Editing Apollo program (section)

==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 [[AS-201|AS-201 first uncrewed CSM test]]
rect 92 0 181 494 [[AS-203|AS-203 S-IVB stage development test]]
rect 182 0 270 494 [[AS-202|AS-202 second uncrewed CSM test]]
rect 271 0 340 494 [[Apollo 4|Apollo 4 first uncrewed Saturn V test]]
rect 341 0 434 494 [[Apollo 5|Apollo 5 uncrewed LM test]]
rect 435 0 494 494 [[Apollo 6|Apollo 6 second uncrewed Saturn V test]]
</imagemap>
[[File:The Journeys of Apollo.webm|thumb|''The Journeys of Apollo'', a NASA documentary about the Apollo program]]
{{Main list|List of Apollo missions}}

Two Block I CSMs were launched from LC-34 on suborbital flights in 1966 with the Saturn IB. The first, [[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 [[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, [[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, [[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 [[Gemini space suit#Apollo program|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/Skylab A7L|Apollo A6L spacesuit]], designed to accommodate lunar [[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>

[[Deke Slayton]], the grounded [[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 [[Donn F. Eisele]] as Pilot. But Eisele dislocated his shoulder twice aboard the [[reduced gravity aircraft|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 [[David Scott]], with rookie [[Rusty Schweickart|Russell L. "Rusty" Schweickart]]. Mercury/Gemini veteran [[Wally Schirra]], Eisele, and rookie [[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 [[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]]" 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 |date=October 22, 2004 |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, [[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|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 |author-link=Robert 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 |archive-date=November 5, 2015 |archive-url=https://web.archive.org/web/20151105102355/http://www.hq.nasa.gov/pao/History/Apollo204/find.html |url-status=dead }}</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|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.|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 door|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 [[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 et al.|Ertel & al. 1978]], Part 1(H)</ref>

In September 1967, Mueller approved a [[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.|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.

[[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. |author-link=George Low |editor-last=Cortright |editor-first=Edgar M |editor-link=Edgar Cortright |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 |archive-date=February 19, 2008 |archive-url=https://web.archive.org/web/20080219204538/https://history.nasa.gov/SP-350/ch-9-5.html |url-status=dead }}</ref>

This was followed on April 4, 1968, by [[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 [[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 [[Apollo 1|Apollo 1 unsuccessful first crewed CSM test]]
rect  596   0 1376 600 [[Apollo 7|Apollo 7 first crewed CSM test]]
rect 1377   0 2076 600 [[Apollo 8|Apollo 8 first crewed flight to the Moon]]
rect    0 601  595 1200 [[Apollo 9|Apollo 9 crewed Earth orbital LM test]]
rect  596 601 1376 1200 [[Apollo 10|Apollo 10 crewed lunar orbital LM test]]
rect 1377 601 2076 1200 [[Apollo 11|Apollo 11 first crewed Moon landing]]
</imagemap>

[[Apollo 7]], launched from LC-34 on October 11, 1968, was the C{{nbsp}}mission, crewed by [[Wally Schirra|Schirra]], [[Donn F. Eisele|Eisele]], and [[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>

[[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 [[Zond 5]], and it was believed they might soon repeat the feat with human cosmonauts.<ref name="Chaikin">{{cite book |last=Chaikin |first=Andrew |author-link=Andrew Chaikin |title=[[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=[[Time (magazine)|Time]] |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 [[Jim Lovell]], and rookie [[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 [[Apollo 9]], and Schweickart tested the full lunar [[Apollo a7l|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 [[Apollo 10]] in May 1969 by Gemini veterans [[Thomas P. Stafford]], [[John Young (astronaut)|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 [[Apollo 11]] in July 1969 by an all-Gemini veteran crew consisting of [[Neil Armstrong]], [[Michael Collins (astronaut)|Michael Collins]] and [[Buzz Aldrin]]. Armstrong and Aldrin performed the first landing at the [[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=[[Snopes.Com|Urban Legends Reference Pages]] |access-date=September 19, 2009}}</ref>}}

===Production lunar landings===
In November 1969, [[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 Armstrong|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 [[Apollo 12|Apollo 12 second crewed Moon landing]]
rect  603   0 1205 600 [[Apollo 13|Apollo 13 unsuccessful Moon landing attempt]]
rect 1206   0 1885 600 [[Apollo 14|Apollo 14 third crewed Moon landing]]
rect    0 601  602 1200 [[Apollo 15|Apollo 15 fourth crewed Moon landing]]
rect  603 601 1205 1200 [[Apollo 16|Apollo 16 fifth crewed Moon landing]]
rect 1206 601 1885 1200 [[Apollo 17|Apollo 17 sixth crewed Moon landing]]
</imagemap>

Conrad and rookie [[Alan Bean|Alan L. Bean]] made a precision landing of Apollo 12 within walking distance of the [[Surveyor 3]] uncrewed lunar probe, which had landed in April 1967 on the [[Ocean of Storms]]. The command module pilot was Gemini veteran [[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. |author-link1=Pete Conrad |last2=Shepard |first2=Alan B Jr. |author-link2=Alan Shepard |editor-last=Cortright |editor-first=Edgar M |editor-link=Edgar Cortright |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 |archive-date=February 19, 2008 |archive-url=https://web.archive.org/web/20080219204538/https://history.nasa.gov/SP-350/ch-9-5.html |url-status=dead }}</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 [[Lunar Roving Vehicle]] (LRV) increasing the exploration area and allowing televised liftoff of the LM. Also, the Block II spacesuit was [[Apollo/Skylab A7L#A7LB Spacesuit (Apollo, Skylab and ASTP)|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|archive-date=February 12, 2023|archive-url=https://web.archive.org/web/20230212183759/https://www.hq.nasa.gov/office/pao/History/SP-4214/ch12-4.html|url-status=dead}}</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 [[Fred Haise]] in April 1970, headed for the [[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 [[Space Shuttle design process|development]] of the upcoming [[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|archive-date=February 12, 2023|archive-url=https://web.archive.org/web/20230212183758/https://www.hq.nasa.gov/office/pao/History/SP-4214/ch12-2.html|url-status=dead}}</ref> The two unused Saturn Vs became museum exhibits at the [[John F. Kennedy Space Center]] on Merritt Island, Florida, [[Marshall Space Flight Center|George C. Marshall Space Center]] in [[Huntsville, Alabama|Huntsville]], Alabama, [[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. [[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 [[Apollo 14]], commanded in February 1971 by Mercury veteran [[Alan Shepard]], with [[Stuart Roosa]] and [[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 [[David Scott]], [[Alfred Worden]] and [[James Irwin]]. Scott and Irwin landed on July 30 near [[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 [[Descartes Highlands]] on April 20, 1972. The crew was commanded by John Young, with [[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 [[Taurus–Littrow]] region in December 1972. Eugene Cernan commanded [[Ronald Evans (astronaut)|Ronald E. Evans]] and NASA's first scientist-astronaut, geologist [[Harrison Schmitt|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|Canceled Apollo missions}}

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