Editing Apollo program (section)

==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>
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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 [[parking orbit]]. The third stage burns a small portion of its fuel to achieve orbit.
File:Apollo11-02.png|'''[[Trans-lunar injection|Translunar injection]]''' After one to two orbits to verify readiness of spacecraft systems, the [[S-IVB]] third stage reignites for about six minutes to send the spacecraft to the Moon.
File:Apollo11-03.png|'''[[Transposition, docking, and extraction|Transposition and docking]]''' The [[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 [[Apollo command and service module#Service module (SM)|SM]] engine.
File:Apollo11-05.png|'''[[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|'''[[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 [[Extravehicular activity|EVA]]s exploring the lunar surface and collecting samples, alternating with rest periods.
File:Apollo11-10.png|The [[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|'''[[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 [[Pacific Ocean]]. The astronauts are recovered and brought to an [[aircraft carrier]].
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{{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|Lunar Module ''Eagle'']] and lands himself and navigator [[Buzz Aldrin]] on the Moon, July 20, 1969.]]

* The first three lunar missions (Apollo 8, [[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 [[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 [[Apollo 16]], where a loss of [[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=[[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>