Editing Apollo program (section)

===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"]}}