were awarded to [[Company:Convair|General Dynamics/Convair]], [[Company:General Electric|General Electric]], and the [[Company:Glenn L. Martin Company|Glenn L. Martin Company]]. Meanwhile, NASA performed its own in-house spacecraft design studies led by Maxime Faget, to serve as a gauge to judge and monitor the three industry designs.<ref name="chariots_feasibility">{{harvnb|Brooks|Grimwood|Swenson|1979|loc=Ch. 1.7: [http://www.hq.nasa.gov/office/pao/History/SP-4205/ch1-7.html "Feasility Studies"]. pp. 16–21.}}</ref>

===Political pressure builds===
{{main|Astronomy:Space Race|Engineering:Sputnik crisis}}

In November 1960, [[Biography:John F. Kennedy|John F. Kennedy]] was elected president after a campaign that promised American superiority over the [[Place:Soviet Union|Soviet Union]] in the fields of [[Astronomy:Space exploration|space exploration]] and missile defense. Up to the election of 1960, Kennedy had been speaking out against the "[[Engineering:Missile gap|missile gap]]" that he and many other senators felt had developed between the Soviet Union and the United States due to the inaction of President Eisenhower.<ref>{{cite journal |first=Christopher A. |last=Preble |title="Who Ever Believed in the 'Missile Gap'?": John F. Kennedy and the Politics of National Security |journal=Presidential Studies Quarterly |volume=33 |number=4 |date=2003 |page=813 |doi=10.1046/j.0360-4918.2003.00085.x |jstor=27552538}}</ref> Beyond military power, Kennedy used aerospace technology as a symbol of national prestige, pledging to make the US not "first but, first and, first if, but first period".<ref>Beschloss 1997</ref> Despite Kennedy's rhetoric, he did not immediately come to a decision on the status of the Apollo program once he became president. He knew little about the technical details of the space program, and was put off by the massive financial commitment required by a crewed Moon landing.<ref>Sidey 1963, pp. 117–118</ref> When Kennedy's newly appointed NASA Administrator James E. Webb requested a 30 percent budget increase for his agency, Kennedy supported an acceleration of NASA's large booster program but deferred a decision on the broader issue.<ref>Beschloss 1997, p. 55</ref>

On April 12, 1961, Soviet [[Astronaut#Russian|cosmonaut]] [[Biography:Yuri Gagarin|Yuri Gagarin]] became the first person to fly in space, reinforcing American fears about being left behind in a technological competition with the Soviet Union. At a meeting of the US House Committee on Science and Astronautics one day after Gagarin's flight, many congressmen pledged their support for a crash program aimed at ensuring that America would catch up.<ref>87th Congress 1961</ref> Kennedy was circumspect in his response to the news, refusing to make a commitment on America's response to the Soviets.<ref>Sidey 1963, p. 114</ref>

[[File:Kennedy Giving Historic Speech to Congress - GPN-2000-001658.jpg|thumb|right|President Kennedy delivers his proposal to put a man on the Moon before a joint session of Congress, May 25, 1961.|alt=President John F. Kennedy addresses a joint session of Congress, with Vice President Lyndon B. Johnson and House Speaker Sam Rayburn seated behind him]]
On April 20, Kennedy sent a memo to Vice President [[Biography:Lyndon B. Johnson|Lyndon B. Johnson]], asking Johnson to look into the status of America's space program, and into programs that could offer NASA the opportunity to catch up.<ref name="jfkmemo">{{cite web |url=http://www.jfklibrary.org/Asset-Viewer/6XnAYXEkkkSMLfp7ic_o-Q.aspx |title=Memorandum for Vice President |last=Kennedy |first=John F. |date=April 20, 1961 |work=The White House |publisher=John F. Kennedy Presidential Library and Museum |location=Boston, MA |type=Memorandum |access-date=August 1, 2013 |archive-date=July 21, 2016 |archive-url=https://web.archive.org/web/20160721230444/http://www.jfklibrary.org/Asset-Viewer/6XnAYXEkkkSMLfp7ic_o-Q.aspx |url-status=dead }}</ref><ref>{{cite book |last=Launius |first=Roger D. |title=Apollo: A Retrospective Analysis |url=http://www.hq.nasa.gov/office/pao/History/Apollomon/cover.html |format=PDF |access-date=August 1, 2013 |series=Monographs in Aerospace History |number=3 |date=July 1994 |publisher=NASA |location=Washington, D.C. |oclc=31825096 |chapter=President John F. Kennedy Memo for Vice President, 20 April 1961 |chapter-url=http://www.hq.nasa.gov/office/pao/History/Apollomon/apollo1.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.hq.nasa.gov/office/pao/History/Apollomon/apollo1.pdf |archive-date=2022-10-09 |url-status=live }} [http://www.hq.nasa.gov/office/pao/History/Apollomon/docs.htm Key Apollo Source Documents] {{Webarchive|url=https://web.archive.org/web/20201108100815/http://www.hq.nasa.gov/office/pao/History/Apollomon/docs.htm |date=November 8, 2020 }}.</ref> Johnson responded approximately one week later, concluding that "we are neither making maximum effort nor achieving results necessary if this country is to reach a position of leadership."<ref name="lbjmemo">{{cite web |url=http://www.jfklibrary.org/Asset-Viewer/DjiWpQJegkuIlX7WZAUCtQ.aspx |title=Memorandum for the President |last=Johnson |first=Lyndon B. |author-link=Lyndon B. Johnson |type=Memorandum |date=April 28, 1961 |work=Office of the Vice President |publisher=John F. Kennedy Presidential Library and Museum |location=Boston, MA |access-date=August 1, 2013 |archive-date=July 1, 2016 |archive-url=https://web.archive.org/web/20160701151811/http://www.jfklibrary.org/Asset-Viewer/DjiWpQJegkuIlX7WZAUCtQ.aspx |url-status=dead }}</ref><ref>{{cite book |last=Launius |first=Roger D. |title=Apollo: A Retrospective Analysis |url=http://www.hq.nasa.gov/office/pao/History/Apollomon/cover.html |format=PDF |access-date=August 1, 2013 |series=Monographs in Aerospace History |number=3 |date=July 1994 |publisher=NASA |location=Washington, D.C. |oclc=31825096 |chapter=Lyndon B. Johnson, Vice President, Memo for the President, 'Evaluation of Space Program,' 28 April 1961 |chapter-url=http://www.hq.nasa.gov/office/pao/History/Apollomon/apollo2.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.hq.nasa.gov/office/pao/History/Apollomon/apollo2.pdf |archive-date=2022-10-09 |url-status=live }} [http://www.hq.nasa.gov/office/pao/History/Apollomon/docs.htm Key Apollo Source Documents] {{Webarchive|url=https://web.archive.org/web/20201108100815/http://www.hq.nasa.gov/office/pao/History/Apollomon/docs.htm |date=November 8, 2020 }}.</ref> His memo concluded that a crewed Moon landing was far enough in the future that it was likely the United States would achieve it first.<ref name="lbjmemo" />

On May 25, 1961, twenty days after the first US crewed spaceflight [[Engineering:Mercury-Redstone 3|''Freedom 7'']], Kennedy proposed the crewed Moon landing in a ''Special Message to the Congress on Urgent National Needs'':
{{blockquote|Now it is time to take longer strides—time for a great new American enterprise—time for this nation to take a clearly leading role in space achievement, which in many ways may hold the key to our future on Earth.

...{{nbsp}}I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to the Earth. No single space project in this period will be more impressive to mankind, or more important in the long-range exploration of space; and none will be so difficult or expensive to accomplish.<ref name="Special Message">{{cite AV media |people=Kennedy, John F. |date=May 25, 1961 |title=Special Message to Congress on Urgent National Needs |medium=Motion picture (excerpt) |url=http://www.jfklibrary.org/Asset-Viewer/xzw1gaeeTES6khED14P1Iw.aspx |access-date=August 1, 2013 |publisher=John F. Kennedy Presidential Library and Museum |location=Boston, MA |id=Accession number: TNC:200; digital identifier: TNC-200-2}}</ref>{{efn|{{Cws |title=Full text |link=Special Message to the Congress on Urgent National Needs|nobullet=yes}}}}
}}

==NASA expansion==
At the time of Kennedy's proposal, only one American had flown in space—less than a month earlier—and NASA had not yet sent an astronaut into orbit. Even some NASA employees doubted whether Kennedy's ambitious goal could be met.<ref>Murray & Cox 1989, pp. 16–17</ref> By 1963, Kennedy even came close to agreeing to a joint US-USSR Moon mission, to eliminate duplication of effort.<ref>{{cite news |title=Soviets Planned to Accept JFK's Joint Lunar Mission Offer |first=Frank |last=Sietzen |url=http://www.spacedaily.com/news/russia-97h.html |agency=SpaceCast News Service |work=SpaceDaily |date=October 2, 1997 |access-date=August 1, 2013}}</ref>

With the clear goal of a crewed landing replacing the more nebulous goals of space stations and circumlunar flights, NASA decided that, in order to make progress quickly, it would discard the feasibility study designs of Convair, GE, and Martin, and proceed with Faget's command and service module design. The mission module was determined to be useful only as an extra room, and therefore unnecessary.<ref>{{cite web|url=http://www.hq.nasa.gov/pao/History/SP-4209/ch3-7.htm|title= Soyuz – Development of the Space Station; Apollo – Voyage to the Moon|access-date=June 12, 2016}}</ref> They used Faget's design as the specification for another competition for spacecraft procurement bids in October 1961. On November 28, 1961, it was announced that [[Company:North American Aviation|North American Aviation]] had won the contract, although its bid was not rated as good as the Martin proposal. Webb, Dryden and [[Biography:Robert Seamans|Robert Seamans]] chose it in preference due to North American's longer association with NASA and [[Organization:National Advisory Committee for Aeronautics|its predecessor]].{{sfn|Brooks|Grimwood|Swenson|1979|loc=Ch. 2.5: [http://www.hq.nasa.gov/office/pao/History/SP-4205/ch2-5.html "Contracting for the Command Module"]. pp. 41–44}}

Landing humans on the Moon by the end of 1969 required the most sudden burst of technological creativity, and the largest commitment of resources ($25&nbsp;billion; ${{format price|{{Inflation|US-GDP|25400000000|1966}}}} in {{Inflation-year|US-GDP}} US dollars){{Inflation-fn|US-GDP}} ever made by any nation in peacetime. At its peak, the Apollo program employed 400,000 people and required the support of over 20,000 industrial firms and universities.<ref>{{cite web |url=http://www.nasa.gov/centers/langley/news/factsheets/Apollo.html |title=NASA Langley Research Center's Contributions to the Apollo Program |editor-last=Allen |editor-first=Bob |work=[[Organization:Langley Research Center|Langley Research Center]] |publisher=NASA |access-date=August 1, 2013}}</ref>

On July 1, 1960, NASA established the [[Organization:Marshall Space Flight Center|Marshall Space Flight Center]] (MSFC) in Huntsville, Alabama. MSFC designed the heavy lift-class [[Engineering:Saturn (rocket family)|Saturn launch vehicles]], which would be required for Apollo.<ref>{{cite web|url=http://history.msfc.nasa.gov/history_fact_sheet.html|title=Historical Facts|access-date=June 7, 2016|website=MSFC History Office|archive-url=https://web.archive.org/web/20160603125431/http://history.msfc.nasa.gov/history_fact_sheet.html|archive-date=June 3, 2016|url-status=dead}}</ref>

===Manned Spacecraft Center===
{{main|Organization:Johnson Space Center}}

It became clear that managing the Apollo program would exceed the capabilities of Robert R. Gilruth's [[Engineering:Space Task Group|Space Task Group]], which had been directing the nation's crewed space program from NASA's [[Organization:Langley Research Center|Langley Research Center]]. So Gilruth was given authority to grow his organization into a new NASA center, the Manned Spacecraft Center (MSC). A site was chosen in Houston, Texas, on land donated by [[Organization:Rice University|Rice University]], and Administrator Webb announced the conversion on September 19, 1961.<ref name="TNO 12">{{cite book |last1=Swenson |first1=Loyd S. Jr. |first2=James M. |last2=Grimwood |first3=Charles C. |last3=Alexander |title=This New Ocean: A History of Project Mercury |url=http://www.hq.nasa.gov/office/pao/History/SP-4201/toc.htm |access-date=August 1, 2013 |series=The NASA History Series |orig-year=Originally published 1966 |date=1989 |publisher=NASA |location=Washington, D.C. |oclc=569889 |id=NASA SP-4201 |chapter=Chapter 12.3: Space Task Group Gets a New Home and Name |chapter-url=https://history.nasa.gov/SP-4201/ch12-3.htm |archive-date=July 13, 2009 |archive-url=https://web.archive.org/web/20090713233748/http://www.hq.nasa.gov/office/pao/History/SP-4201/toc.htm |url-status=dead }}</ref> It was also clear NASA would soon outgrow its practice of controlling missions from its {{wipe|Cape Canaveral Air Force Station}} launch facilities in Florida, so a new Mission Control Center would be included in the MSC.<ref>{{cite book |last=Dethloff |first=Henry C. |title=Suddenly Tomorrow Came ... A History of the Johnson Space Center |publisher=National Aeronautics and Space Administration |year=1993 |chapter=Chapter 3: Houston – Texas – U.S.A. |isbn=978-1502753588 |url=http://www.jsc.nasa.gov/history/suddenly_tomorrow/suddenly.htm}}</ref>

[[File:President Kennedy speech on the space effort at Rice University, September 12, 1962.ogv|thumb|right|thumbtime=17:32|President Kennedy speaks at Rice University, September 12, 1962 (17 min, 47 s).]]
In September 1962, by which time two Project Mercury astronauts had orbited the Earth, Gilruth had moved his organization to rented space in Houston, and construction of the MSC facility was under way, Kennedy visited Rice to reiterate his challenge in [[Astronomy:We choose to go to the Moon|a famous speech]]:
{{blockquote|But why, some say, the Moon? Why choose this as our goal? And they may well ask, why climb the highest mountain? Why, 35 years ago, [[Engineering:Spirit of St. Louis|fly the Atlantic]]?{{nbsp}}...

We choose to go to the Moon. We choose to go to the Moon in this decade and do the other things, not because they are easy, but because they are hard; because that goal will serve to organize and measure the best of our energies and skills; because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one we intend to win{{nbsp}}...<ref name="Rice Speech">{{cite web|url=http://www.jfklibrary.org/Historical+Resources/Archives/Reference+Desk/Speeches/JFK/003POF03SpaceEffort09121962.htm |url-status=dead |title=Address at Rice University on the Nation's Space Effort |last=Kennedy |first=John F. |date=September 12, 1962 |publisher=John F. Kennedy Presidential Library and Museum |location=Boston, MA |archive-url=https://web.archive.org/web/20100506113709/http://www.jfklibrary.org/Historical%2BResources/Archives/Reference%2BDesk/Speeches/JFK/003POF03SpaceEffort09121962.htm |archive-date=May 6, 2010 |access-date=August 1, 2013}}</ref>{{efn|{{Cws |title=Full text |link=We choose to go to the moon |nobullet=yes}}}}}}

The MSC was completed in September 1963. It was renamed by the US Congress in honor of Lyndon Johnson soon after his death in 1973.<ref>{{cite web |url=http://www.presidency.ucsb.edu/ws/index.php?pid=4109#axzz1RbWN5hpf |title=50—Statement About Signing a Bill Designating the Manned Spacecraft Center in Houston, Texas, as the Lyndon B. Johnson Space Center |first=Richard M. |last=Nixon |date=February 19, 1973 |work=The American Presidency Project |publisher=[[Organization:University of California, Santa Barbara|University of California, Santa Barbara]] |access-date=July 9, 2011}}</ref>

===Launch Operations Center===

It also became clear that Apollo would outgrow the Canaveral launch facilities in Florida. The two newest launch complexes were already being built for the [[Astronomy:Saturn I|Saturn I]] and [[Astronomy:Saturn IB|IB]] rockets at the northernmost end: LC-34 and LC-37. But an even bigger facility would be needed for the mammoth rocket required for the crewed lunar mission, so land acquisition was started in July 1961 for a Launch Operations Center (LOC) immediately north of Canaveral at Merritt Island. The design, development and construction of the center was conducted by [[Biography:Kurt H. Debus|Kurt H. Debus]], a member of [[Biography:Wernher von Braun|Wernher von Braun]]'s original [[Engineering:V-2 rocket|V-2 rocket]] engineering team. Debus was named the LOC's first Director.<ref name="NASA2">{{cite web |url=http://www.nasa.gov/centers/kennedy/about/biographies/debus.html |title=Dr. Kurt H. Debus |date=February 1987 |work=Kennedy Biographies |publisher=NASA |access-date=October 7, 2008}}</ref> Construction began in November 1962. Following [[Social:Assassination of John F. Kennedy|Kennedy's death]], President Johnson issued an executive order on November 29, 1963, to rename the LOC and Cape Canaveral in honor of Kennedy.<ref>{{cite web |url=https://www.archives.gov/federal-register/executive-orders/1963-johnson.html |title=Executive Orders Disposition Tables: Lyndon B. Johnson – 1963: Executive Order 11129 |work=Office of the Federal Register |publisher=[[National Archives and Records Administration]] |access-date=April 26, 2010}}</ref>

[[File:VonBraunMuellerReesSA6.jpg|thumb|George Mueller, Wernher von Braun, and Eberhard Rees watch the AS-101 launch from the firing room.]]
The LOC included [[Astronomy:Kennedy Space Center Launch Complex 39|Launch Complex 39]], a Launch Control Center, and a {{convert|130|e6ft3|m3|adj=on}} [[Astronomy:Vehicle Assembly Building|Vertical Assembly Building]] (VAB).<ref>The building was renamed "Vehicle Assembly Building" on February 3, 1965. {{cite web |title=VAB Nears Completion |url=http://www.hq.nasa.gov/pao/History/SP-4204/ch12-7.html |website=NASA History Program Office |publisher=NASA |access-date=2023-02-12 |quote=The new name, it was felt, would more readily encompass future as well as current programs and would not be tied to the Saturn booster.}}</ref> in which the space vehicle (launch vehicle and spacecraft) would be assembled on a [[Astronomy:Mobile launcher platform|mobile launcher platform]] and then moved by a [[Engineering:Crawler-transporter|crawler-transporter]] to one of several launch pads. Although at least three pads were planned, only two, designated A{{nbsp}}and{{nbsp}}B, were completed in October 1965. The LOC also included an Operations and Checkout Building (OCB) to which [[Astronomy:Project Gemini|Gemini]] and Apollo spacecraft were initially received prior to being mated to their launch vehicles. The Apollo spacecraft could be tested in two [[Engineering:Vacuum chamber|vacuum chamber]]s capable of simulating atmospheric pressure at altitudes up to {{convert|250000|ft|km}}, which is nearly a vacuum.<ref>{{cite web |url=http://kscpartnerships.ksc.nasa.gov/techCap/altitude.htm |url-status=dead |title=KSC Technical Capabilities: O&C Altitude Chambers |editor-last=Craig |editor-first=Kay |work=Center Planning and Development Office |publisher=NASA |archive-url=https://web.archive.org/web/20120328084113/http://kscpartnerships.ksc.nasa.gov/techCap/altitude.htm |archive-date=March 28, 2012 |access-date=July 29, 2011}}</ref><ref>{{cite web |url=http://www.luizmonteiro.com/StdAtm.aspx |title=1976 Standard Atmosphere Properties |work=luizmonteiro.com |publisher=Luizmonteiro, LLC |type=Complete [[International Standard Atmosphere]] calculator (1976 model) |access-date=August 1, 2013}}</ref>

===Organization===
Administrator Webb realized that in order to keep Apollo costs under control, he had to develop greater project management skills in his organization, so he recruited George E. Mueller for a high management job. Mueller accepted, on the condition that he have a say in NASA reorganization necessary to effectively administer Apollo. Webb then worked with Associate Administrator (later Deputy Administrator) Seamans to reorganize the Office of Manned Space Flight (OMSF).<ref name="SecretOfApollo">Johnson 2002</ref> On July 23, 1963, Webb announced Mueller's appointment as Deputy Associate Administrator for Manned Space Flight, to replace then Associate Administrator [[Biography:D. Brainerd Holmes|D. Brainerd Holmes]] on his retirement effective September 1. Under Webb's reorganization, the directors of the Manned Spacecraft Center (Gilruth), [[Organization:Marshall Space Flight Center|Marshall Space Flight Center]] ([[Biography:Wernher von Braun|von Braun]]), and the Launch Operations Center ([[Biography:Kurt H. Debus|Debus]]) reported to Mueller.<ref>{{Cite web |title=Stages to Saturn |url=https://history.nasa.gov/SP-4206/p443.htm |page=443 |access-date=2023-02-12 |website=history.nasa.gov |id=SP-4206}}</ref>

Based on his industry experience on Air Force missile projects, Mueller realized some skilled managers could be found among high-ranking officers in the {{wipe|U.S. Air Force}}, so he got Webb's permission to recruit General [[Biography:Samuel C. Phillips|Samuel C. Phillips]], who gained a reputation for his effective management of the [[LGM-30 Minuteman|Minuteman]] program, as OMSF program controller. Phillips's superior officer Bernard A. Schriever agreed to loan Phillips to NASA, along with a staff of officers under him, on the condition that Phillips be made Apollo Program Director. Mueller agreed, and Phillips managed Apollo from January 1964, until it achieved the first human landing in July 1969, after which he returned to Air Force duty.<ref>{{Cite news |title=Samuel C. Phillips, Who Directed Apollo Lunar Landing, Dies at 68 |first=Alfonso A. |last=Narvaez |url=https://www.nytimes.com/1990/02/01/obituaries/samuel-c-phillips-who-directed-apollo-lunar-landing-dies-at-68.html?pagewanted=1 |newspaper={{wipe|The New York Times}} |date=February 1, 1990 |access-date=April 14, 2010}}</ref>

Charles Fishman, in ''One Giant Leap'', estimated the number of people and organizations involved into the Apollo program as "410,000 men and women at some 20,000 different companies contributed to the effort".<ref name=npr>{{cite web |last1=Davies |first1=Dave |title='One Giant Leap' Explores The Herculean Effort Behind The 1969 Moon Landing |url=https://www.npr.org/2019/06/12/731660780/one-giant-leap-explores-the-herculean-effort-behind-the-1969-moon-landing |work=NPR |location=US |date=2019-06-12 |access-date=5 July 2023}}</ref>
<!----This probably completes this section, the intent of which is to keep the narrative flow of Webb's big 1963 reorganization. These remainders should be highlighted, probably as appropriate in later sections.
* Shea
* Christopher Kraft
* Gene Kranz
* Deke Slayton
* Rocco Petrone
---->

==Choosing a mission mode==
[[File:John C. Houbolt - GPN-2000-001274.jpg|right|thumb|John Houbolt explaining the LOR concept]]
[[File:Apollo Direct Ascent.png|thumb|right|Early Apollo configuration for Direct Ascent and Earth Orbit Rendezvous, 1961]]

Once Kennedy had defined a goal, the Apollo mission planners were faced with the challenge of designing a spacecraft that could meet it while minimizing risk to human life, cost, and demands on technology and astronaut skill. Four possible mission modes were considered:
* '''[[Astronomy:Direct ascent|Direct Ascent]]:''' The spacecraft would be launched as a unit and travel directly to the lunar surface, without first going into lunar orbit. A {{convert|50000|lb|kg|adj=on}} Earth return ship would land all three astronauts atop a {{convert|113000|lb|kg|adj=on}} descent propulsion stage,<ref name="Nova_scale">Using the Apollo 11 lunar lander's mass ratio of {{convert|22667|lb|kg|adj=on}} descent stage to {{convert|10042|lb|kg|adj=on}} ascent stage, scaled up to Nova's {{convert|163000|lb|kg|adj=on}} payload.</ref> which would be left on the Moon. This design would have required development of the extremely powerful [[Engineering:Saturn C-8|Saturn C-8]] or [[Engineering:Nova (rocket)|Nova]] launch vehicle to carry a {{convert|163000|lb|kg|adj=on}} payload to the Moon.{{sfn|Brooks|Grimwood|Swenson|1979|loc=[http://www.hq.nasa.gov/office/pao/History/SP-4205/ch2-6.html Ch. 2.6, "Influences on Booster Determination"]}}
* '''[[Astronomy:Earth orbit rendezvous|Earth Orbit Rendezvous]] (EOR):''' Multiple rocket launches (up to 15 in some plans) would carry parts of the Direct Ascent spacecraft and propulsion units for [[Astronomy:Trans-lunar injection|translunar injection]] (TLI). These would be assembled into a single spacecraft in Earth orbit.
* '''Lunar Surface Rendezvous:''' Two spacecraft would be launched in succession. The first, an automated vehicle carrying propellant for the return to Earth, would land on the Moon, to be followed some time later by the crewed vehicle. Propellant would have to be transferred from the automated vehicle to the crewed vehicle.{{sfn|Brooks|Grimwood|Swenson|1979|loc=Chapter 3.2: [http://www.hq.nasa.gov/office/pao/History/SP-4205/ch3-2.html ''Early Reaction to LOR'']. pp. 61–67}}
* '''Lunar Orbit Rendezvous (LOR):''' This turned out to be the winning configuration, which achieved the goal with [[Engineering:Apollo 11|Apollo 11]] on July 20, 1969: a single [[Engineering:Saturn V|Saturn V]] launched a {{convert|96886|lb|kg|adj=on}} spacecraft that was composed of a {{convert|63608|lb|kg|adj=on}} [[Engineering:Apollo command and service module|Apollo command and service module]] which remained in orbit around the Moon and a {{convert|33278|lb|kg|adj=on}} two-stage [[Engineering:Apollo Lunar Module|Apollo Lunar Module]] spacecraft which was flown by two astronauts to the surface, flown back to dock with the command module and was then discarded.<ref>{{cite book |last1=Orloff |first1=Richard W. |title=Apollo by the Numbers: A Statistical Reference. Launch Vehicle/Spacecraft Key Facts – 2nd table |date=September 2004 |publisher=NASA History Division |location=Washington DC |isbn=016-050631-X |url=https://history.nasa.gov/SP-4029/Apollo_18-12_Launch_Vehicle-Spacecraft_Key_Facts.htm |access-date=August 8, 2018}}</ref> Landing the smaller spacecraft on the Moon, and returning an even smaller part ({{convert|10042|lb|disp=or}}) to lunar orbit, minimized the total mass to be launched from Earth, but this was the last method initially considered because of the perceived risk of rendezvous and docking.

In early 1961, direct ascent was generally the mission mode in favor at NASA. Many engineers feared that rendezvous and docking, maneuvers that had not been attempted in [[Astronomy:Geocentric orbit|Earth orbit]], would be nearly impossible in [[Astronomy:Lunar orbit|lunar orbit]]. LOR advocates including John Houbolt at Langley Research Center emphasized the important weight reductions that were offered by the LOR approach. Throughout 1960 and 1961, Houbolt campaigned for the recognition of LOR as a viable and practical option. Bypassing the NASA hierarchy, he sent a series of memos and reports on the issue to Associate Administrator Robert Seamans; while acknowledging that he spoke "somewhat as a voice in the wilderness", Houbolt pleaded that LOR should not be discounted in studies of the question.{{sfn|Brooks|Grimwood|Swenson|1979|loc=Ch. 3.4: [http://www.hq.nasa.gov/office/pao/History/SP-4205/ch3-4.html "Early Reaction to LOR"]. p. 71}}

{{anchor|Nicholas E. Golovin}}
Seamans's establishment of an ad hoc committee headed by his special technical assistant Nicholas E. Golovin in July 1961, to recommend a [[Engineering:Launch vehicle|launch vehicle]] to be used in the Apollo program, represented a turning point in NASA's mission mode decision.<ref name="hansen21">Hansen 1999, p. 32</ref> This committee recognized that the chosen mode was an important part of the launch vehicle choice, and recommended in favor of a hybrid EOR-LOR mode. Its consideration of LOR—as well as Houbolt's ceaseless work—played an important role in publicizing the workability of the approach. In late 1961 and early 1962, members of the Manned Spacecraft Center began to come around to support LOR, including the newly hired deputy director of the Office of Manned Space Flight, Joseph Shea, who became a champion of LOR.<ref name="hansen24">Hansen 1999, pp. 35–39</ref> The engineers at Marshall Space Flight Center (MSFC), which had much to lose from the decision, took longer to become convinced of its merits, but their conversion was announced by Wernher von Braun at a briefing on June 7, 1962.{{sfn|Brooks|Grimwood|Swenson|1979|loc=Ch. 3.6: [http://www.hq.nasa.gov/office/pao/History/SP-4205/ch3-6.html "Settling the Mode Issue"]. pp. 81–83}}

But even after NASA reached internal agreement, it was far from smooth sailing. Kennedy's science advisor Jerome Wiesner, who had expressed his opposition to human spaceflight to Kennedy before the President took office,<ref>{{Cite report |title=Managing NASA in the Apollo Era |chapter=2: The Lunar Landing Decision and Its Aftermath |url=https://history.nasa.gov/SP-4102/ch2.htm|access-date=2023-02-12 |website=history.nasa.gov}}</ref> and had opposed the decision to land people on the Moon, hired Golovin, who had left NASA, to chair his own "Space Vehicle Panel", ostensibly to monitor, but actually to second-guess NASA's decisions on the [[Engineering:Saturn V|Saturn V]] launch vehicle and LOR by forcing Shea, Seamans, and even Webb to defend themselves, delaying its formal announcement to the press on July 11, 1962, and forcing Webb to still hedge the decision as "tentative".{{sfn|Brooks|Grimwood|Swenson|1979|loc=[http://www.hq.nasa.gov/office/pao/History/SP-4205/ch3-7.html Ch. 3.7, "Casting the Die"]}}

Wiesner kept up the pressure, even making the disagreement public during a two-day September visit by the President to [[Organization:Marshall Space Flight Center|Marshall Space Flight Center]]. Wiesner blurted out "No, that's no good" in front of the press, during a presentation by von Braun. Webb jumped in and defended von Braun, until Kennedy ended the squabble by stating that the matter was "still subject to final review". Webb held firm and issued a [[Finance:Request for proposal|request for proposal]] to candidate Lunar Excursion Module (LEM) contractors. Wiesner finally relented, unwilling to settle the dispute once and for all in Kennedy's office, because of the President's involvement with the October Cuban Missile Crisis, and fear of Kennedy's support for Webb. NASA announced the selection of [[Company:Grumman|Grumman]] as the LEM contractor in November 1962.{{sfn|Brooks|Grimwood|Swenson|1979|loc=[http://www.hq.nasa.gov/office/pao/History/SP-4205/ch4-4.html Ch. 4.4, "Pressures by PSAC"]}}

Space historian James Hansen concludes that:
{{blockquote|Without NASA's adoption of this stubbornly held minority opinion in 1962, the United States may still have reached the Moon, but almost certainly it would not have been accomplished by the end of the 1960s, President Kennedy's target date.<ref>Hansen 1999, p. 42</ref>}}

The LOR method had the advantage of allowing the lander spacecraft to be used as a "lifeboat" in the event of a failure of the command ship. Some documents prove this theory was discussed before and after the method was chosen. In 1964 an MSC study concluded, "The [[Engineering:Apollo Lunar Module|LM]] [as lifeboat]{{nbsp}}... was finally dropped, because no single reasonable [[Engineering:Apollo command and service module|CSM]] failure could be identified that would prohibit use of the [[Engineering:Apollo command and service module#Service propulsion system|SPS]]."<ref>{{cite book |last = Letterman |first = John B. |title = Survivors: True Tales of Endurance: 500 Years of the Greatest Eyewitness Accounts |page=404 |publisher = Simon & Schuster |date = 2003 |location = New York |isbn = 0-7432-4547-4 |url = https://archive.org/details/survivorstruetal00lett |chapter=Explosion on Apollo 13; April 1970: From the Earth to the Moon and Back |quote=Lovell writes, 'Naturally, I'm glad that view didn't prevail, and I'm thankful that by the time of Apollo 10, the first lunar mission carrying the LM, the LM as a lifeboat was again being discussed.'}}</ref> Ironically, just such a failure happened on [[Engineering:Apollo 13|Apollo 13]] when an oxygen tank explosion left the CSM without electrical power. The lunar module provided propulsion, electrical power and life support to get the crew home safely.<ref name="KSC-Apollo_13">{{cite web |url=http://science.ksc.nasa.gov/history/apollo/apollo-13/apollo-13.html |last=Dumoulin |first=Jim |title=Apollo-13 (29) |work=Historical Archive for Manned Missions |publisher=NASA |date=June 29, 2001 |access-date=September 12, 2012 |archive-date=August 19, 2011 |archive-url=https://web.archive.org/web/20110819103041/http://science.ksc.nasa.gov/history/apollo/apollo-13/apollo-13.html |url-status=dead }}</ref>

==Spacecraft==
{{main|Engineering:Apollo (spacecraft)}}
[[File: Winslow-Meteor Crater- Apollo Test Capsule.jpg|thumb|An Apollo [[Engineering:Boilerplate (spaceflight)|boilerplate]] command module is on exhibit in the Meteor Crater Visitor Center in Winslow, Arizona.]]

Faget's preliminary Apollo design employed a cone-shaped command module, supported by one of several service modules providing propulsion and electrical power, sized appropriately for the space station, cislunar, and lunar landing missions. Once Kennedy's Moon landing goal became official, detailed design began of a command and service module (CSM) in which the crew would spend the entire direct-ascent mission and lift off from the lunar surface for the return trip, after being soft-landed by a larger landing propulsion module. The final choice of lunar orbit rendezvous changed the CSM's role to the translunar ferry used to transport the crew, along with a new spacecraft, the Lunar Excursion Module (LEM, later shortened to LM (Lunar Module) but still pronounced {{IPAc-en|ˈ|l|ɛ|m}}) which would take two individuals to the lunar surface and return them to the CSM.<ref name="SummaryReport" />

===Command and service module===
{{main|Engineering:Apollo command and service module}}
[[File:Apollo CSM lunar orbit.jpg|thumb|upright=1.2|left|Apollo 15 CSM ''Endeavour'' in lunar orbit|alt=The cone-shaped command module, attached to the cylindrical service module, orbits the Moon with a panel removed, exposing the scientific instrument module]]

The [[Engineering:Apollo command and service module#Command module (CM)|command module]] (CM) was the conical crew cabin, designed to carry three astronauts from launch to lunar orbit and back to an Earth ocean landing. It was the only component of the Apollo spacecraft to survive without major configuration changes as the program evolved from the early Apollo study designs. Its exterior was covered with an ablative heat shield, and had its own [[Engineering:Reaction control system|reaction control system]] (RCS) engines to [[Astronomy:Spacecraft attitude control|control its attitude]] and steer its [[Astronomy:Atmospheric entry|atmospheric entry]] path. Parachutes were carried to slow its descent to splashdown. The module was {{convert|11.42|ft|m}} tall, {{convert|12.83|ft|m}} in diameter, and weighed approximately {{convert|12250|lb|kg}}.<ref name="ABTN_LV2" />

[[File:NASM-NASM2013-02663.jpg|thumb|Original cockpit of the command module of Apollo 11 with three seats, photographed from above. It is located in the National Air and Space Museum; the very high resolution image was produced in 2007 by the Smithsonian Institution.]]
A cylindrical service module (SM) supported the command module, with a service propulsion engine and an RCS with propellants, and a [[Physics:Fuel cell|fuel cell]] power generation system with [[Chemistry:Liquid hydrogen|liquid hydrogen]] and [[Physics:Liquid oxygen|liquid oxygen]] reactants. A high-gain [[Astronomy:S band|S-band]] antenna was used for long-distance communications on the lunar flights. On the extended lunar missions, an orbital scientific instrument package was carried. The service module was discarded just before reentry. The module was {{convert|24.6|ft|m}} long and {{convert|12.83|ft|m}} in diameter. The initial lunar flight version weighed approximately {{convert|51300|lb|kg}} fully fueled, while a later version designed to carry a lunar orbit scientific instrument package weighed just over {{convert|54000|lb|kg}}.<ref name="ABTN_LV2"/>

[[Company:North American Aviation|North American Aviation]] won the contract to build the CSM, and also the second stage of the Saturn V launch vehicle for NASA. Because the CSM design was started early before the selection of lunar orbit rendezvous, the service propulsion engine was sized to lift the CSM off the Moon, and thus was oversized to about twice the thrust required for translunar flight.<ref>Wilford 1969, p. 167</ref> Also, there was no provision for docking with the lunar module. A 1964 program definition study concluded that the initial design should be continued as Block I which would be used for early testing, while Block II, the actual lunar spacecraft, would incorporate the docking equipment and take advantage of the lessons learned in Block I development.<ref name="SummaryReport">{{cite web |url=https://history.nasa.gov/apsr/Apollopt2-2.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://history.nasa.gov/apsr/Apollopt2-2.pdf |archive-date=2022-10-09 |url-status=live |title=Apollo Program Summary Report |date=April 1975 |publisher=NASA |location=Houston, TX |pages=3–66 to 4–12 |id=JSC-09423 |access-date=August 1, 2013}}</ref>

===Apollo Lunar Module===
{{main|Engineering:Apollo Lunar Module}}
[[File:Apollo 11 Lunar Lander - 5927 NASA.jpg|thumb|upright=1.2|Apollo 11 Lunar Module ''Eagle'' (and Buzz Aldrin) on the Moon, photographed by Neil Armstrong]]

The [[Engineering:Apollo Lunar Module|Apollo Lunar Module]] (LM) was designed to descend from lunar orbit to land two astronauts on the Moon and take them back to orbit to rendezvous with the command module. Not designed to fly through the Earth's atmosphere or return to Earth, its fuselage was designed totally without aerodynamic considerations and was of an extremely lightweight construction. It consisted of separate descent and ascent stages, each with its own engine. The descent stage contained storage for the descent propellant, surface stay consumables, and surface exploration equipment. The ascent stage contained the crew cabin, ascent propellant, and a reaction control system. The initial LM model weighed approximately {{convert|33300|lb|kg}}, and allowed surface stays up to around 34 hours. An extended lunar module weighed over {{convert|36200|lb|kg}}, and allowed surface stays of more than three days.<ref name="ABTN_LV2">{{Cite web|title=Launch Vehicle|url=https://history.nasa.gov/SP-4029/Apollo_18-12_Launch_Vehicle-Spacecraft_Key_Facts.htm|access-date=2023-02-12|website=history.nasa.gov}}</ref> The contract for design and construction of the lunar module was awarded to [[Company:Grumman|Grumman Aircraft Engineering Corporation]], and the project was overseen by [[Biography:Thomas J. Kelly (aerospace engineer)|Thomas J. Kelly]].<ref>{{cite news |title=T. J. Kelly, 72, Dies; Father of Lunar Module |first=Warren E. |last=Leary |url=https://www.nytimes.com/2002/03/27/nyregion/t-j-kelly-72-dies-father-of-lunar-module.html |newspaper=The New York Times |date=March 27, 2002 |access-date=August 1, 2013}}</ref>

==Launch vehicles==
[[File:Saturnsandlittlejoe2.gif|thumb|right|upright=1.35|Four Apollo rocket assemblies, drawn to scale: Little Joe II, Saturn I, Saturn IB, and Saturn V]]

Before the Apollo program began, Wernher von Braun and his team of rocket engineers had started work on plans for very large launch vehicles, the [[Engineering:Saturn (rocket family)|Saturn series]], and the even larger [[Engineering:Nova (rocket)|Nova]] series. In the midst of these plans, von Braun was transferred from the Army to NASA and was made Director of the Marshall Space Flight Center. The initial direct ascent plan to send the three-person Apollo command and service module directly to the lunar surface, on top of a large descent rocket stage, would require a Nova-class launcher, with a lunar payload capability of over {{convert|180000|lb|kg|abbr=out}}.<ref>{{Cite web|title=Aerospace Alphabet: ABMA, ARPA, MSFC|url=https://history.nasa.gov/SP-4206/ch2.htm|access-date=2023-02-12|website=history.nasa.gov}}</ref> The June 11, 1962, decision to use lunar orbit rendezvous enabled the Saturn V to replace the Nova, and the MSFC proceeded to develop the [[Engineering:Saturn (rocket family)|Saturn rocket family]] for Apollo.<ref>{{Cite web|title=Missions, Modes, and Manufacturing|url=https://history.nasa.gov/SP-4206/ch3.htm|access-date=2023-02-12|website=history.nasa.gov}}</ref>

Since Apollo, like Mercury, used more than one launch vehicle for space missions, NASA used spacecraft-launch vehicle combination series numbers: AS-10x for Saturn I, AS-20x for Saturn IB, and AS-50x for Saturn V (compare [[Engineering:Mercury-Redstone 3|Mercury-Redstone 3]], [[Astronomy:Mercury-Atlas 6|Mercury-Atlas 6]]) to designate and plan all missions, rather than numbering them sequentially as in Project Gemini. This was changed by the time human flights began.<ref name="missionNumbers" />

===Little Joe II===
{{main|Engineering:Little Joe II}}

Since Apollo, like Mercury, would require a [[Astronomy:Launch escape system|launch escape system]] (LES) in case of a launch failure, a relatively small rocket was required for qualification flight testing of this system. A rocket bigger than the [[Engineering:Little Joe (rocket)|Little Joe]] used by Mercury would be required, so the [[Engineering:Little Joe II|Little Joe II]] was built by [[Company:General Dynamics|General Dynamics]]/[[Company:Convair|Convair]]. After an August 1963 [[Engineering:Little Joe II Qualification Test Vehicle|qualification test flight]],<ref>Townsend 1973, p. 14</ref> four LES test flights ([[Engineering:A-001|A-001]] through [[Engineering:A-004|004]]) were made at the White Sands Missile Range between May 1964 and January 1966.<ref>Townsend 1973, p. 22</ref>

===Saturn I===
{{main|Astronomy:Saturn I}}
[[File:Apollo 7 launch2.jpg|thumb|right|upright=0.7|A Saturn IB rocket launches Apollo 7, 1968]]

Saturn I, the first US heavy lift launch vehicle, was initially planned to launch partially equipped CSMs in low Earth orbit tests. The [[Engineering:S-I|S-I]] first stage burned [[Chemistry:RP-1|RP-1]] with liquid oxygen (LOX) oxidizer in eight clustered Rocketdyne H-1 engines, to produce {{convert|1500000|lbf|kN|sigfig=3}} of thrust. The [[Astronomy:S-IV|S-IV]] second stage used six liquid hydrogen-fueled Pratt & Whitney RL-10 engines with {{convert|90000|lbf|kN|sigfig=3}} of thrust. The [[Engineering:S-V|S-V]] third stage flew inactively on Saturn I four times.<ref>Dawson & Bowles 2004, p. 85. See footnote 61.</ref>

The first four Saturn I test flights were launched from LC-34, with only the first stage live, carrying dummy upper stages filled with water. The first flight with a live S-IV was launched from LC-37. This was followed by five launches of [[Engineering:Boilerplate (spaceflight)|boilerplate]] CSMs (designated [[Engineering:AS-101|AS-101]] through [[Engineering:AS-105|AS-105]]) into orbit in 1964 and 1965. The last three of these further supported the Apollo program by also carrying [[Engineering:Pegasus (satellite)|Pegasus]] satellites, which verified the safety of the translunar environment by measuring the frequency and severity of [[Chemistry:Micrometeorite|micrometeorite]] impacts.{{sfn|Brooks|Grimwood|Swenson|1979|loc=Ch. 7.6: [http://www.hq.nasa.gov/office/pao/History/SP-4205/ch7-6.html "Portents for Operations"]}}

In September 1962, NASA planned to launch four crewed CSM flights on the Saturn I from late 1965 through 1966, concurrent with Project Gemini. The {{convert|22500|lb|kg|adj=on}} payload capacity<ref>{{cite book|url=http://www.alternatewars.com/SpaceRace/Saturn/ASD_II_Saturn_Launch_Vehicles-2-1964.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.alternatewars.com/SpaceRace/Saturn/ASD_II_Saturn_Launch_Vehicles-2-1964.pdf |archive-date=2022-10-09 |url-status=live|title=Apollo Systems Description|date=February 1, 1964|publisher=NASA|volume=II: Saturn Launch Vehicles|page=3|type=Technical Memorandum|id=NASA TM-X-881|access-date=August 1, 2013}}<!----Original URL for document on NTRS server: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19710065502_1971065502.pdf----></ref> would have severely limited the systems which could be included, so the decision was made in October 1963 to use the uprated [[Astronomy:Saturn IB|Saturn IB]] for all crewed Earth orbital flights.<ref>{{cite encyclopedia |url=http://www.astronautix.com/flights/apoosa11.htm |last=Wade |first=Mark |title=Apollo SA-11 |encyclopedia=Encyclopedia Astronautica |access-date=June 21, 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120617193358/http://www.astronautix.com/flights/apoosa11.htm |archive-date=June 17, 2012 |df=mdy-all}}</ref>

===Saturn IB===
{{main|Astronomy:Saturn IB}}

The Saturn IB was an upgraded version of the Saturn I. The [[Engineering:S-IB|S-IB]] first stage increased the thrust to {{convert|1600000|lbf|kN|sigfig=3}} by uprating the H-1 engine. The second stage replaced the S-IV with the [[Astronomy:S-IVB|S-IVB-200]], powered by a single [[Engineering:Rocketdyne J-2|J-2]] engine burning liquid hydrogen fuel with LOX, to produce {{convert|200000|lbf|kN|sigfig=3|lk=on}} of thrust.<ref>{{cite web|url=https://history.nasa.gov/SP-4205.pdf|title=Influences on Booster Determination|pages=44–46|website=NASA HQ|access-date=November 11, 2022}}</ref> A restartable version of the S-IVB was used as the third stage of the Saturn V. The Saturn IB could send over {{convert|40000|lb|kg|sigfig=3}} into low Earth orbit, sufficient for a partially fueled CSM or the LM.<ref>{{cite book |title=Saturn IB News Reference |url=https://www.scribd.com/doc/58939029/Saturn-IB-News-Reference |format=PDF |access-date=August 1, 2013 |date=December 1965 |publisher=NASA; [[Company:Chrysler|Chrysler Corporation]]; [[Company:Douglas Aircraft Company|McDonnell Douglas Astronautics Company]]; [[Company:IBM|International Business Machines Corporation]]; [[Company:Rocketdyne|Rocketdyne]] |oclc=22102803 |chapter=Saturn IB Design Features}}</ref> Saturn IB launch vehicles and flights were designated with an AS-200 series number, "AS" indicating "Apollo Saturn" and the "2" indicating the second member of the Saturn rocket family.<ref name="Origin of NASA's Names" />

===Saturn V===
{{main|Engineering:Saturn V}}
[[File:Apollo 11 Launch - GPN-2000-000630.jpg|thumb|upright=0.7|A Saturn V rocket launches Apollo 11, 1969]]

Saturn V launch vehicles and flights were designated with an AS-500 series number, "AS" indicating "Apollo Saturn" and the "5" indicating Saturn V.<ref name="Origin of NASA's Names">{{cite web|url=https://history.nasa.gov/SP-4402/ch4.htm|title=Origin of NASA's Names: Manned Spaceflight |access-date=July 19, 2016}}</ref> The three-stage Saturn V was designed to send a fully fueled CSM and LM to the Moon. It was {{convert|33|ft|m|sigfig=3}} in diameter and stood {{convert|363|ft|m|sigfig=4}} tall with its {{convert|96800|lb|kg|sigfig=3|adj=on}} lunar payload. Its capability grew to {{convert|103600|lb|kg|sigfig=3}} for the later advanced lunar landings. The [[Astronomy:S-IC|S-IC]] first stage burned RP-1/LOX for a rated thrust of {{convert|7500000|lbf|kN|sigfig=3}}, which was upgraded to {{convert|7610000|lbf|kN|sigfig=3}}. The second and third stages burned liquid hydrogen; the third stage was a modified version of the S-IVB, with thrust increased to {{convert|230000|lbf|kN|sigfig=3}} and capability to restart the engine for translunar injection after reaching a [[Astronomy:Parking orbit|parking orbit]].<ref name="ABTN_LV1">{{Cite web|title=Launch Vehicle|url=https://history.nasa.gov/SP-4029/Apollo_18-11_Launch_Vehicle-Spacecraft_Key_Facts.htm|access-date=2023-02-12|website=history.nasa.gov}}</ref>

==Astronauts==
{{main|Astronomy:List of Apollo astronauts}}
[[File:Apollo 1 Prime Crew - GPN-2000-001159.jpg|thumb|left|Apollo 1 crew: Ed White, command pilot Gus Grissom, and Roger Chaffee]]

NASA's director of flight crew operations during the Apollo program was [[Biography:Deke Slayton|Donald K. "Deke" Slayton]], one of the original [[Engineering:Mercury Seven|Mercury Seven]] astronauts who was medically grounded in September 1962 due to a [[Physics:Heart murmur|heart murmur]]. Slayton was responsible for making all Gemini and Apollo crew assignments.<ref>{{cite web |url=http://www.jsc.nasa.gov/Bios/htmlbios/slayton.html |title=Astronaut Bio: Deke Slayton 6/93 |publisher=NASA |date=June 1993 |access-date=August 1, 2013 |archive-url=https://web.archive.org/web/20060929001149/http://www.jsc.nasa.gov/Bios/htmlbios/slayton.html |archive-date=September 29, 2006 |url-status=dead}}</ref>

Thirty-two astronauts were assigned to fly missions in the Apollo program. Twenty-four of these left Earth's orbit and flew around the Moon between December 1968 and December 1972 (three of them twice). Half of the 24 walked on the Moon's surface, though none of them returned to it after landing once. One of the moonwalkers was a trained geologist. Of the 32, Gus Grissom, [[Astronomy:Ed White (astronaut)|Ed White]], and Roger Chaffee were killed during a ground test in preparation for the [[Engineering:Apollo 1|Apollo 1]] mission.<ref name="missionNumbers" />

[[File:apollo 11.jpg|thumb|right|Apollo 11 crew, from left: Commander Neil Armstrong, Command Module Pilot Michael Collins, and Lunar Module Pilot Buzz Aldrin]]
The Apollo astronauts were chosen from the Project Mercury and Gemini veterans, plus from two later astronaut groups. All missions were commanded by Gemini or Mercury veterans. Crews on all development flights (except the Earth orbit CSM development flights) through the first two landings on Apollo 11 and [[Engineering:Apollo 12|Apollo 12]], included at least two (sometimes three) Gemini veterans. Harrison Schmitt, a geologist, was the first NASA scientist astronaut to fly in space, and landed on the Moon on the last mission, Apollo 17. Schmitt participated in the lunar geology training of all of the Apollo landing crews.<ref>{{cite web |url=http://www.jsc.nasa.gov/Bios/htmlbios/schmitt-hh.html |title=Astronaut Bio: Harrison Schmitt |publisher=NASA |date=December 1994 |access-date=September 12, 2012 |archive-url=https://web.archive.org/web/20110317220959/http://www.jsc.nasa.gov/Bios/htmlbios/schmitt-hh.html |archive-date=March 17, 2011 |url-status=dead}}</ref>

NASA awarded all 32 of these astronauts its highest honor, the Distinguished Service Medal, given for "distinguished service, ability, or courage", and personal "contribution representing substantial progress to the NASA mission". The medals were awarded posthumously to Grissom, White, and Chaffee in 1969, then to the crews of all missions from [[Engineering:Apollo 8|Apollo 8]] onward. The crew that flew the first Earth orbital test mission [[Engineering:Apollo 7|Apollo 7]], [[Biography:Wally Schirra|Walter M. Schirra]], Donn Eisele, and [[Biography:Walter Cunningham|Walter Cunningham]], were awarded the lesser NASA Exceptional Service Medal, because of discipline problems with the [[Engineering:Flight controller#FLIGHT|flight director]]'s orders during their flight. In October 2008, the NASA Administrator decided to award them the Distinguished Service Medals. For Schirra and Eisele, this was posthumously.<ref name="Apollo Crew Honored 2008" >{{cite web |url=http://www.collectspace.com/news/news-102008a.html |title=First Apollo flight crew last to be honored |last=Pearlman |first=Robert Z. |date=October 20, 2008 |website=collectSPACE |publisher=Robert Pearlman |access-date=June 12, 2014}}</ref>

==Lunar mission profile==
The first lunar landing mission was planned to proceed:<ref>{{cite book|last1=Gatland|first1=Kenneth|title=Manned Spacecraft|date=1976|publisher=MacMillan|location=New York|pages=75–85, 88–89}}</ref>
<gallery mode=packed widths="190" heights="131">
File:Apollo11-01.png|'''Launch''' The three Saturn{{nbsp}}V stages burn for about 11 minutes to achieve a {{convert|100|nmi|km|adj=on}} circular [[Astronomy:Parking orbit|parking orbit]]. The third stage burns a small portion of its fuel to achieve orbit.
File:Apollo11-02.png|'''[[Astronomy:Trans-lunar injection|Translunar injection]]''' After one to two orbits to verify readiness of spacecraft systems, the [[Astronomy:S-IVB|S-IVB]] third stage reignites for about six minutes to send the spacecraft to the Moon.
File:Apollo11-03.png|'''[[Astronomy:Transposition, docking, and extraction|Transposition and docking]]''' The [[Engineering:Apollo (spacecraft)#Spacecraft Lunar Module Adapter (SLA)|Spacecraft Lunar Module Adapter]] (SLA) panels separate to free the CSM and expose the LM. The command module pilot (CMP) moves the CSM out a safe distance, and turns 180°.
File:Apollo11-04.png|'''Extraction''' The CMP docks the CSM with the LM, and pulls the complete spacecraft away from the S-IVB. The lunar voyage takes between two and three days. Midcourse corrections are made as necessary using the [[Engineering:Apollo command and service module#Service module (SM)|SM]] engine.
File:Apollo11-05.png|'''[[Astronomy:Lunar orbit|Lunar orbit]] insertion''' The spacecraft passes about {{convert|60|nmi|km}} behind the Moon, and the SM engine is fired to slow the spacecraft and put it into a {{convert|60|by|170|nmi|km|adj=on}} orbit, which is soon circularized at 60 nautical miles by a second burn.
File:Apollo11-07.png|After a rest period, the commander (CDR) and lunar module pilot (LMP) move to the LM, power up its systems, and deploy the landing gear. The CSM and LM separate; the CMP visually inspects the LM, then the LM crew move a safe distance away and fire the descent engine for '''Descent orbit insertion''', which takes it to a perilune of about {{convert|50000|ft|km}}.
File:Apollo11-08.png|'''[[Engineering:Powered Descent Initiation|Powered descent]]''' At perilune, the descent engine fires again to start the descent. The CDR takes control after pitchover for a vertical landing.
File:Apollo11-09.png|The CDR and LMP perform one or more [[Astronomy:Extravehicular activity|EVA]]s exploring the lunar surface and collecting samples, alternating with rest periods.
File:Apollo11-10.png|The [[Engineering:Apollo Lunar Module#Ascent stage|ascent stage]] lifts off, using the descent stage as a launching pad.
File:Apollo11-11.png|The LM rendezvouses and docks with the CSM.
File:Apollo11-12.png|The CDR and LMP transfer back to the CM with their material samples, then the LM ascent stage is jettisoned, to eventually fall out of orbit and crash on the surface.
File:Apollo11-13.png|'''[[Astronomy:Trans-Earth injection|Trans-Earth injection]]''' The SM engine fires to send the CSM back to Earth.
File:Apollo11-14.png|The SM is jettisoned just before reentry, and the CM turns 180° to face its blunt end forward for reentry.
File:Apollo11-15.png|Atmospheric drag slows the CM. Aerodynamic heating surrounds it with an envelope of ionized air which causes a communications blackout for several minutes.
File:Apollo11-16.png|Parachutes are deployed, slowing the CM for a splashdown in the [[Earth:Pacific Ocean|Pacific Ocean]]. The astronauts are recovered and brought to an [[Engineering:Aircraft carrier|aircraft carrier]]. 
</gallery>

{{Wide image|Apollo Mission Flight Plan - 1967.jpg|1200|Apollo Mission Flight Plan, 1967}}

===Profile variations===
[[File:AP11 FINAL APPROACH.ogv|thumb|Neil Armstrong pilots the Apollo Lunar Module ''Eagle'' and lands himself and navigator Buzz Aldrin on the Moon, July 20, 1969.]]

* The first three lunar missions (Apollo 8, [[Engineering:Apollo 10|Apollo 10]], and Apollo 11) used a free return trajectory, keeping a flight path coplanar with the lunar orbit, which would allow a return to Earth in case the SM engine failed to make lunar orbit insertion. Landing site lighting conditions on later missions dictated a lunar orbital plane change, which required a course change maneuver soon after TLI, and eliminated the free-return option.<ref>{{cite book|last1=McDivitt|first1=James A.|title=Apollo 12 Mission Report|date=March 1970|publisher=NASA Manned Spacecraft Center|location=Houston, Texas|page={{Not a typo|5–4}}<!-- A single page in document -->|url=http://www.hq.nasa.gov/alsj/a12/A12_MissionReport.pdf}}</ref>
* After Apollo 12 placed the second of several [[Earth:Seismometer|seismometer]]s on the Moon,<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1969-099C|title=Apollo 12 Lunar Module / ALSEP|access-date=June 15, 2016|website=NASA Space Science Data Coordinate Archive}}</ref> the jettisoned LM ascent stages on Apollo 12 and later missions were deliberately crashed on the Moon at known locations to induce vibrations in the Moon's structure. The only exceptions to this were the Apollo 13 LM which burned up in the Earth's atmosphere, and [[Engineering:Apollo 16|Apollo 16]], where a loss of [[Astronomy:Spacecraft attitude control|attitude control]] after jettison prevented making a targeted impact.<ref>{{cite web |url=http://nssdc.gsfc.nasa.gov/planetary/lunar/apolloloc.html |title=Apollo: Where are they now? |last=Williams |first=David R. |work=[[Astronomy:National Space Science Data Center|National Space Science Data Center]] |publisher=NASA |access-date=December 2, 2011}}</ref>
* As another active seismic experiment, the S-IVBs on Apollo 13 and subsequent missions were deliberately crashed on the Moon instead of being sent to solar orbit.<ref>{{cite web|url=https://www.nasa.gov/mission_pages/LRO/multimedia/lroimages/lroc-20100322-apollo13booster.html#.V2JPbfkrLD4|title=Apollo 13's Booster Impact|website=NASA|access-date=June 16, 2016}}</ref>
* Starting with Apollo 13, descent orbit insertion was to be performed using the service module engine instead of the LM engine, in order to allow a greater fuel reserve for landing. This was actually done for the first time on Apollo 14, since the Apollo 13 mission was aborted before landing.<ref>{{cite book|last1=McDivitt|first1=James A.|title=Apollo 14 Mission Report|date=April 1971|publisher=NASA Manned Spacecraft Center|location=Houston, Texas|chapter-url=http://www.hq.nasa.gov/alsj/a14/a14mr07.htm|access-date=19 May 2016|chapter=7.0 Command and Service Module Performance}}</ref>

==Development history==
===Uncrewed flight tests===
<imagemap>
File:Apollo unmanned launches.png|thumb|right|upright=1.15|Apollo uncrewed development mission launches. Click on a launch image to read the main article about each mission.|alt=Composite image of uncrewed development Apollo mission launches in chronological sequence.
rect 0 0 91 494 [[Engineering:AS-201|AS-201 first uncrewed CSM test]]
rect 92 0 181 494 [[Engineering:AS-203|AS-203 S-IVB stage development test]]
rect 182 0 270 494 [[Engineering:AS-202|AS-202 second uncrewed CSM test]]
rect 271 0 340 494 [[Engineering:Apollo 4|Apollo 4 first uncrewed Saturn V test]]
rect 341 0 434 494 [[Engineering:Apollo 5|Apollo 5 uncrewed LM test]]
rect 435 0 494 494 [[Engineering:Apollo 6|Apollo 6 second uncrewed Saturn V test]]
</imagemap>
{{Main list|Astronomy:List of Apollo missions}}

Two Block I CSMs were launched from LC-34 on suborbital flights in 1966 with the Saturn IB. The first, [[Engineering:AS-201|AS-201]] launched on February 26, reached an altitude of {{convert|265.7|nmi|km}} and splashed down {{convert|4577|nmi|km}} downrange in the [[Earth:Atlantic Ocean|Atlantic Ocean]].<ref>{{cite book|url=https://www.scribd.com/doc/59688171/Post-Launch-Report-for-Mission-as-201-Apollo-Spacecraft-009|title=Postlaunch Report for Mission AS-201 (Apollo Spacecraft 009)|date=May 6, 1966|publisher=NASA|location=Houston, TX|format=PDF|id=MSC-A-R-66-4|access-date=August 1, 2013}}<!----Original URL for document on NTRS server: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19750065090_1975065090.pdf----></ref> The second, [[Engineering:AS-202|AS-202]] on August 25, reached {{convert|617.1|nmi|km}} altitude and was recovered {{convert|13900|nmi|km}} downrange in the Pacific Ocean. These flights validated the service module engine and the command module heat shield.<ref>{{cite book|url=https://www.scribd.com/doc/59690251/Post-Launch-Report-for-Mission-AS-202|title=Postlaunch Report for Mission AS-202 (Apollo Spacecraft 011)|date=October 12, 1966|publisher=NASA|location=Houston, TX|format=PDF|id=MSC-A-R-66-5|access-date=August 1, 2013}}<!----Original URL for document on NTRS server: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19740075039_1974075039.pdf----></ref>

A third Saturn IB test, [[Engineering:AS-203|AS-203]] launched from pad 37, went into orbit to support design of the S-IVB upper stage restart capability needed for the Saturn V. It carried a nose cone instead of the Apollo spacecraft, and its payload was the unburned liquid hydrogen fuel, the behavior of which engineers measured with temperature and pressure sensors, and a TV camera. This flight occurred on July 5, before AS-202, which was delayed because of problems getting the Apollo spacecraft ready for flight.<ref name=NASAreport>{{cite tech report |author=Chrysler Corp. |title= Evaluation of AS-203 Low Gravity Orbital Experiment |date=January 13, 1967 |publisher=NASA}}</ref>

===Preparation for crewed flight===
Two crewed orbital Block I CSM missions were planned: AS-204 and AS-205. The Block I crew positions were titled Command Pilot, Senior Pilot, and Pilot. The Senior Pilot would assume navigation duties, while the Pilot would function as a systems engineer.<ref>{{cite web|url=http://www.astronautix.com/details/apo17594.htm|title=Apollo flight crew nomenclature changes|access-date=July 8, 2016|website=Astronautix|archive-url=https://web.archive.org/web/20100201000351/http://astronautix.com/details/apo17594.htm|archive-date=February 1, 2010|url-status=dead}}</ref> The astronauts would wear a modified version of the Gemini spacesuit.<ref>{{cite web|url=http://www.astronautix.com/a/a1c.html|archive-url=https://web.archive.org/web/20160820051220/http://www.astronautix.com/a/a1c.html|url-status=dead|archive-date=August 20, 2016|title=A1C|access-date=July 8, 2016|website=Astronautix}}</ref>

After an uncrewed LM test flight AS-206, a crew would fly the first Block II CSM and LM in a dual mission known as AS-207/208, or AS-278 (each spacecraft would be launched on a separate Saturn IB).{{sfn|Brooks|Grimwood|Swenson|1979|loc=Plans and Progress in Space Flight}} The Block II crew positions were titled Commander, Command Module Pilot, and Lunar Module Pilot. The astronauts would begin wearing a new Apollo A6L spacesuit, designed to accommodate lunar [[Astronomy:Extravehicular activity|extravehicular activity]] (EVA). The traditional visor helmet was replaced with a clear "fishbowl" type for greater visibility, and the lunar surface EVA suit would include a water-cooled undergarment.<ref name="EMU_development">{{cite journal|last1=Lutz|first1=Charles C.|last2=Carson|first2=Maurice A.|title=Apollo Experience Report – Development of the Extravehicular Mobility Unit|journal=NASA Technical Note|date=November 1975|volume=TN D-8093|pages=22–25|url=http://www.hq.nasa.gov/alsj/tnD8093EMUDevelop.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.hq.nasa.gov/alsj/tnD8093EMUDevelop.pdf |archive-date=2022-10-09 |url-status=live|access-date=18 May 2016}}</ref>

[[Biography:Deke Slayton|Deke Slayton]], the grounded [[Engineering:Mercury Seven|Mercury astronaut]] who became director of flight crew operations for the Gemini and Apollo programs, selected the first Apollo crew in January 1966, with Grissom as Command Pilot, White as Senior Pilot, and rookie [[Biography:Donn F. Eisele|Donn F. Eisele]] as Pilot. But Eisele dislocated his shoulder twice aboard the KC135 weightlessness training aircraft, and had to undergo surgery on January 27. Slayton replaced him with Chaffee.<ref name=whatshisname/> NASA announced the final crew selection for AS-204 on March 21, 1966, with the backup crew consisting of Gemini veterans James McDivitt and [[Biography:David Scott|David Scott]], with rookie [[Biography:Rusty Schweickart|Russell L. "Rusty" Schweickart]]. Mercury/Gemini veteran [[Biography:Wally Schirra|Wally Schirra]], Eisele, and rookie [[Biography:Walter Cunningham|Walter Cunningham]] were announced on September 29 as the prime crew for AS-205.<ref name=whatshisname>{{Cite web |last= Teitel |first= Amy Shira |title= How Donn Eisele Became "Whatshisname," the Command Module Pilot of Apollo 7 |website= Popular Science |date= December 4, 2013 |orig-year= 2013 |url= http://www.popsci.com/blog-network/vintage-space/how-donn-eisele-became-whatshisname-command-module-pilot-apollo-7}}</ref>

In December 1966, the AS-205 mission was canceled, since the validation of the CSM would be accomplished on the 14-day first flight, and AS-205 would have been devoted to space experiments and contribute no new engineering knowledge about the spacecraft. Its Saturn IB was allocated to the dual mission, now redesignated AS-205/208 or AS-258, planned for August 1967. McDivitt, Scott and Schweickart were promoted to the prime AS-258 crew, and Schirra, Eisele and Cunningham were reassigned as the Apollo{{nbsp}}1 backup crew.{{sfn|Brooks|Grimwood|Swenson|1979|loc=Ch. 8.7: [http://www.hq.nasa.gov/office/pao/History/SP-4205/ch8-7.html "Preparations for the First Manned Apollo Mission"]}}

====Program delays====
The spacecraft for the AS-202 and AS-204 missions were delivered by North American Aviation to the Kennedy Space Center with long lists of equipment problems which had to be corrected before flight; these delays caused the launch of AS-202 to slip behind AS-203, and eliminated hopes the first crewed mission might be ready to launch as soon as November 1966, concurrently with the last Gemini mission. Eventually, the planned AS-204 flight date was pushed to February 21, 1967.<ref name="SP4029">{{Cite web |title=Apollo 1: The Fire |url=https://history.nasa.gov/SP-4029/Apollo_01a_Summary.htm |date=1967-01-27|access-date=2023-02-12 |website=history.nasa.gov}}</ref>

North American Aviation was prime contractor not only for the Apollo CSM, but for the Saturn{{nbsp}}V [[Astronomy:S-II|S-II]] second stage as well, and delays in this stage pushed the first uncrewed Saturn{{nbsp}}V flight AS-501 from late 1966 to November 1967. (The initial assembly of AS-501 had to use a dummy spacer spool in place of the stage.)<ref>{{cite book |last1=Benson |first1=Charles D. |last2=Faherty |first2=William Barnaby |title=Moonport: A History of Apollo Launch Facilities and Operations |url=http://www.hq.nasa.gov/office/pao/History/SP-4204/contents.html |archive-url=https://web.archive.org/web/20080123133438/http://www.hq.nasa.gov/office/pao/History/SP-4204/contents.html |archive-date=January 23, 2008 |access-date=August 1, 2013 |series=The NASA History Series |date=1978 |publisher=Scientific and Technical Information Office, NASA |location=Washington, D.C. |oclc=3608505 |lccn=77029118 |id=NASA SP-4204 |chapter=Delay after Delay after Delay |chapter-url=http://www.hq.nasa.gov/office/pao/History/SP-4204/ch19-3.html |url-status=live}}</ref>

The problems with North American were severe enough in late 1965 to cause Manned Space Flight Administrator George Mueller to appoint program director Samuel Phillips to head a "[[Tiger team|tiger team]]" to investigate North American's problems and identify corrections. Phillips documented his findings in a December 19 letter to NAA president Lee Atwood, with a strongly worded letter by Mueller, and also gave a presentation of the results to Mueller and Deputy Administrator Robert Seamans.<ref>NASA never volunteered the tiger team findings to the US Congress in the course of its regular oversight, but its existence was publicly disclosed as "the Phillips report" in the course of the Senate investigation into the Apollo 204 fire. {{cite web |url=https://history.nasa.gov/Apollo204/phillip1.html |title=The Phillips Report |publisher=NASA History Office |access-date=April 14, 2010 |archive-url=https://web.archive.org/web/20100415050958/https://history.nasa.gov/Apollo204/phillip1.html |archive-date=April 15, 2010 |url-status=live}}</ref> Meanwhile, [[Company:Grumman|Grumman]] was also encountering problems with the Lunar Module, eliminating hopes it would be ready for crewed flight in 1967, not long after the first crewed CSM flights.{{sfn|Brooks|Grimwood|Swenson|1979|loc=Ch. 7.4: [http://www.hq.nasa.gov/office/pao/History/SP-4205/ch7-4.html "The LEM Test Program: A Pacing Item"]}}

====Apollo 1 fire====
[[File:Apollo 1 fire.jpg|thumb|right|Charred Apollo 1 cabin interior]]
{{main|Engineering:Apollo 1}}

Grissom, White, and Chaffee decided to name their flight Apollo{{nbsp}}1 as a motivational focus on the first crewed flight. They trained and conducted tests of their spacecraft at North American, and in the altitude chamber at the Kennedy Space Center. A "plugs-out" test was planned for January, which would simulate a launch countdown on LC-34 with the spacecraft transferring from pad-supplied to internal power. If successful, this would be followed by a more rigorous countdown simulation test closer to the February 21 launch, with both spacecraft and launch vehicle fueled.<ref name="sea4">{{cite book |first=Robert C. Jr. |last=Seamans |publisher=NASA History Office |title=Report of Apollo 204 Review Board |chapter=Description of Test Sequence and Objectives |url=http://www.hq.nasa.gov/pao/History/Apollo204/desc.html |date=April 5, 1967 |access-date=October 7, 2007}}</ref>

The plugs-out test began on the morning of January 27, 1967, and immediately was plagued with problems. First, the crew noticed a strange odor in their spacesuits which delayed the sealing of the hatch. Then, communications problems frustrated the astronauts and forced a hold in the simulated countdown. During this hold, an electrical fire began in the cabin and spread quickly in the high pressure, 100% oxygen atmosphere. Pressure rose high enough from the fire that the cabin inner wall burst, allowing the fire to erupt onto the pad area and frustrating attempts to rescue the crew. The astronauts were asphyxiated before the hatch could be opened.<ref name="sea5">{{cite book |first=Robert C. Jr. |last=Seamans |publisher=NASA History Office |title=Report of Apollo 204 Review Board |chapter=Findings, Determinations And Recommendations |url=http://www.hq.nasa.gov/pao/History/Apollo204/find.html |date=April 5, 1967 |access-date=October 7, 2007}}</ref>

[[File:Irwin i Bull testują kombinezony kosmiczne S68-15931.jpg|thumb|Block II spacesuit in January 1968, before (left) and after changes recommended after the Apollo{{nbsp}}1 fire]]
NASA immediately convened an accident review board, overseen by both houses of Congress. While the determination of responsibility for the accident was complex, the review board concluded that "deficiencies existed in command module design, workmanship and quality control".<ref name="sea5" /> At the insistence of NASA Administrator Webb, North American removed Harrison Storms as command module program manager.<ref>Gray 1994</ref> Webb also reassigned Apollo Spacecraft Program Office (ASPO) Manager Joseph Francis Shea, replacing him with George Low.<ref name="KeyPersonnelChange">Ertel et al. 1978, p. 119</ref>

To remedy the causes of the fire, changes were made in the Block II spacecraft and operational procedures, the most important of which were use of a nitrogen/oxygen mixture instead of pure oxygen before and during launch, and removal of flammable cabin and space suit materials.<ref name="chariot">{{harvnb|Brooks|Grimwood|Swenson|1979|loc=[http://www.hq.nasa.gov/office/pao/History/SP-4205/ch9-4.html "The Slow Recovery"]}}</ref> The Block II design already called for replacement of the Block I plug-type hatch cover with a quick-release, outward opening door.<ref name="chariot"/> NASA discontinued the crewed Block I program, using the Block{{nbsp}}I spacecraft only for uncrewed Saturn{{nbsp}}V flights. Crew members would also exclusively wear modified, fire-resistant A7L Block II space suits, and would be designated by the Block II titles, regardless of whether a LM was present on the flight or not.<ref name="EMU_development"/>

====Uncrewed Saturn V and LM tests====
On April 24, 1967, Mueller published an official Apollo mission numbering scheme, using sequential numbers for all flights, crewed or uncrewed. The sequence would start with [[Engineering:Apollo 4|Apollo 4]] to cover the first three uncrewed flights while retiring the Apollo{{nbsp}}1 designation to honor the crew, per their widows' wishes.<ref name="missionNumbers">{{Cite web |title=Apollo 11 30th Anniversary: Manned Apollo Missions |publisher=NASA History Office |date=1999 |url=https://history.nasa.gov/ap11ann/missions.htm |access-date=March 3, 2011 |archive-url=https://web.archive.org/web/20110220232013/https://history.nasa.gov/ap11ann/missions.htm |archive-date=February 20, 2011 |url-status= live}}</ref><ref>Ertel & al. 1978, Part 1(H)</ref>

In September 1967, Mueller approved a [[Astronomy:List of Apollo missions#Alphabetical mission types|sequence of mission types]] which had to be successfully accomplished in order to achieve the crewed lunar landing. Each step had to be successfully accomplished before the next ones could be performed, and it was unknown how many tries of each mission would be necessary; therefore letters were used instead of numbers. The '''A''' missions were uncrewed Saturn V validation; '''B''' was uncrewed LM validation using the Saturn IB; '''C''' was crewed CSM Earth orbit validation using the Saturn IB; '''D''' was the first crewed CSM/LM flight (this replaced AS-258, using a single Saturn V launch); '''E''' would be a higher Earth orbit CSM/LM flight; '''F''' would be the first lunar mission, testing the LM in lunar orbit but without landing (a "dress rehearsal"); and '''G''' would be the first crewed landing. The list of types covered follow-on lunar exploration to include '''H''' lunar landings, '''I''' for lunar orbital survey missions, and '''J''' for extended-stay lunar landings.<ref name="3Q1967">Ertel et al. 1978, p. 157</ref>

The delay in the CSM caused by the fire enabled NASA to catch up on human-rating the LM and Saturn{{nbsp}}V. Apollo{{nbsp}}4 (AS-501) was the first uncrewed flight of the Saturn{{nbsp}}V, carrying a Block{{nbsp}}I CSM on November 9, 1967. The capability of the command module's heat shield to survive a trans-lunar reentry was demonstrated by using the service module engine to ram it into the atmosphere at higher than the usual Earth-orbital reentry speed.

[[Engineering:Apollo 5|Apollo 5]] (AS-204) was the first uncrewed test flight of the LM in Earth orbit, launched from pad 37 on January 22, 1968, by the Saturn IB that would have been used for Apollo 1. The LM engines were successfully test-fired and restarted, despite a computer programming error which cut short the first descent stage firing. The ascent engine was fired in abort mode, known as a "fire-in-the-hole" test, where it was lit simultaneously with jettison of the descent stage. Although Grumman wanted a second uncrewed test, George Low decided the next LM flight would be crewed.<ref>{{cite book |last=Low |first=George M. |editor-last=Cortright |editor-first=Edgar M |title=Apollo Expeditions to the Moon |url=http://www.hq.nasa.gov/pao/History/SP-350/cover.html |access-date=August 1, 2013 |date=1975 |publisher=Scientific and Technical Information Office, NASA |location=Washington, D.C. |oclc=1623434 |lccn=75600071 |id=NASA SP-350 |chapter=Testing and Retesting To Get Ready For flight |chapter-url=http://www.hq.nasa.gov/office/pao/History/SP-350/ch-4-6.html}}</ref>

This was followed on April 4, 1968, by [[Engineering:Apollo 6|Apollo 6]] (AS-502) which carried a CSM and a LM Test Article as ballast. The intent of this mission was to achieve trans-lunar injection, followed closely by a simulated direct-return abort, using the service module engine to achieve another high-speed reentry. The Saturn V experienced [[Engineering:Pogo oscillation|pogo oscillation]], a problem caused by non-steady engine combustion, which damaged fuel lines in the second and third stages. Two S-II engines shut down prematurely, but the remaining engines were able to compensate. The damage to the third stage engine was more severe, preventing it from restarting for trans-lunar injection. Mission controllers were able to use the service module engine to essentially repeat the flight profile of Apollo 4. Based on the good performance of Apollo{{nbsp}}6 and identification of satisfactory fixes to the Apollo{{nbsp}}6 problems, NASA declared the Saturn{{nbsp}}V ready to fly crew, canceling a third uncrewed test.{{sfn|Brooks|Grimwood|Swenson|1979|loc=Ch. 10.5: [http://www.hq.nasa.gov/office/pao/History/SP-4205/ch10-5.html "Apollo 6: Saturn V's Shaky Dress Rehearsal"]}}

===Crewed development missions===
<imagemap>
File:Apollo manned development missions insignia.png|thumb|right|upright=1.15|Apollo crewed development mission patches. Click on a patch to read the main article about that mission.|alt=Composite image of six crewed Apollo development mission patches, from Apollo{{nbsp}}1 to Apollo 11.
rect    0   0  595 600 [[Engineering:Apollo 1|Apollo 1 unsuccessful first crewed CSM test]]
rect  596   0 1376 600 [[Engineering:Apollo 7|Apollo 7 first crewed CSM test]]
rect 1377   0 2076 600 [[Engineering:Apollo 8|Apollo 8 first crewed flight to the Moon]]
rect    0 601  595 1200 [[Engineering:Apollo 9|Apollo 9 crewed Earth orbital LM test]]
rect  596 601 1376 1200 [[Engineering:Apollo 10|Apollo 10 crewed lunar orbital LM test]]
rect 1377 601 2076 1200 [[Engineering:Apollo 11|Apollo 11 first crewed Moon landing]]
</imagemap>

[[Engineering:Apollo 7|Apollo 7]], launched from LC-34 on October 11, 1968, was the C{{nbsp}}mission, crewed by [[Biography:Wally Schirra|Schirra]], [[Biography:Donn F. Eisele|Eisele]], and [[Biography:Walter Cunningham|Cunningham]]. It was an 11-day Earth-orbital flight which tested the CSM systems.<ref>{{cite web|url=http://www.nasa.gov/mission_pages/apollo/missions/apollo7.html|title=Mission Objective|date=July 8, 2015 |access-date=July 8, 2016}}</ref>

[[Engineering:Apollo 8|Apollo 8]] was planned to be the D mission in December 1968, crewed by McDivitt, Scott and Schweickart, launched on a Saturn{{nbsp}}V instead of two Saturn IBs.<ref>{{cite web|url=https://www.nasa.gov/mission_pages/apollo/missions/apollo8.html#.V4BhBRUrJeV|title=Mission Objective|date=July 8, 2009 |access-date=July 8, 2016}}</ref> In the summer it had become clear that the LM would not be ready in time. Rather than waste the Saturn V on another simple Earth-orbiting mission, ASPO Manager George Low suggested the bold step of sending Apollo{{nbsp}}8 to orbit the Moon instead, deferring the D{{nbsp}}mission to the next mission in March 1969, and eliminating the E mission. This would keep the program on track. The Soviet Union had sent two tortoises, mealworms, wine flies, and other lifeforms around the Moon on September 15, 1968, aboard [[Astronomy:Zond 5|Zond 5]], and it was believed they might soon repeat the feat with human cosmonauts.<ref name="Chaikin">{{cite book |last=Chaikin |first=Andrew |title=[[Astronomy:A Man on the Moon|A Man on the Moon]]: The Voyages of the Apollo Astronauts |date=1994 |publisher=Viking |location=New York |isbn=978-0-670-81446-6 |lccn=93048680 |ref=Chaikin}}</ref><ref name="Moon Race 1968">{{cite magazine |title=Poised for the Leap |url=http://www.time.com/time/subscriber/article/0,33009,844661-1,00.html |archive-url=https://archive.today/20130204221712/http://www.time.com/time/subscriber/article/0,33009,844661-1,00.html |url-status=dead |archive-date=February 4, 2013 |access-date=December 15, 2011 |magazine={{wipe|Time (magazine)}} |date=December 6, 1968 |location=New York}}</ref> The decision was not announced publicly until successful completion of Apollo 7. Gemini veterans Frank Borman and [[Biography:Jim Lovell|Jim Lovell]], and rookie [[Biography:William Anders|William Anders]] captured the world's attention by making ten lunar orbits in 20 hours, transmitting television pictures of the lunar surface on Christmas Eve, and returning safely to Earth.{{sfn|Brooks|Grimwood|Swenson|1979|loc=Ch. 11.6: [http://www.hq.nasa.gov/office/pao/History/SP-4205/ch11-6.html "Apollo 8: The First Lunar Voyage"]. pp. 274–284}}

[[File:Apollo 11 first step.jpg|thumb|left|Neil Armstrong descends the LM's ladder in preparation for the first steps on the lunar surface, as televised live on July 20, 1969.]]
The following March, LM flight, rendezvous and docking were successfully demonstrated in Earth orbit on [[Engineering:Apollo 9|Apollo 9]], and Schweickart tested the full lunar EVA suit with its portable life support system (PLSS) outside the LM.<ref>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1969-018A|title=Apollo 9|website= NASA Space Science Data Coordinated Archive|access-date=July 8, 2016}}</ref> The F mission was successfully carried out on [[Engineering:Apollo 10|Apollo 10]] in May 1969 by Gemini veterans Thomas P. Stafford, John Young and Eugene Cernan. Stafford and Cernan took the LM to within {{convert|50000|ft|km|sigfig=2}} of the lunar surface.<ref>{{cite web|url=http://er.jsc.nasa.gov/seh/Ap10.html|title=Apollo 10|website=NASA JSC|access-date=July 8, 2016}}</ref>

The G mission was achieved on [[Engineering:Apollo 11|Apollo 11]] in July 1969 by an all-Gemini veteran crew consisting of Neil Armstrong, Michael Collins and [[Biography:Buzz Aldrin|Buzz Aldrin]]. Armstrong and Aldrin performed the first landing at the [[Astronomy:Mare Tranquillitatis|Sea of Tranquility]] at 20:17:40 [[UTC]] on July 20, 1969. They spent a total of 21 hours, 36 minutes on the surface, and spent 2{{nbsp}}hours, 31 minutes outside the spacecraft,<ref name="statrefeva"/> walking on the surface, taking photographs, collecting material samples, and deploying automated scientific instruments, while continuously sending black-and-white television back to Earth. The astronauts returned safely on July 24.<ref>{{cite web|url=https://www.nasa.gov/mission_pages/apollo/missions/apollo11.html|title=Apollo 11 Mission Overview|website=NASA|date=April 17, 2015|access-date=July 8, 2016}}</ref>

{{blockquote|text=That's one small step for [a] man, one giant leap for mankind.|sign=Neil Armstrong, just after stepping onto the Moon's surface<ref name="Snopes">{{cite web |url=http://www.snopes.com/quotes/onesmall.asp |title=One Small Misstep: Neil Armstrong's First Words on the Moon |last1=Mikkelson |first1=Barbara |last2=Mikkelson |first2=David P. |date=October 2006 |work=Snopes.com |publisher=Urban Legends Reference Pages |access-date=September 19, 2009}}</ref>}}

===Production lunar landings===
In November 1969, [[Biography:Pete Conrad|Charles "Pete" Conrad]] became the third person to step onto the Moon, which he did while speaking more informally than had Armstrong:
{{blockquote|Whoopee! Man, that may have been a small one for Neil, but that's a long one for me. |source=Pete Conrad<ref name=journal>{{cite web |url=https://www.hq.nasa.gov/alsj/a12/a12.eva1prelim.html |publisher=NASA |work=Apollo 12 Lunar Surface Journal |title=That may have been a small one for Neil... |last1=Jones |first1=Eric |access-date=February 5, 2018}}</ref>}}

<imagemap>
File:Apollo lunar landing missions insignia.png|thumb|right|upright=1.15|Apollo production crewed lunar landing mission patches. Click on a patch to read the main article about that mission.|alt=Composite image of six production crewed Apollo lunar landing mission patches, from Apollo 12 to Apollo 17.
rect    0   0  602 600 [[Engineering:Apollo 12|Apollo 12 second crewed Moon landing]]
rect  603   0 1205 600 [[Engineering:Apollo 13|Apollo 13 unsuccessful Moon landing attempt]]
rect 1206   0 1885 600 [[Engineering:Apollo 14|Apollo 14 third crewed Moon landing]]
rect    0 601  602 1200 [[Engineering:Apollo 15|Apollo 15 fourth crewed Moon landing]]
rect  603 601 1205 1200 [[Engineering:Apollo 16|Apollo 16 fifth crewed Moon landing]]
rect 1206 601 1885 1200 [[Engineering:Apollo 17|Apollo 17 sixth crewed Moon landing]]
</imagemap>

Conrad and rookie Alan L. Bean made a precision landing of Apollo 12 within walking distance of the [[Astronomy:Surveyor 3|Surveyor 3]] uncrewed lunar probe, which had landed in April 1967 on the Ocean of Storms. The command module pilot was Gemini veteran [[Biography:Richard F. Gordon Jr.|Richard F. Gordon Jr.]] Conrad and Bean carried the first lunar surface color television camera, but it was damaged when accidentally pointed into the Sun. They made two EVAs totaling 7{{nbsp}}hours and 45 minutes.<ref name=statrefeva>{{cite web |url=https://history.nasa.gov/SP-4029/Apollo_18-30_Extravehicular_Activity.htm |title=Extravehicular Activity |access-date=June 11, 2016}}</ref> On one, they walked to the Surveyor, photographed it, and removed some parts which they returned to Earth.<ref>{{cite book |last1=Conrad |first1=Charles Jr. |last2=Shepard |first2=Alan B Jr. |author-link2=Alan Shepard |editor-last=Cortright |editor-first=Edgar M |title=Apollo Expeditions to the Moon |url=http://www.hq.nasa.gov/pao/History/SP-350/cover.html |access-date=August 1, 2013 |date=1975 |publisher=Scientific and Technical Information Office, NASA |location=Washington, D.C. |oclc=1623434 |lccn=75600071 |id=NASA SP-350 |chapter=Tan Dust On Surveyor |chapter-url=https://history.nasa.gov/SP-350/ch-12-3.html}}</ref>

The contracted batch of 15 Saturn Vs was enough for lunar landing missions through Apollo 20. Shortly after Apollo 11, NASA publicized a preliminary list of eight more planned landing sites after Apollo 12, with plans to increase the mass of the CSM and LM for the last five missions, along with the payload capacity of the Saturn V. These final missions would combine the I and J types in the 1967 list, allowing the CMP to operate a package of lunar orbital sensors and cameras while his companions were on the surface, and allowing them to stay on the Moon for over three days. These missions would also carry the [[Astronomy:Lunar Roving Vehicle|Lunar Roving Vehicle]] (LRV) increasing the exploration area and allowing televised liftoff of the LM. Also, the Block II spacesuit was revised for the extended missions to allow greater flexibility and visibility for driving the LRV.<ref>{{Cite web|title=Where No Man Has Gone Before, Ch12-4|url=https://www.hq.nasa.gov/office/pao/History/SP-4214/ch12-4.html|access-date=2023-02-12|website=www.hq.nasa.gov}}</ref>

[[File:Apollo landing sites.jpg|thumb|left|Apollo landings on the Moon, 1969–1972]]
The success of the first two landings allowed the remaining missions to be crewed with a single veteran as commander, with two rookies. Apollo 13 launched Lovell, Jack Swigert, and [[Biography:Fred Haise|Fred Haise]] in April 1970, headed for the [[Astronomy:Fra Mauro formation|Fra Mauro formation]]. But two days out, a liquid oxygen tank exploded, disabling the service module and forcing the crew to use the LM as a "lifeboat" to return to Earth. Another NASA review board was convened to determine the cause, which turned out to be a combination of damage of the tank in the factory, and a subcontractor not making a tank component according to updated design specifications.<ref name="KSC-Apollo_13" /> Apollo was grounded again, for the remainder of 1970 while the oxygen tank was redesigned and an extra one was added.<ref>{{Cite web|title=Where No Man Has Gone Before, Ch11-7|url=https://www.hq.nasa.gov/office/pao/History/SP-4214/ch11-7.html|access-date=2023-02-12|website=www.hq.nasa.gov|archive-date=February 12, 2023|archive-url=https://web.archive.org/web/20230212183759/https://www.hq.nasa.gov/office/pao/History/SP-4214/ch11-7.html|url-status=dead}}</ref>

====Mission cutbacks====
About the time of the first landing in 1969, it was decided to use an existing Saturn V to launch the Skylab orbital laboratory pre-built on the ground, replacing the original plan to construct it in orbit from several Saturn IB launches; this eliminated Apollo 20. NASA's yearly budget also began to shrink in light of the successful landing, and NASA also had to make funds available for the [[Engineering:Space Shuttle design process|development]] of the upcoming [[Engineering:Space Shuttle|Space Shuttle]]. By 1971, the decision was made to also cancel missions 18 and 19.<ref>{{Cite web|title=Where No Man Has Gone Before, Ch12-2|url=https://www.hq.nasa.gov/office/pao/History/SP-4214/ch12-2.html|access-date=2023-02-12|website=www.hq.nasa.gov}}</ref> The two unused Saturn Vs became museum exhibits at the John F. Kennedy Space Center on Merritt Island, Florida, [[Organization:Marshall Space Flight Center|George C. Marshall Space Center]] in Huntsville, Alabama, [[Organization:Michoud Assembly Facility|Michoud Assembly Facility]] in New Orleans, Louisiana, and Lyndon B. Johnson Space Center in Houston, Texas.<ref>{{cite web |url=http://history.msfc.nasa.gov/saturn_apollo/display.html |archive-url=https://web.archive.org/web/20051115064337/http://history.msfc.nasa.gov/saturn_apollo/display.html |url-status=dead |archive-date=November 15, 2005 |title=Three Saturn Vs on Display Teach Lessons in Space History |publisher=Marshall Space Flight Center History Office |first=Mike |last=Wright |access-date=July 19, 2016}}</ref>

The cutbacks forced mission planners to reassess the original planned landing sites in order to achieve the most effective geological sample and data collection from the remaining four missions. [[Engineering:Apollo 15|Apollo 15]] had been planned to be the last of the H series missions, but since there would be only two subsequent missions left, it was changed to the first of three J missions.<ref>{{cite web |url=http://nssdc.gsfc.nasa.gov/planetary/lunar/apollo_18_20.html |last1=Williams |first1=David |website=NASA Space Science Data Coordinated Archive |title=Apollo 18 through 20 – The Cancelled Missions |access-date=June 11, 2016 |date=December 11, 2003}}</ref>

Apollo 13's Fra Mauro mission was reassigned to [[Engineering:Apollo 14|Apollo 14]], commanded in February 1971 by Mercury veteran Alan Shepard, with [[Biography:Stuart Roosa|Stuart Roosa]] and [[Biography:Edgar Mitchell|Edgar Mitchell]].<ref name=apollo14>{{cite web |url=https://www.nasa.gov/mission_pages/apollo/missions/apollo14.html#.V1xEp5ErJeU |title=Apollo 14 |website=NASA |access-date=June 11, 2016 |date=July 8, 2009}}</ref> This time the mission was successful. Shepard and Mitchell spent 33 hours and 31 minutes on the surface,<ref>{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1971-008A |title=Apollo 14 Command and Service Module (CSM) |website=NASA Space Science Data Coordinated Archive |access-date=June 11, 2016}}</ref> and completed two EVAs totalling 9{{nbsp}}hours 24 minutes, which was a record for the longest EVA by a lunar crew at the time.<ref name=apollo14/>

In August 1971, just after conclusion of the Apollo 15 mission, President Richard Nixon proposed canceling the two remaining lunar landing missions, Apollo 16 and 17. Office of Management and Budget Deputy Director Caspar Weinberger was opposed to this, and persuaded Nixon to keep the remaining missions.<ref>"MEMORANDUM FOR THE PRESIDENT" by Caspar Weinberger (via George Shultz), Aug 12, 1971, Page32(of 39) [http://ocw.mit.edu/courses/aeronautics-and-astronautics/16-885j-aircraft-systems-engineering-fall-2005/video-lectures/logsdn_lec_notes.pdf]</ref>

====Extended missions====
[[File:Apollo 15 Lunar Rover and Irwin.jpg|thumb|Lunar Roving Vehicle used on Apollos 15–17]]

Apollo 15 was launched on July 26, 1971, with [[Biography:David Scott|David Scott]], Alfred Worden and James Irwin. Scott and Irwin landed on July 30 near [[Astronomy:Mons Hadley|Hadley Rille]], and spent just under two days, 19 hours on the surface. In over 18 hours of EVA, they collected about {{convert|77|kg|lb}} of lunar material.<ref>{{cite web |url=https://www.nasa.gov/mission_pages/apollo/missions/apollo15.html |title=Apollo 15 |date=July 8, 2009 |website=NASA |access-date=June 9, 2016}}</ref>

Apollo 16 landed in the [[Astronomy:Descartes Highlands|Descartes Highlands]] on April 20, 1972. The crew was commanded by John Young, with [[Biography:Ken Mattingly|Ken Mattingly]] and Charles Duke. Young and Duke spent just under three days on the surface, with a total of over 20 hours EVA.<ref>{{cite web |url=https://www.nasa.gov/mission_pages/apollo/missions/apollo16.html |title=Apollo 16 |website=NASA |date=July 8, 2009 |access-date=June 9, 2016}}</ref>

Apollo 17 was the last of the Apollo program, landing in the [[Astronomy:Taurus–Littrow|Taurus–Littrow]] region in December 1972. Eugene Cernan commanded Ronald E. Evans and NASA's first scientist-astronaut, geologist Harrison H. Schmitt.<ref name=apollo17>{{cite web |url=http://www.nasa.gov/mission_pages/apollo/missions/apollo17.html |title=Apollo 17 |website=NASA |date=July 30, 2015 |access-date=June 9, 2016}}</ref> Schmitt was originally scheduled for Apollo 18,<ref>{{cite web |url=http://www.nasa.gov/centers/kennedy/about/history/Apollo_18.html |title=Apollo 18' Myths Debunked, NASA-style |website=NASA |date=September 28, 2011 |access-date=June 10, 2016 |last1=Grinter |first1=Kay}}</ref> but the lunar geological community lobbied for his inclusion on the final lunar landing.<ref>{{cite web |url=http://www.space.com/20789-harrison-schmitt-astronaut-biography.html |title=Harrison Schmitt: Geologist on the Moon |date=April 23, 2013 |access-date=June 10, 2016 |last1=Howell |first1=Elizabeth |website=Space.com}}</ref> Cernan and Schmitt stayed on the surface for just over three days and spent just over 23 hours of total EVA.<ref name="apollo17" />

==== Canceled missions ====
{{Main|Astronomy:Canceled Apollo missions}}

Several missions were planned for but were canceled before details were finalized.

== Mission summary ==
{{Main list|Astronomy:List of Apollo missions}}

{| class="wikitable"
|-
! Designation !! Date !! Launch <br />vehicle !! CSM !! LM !! Crew !! Summary
|-
| AS-201 ||width=120px| Feb 26, 1966|| SA-201 ||width=60px| CSM-009|| None||width=130px| None|| First flight of Saturn IB and Block I CSM; suborbital to Atlantic Ocean; qualified heat shield to orbital reentry speed.
|-
| AS-203 || Jul 5, 1966|| SA-203 || None|| None|| None|| No spacecraft; observations of liquid hydrogen fuel behavior in orbit, to support design of S-IVB restart capability.
|-
| AS-202 || Aug 25, 1966|| SA-202 || CSM-011|| None|| None|| Suborbital flight of CSM to Pacific Ocean.
|-
| [[Engineering:Apollo 1|Apollo 1]] || Feb 21, 1967|| SA-204 || CSM-012|| None||Gus Grissom <br />[[Astronomy:Ed White (astronaut)|Ed White]] <br />Roger B. Chaffee || Not flown. All crew members died in a fire during a launch pad test on January 27, 1967.
|-
| [[Engineering:Apollo 4|Apollo 4]] || Nov 9, 1967|| SA-501 || CSM-017|| LTA-10R|| None|| First test flight of Saturn V, placed a CSM in a high Earth orbit; demonstrated S-IVB restart; qualified CM heat shield to lunar reentry speed.
|-
| [[Engineering:Apollo 5|Apollo 5]] || Jan 22–23, 1968|| SA-204 || None|| LM-1|| None|| Earth orbital flight test of LM, launched on Saturn IB; demonstrated ascent and descent propulsion; human-rated the LM.
|-
| [[Engineering:Apollo 6|Apollo 6]] || Apr 4, 1968|| SA-502 || CM-020 <br />SM-014|| LTA-2R|| None|| Uncrewed, second flight of Saturn V, attempted demonstration of trans-lunar injection, and direct-return abort using SM engine; three engine failures, including failure of S-IVB restart. Flight controllers used SM engine to repeat Apollo 4's flight profile. Human-rated the Saturn V.
|-
| [[Engineering:Apollo 7|Apollo 7]] || Oct 11–22, 1968|| SA-205 || CSM-101|| None||[[Biography:Wally Schirra|Wally Schirra]] <br />[[Biography:Walter Cunningham|Walt Cunningham]] <br />[[Biography:Donn F. Eisele|Donn Eisele]]|| First crewed Earth orbital demonstration of Block II CSM, launched on Saturn IB. First live television broadcast from a crewed mission.
|-
| [[Engineering:Apollo 8|Apollo 8]] || Dec 21–27, 1968|| SA-503 || CSM-103|| LTA-B||Frank Borman <br />[[Biography:Jim Lovell|James Lovell]] <br />[[Biography:William Anders|William Anders]]|| First crewed flight of Saturn V; First crewed flight to Moon; CSM made 10 lunar orbits in 20 hours.
|-
| [[Engineering:Apollo 9|Apollo 9]] || Mar 3–13, 1969|| SA-504 || CSM-104 ''Gumdrop''|| LM-3 <br />''Spider''|| James McDivitt <br /> [[Biography:David Scott|David Scott]] <br />[[Biography:Rusty Schweickart|Russell Schweickart]]|| Second crewed flight of Saturn V; First crewed flight of CSM and LM in Earth orbit; demonstrated portable life support system to be used on the lunar surface.
|-
| [[Engineering:Apollo 10|Apollo 10]] || May 18–26, 1969|| SA-505 || CSM-106 ''Charlie Brown''|| LM-4 <br />''Snoopy''||Thomas Stafford <br />John Young <br />[[Biography:Gene Cernan|Eugene Cernan]] || Dress rehearsal for first lunar landing; flew LM down to {{convert|50000|ft|km}} from lunar surface.
|-
| [[Engineering:Apollo 11|Apollo 11]] || Jul 16–24, 1969|| SA-506 ||CSM-107 ''[[Engineering:Command module Columbia|Columbia]]''|| LM-5 ''[[Engineering:Lunar Module Eagle|Eagle]]''||Neil Armstrong <br />Michael Collins <br />[[Biography:Buzz Aldrin|Buzz Aldrin]]|| First crewed landing, in [[Astronomy:Tranquility Base|Tranquility Base]], [[Astronomy:Mare Tranquillitatis|Sea of Tranquility]]. Surface EVA time: 2:31 hr. Samples returned: {{convert|47.51|lb|kg}}.
|-
| [[Engineering:Apollo 12|Apollo 12]] || Nov 14–24, 1969|| SA-507 ||CSM-108 ''Yankee Clipper''|| LM-6 <br />''Intrepid''||[[Biography:Pete Conrad|C. "Pete" Conrad]] <br />[[Biography:Richard F. Gordon Jr.|Richard Gordon]] <br />Alan Bean|| Second landing, in [[Astronomy:Oceanus Procellarum|Ocean of Storms]] near [[Astronomy:Surveyor 3|Surveyor 3]]. Surface EVA time: 7:45 hr. Samples returned: {{convert|75.62|lb|kg}}.
|-
| [[Engineering:Apollo 13|Apollo 13]] || Apr 11–17, 1970|| SA-508 || CSM-109 ''Odyssey''|| LM-7 <br />''Aquarius''||James Lovell <br />Jack Swigert <br />[[Biography:Fred Haise|Fred Haise]]|| Third landing attempt aborted in transit to the Moon, due to SM failure. Crew used LM as "lifeboat" to return to Earth. Mission labeled as a "successful failure".<ref>{{cite web |url=https://www.nasa.gov/mission_pages/apollo/missions/apollo13.html |title=Apollo 13 |publisher=NASA |location=US |date=July 9, 2009 |access-date=November 7, 2019}}</ref>
|-
| [[Engineering:Apollo 14|Apollo 14]] || Jan 31 – Feb 9, 1971|| SA-509 || CSM-110 ''Kitty Hawk''|| LM-8 <br />''Antares''||Alan Shepard <br />[[Biography:Stuart Roosa|Stuart Roosa]] <br />[[Biography:Edgar Mitchell|Edgar Mitchell]]|| Third landing, in [[Astronomy:Fra Mauro formation|Fra Mauro formation]], located northeast of the Ocean of Storms. Surface EVA time: 9:21 hr. Samples returned: {{convert|94.35|lb|kg}}.
|-
| [[Engineering:Apollo 15|Apollo 15]] || Jul 26 – Aug 7, 1971|| SA-510 || CSM-112 ''Endeavour''|| LM-10 <br />''Falcon''||David Scott <br />Alfred Worden <br />James Irwin|| First Extended LM and rover, landed in Hadley-Apennine, located near the Sea of Showers/Rains. Surface EVA time: 18:33 hr. Samples returned: {{convert|169.10|lb|kg}}.
|-
| [[Engineering:Apollo 16|Apollo 16]] || Apr 16–27, 1972|| SA-511 || CSM-113 ''Casper''|| LM-11 <br />''Orion''||John Young <br />[[Biography:Ken Mattingly|T. Kenneth Mattingly]] <br />Charles Duke|| Landed in [[Astronomy:Descartes Highlands|Plain of Descartes]]. Rover on Moon. Surface EVA time: 20:14 hr. Samples returned: {{convert|207.89|lb|kg}}.
|-
| [[Engineering:Apollo 17|Apollo 17]] || Dec 7–19, 1972|| SA-512 || CSM-114 ''America''|| LM-12 <br />''Challenger''|| Eugene Cernan<br />Ronald Evans <br />Harrison Schmitt|| Only Saturn V night launch. Landed in [[Astronomy:Taurus–Littrow|Taurus–Littrow]]. Rover on Moon. First geologist on the Moon. Apollo's last crewed Moon landing. Surface EVA time: 22:02 hr. Samples returned: {{convert|243.40|lb|kg}}.
|}
Source: ''Apollo by the Numbers: A Statistical Reference'' (Orloff 2004)<ref name="Orloff-EVA">{{Cite web|title=Extravehicular Activity|url=https://history.nasa.gov/SP-4029/Apollo_18-30_Extravehicular_Activity.htm|access-date=2023-02-12|website=history.nasa.gov}}</ref>

==Samples returned==
{{main|Astronomy:Moon rock}}
{{multiple image
| align             = right
| total_width       = 350
| image1            = Apollo 15 Genesis Rock.jpg
| caption1          = The most famous of the Moon rocks recovered, the Genesis Rock, returned from Apollo&nbsp;15.
| image2            = Lunar_Sample_61016_-_Big_Muley.jpg
| caption2          = Apollo 16's sample 61016, better known as Big Muley, is the largest sample collected during the Apollo program
}}

The Apollo program returned over {{convert|382|kg|lb|abbr=on}} of lunar rocks and [[Astronomy:Lunar soil|soil]] to the [[Organization:Lunar Receiving Laboratory|Lunar Receiving Laboratory]] in Houston.<ref>{{cite web |url=https://curator.jsc.nasa.gov/lunar/lun-fac.cfm |title=NASA Lunar Sample Laboatory Facility |date=September 1, 2016 |website=NASA Curation Lunar |publisher=NASA |access-date=February 15, 2017 |quote=A total of 382 kilograms of lunar material, comprising 2200 individual specimens returned from the Moon{{nbsp}}...}}</ref><ref name="Orloff-EVA"/><ref>{{cite book|last1=Chaikin|first1=Andrew|title=A Man On the Moon: The Voyages of the Apollo Astronauts|year=2007|publisher=Penguin Books|location=New York|pages=611–613|edition=Third}}</ref> Today, 75% of the samples are stored at the [[Organization:Lunar Sample Laboratory Facility|Lunar Sample Laboratory Facility]] built in 1979.<ref>{{cite web|title=Rock Solid: JSC's Lunar Sample Lab Turns 30|url=http://www.nasa.gov/mission_pages/apollo/40th/jsc_lunar_sample_lab_30.html|work= 40th Anniversary of Apollo Program|publisher=NASA|access-date=June 29, 2012|author=Kristen Erickson|editor=Amiko Kauderer|date=July 16, 2009}}</ref>

The rocks collected from the Moon are extremely old compared to rocks found on Earth, as measured by [[Physics:Radiometric dating|radiometric dating]] techniques. They range in age from about 3.2&nbsp;billion years for the [[Earth:Basalt|basalt]]ic samples derived from the [[Astronomy:Lunar mare|lunar maria]], to about 4.6&nbsp;billion years for samples derived from the highlands crust.<ref>Papike et al. 1998, pp. 5-001–5-234</ref> As such, they represent samples from a very early period in the development of the [[Astronomy:Solar System|Solar System]], that are largely absent on Earth. One important rock found during the Apollo Program is dubbed the Genesis Rock, retrieved by astronauts David Scott and James Irwin during the Apollo 15 mission.{{sfn|Harland|2008|pp=132–133}} This [[Earth:Anorthosite|anorthosite]] rock is composed almost exclusively of the calcium-rich feldspar mineral [[Chemistry:Anorthite|anorthite]], and is believed to be representative of the highland crust.{{sfn|Harland|2008|p=171}} A geochemical component called [[Chemistry:KREEP|KREEP]] was discovered by Apollo 12, which has no known terrestrial counterpart.{{sfn|Harland|2008|pp=49–50}} KREEP and the anorthositic samples have been used to infer that the outer portion of the Moon was once completely molten (see [[Astronomy:Lunar magma ocean|lunar magma ocean]]).{{sfn|Harland|2008|pp=323–327}}

Almost all the rocks show evidence of impact process effects. Many samples appear to be pitted with [[Astronomy:Micrometeoroid|micrometeoroid]] impact craters, which is never seen on Earth rocks, due to the thick atmosphere. Many show signs of being subjected to high-pressure shock waves that are generated during impact events. Some of the returned samples are of ''impact melt'' (materials melted near an impact crater.) All samples returned from the Moon are highly brecciated as a result of being subjected to multiple impact events.{{sfn|Harland|2008|pp=330–332}}

From analyses of the composition of the returned lunar samples, it is now believed that the Moon was [[Astronomy:Giant-impact hypothesis|created through the impact]] of a large astronomical body with Earth.<ref>Burrows 1999, p. 431</ref>

==Costs==
Apollo cost $25.4&nbsp;billion (or approximately ${{format price|{{Inflation|US-GDP|25400000000|1966}}}} in {{Inflation-year|US-GDP}} dollars when adjusted for inflation via the [[Finance:GDP deflator|GDP deflator]] index).<ref name="ApolloCost">{{Cite book|url=https://catalog.hathitrust.org/Record/003212095|title=1974 NASA authorization hearings, Ninety-third Congress, first session, on H.R. 4567 (superseded by H.R. 7528).|date=1973|publisher=U.S. Govt. Print. Off.|location=Washington}}</ref>

Of this amount, $20.2&nbsp;billion (${{format price|{{Inflation|US-GDP|20200000000|1966}}}} adjusted) was spent on the design, development, and production of the [[Engineering:Saturn (rocket family)|Saturn family]] of launch vehicles, the [[Engineering:Apollo (spacecraft)|Apollo spacecraft]], spacesuits, [[Astronomy:Apollo Lunar Surface Experiments Package|scientific experiments]], and mission operations. The cost of constructing and operating Apollo-related ground facilities, such as the NASA human spaceflight centers and the global tracking and data acquisition network, added an additional $5.2&nbsp;billion (${{format price|{{Inflation|US-GDP|5200000000|1966}}}} adjusted).

The amount grows to $28&nbsp;billion (${{format price|{{Inflation|US-GDP|28000000000|1966}}}} adjusted) if the costs for related projects such as Project Gemini and the robotic Ranger, [[Astronomy:Surveyor program|Surveyor]], and [[Astronomy:Lunar Orbiter program|Lunar Orbiter]] programs are included.<ref>{{cite web |title=How much did the Apollo program cost? |url=http://www.planetary.org/get-involved/be-a-space-advocate/become-an-expert/cost-of-apollo-program.html |website= planetary.org |publisher=The Planetary Society |access-date=21 June 2019 |language=en}}</ref>

NASA's official cost breakdown, as reported to Congress in the Spring of 1973, is as follows:
{| class="wikitable"
! Project Apollo !! Cost (original, billion $)
|-
| Apollo spacecraft || align=right|8.5
|-
| Saturn launch vehicles || align=right|9.1
|-
| Launch vehicle engine development || align=right|0.9
|-
| Operations || align=right|1.7
|-
| '''Total R&D''' || align=right|'''20.2'''
|-
| Tracking and data acquisition || align=right|0.9
|-
| Ground facilities || align=right|1.8
|-
| Operation of installations || align=right|2.5
|-
| '''Total''' || align=right|'''25.4'''
|}

Accurate estimates of human spaceflight costs were difficult in the early 1960s, as the capability was new and management experience was lacking. Preliminary cost analysis by NASA estimated $7&nbsp;billion – $12&nbsp;billion for a crewed lunar landing effort. NASA Administrator James Webb increased this estimate to $20&nbsp;billion before reporting it to Vice President Johnson in April 1961.<ref name=Butts>{{cite web |last1=Butts |first1=Glenn |last2=Linton |first2=Kent |title=The Joint Confidence Level Paradox: A History of Denial |work=2009 NASA Cost Symposium |publisher=Cost Analysis Division |date=April 28, 2009 |pages=25–26 |url=http://science.ksc.nasa.gov/shuttle/nexgen/Nexgen_Downloads/Butts_NASA's_Joint_Cost-Schedule_Paradox_-_A_History_of_Denial.pdf |url-status=dead |archive-url=https://web.archive.org/web/20111026132859/http://science.ksc.nasa.gov/shuttle/nexgen/Nexgen_Downloads/Butts_NASA%27s_Joint_Cost-Schedule_Paradox_-_A_History_of_Denial.pdf |archive-date=October 26, 2011 |df=mdy-all |access-date=December 15, 2021 }}</ref>

Project Apollo was a massive undertaking, representing the largest research and development project in peacetime. At its peak, it employed over 400,000 employees and contractors around the country and accounted for more than half of NASA's total spending in the 1960s.<ref>{{cite book |last1=Skolnikoff |first1=Eugene B. |last2=Hoagland |first2=John H. |title=The World-wide Spread of Space Technology |series=69-5 |date=1968 |publisher=MIT Center for Space Research |location=Cambridge, MA |oclc=14154430 |ref=Skolnikoff & Hoagland}}</ref> After the first Moon landing, public and political interest waned, including that of President Nixon, who wanted to rein in federal spending.<ref>{{cite web |last1=Callahan |first1=Jason |title=How Richard Nixon Changed NASA |url=http://www.planetary.org/blogs/guest-blogs/jason-callahan/20141003-how-richard-nixon-changed-nasa.html |website= planetary.org |publisher=The Planetary Society |access-date=20 June 2019 |language=en}}</ref> NASA's budget could not sustain Apollo missions which cost, on average, $445&nbsp;million (${{format price|{{Inflation|US-GDP|440000000|1970}}}} adjusted)<ref name="ApolloCost"/> each while simultaneously [[Engineering:Space Shuttle design process|developing the Space Shuttle]]. The final fiscal year of Apollo funding was 1973.

==Apollo Applications Program==
{{main|Astronomy:Apollo Applications Program}}

Looking beyond the crewed lunar landings, NASA investigated several post-lunar applications for Apollo hardware. The Apollo Extension Series (''Apollo X'') proposed up to 30 flights to Earth orbit, using the space in the [[Engineering:Apollo (spacecraft)#Spacecraft Lunar Module Adapter (SLA)|Spacecraft Lunar Module Adapter]] (SLA) to house a small orbital laboratory (workshop). Astronauts would continue to use the CSM as a ferry to the station. This study was followed by design of a larger orbital workshop to be built in orbit from an empty S-IVB Saturn upper stage and grew into the Apollo Applications Program (AAP). The workshop was to be supplemented by the [[Astronomy:Apollo Telescope Mount|Apollo Telescope Mount]], which could be attached to the ascent stage of the lunar module via a rack.<ref>{{cite web|url=https://history.nasa.gov/SP-4208/ch4.htm|title=A Science Program for Manned Spaceflight|date=January 1983 |access-date=June 11, 2016 |last1=Compton |first1=W. D. |last2=Benson |first2=C. D. }}</ref> The most ambitious plan called for using an empty S-IVB as an interplanetary spacecraft for a Venus fly-by mission.<ref>{{cite web |url=http://forum.nasaspaceflight.com/index.php?PHPSESSID=j74hfnr889reqoinelc27u5877&action=dlattach;topic=34776.0;attach=584256;sess=0 |title=Manned Venus Flyby |date=February 1, 1967 |publisher=NASA |access-date=July 19, 2016}}</ref>

The S-IVB orbital workshop was the only one of these plans to make it off the drawing board. Dubbed [[Engineering:Skylab|Skylab]], it was assembled on the ground rather than in space, and launched in 1973 using the two lower stages of a Saturn V. It was equipped with an Apollo Telescope Mount. Skylab's last crew departed the station on February 8, 1974, and the station itself re-entered the atmosphere in 1979 after development of the [[Engineering:Space Shuttle|Space Shuttle]] was delayed too long to save it.<ref>{{cite web|url=https://history.nasa.gov/SP-4208/ch19.htm|title=What Goes Up{{nbsp}}... |date=January 1983 |access-date=June 11, 2016 |last1=Compton |first1=W. D. |last2=Benson |first2=C. D. }}</ref><ref name="Legacy" />

The [[Engineering:Apollo–Soyuz|Apollo–Soyuz]] program also used Apollo hardware for the first joint nation spaceflight, paving the way for future cooperation with other nations in the [[Engineering:Space Shuttle|Space Shuttle]] and [[Astronomy:International Space Station|International Space Station]] programs.<ref name="Legacy">{{Cite web|title=Legacy|url=https://history.nasa.gov/SP-4206/ch13.htm|access-date=2023-02-12|website=history.nasa.gov}}</ref><ref>{{cite web |url=http://www.nasa.gov/topics/history/features/astp.html |date=July 10, 2015 |title=Apollo-Soyuz: An Orbital Partnership Begins |publisher=NASA |access-date=July 19, 2016}}</ref>

==Recent observations==
[[File:Apollo11-LRO-March2012.jpg|thumb|right|Tranquility Base, imaged in March 2012 by the Lunar Reconnaissance Orbiter]]

In 2008, Japan Aerospace Exploration Agency's [[Astronomy:SELENE|SELENE]] probe observed evidence of the halo surrounding the Apollo 15 Lunar Module blast crater while orbiting above the lunar surface.<ref>{{cite press release |title=The 'halo' area around Apollo 15 landing site observed by Terrain Camera on SELENE(KAGUYA) |date=May 20, 2008 |publisher=Japan Aerospace Exploration Agency |location=Chōfu, Tokyo |url=http://www.jaxa.jp/press/2008/05/20080520_kaguya_e.html |access-date=November 19, 2009 |archive-url= https://web.archive.org/web/20091212114843/http://www.jaxa.jp/press/2008/05/20080520_kaguya_e.html |archive-date=December 12, 2009 |url-status=live}}</ref>

Beginning in 2009, NASA's [[Engineering:Robotic spacecraft|robotic]] [[Astronomy:Lunar Reconnaissance Orbiter|Lunar Reconnaissance Orbiter]], while orbiting {{convert|50|km|mi|sigfig=2|sp=us}} above the Moon, photographed the remnants of the Apollo program left on the lunar surface, and each site where crewed Apollo flights landed.<ref>{{cite web |url=http://www.nasa.gov/mission_pages/LRO/multimedia/lroimages/apollosites.html |title=LRO Sees Apollo Landing Sites |last1=Hautaluoma |first1=Grey |last2=Freeberg |first2=Andy |editor-last=Garner |editor-first=Robert|date=July 17, 2009 |publisher=NASA |access-date=November 19, 2009 |archive-url= https://web.archive.org/web/20091116012309/http://www.nasa.gov/mission_pages/LRO/multimedia/lroimages/apollosites.html| archive-date= November 16, 2009 |url-status= live}}</ref><ref>{{cite web |url=http://www.nasa.gov/mission_pages/apollo/revisited/index.html |editor-last=Townsend |editor-first=Jason |title=Apollo Landing Sites Revisited |publisher=NASA |access-date=November 19, 2009| archive-url= https://web.archive.org/web/20091113094613/http://www.nasa.gov/mission_pages/apollo/revisited/index.html| archive-date= November 13, 2009 |url-status= live}}</ref> All of the U.S. flags left on the Moon during the Apollo missions were found to still be standing, with the exception of the one left during the Apollo 11 mission, which was blown over during that mission's lift-off from the lunar surface; the degree to which these flags retain their original colors remains unknown.<ref>{{cite web |url=http://lroc.sese.asu.edu/news/index.php?/archives/620-Question-Answered!.html |title=Question Answered! |last=Robinson |first=Mark |date=July 27, 2012 |work=LROC News System |publisher=[[Organization:Arizona State University|Arizona State University]] |access-date=October 28, 2012 |archive-url=https://web.archive.org/web/20121024061649/http://lroc.sese.asu.edu/news/index.php?%2Farchives%2F620-Question-Answered%21.html |archive-date=October 24, 2012 |url-status=dead |df=mdy-all}}</ref> The flags cannot be seen through a telescope from Earth.

In a November 16, 2009, editorial, ''{{wipe|The New York Times}}'' opined:
{{blockquote|[T]here's something terribly wistful about these photographs of the Apollo landing sites. The detail is such that if Neil Armstrong were walking there now, we could make him out, make out his footsteps even, like the astronaut footpath clearly visible in the photos of the Apollo 14 site. Perhaps the wistfulness is caused by the sense of simple grandeur in those Apollo missions. Perhaps, too, it's a reminder of the risk we all felt after the Eagle had landed—the possibility that it might be unable to lift off again and the astronauts would be stranded on the Moon. But it may also be that a photograph like this one is as close as we're able to come to looking directly back into the human past{{nbsp}}...

There the [Apollo 11] lunar module sits, parked just where it landed 40 years ago, as if it still really were 40 years ago and all the time since merely imaginary.<ref name="nyt_lro_lm_img">{{cite news|title=The Human Moon |url=https://www.nytimes.com/2009/11/17/opinion/17tue4.html |work=The New York Times |date=November 16, 2009 |access-date=November 19, 2009 |archive-url=https://web.archive.org/web/20121231162941/http://www.nytimes.com/2009/11/17/opinion/17tue4.html |archive-date=December 31, 2012 |url-status=live}}</ref>}}

==Legacy==
===Science and engineering===
{{further|Engineering:NASA spin-off technologies}}

The Apollo program has been described as the greatest technological achievement in human history.<ref>{{Cite web |title=Apollo 11 30th Anniversary: Introduction |publisher=NASA History Office |date=1999 |url=https://history.nasa.gov/ap11ann/introduction.htm |access-date=April 26, 2013}}</ref> Apollo stimulated many areas of technology, leading to over 1,800 spinoff products as of 2015, including advances in the development of [[Engineering:Cordless|cordless]] power tools, [[Engineering:Fireproofing|fireproof materials]], heart monitors, [[Physics:Solar panel|solar panel]]s, [[Digital imaging|digital imaging]], and the use of liquid methane as fuel.<ref name="January 2005">{{Cite web |last=January 2005 |first=Eleanor A. O’Rangers 26 |date=January 26, 2005 |title=NASA Spin-offs: Bringing Space Down to Earth |url=https://www.space.com/731-nasa-spin-offs-bringing-space-earth.html |access-date=2021-05-07 |website=Space.com |language=en}}</ref><ref name=":0">{{Cite web |title=Benefits from Apollo: Giant Leaps in Technology |url=https://www.nasa.gov/sites/default/files/80660main_ApolloFS.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://www.nasa.gov/sites/default/files/80660main_ApolloFS.pdf |archive-date=2022-10-09 |url-status=live |website=NASA}}</ref><ref>{{cite web|author=NASA Spinoff Database|url=http://spinoff.nasa.gov/spinoff/database|publisher=National Aeronautics and Space Administration|title=NASA Spinoff Database|date=April 8, 2016|access-date=April 8, 2016|archive-url=https://web.archive.org/web/20190904164206/https://spinoff.nasa.gov/spinoff/database/|archive-date=September 4, 2019|url-status=dead}}</ref> The [[Engineering:Apollo Guidance Computer|flight computer]] design used in both the lunar and command modules was, along with the Polaris and [[LGM-30 Minuteman|Minuteman]] missile systems, the driving force behind early research into [[Engineering:Integrated circuit|integrated circuit]]s (ICs). By 1963, Apollo was using 60 percent of the United States' production of ICs. The crucial difference between the requirements of Apollo and the missile programs was Apollo's much greater need for reliability. While the Navy and Air Force could work around reliability problems by deploying more missiles, the political and financial cost of failure of an Apollo mission was unacceptably high.{{sfn|Mindell|2008|pp=125–131}}

Technologies and techniques required for Apollo were developed by Project Gemini.{{sfn|Brooks|Grimwood|Swenson|1979|pp=181–182, 205–208}} The Apollo project was enabled by NASA's adoption of new advances in [[Physics:Semiconductor|semiconductor]] electronic technology, including metal–oxide–semiconductor field-effect transistors (MOSFETs) in the [[Astronomy:Interplanetary Monitoring Platform|Interplanetary Monitoring Platform]] (IMP)<ref>{{cite book |title=Interplanetary Monitoring Platform |date=29 August 1989 |publisher=[[Organization:NASA|NASA]] |pages=1, 11, 134 |url=https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19800012928.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19800012928.pdf |archive-date=2022-10-09 |url-status=live |access-date=12 August 2019|last1=Butler |first1=P. M. }}</ref><ref>{{cite journal |last1=White |first1=H. D. |last2=Lokerson |first2=D. C. |title=The Evolution of IMP Spacecraft Mosfet Data Systems |journal=IEEE Transactions on Nuclear Science |date=1971 |volume=18 |issue=1 |pages=233–236 |doi=10.1109/TNS.1971.4325871 |bibcode=1971ITNS...18..233W |issn=0018-9499}}</ref> and [[Chemistry:Silicon|silicon]] [[Engineering:Integrated circuit|integrated circuit]] chips in the [[Engineering:Apollo Guidance Computer|Apollo Guidance Computer]] (AGC).<ref>{{cite web |title=Apollo Guidance Computer and the First Silicon Chips |url=https://airandspace.si.edu/stories/editorial/apollo-guidance-computer-and-first-silicon-chips |website=National Air and Space Museum |publisher=Smithsonian Institution |access-date=1 September 2019 |date=14 October 2015}}</ref>

===Cultural impact===
[[File:The Earth seen from Apollo 17.jpg|thumb|right|''The Blue Marble'' photograph taken on December{{nbsp}}7, 1972, during Apollo 17. "We went to explore the Moon, and in fact discovered the Earth." —Eugene Cernan]]

The crew of Apollo 8 sent the first live televised pictures of the Earth and the Moon back to Earth, and read from the creation story in the [[Religion:Book of Genesis|Book of Genesis]], on Christmas Eve 1968.<ref>{{cite web|url=https://www.nasa.gov/topics/history/features/apollo_8.html|website=NASA|access-date=July 20, 2016|title=Apollo 8: Christmas at the Moon|date=February 19, 2015}}</ref> An estimated one-quarter of the population of the world saw—either live or delayed—the Christmas Eve transmission during the ninth orbit of the Moon,<ref>Chaikin 1994, p. 120</ref> and an estimated one-fifth of the population of the world watched the live transmission of the Apollo 11 moonwalk.<ref>Burrows 1999, p. 429</ref>

The Apollo program also affected environmental activism in the 1970s due to photos taken by the astronauts. The most well known include ''[[Astronomy:Earthrise|Earthrise]]'', taken by [[Biography:William Anders|William Anders]] on Apollo 8, and ''[[Astronomy:The Blue Marble|The Blue Marble]]'', taken by the Apollo 17 astronauts. ''The Blue Marble'' was released during a surge in environmentalism, and became a symbol of the environmental movement as a depiction of Earth's frailty, vulnerability, and isolation amid the vast expanse of space.<ref name=Petsko>{{cite journal |last=Petsko |first=Gregory A|title=The blue marble |journal=[[Biology:Genome Biology|Genome Biology]] |volume=12 |issue=4 |page=112 |doi=10.1186/gb-2011-12-4-112 |date=2011|pmc=3218853 |pmid=21554751 |doi-access=free }}</ref>

According to ''[[Finance:The Economist|The Economist]]'', Apollo succeeded in accomplishing President Kennedy's goal of taking on the Soviet Union in the [[Astronomy:Space Race|Space Race]] by accomplishing a singular and significant achievement, to demonstrate the superiority of the [[Philosophy:Capitalism|free-market system]]. The publication noted the irony that in order to achieve the goal, the program required the organization of tremendous public resources within a vast, centralized government bureaucracy.<ref>{{cite news |title=Apollo plus 50 |editor-last=Lexington |url=http://www.economist.com/node/18712369 |newspaper=[[Finance:The Economist|The Economist]] |publisher=The Economist Newspaper Limited |location=London |date=May 21, 2011 |page=36 |access-date=August 1, 2013}}</ref>

===Apollo 11 broadcast data restoration project===
{{main|Astronomy:Apollo 11 missing tapes}}

Prior to Apollo 11's 40th anniversary in 2009, NASA searched for the original videotapes of the mission's live televised moonwalk. After an exhaustive three-year search, it was concluded that the tapes had probably been erased and reused. A new digitally remastered version of the best available broadcast television footage was released instead.<ref name=NPR_tapes>{{cite web |url=https://www.npr.org/templates/story/story.php?storyId=106637066 |title=Houston, We Erased The Apollo 11 Tapes |last=Greenfieldboyce |first=Nell |date=July 16, 2009 |work=NPR |publisher=National Public Radio, Inc. |location=Washington, D.C. |access-date=August 1, 2013}}</ref>

==Depictions on film==

===Documentaries===
Numerous documentary films cover the Apollo program and the Space Race, including:
{{Div col|colwidth=30em}}
* ''Footprints on the Moon'' (1969)
* ''[[Astronomy:Moonwalk One|Moonwalk One]]'' (1970)<ref>{{cite web|url=https://www.theguardian.com/film/2009/may/25/apollo-11-anniversary|title=The moon shoot: film of Apollo mission on show again after 35 years in the can|last=Jones|first=Sam|date=May 25, 2009|website=The Guardian|access-date=September 5, 2019}}</ref>
* ''The Greatest Adventure'' (1978)<ref>{{cite web|url=https://www.upi.com/Archives/1984/08/13/TV-WorldNEWLNRace-to-moon-reviewed-with-NASA-film-on-PBS/5530461217600/ph|title=TV World;NEWLN:Race to moon reviewed with NASA film on PBS|last=Hastings|first=Julianne|date=August 13, 1984|website=UPI|access-date=May 2, 2023}}</ref>
* ''For All Mankind'' (1989)<ref>{{cite web |url=https://www.abc.net.au/news/2019-07-18/apollo-11-review-documentary-captures-moon-landing-mission/11315242 |title=Apollo 11 documentary is a time capsule for the fleeting optimism of mankind's first Moon landing|last=Goodsell|first=Luke|website=ABC|access-date=September 5, 2019|date=July 17, 2019}}</ref>
* ''[[Astronomy:Moon Shot#Miniseries|Moon Shot]]'' (1994 miniseries)
* "Moon" from the BBC miniseries ''The Planets'' (1999)
* ''Magnificent Desolation: Walking on the Moon 3D'' (2005)
* ''The Wonder of It All'' (2007)
* ''In the Shadow of the Moon'' (2007)<ref>{{cite magazine| url=http://www.ew.com/ew/article/0,,20053781,00.html |magazine=Entertainment Weekly |title=Movie Review: In the Shadow of the Moon |date=August 29, 2007|last1=Gleiberman|first1=Owen}}</ref>
* ''When We Left Earth: The NASA Missions'' (2008 miniseries)
* ''[[Engineering:Moon Machines|Moon Machines]]'' (2008 miniseries)
* ''James May on the Moon'' (2009)
* ''NASA's Story'' (2009 miniseries)
* ''Apollo 11'' (2019)<ref>{{cite news |last=Kenny |first=Glenn |title='Apollo 11' Review: The 1969 Moon Mission Still Has the Power to Thrill |url=https://www.nytimes.com/2019/02/27/movies/apollo-11-review.html |archive-url=https://ghostarchive.org/archive/20220101/https://www.nytimes.com/2019/02/27/movies/apollo-11-review.html |archive-date=2022-01-01 |url-access=limited |date=February 27, 2019 |newspaper={{wipe|The New York Times}} |access-date=February 28, 2019}}{{cbignore}}</ref><ref>{{cite magazine|url=https://variety.com/2019/film/news/apollo-11-documentary-imax-release-1203138469/|title='Apollo 11' Documentary Gets Exclusive Imax Release|magazine=Variety|date=February 13, 2019|last1=Rubin|first1=Rebecca|access-date=July 20, 2019}}</ref>
* ''Chasing the Moon'' (2019 miniseries)
{{div col end}}

===Docudramas===
Some missions have been dramatized: 
{{Div col|colwidth=30em}}
* ''Apollo 13'' (1995)
* ''Apollo 11'' (1996)
* ''From the Earth to the Moon'' (1998)
* ''The Dish'' (2000)
* ''Space Race'' (2005)
* ''Moonshot'' (2009)
* ''First Man'' (2018)
{{div col end}}

===Fictional===
The Apollo program has been the focus of several works of fiction, including:
*''Apollo 18'' (2011), horror movie which was released to negative reviews.
*''[[Astronomy:Men in Black 3|Men in Black 3]]'' (2012), Science Fiction/Comedy movie. Agent J played by Will Smith goes back to the Apollo 11 launch in 1969 to ensure that a global protection system is launched in to space.
*''For All Mankind'' (2019), TV series depicting an alternate history in which the Soviet Union was the first country to successfully land a man on the Moon.
*''[[Astronomy:Indiana Jones and the Dial of Destiny|Indiana Jones and the Dial of Destiny]]'' (2023), fifth Indiana Jones film, in which Jürgen Voller, a NASA member and ex-Nazi involved with the Apollo program, wants to time travel. The New York City parade for the Apollo 11 crew is portrayed as a plot point.<ref>{{cite news |last1=Travis |first1=Ben |title=Indiana Jones 5 Will Pit Indy Against Nazis Again, In 1969 – Exclusive |url=https://www.empireonline.com/movies/news/indiana-jones-5-nazis-1969-exclusive |access-date=December 24, 2022 |work=Empire |date=November 11, 2022}}</ref>

==See also==
{{Div col}}
* [[Astronomy:Apollo 11 in popular culture|Apollo 11 in popular culture]]
* [[Astronomy:Apollo Lunar Surface Experiments Package|Apollo Lunar Surface Experiments Package]]
* [[Astronomy:Exploration of the Moon|Exploration of the Moon]]
* Leslie Cantwell collection
* [[Astronomy:List of artificial objects on the Moon|List of artificial objects on the Moon]]
* [[Engineering:List of crewed spacecraft|List of crewed spacecraft]]
* [[Astronomy:Soviet crewed lunar programs|Soviet crewed lunar programs]]
* [[Astronomy:Stolen and missing Moon rocks|Stolen and missing Moon rocks]]
* Artemis Program
{{div col end}}

== Notes ==
{{notelist}}

== References ==
=== Citations ===
{{Reflist}}

=== Sources ===
{{refbegin}}
* {{NASA}}
* {{cite book |last=Beschloss |first=Michael R. |editor1-last=Launius |editor1-first=Roger D. |editor2-last=McCurdy |editor2-first=Howard E. |title=Spaceflight and the Myth of Presidential Leadership |date=1997 |publisher=University of Illinois Press |location=Champaign, IL |isbn=0-252-06632-4 |lccn=96051213 |chapter=Kennedy and the Decision to Go to the Moon |ref=Beschloss}}
* {{cite book |last=Bilstein |first=Roger E. |others=Foreword by William R. Lucas |title=Stages to Saturn: A Technological History of the Apollo/Saturn Launch Vehicles |url=https://history.nasa.gov/SP-4206/contents.htm |access-date=August 1, 2013 |series=The NASA History Series |orig-year=Originally published 1980 |date=1996 |publisher=NASA |location=Washington D.C. |oclc=36332191 |id=NASA SP-4206 |ref=Bilstein }}
* {{cite book |last1=Brooks |first1=Courtney G. |last2=Grimwood |first2=James M. |last3=Swenson |first3=Loyd S. Jr. |others=Foreword by [[Biography:Samuel C. Phillips|Samuel C. Phillips]] |title=Chariots for Apollo: A History of Manned Lunar Spacecraft |url=http://www.hq.nasa.gov/office/pao/History/SP-4205/cover.html |access-date=August 1, 2013 |series=The NASA History Series |date=1979 |publisher=Scientific and Technical Information Branch, NASA |location=Washington, D.C. |isbn=978-0-486-46756-6 |oclc=4664449 |lccn=79001042 |id=NASA SP-4205 |archive-date=October 20, 2015 |archive-url=https://web.archive.org/web/20151020095653/http://www.hq.nasa.gov/office/pao/History/SP-4205/cover.html |url-status=dead }}
* {{cite book |last=Burrows |first=William E. |title=This New Ocean: The Story of the First Space Age |date=1999 |publisher=Modern Library |location=New York |isbn=0-375-75485-7 |oclc=42136309 |ref=Burrows}}
* {{cite book |last=Chaikin |first=Andrew |title=[[Astronomy:A Man on the Moon|A Man on the Moon]] |date=1994 |publisher=Penguin Books |location=New York |isbn=0-14-027201-1 |oclc=38918860 |ref=Chaikin }} Chaikin interviewed all the surviving astronauts and others who worked with the program.
* {{cite book |last=Compton |first=William David |title=Where no man has gone before : a history of Apollo lunar exploration missions |location=Washington, DC |publisher=National Aeronautics and Space Administration |year=1989 |series=NASA history series |id=NASA SP-4214 |url=https://history.nasa.gov/SP-4214/cover.html |oclc=18223277 |ref=Compton }}
* {{cite book |title=Discussion of Soviet Man-in-space Shot |type=Hearing |date=April 13, 1961 |publisher=87th Congress, first session |location=Washington, D.C. |oclc=4052829 |lccn=61061306 |ref=87th Congress}}
* {{cite book |title=1974 NASA Authorization Hearings |type=Hearing on H.R. 4567 |date=1973 |publisher=93rd Congress, first session |location=Washington, D.C. |oclc=23229007 |ref=93rd Congress}}
* {{cite book |last1=Dawson |first1=Virginia P. |last2=Bowles |first2=Mark D. |title=Taming Liquid Hydrogen: The Centaur Upper Stage Rocket 1958–2002 |url=http://www.history.nasa.gov/SP-4230.pdf |access-date=September 12, 2012 |series=The NASA History Series |date=2004 |publisher=NASA |location=Washington D.C. |id=NASA SP-2400-4320 |oclc=51518552 |ref=Dawson & Bowles }}
* {{cite book |last1=Ertel |first1=Ivan D. |last2=Newkirk |first2=Roland W. |last3=Brooks |first3=Courtney G. |others=Foreword by Kenneth S. Kleinknecht |title=The Apollo Spacecraft: A Chronology |url=http://www.lpi.usra.edu/lunar/documents/NTRS/collection3/NASA_SP_4009-4.pdf |access-date=August 1, 2013 |volume=IV |date=1978 |publisher=Scientific and Technical Information Office, NASA |location=Washington, D.C. |id=NASA SP-4009 |oclc=23818 |lccn=69060008 |display-authors=2 |ref=Ertel et al. }}
* {{cite book |last=Gray |first=Mike |title=Angle of Attack: Harrison Storms and the Race to the Moon |orig-year=First published W. W. Norton & Company 1992 |date=1994 |publisher=Penguin Books |location=New York |isbn=0-14-023280-X |oclc=30520885 |ref=Gray |url= https://archive.org/details/angleofattackhar0000gray/page/n5/mode/1up}}
* {{cite book |last=Hansen |first=James R. |title=Enchanted Rendezvous: John C. Houbolt and the Genesis of the Lunar-Orbit Rendezvous Concept |url=https://history.nasa.gov/monograph4.pdf |access-date=May 3, 2012 |series=Monographs in Aerospace History |number=4 |date=1999 |publisher=NASA |location=Washington, D.C. |oclc=69343822 |ref=Hansen }}
* {{cite book |last=Harland |first=David M. |title = Exploring the Moon: the Apollo Expeditions |location=Chichester, England |publisher=Springer |series=Springer-Praxis books in space exploration |year=2008 |isbn=9780387746388 |oclc=495296214}}
* {{cite book |last=Heppenheimer |first=T.A. |title=The Space Shuttle Decision: NASA's Search for a Reusable Space Vehicle |url=https://history.nasa.gov/SP-4221/sp4221.htm |access-date=August 1, 2013 |series=The NASA History Series |date=1999 |publisher=NASA |location=Washington, D.C. |oclc=40305626 |id=NASA SP-4221 |ref=Heppenheimer }}
* {{cite book |last=Johnson |first=Stephen B. |title=The Secret of Apollo: Systems Management in American and European Space Programs |url=https://archive.org/details/secretofapollosy0000john |url-access=registration |series=New series in NASA history |date=2002 |publisher=Johns Hopkins University Press |location=Baltimore |isbn=0-8018-6898-X |oclc=48003131 |lccn=2001005688 |ref=Johnson }}
* {{cite book |editor1-last=Launius |editor1-first=Roger D. |editor2-last=McCurdy |editor2-first=Howard E. |title=Spaceflight and the Myth of Presidential Leadership |date=1997 |publisher=University of Illinois Press |isbn=0-252-06632-4 |lccn=96051213 |location=Champaign, IL |ref=Launius & McCurdy }}
* {{cite book |last=Launius |first=Roger D. |title=Apollo: A Retrospective Analysis |url=https://archive.org/details/nasa_techdoc_20040084534 |access-date=August 1, 2013 |edition=Reprint |series=Monographs in Aerospace History |number=3 |orig-year=Originally published July 1994 |date=July 2004 |publisher=NASA |location=Washington, D.C. |ref=Launius }}
* {{cite book |last=Mindell |first=David A. |title=Digital Apollo: Human and Machine in Spaceflight |date=2008 |publisher=The MIT Press |location=Cambridge, Massachusetts |isbn=978-0-262-13497-2 |oclc=733307011}}
* {{cite book |last1=Murray |first1=Charles |last2=Cox |first2=Catherine Bly |title = Apollo: The Race to the Moon |date=1989 |publisher=Simon & Schuster |location=New York |isbn=0-671-61101-1 |oclc=19589707 |lccn=89006333 |ref=Murray & Cox }}
* {{cite book |last=Orloff |first=Richard W. |title=Apollo by the Numbers: A Statistical Reference |url=https://history.nasa.gov/SP-4029/SP-4029.htm |access-date=August 1, 2013 |series=The NASA History Series |orig-year=First published 2000 |date=September 2004 |publisher=[[Organization:NASA|NASA]] |location=Washington, D.C. |isbn=0-16-050631-X |lccn=00061677 |id=NASA SP-2000-4029 |ref=Orloff }}
* {{cite journal |last1=Papike |first1=James J. |last2=Ryder |first2=Graham |last3=Shearer |first3=Charles K. |date=January 1998 |title=Planetary Materials: Lunar Samples |journal=[[Chemistry:Reviews in Mineralogy and Geochemistry|Reviews in Mineralogy and Geochemistry]] |volume= 36 |issue=1 |pages=5.1–5.234 |location=Washington, D.C. |publisher=Mineralogical Society of America |isbn=0-939950-46-4 |lccn=99474392 |issn=0275-0279 |ref=Papike et al.}}
* {{cite book |last=Sidey |first=Hugh |title=John F. Kennedy, President |date=1963 |publisher=Atheneum |edition=1st |location=New York |url=https://archive.org/details/johnfkennedypres000540mbp |access-date=August 1, 2013 |lccn=63007800 |ref=Sidey }}
* {{Cite book |last=Townsend |first=Neil A. |date=March 1973 |title=Apollo Experience Report: Launch Escape Propulsion Subsystem |publisher=NASA |location=Washington, D.C. |id=NASA TN D-7083 |url=http://klabs.org/history/apollo_experience_reports/tn-d7083_apollo_launch_escape_propulsion.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://klabs.org/history/apollo_experience_reports/tn-d7083_apollo_launch_escape_propulsion.pdf |archive-date=2022-10-09 |url-status=live |access-date=September 12, 2012 |ref=Townsend }}
* {{cite book |last=Wilford |first=John Noble |title = We Reach the Moon: The New York Times Story of Man's Greatest Adventure |date=1969 |publisher=Bantam Paperbacks |location=New York |oclc=29123 |ref=Wilford}}
{{refend}}

== Further reading ==
{{Library resources box|onlinebooks=yes}}
{{refbegin}}
* {{cite book |url = http://www.hq.nasa.gov/alsj/APSR-JSC-09423.pdf |title = Apollo Program Summary Report}}&nbsp;{{small|(46.3&nbsp;MB)}} NASA Report JSC-09423, April 1975
* {{cite book |last=Collins |first=Michael |others=Foreword by Charles Lindbergh |title=Carrying the Fire: An Astronaut's Journeys |orig-year=Originally published 1974; New York: Farrar, Straus and Giroux |date=2001 |publisher=Cooper Square Press |location=New York |isbn=978-0-8154-1028-7 |lccn=2001017080 |ref=Collins |url=https://archive.org/details/carryingfire00mich}} Astronaut Mike Collins autobiography of his experiences as an astronaut, including his flight aboard Apollo 11.
* {{cite book |last=Cooper |first=Henry S.F. Jr. |title=Thirteen: The Apollo Flight That Failed |orig-year=Originally published 1972; New York: Dial Press |date=1995 |publisher=Johns Hopkins University Press |location=Baltimore |isbn=0-8018-5097-5 |oclc=31375285 |lccn=94039726 |ref=Cooper |url=https://archive.org/details/thirteenapollofl00coop}} Although this book focuses on Apollo 13, it provides a wealth of background information on Apollo technology and procedures.
* {{cite book |last1=French |first1=Francis |last2=Burgess |first2=Colin |author-link2=Colin Burgess (author) |others=Foreword by [[Biography:Walter Cunningham|Walter Cunningham]] |title=In the Shadow of the Moon: A Challenging Journey to Tranquility, 1965–1969 |date=2007 |publisher=University of Nebraska Press |location=Lincoln |isbn=978-0-8032-1128-5 |oclc=182559769 |lccn=2006103047 |ref=French & Burgess}} History of the Apollo program from Apollos 1–11, including many interviews with the Apollo astronauts.
* Gleick, James, "Moon Fever" [review of Oliver Morton, ''The Moon: A History of the Future''; ''Apollo's Muse: The Moon in the Age of Photography'', an exhibition at the Metropolitan Museum of Art, {{wipe|New York City}}, July 3 – September 22, 2019; Douglas Brinkley, ''American Moonshot: John F. Kennedy and the Great Space Race''; Brandon R. Brown, ''The Apollo Chronicles: Engineering America's First Moon Missions''; Roger D. Launius, ''Reaching for the Moon: A Short History of the Space Race''; ''Apollo 11'', a documentary film directed by Todd Douglas Miller; and Michael Collins, ''Carrying the Fire: An Astronaut's Journeys (50th Anniversary Edition)''], ''The New York Review of Books'', vol. LXVI, no. 13 (15 August 2019), pp.&nbsp;54–58.
* {{cite book |last=Kranz |first=Gene |title=Failure is Not an Option: Mission Control from Mercury to Apollo 13 and Beyond |date=2000 |publisher=Simon & Schuster |location=New York |isbn=0-7432-0079-9 |oclc=43590801 |lccn=00027720 |ref=Kranz |url=https://archive.org/details/isbn_9780743200790}} Factual, from the standpoint of a flight controller during the [[Astronomy:Project Mercury|Mercury]], [[Astronomy:Project Gemini|Gemini]], and Apollo space programs.
* {{cite book |last1=Lovell |first1=Jim |last2=Kluger |first2=Jeffrey |author-link2=Jeffrey Kluger |title=[[Astronomy:Lost Moon|Apollo 13]] |orig-year=Previously published 1994 as ''[[Astronomy:Lost Moon|Lost Moon]]'' |date=2000 |publisher=Houghton Mifflin Company |location=Boston |isbn=0-618-05665-3 |oclc=43118301 |lccn=99089647 |ref=Lovell & Kluger}} Details the flight of Apollo 13.
* {{cite journal |last1=McMahon |first1=Adam |title=To the Moon and Back: Reexamining Presidential Decision-Making and the Apollo Program |journal=Space Policy |volume=62 |year=2022 |page=101516 |doi=10.1016/j.spacepol.2022.101516 |bibcode=2022SpPol..6201516M |ref=none|doi-access=free}}
* {{cite journal |last1=Musgrave |first1=Paul |last2=Nexon |first2=Daniel |title=Defending Hierarchy from the Moon to the Indian Ocean: Symbolic Capital and Political Dominance in Early Modern China and the Cold War |journal=International Organization |volume=72 |issue=3 |year=2018 |pages=591–626 |doi=10.1017/S0020818318000139 |ref=none|doi-access=free}}
* {{cite book |last1=Pellegrino |first1=Charles R. |last2=Stoff |first2=Joshua |title=Chariots for Apollo: The Untold Story Behind the Race to the Moon |date=1999 |publisher=Avon Books |location=New York |isbn=0-380-80261-9 |oclc=41579174 |ref=Pellegrino & Stoff}} Tells [[Company:Grumman|Grumman]]'s story of building the lunar modules.
* {{Cite book |last1=Scott |first1=David |last2=Leonov |first2=Alexei |author-link2=Alexei Leonov |last3=Toomey |first3=Christine |others=Foreword by Neil Armstrong; introduction by [[Biography:Tom Hanks|Tom Hanks]] |title=Two Sides of the Moon: Our Story of the Cold War Space Race |edition=1st U.S. |date=2004 |publisher=Thomas Dunne Books |location=New York |isbn=0-312-30865-5 |oclc=56587777 |lccn=2004059381 |ref=Scott & Leonov |url=https://archive.org/details/twosidesofmoon00scot}}
* {{cite book |last=Seamans |first=Robert C. Jr. |title=Project Apollo: The Tough Decisions |series=Monographs in Aerospace History|number=37 |date=2005 |publisher=NASA |location=Washington, D.C. |isbn=0-16-074954-9 |oclc=64271009 |lccn=2005003682 |id=NASA SP-4537 |ref=Seamans}} History of the crewed space program from 1{{nbsp}}September 1960, to 5{{nbsp}}January 1968.
* {{cite book |last1=Slayton |first1=Donald K. |last2=Cassutt |first2=Michael |title = Deke!: An Autobiography |date=1995 |publisher=St. Martin's Press |location=New York |isbn=0-312-85918-X |ref=Slayton & Cassutt }} Account of Deke Slayton's life as an astronaut and of his work as chief of the astronaut office, including selection of Apollo crews.
* {{Cite book |url = https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19690022643_1969022643.pdf |title = The Apollo Spacecraft: A Chronology |volume=1}}&nbsp;{{small|(131.2&nbsp;MB)}} From origin to November 7, 1962
* {{Cite book |url = https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19740004394_1974004394.pdf |title = The Apollo Spacecraft: A Chronology |volume=2}}&nbsp;{{small|(13.4&nbsp;MB)}} November 8, 1962 – September 30, 1964
* {{Cite book |url = https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19760014180_1976014180.pdf |title = The Apollo Spacecraft: A Chronology |volume=3}}&nbsp;{{small|(57.7&nbsp;MB)}} October 1, 1964 – January 20, 1966
* {{Cite book |url= https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19800011953_1980011953.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19800011953_1980011953.pdf |archive-date=2022-10-09 |url-status=live |title = The Apollo Spacecraft: A Chronology |volume=4}}&nbsp;{{small|(24.2&nbsp;MB)}} January 21, 1966 – July 13, 1974
* {{Cite book |last=Wilhelms |first=Don E. |title = To a Rocky Moon: A Geologist's History of Lunar Exploration |url = https://archive.org/details/torockymoongeolo0000wilh |url-access=registration |date=1993 |publisher=University of Arizona Press |location=Tucson |isbn=0-8165-1065-2 |oclc=26720457 |lccn=92033228 |ref=Wilhelms}} The history of lunar exploration from a geologist's point of view.
{{refend}}

== External links ==
* [https://web.archive.org/web/19991013042039/http://spaceflight.nasa.gov/history/apollo/index.html Apollo program history] at NASA's Human Space Flight (HSF) website
* [https://history.nasa.gov/apollo.html The Apollo Program] at the NASA History Program Office
* {{cite web |url=http://www.sti.nasa.gov/tto/apollo.htm |title=Apollo Spinoffs |url-status=dead |archive-url=https://web.archive.org/web/20120404160907/http://www.sti.nasa.gov/tto/apollo.htm |archive-date=April 4, 2012}}
* [http://airandspace.si.edu/explore-and-learn/topics/apollo/ The Apollo Program] at the National Air and Space Museum
* [https://web.archive.org/web/20040804051632/http://www.nasa.gov/externalflash/apollo11/index1.html Apollo 35th Anniversary Interactive Feature] at NASA (in [[Software:Adobe Flash|Flash]])
* [http://www.lpi.usra.edu/expmoon/apollo_landings.html Lunar Mission Timeline] at the [[Organization:Lunar and Planetary Institute|Lunar and Planetary Institute]]
* [http://libarchstor.uah.edu:8081/repositories/2/resources/69 Apollo Collection, The University of Alabama in Huntsville Archives and Special Collections]

===NASA reports===
* [https://history.nasa.gov/apsr/apsr.htm Apollo Program Summary Report] (PDF), NASA, JSC-09423, April 1975
* [https://history.nasa.gov/series95.html NASA History Series Publications]
* [https://history.nasa.gov/diagrams/apollo.html Project Apollo Drawings and Technical Diagrams] at the NASA History Program Office
* [http://www.hq.nasa.gov/alsj/frame.html The ''Apollo Lunar Surface Journal''] edited by Eric M. Jones and Ken Glover
* [https://history.nasa.gov/afj/ The ''Apollo Flight Journal''] by W. David Woods, et al.

===Multimedia===
* [https://www.nasa.gov/mission_pages/apollo/index.html NASA Apollo Program images and videos]
* [http://apollo.sese.asu.edu/ Apollo Image Archive] at [[Organization:Arizona State University|Arizona State University]]
* [https://web.archive.org/web/20160601211812/http://millercenter.org/presidentialrecordings/jfk-mtg-63 Audio recording and transcript of President John F. Kennedy, NASA administrator James Webb, et al., discussing the Apollo agenda] (White House Cabinet Room, November 21, 1962)
* [http://www.apolloarchive.com/ The Project Apollo Archive] by Kipp Teague is a large repository of Apollo images, videos, and audio recordings
* [https://www.flickr.com/photos/projectapolloarchive/ The Project Apollo Archive on Flickr]
* [http://www.lpi.usra.edu/resources/apollo/ Apollo Image Atlas]—almost 25,000 lunar images, Lunar and Planetary Institute
* {{Internet Archive short film |id = gov.ntis.ava03129vnb1 |name = Time of Apollo (1975) }}

{{Apollo program}}
{{Apollo program hardware}}
{{People who have traveled to the Moon}}
{{US human spaceflight programs|before=[[Astronomy:Project Gemini|Gemini]]|after=[[Engineering:Skylab|Skylab]]}}
{{Crewed spacecraft}}
{{NASA navbox|state=collapsed}}
{{The Moon}}
{{Lunar rovers}}
{{Moon spacecraft}}
{{Spaceflight}}

[[Category:Apollo program| ]]
[[Category:Engineering projects]]
[[Category:Exploration of the Moon]]
[[Category:Human spaceflight programs]]
[[Category:NASA programs]]

{{Sourceattribution|Apollo program}}