Editing Apollo 12 (section)

==Mission highlights==
[[File:Apollo 12 launches from Kennedy Space Center.jpg|thumb|Apollo 12 launches from [[Kennedy Space Center]], November 14, 1969]]

===Launch===
With President [[Richard Nixon]] in attendance, the first time a current U.S. president had witnessed a crewed space launch,{{sfn|Lattimer 1985|p=74}} as well as Vice President [[Spiro Agnew]],{{sfn|Harland 2011|p=91}} Apollo 12 launched as planned on November 14, 1969, from the Kennedy Space Center at 16:22:00&nbsp;[[UTC]] (11:22&nbsp;am&nbsp;[[Eastern Standard Time|EST]], local time at the launch site). This was at the start of a launch window of three hours and four minutes to reach the Moon with optimal lighting conditions at the planned landing point.{{sfn|Orloff & Harland 2006|p=329}}{{sfn|Press Kit|p=10}} There were completely overcast rainy skies, and the vehicle encountered winds of {{convert|151.7|kn||abbr=}} during ascent, the strongest of any Apollo mission.<ref>{{Cite web|url=https://history.nasa.gov/SP-4029/Apollo_18-15_Launch_Weather.htm|title=Launch Weather|publisher=[[NASA]]|access-date=January 7, 2021|page=279}}</ref> There was a NASA rule against launching into a [[cumulonimbus cloud]]; this had been waived and it was later determined that the launch vehicle never entered such a cloud.{{sfn|Orloff & Harland 2006|pp=329–330}} Had the mission been postponed, it could have been launched on November 16 with landing at a backup site where there would be no Surveyor, but since time pressure to achieve a lunar landing had been removed by Apollo 11's success, NASA might have waited until December for the next opportunity to go to the Surveyor crater.{{sfn|Harland 2011|pp=28, 30, 81}}

Lightning struck the Saturn V 36.5 seconds after lift-off, triggered by the vehicle itself. The static discharge caused a voltage transient that knocked all three fuel cells offline, meaning the spacecraft was being powered entirely from its batteries, which could not supply enough current to meet demand. A second strike at 52 seconds knocked out the "8-ball" [[attitude indicator]]. The [[telemetry]] stream at [[Christopher C. Kraft Jr. Mission Control Center#Houston (1965–present)|Mission Control]] was garbled, but the Saturn V continued to fly normally; the strikes had not affected the [[Saturn V instrument unit]] guidance system, which functioned independently from the CSM. The astronauts unexpectedly had a board red with caution and warning lights, but could not tell exactly what was wrong.{{sfn|Orloff & Harland 2006|pp=329–331}}<ref name="launch">{{cite web|date=March 27, 2020|editor-last=Woods|editor-first=W. David|title=Day 1, Part 1: Launch and Reaching Earth Orbit|url=https://history.nasa.gov/afj/ap12fj/01launch_to_earth_orbit.html#0000136|access-date=2021-03-03|work=Apollo 12 Flight Journal|publisher=NASA|editor-last2=Waugh|editor-first2=Lennox J.|df=mdy-all}}</ref>{{sfn|Harland 2011|pp=105–107}}

The [[Flight controller#EECOM|Electrical, Environmental and Consumables Manager]] (EECOM) in Mission Control, [[John Aaron]], remembered the telemetry failure pattern from an earlier test when a power loss caused a malfunction in the CSM signal conditioning electronics (SCE), which converted raw signals from instrumentation to data that could be displayed on Mission Control's consoles, and knew how to fix it.<ref name = "launch" /><ref>{{cite book |last1=Kranz |first1=Eugene F. |author-link1=Gene Kranz |last2=Covington |first2=James Otis |title=What Made Apollo a Success? |url=https://history.nasa.gov/SP-287/sp287.htm |access-date=November 7, 2011 |orig-year="A series of eight articles reprinted by permission from the March 1970 issue of ''Astronautics & Aeronautics'', a publication of the [[American Institute of Aeronautics and Astronautics]]." |year=1971  |publisher=NASA |location=Washington, D.C. |oclc=69849598 |id=NASA SP-287 |chapter=Flight Control in the Apollo Program |chapter-url=https://history.nasa.gov/SP-287/ch5.htm}} Chapter 5.</ref> Aaron made a call, "Flight, EECOM. Try SCE to Aux", to switch the SCE to a backup power supply. The switch was fairly obscure, and neither Flight Director Gerald Griffin, CAPCOM Gerald P. Carr, nor Conrad knew what it was; Bean, who as LMP was the spacecraft's engineer, knew where to find it and threw the switch, after which the telemetry came back online, revealing no significant malfunctions. Bean put the fuel cells back online, and the mission continued.<ref name = "launch" />{{sfn|Chaikin 1995|p=238}}{{sfn|Harland 2011|pp=107–109}} Once in Earth [[parking orbit]], the crew carefully checked out their spacecraft before re-igniting the S-IVB third stage for [[trans-lunar injection]]. The lightning strikes caused no serious permanent damage.{{sfn|Chaikin 1995|pp=240–241}}

Initially, it was feared that the lightning strike could have damaged the explosive bolts that opened the Command Module's parachute compartment. The decision was made not to share this with the astronauts and to continue with the flight plan, since they would die if the parachutes failed to deploy, whether following an Earth-orbit abort or upon a return from the Moon, so nothing was to be gained by aborting.{{sfn|Chaikin 1995|p=241}} The parachutes deployed and functioned normally at the end of the mission.{{sfn|Orloff & Harland 2006|p=338}}

===Outward journey===
[[File:A view of one-third of Earth, with Australia on the horizon, as photographed by the three-man crew of Apollo 12.jpg|thumb|right|View of Earth taken en route to the Moon]]

After systems checks in Earth orbit, performed with great care because of the lightning strikes, the trans-lunar injection burn, made with the S-IVB, took place at 02:47:22.80 into the mission, setting Apollo 12 on course for the Moon. An hour and twenty minutes later, the CSM separated from the S-IVB, after which Gordon performed the [[transposition, docking, and extraction]] maneuver to dock with the LM and separate the combined craft from the S-IVB, which was then sent on an attempt to reach solar orbit.{{sfn|Orloff & Harland 2006|p=333}}<ref name=tpe>{{cite web |url=https://history.nasa.gov/afj/ap12fj/03tde.html |title= Day 1, part 3: Transposition, Docking and Extraction |date=January 12, 2020|editor-last=Woods |editor-first=W. David |editor-last2=Waugh |editor-first2=Lennox J. |work=Apollo 12 Flight Journal |publisher=NASA |access-date=January 8, 2021 |df=mdy-all }}</ref> The stage fired its engines to leave the vicinity of the spacecraft, a change from Apollo 11, where the SM's Service Propulsion System (SPS) engine was used to distance it from the S-IVB.{{sfn|Harland 2011|p=141}}

As there were concerns the LM might have been damaged by the lightning strikes, Conrad and Bean entered it on the first day of flight to check its status, earlier than planned. They found no issues. At 30:52.44.36, the only necessary midcourse correction during the translunar coast was made, placing the craft on a hybrid, non-free-return trajectory. Previous crewed missions to lunar orbit had taken a [[free-return trajectory]], allowing an easy return to Earth if the craft's engines did not fire to enter lunar orbit. Apollo 12 was the first crewed spacecraft to take a hybrid free-return trajectory, that would require another burn to return to Earth, but one that could be executed by the LM's Descent Propulsion System (DPS) if the SPS failed. The use of a hybrid trajectory allowed more flexibility in mission planning. It for example allowed Apollo 12 to launch in daylight and reach the planned landing spot on schedule.{{sfn|Orloff & Harland 2006|pp=333–334}} Use of a hybrid trajectory meant that Apollo 12 took 8 hours longer to go from trans-lunar injection to lunar orbit.{{sfn|Harland 2011|p=154}}

===Lunar orbit and Moon landing===
[[File:Lunar module AS12-51-7507.jpg|right|thumb|[[Lunar Module]] ''Intrepid'' above the Moon. The small crater in the foreground is [[Ammonius (crater)|Ammonius]]; the large crater at right is [[Herschel (lunar crater)|Herschel]]. Photograph by [[Richard F. Gordon Jr.]] on board the [[Apollo command and service module#Command module (CM)|Command Module]] ''Yankee Clipper''.]]

Apollo 12 entered a lunar orbit of {{convert|170.2|by|61.66|nmi|sigfig=4}} with an SPS burn of 352.25 seconds at mission time 83:25:26.36. On the first lunar orbit, there was a television transmission that resulted in good-quality video of the lunar surface. On the third lunar orbit, there was another burn to circularize the craft's orbit to {{convert|66.1|by|54.59|nmi|sigfig=4}}, and on the next revolution, preparations began for the lunar landing. The CSM and LM undocked at 107:54:02.3; a half hour later there was a burn by the CSM to separate them.{{sfn|Orloff & Harland 2006|p=334}} The 14.4 second burn by some of the CSM's thrusters meant that the two craft would be {{convert|2.2|nmi|sigfig=2}} apart when the LM began the burn to move to a lower orbit in preparation for landing on the Moon.{{sfn|Harland 2011|p=200}}

The LM's Descent Propulsion System began a 29-second burn at 109:23:39.9 to move the craft to the lower orbit, from which the 717-second powered descent to the lunar surface began at 110:20:38.1.{{sfn|Orloff & Harland 2006|p=334}} Conrad had trained to expect a pattern of craters known as "the Snowman" to be visible when the craft underwent "pitchover", with the Surveyor crater in its center, but had feared he would see nothing recognizable. He was astonished to see the Snowman right where it should be, meaning they were directly on course. He took over manual control, planning to land the LM, as he had in simulations, in an area near the Surveyor crater that had been dubbed "Pete's Parking Lot", but found it rougher than expected. He had to maneuver,{{sfn|Chaikin 1995|pp=254–260}} and landed the LM
at 110:32:36.2 (06:54:36 UTC on November 19, 1969), just {{convert|535|ft}} from the Surveyor probe.{{sfn|Orloff & Harland 2006|pp=334–335}} This achieved one objective of the mission, to perform a precision landing near the Surveyor craft.<ref name = "second">{{cite web|url=https://history.nasa.gov/SP-4029/Apollo_12a_Summary.htm |title=Apollo 12 – The Sixth Mission: The Second Lunar Landing |publisher=NASA |location=US |access-date=June 26, 2019}}</ref>

The [[Selenographic coordinates|lunar coordinates]] of the landing site were 3.01239° S latitude, 23.42157° W longitude.<ref>{{cite web |url=https://airandspace.si.edu/explore-and-learn/topics/apollo/apollo-program/landing-missions/sites.cfm |title=Apollo landing sites |work=The Apollo Program |publisher=[[National Air and Space Museum]] |access-date=February 10, 2021 |archive-date=July 11, 2021 |archive-url=https://web.archive.org/web/20210711060534/https://airandspace.si.edu/explore-and-learn/topics/apollo/apollo-program/landing-missions/sites.cfm |url-status=dead }}</ref> The landing caused high velocity sandblasting of the Surveyor probe. It was later determined that the sandblasting removed more dust than it delivered onto the Surveyor, because the probe was covered by a thin layer that gave it a tan hue as observed by the astronauts, and every portion of the surface exposed to the direct sandblasting was lightened back toward the original white color through the removal of lunar dust.<ref>{{cite journal |last1=Immer |first1=Christopher A. |last2=Metzger |first2=Philip |author-link2=Philip T. Metzger |last3=Hintze |first3=Paul E. |last4=Nick|first4=Andrew |last5=Horan |first5=Ryan |date=February 2011 |title=Apollo 12 Lunar Module Exhaust Plume Impingement on Lunar ''Surveyor III'' |journal=[[Icarus (journal)|Icarus]] |volume=211 |issue=2 |pages=1089–1102 |location=Amsterdam |publisher=[[Elsevier]] |bibcode=2011Icar..211.1089I |doi=10.1016/j.icarus.2010.11.013 |display-authors=3}}</ref>

===Lunar surface activities===
When Conrad, the shortest man of the initial groups of astronauts, stepped onto the lunar surface his first words were "Whoopie! Man, that may have been a small one for Neil, but that's a long one for me."{{sfn|Chaikin 1995|pp=261–262}} This was not an off-the-cuff remark: Conrad had made a {{USD|500}} bet with reporter [[Oriana Fallaci]] he would say these words, after she had queried whether NASA had instructed Neil Armstrong what to say as he stepped onto the Moon. Conrad later said he was never able to collect the money.{{sfn|Chaikin 1995|pp=261–262, 627}}

[[File:Astronaut Alan L. Bean is about to step off the ladder of the Lunar Module (flopped).jpg|thumb|left|upright=1.36|Bean prepares to step onto the lunar surface.]]

To improve the quality of television pictures from the Moon, a color camera was carried on Apollo 12 (unlike the monochrome camera on Apollo 11). When Bean carried the camera to the place near the LM where it was to be set up, he inadvertently pointed it directly into the Sun, destroying the [[Apollo TV camera#Westinghouse Lunar Color Camera|Secondary Electron Conduction (SEC) tube]]. Television coverage of this mission was thus terminated almost immediately.<ref>{{cite web |url=https://www.hq.nasa.gov/alsj/a12/a12.tvtrbls.html#1161412 |title=TV troubles |date=August 4, 2017|editor-last=Jones |editor-first=Eric M. |work=Apollo 12 Lunar Surface Journal |publisher=NASA |access-date=January 24, 2021}}</ref>{{sfn|Chaikin 1995|p=264}}

After [[Lunar Flag Assembly|raising a U.S. flag on the Moon]], Conrad and Bean devoted much of the remainder of the first EVA to deploying the Apollo Lunar Surface Experiments Package (ALSEP).{{sfn|Orloff & Harland 2006|p=335}} There were minor difficulties with the deployment. Bean had trouble extracting the RTG's plutonium fuel element from its protective cask, and the astronauts had to resort to the use of a hammer to hit the cask and dislodge the fuel element. Some of the ALSEP packages proved hard to deploy, though the astronauts were successful in all cases.{{sfn|Mission Report|pp=9-12–9-14}} With the PSE able to detect their footprints as they headed back to the LM, the astronauts secured a [[core sample|core tube]] full of lunar material, and collected other samples. The first EVA lasted 3 hours, 56 minutes and 3 seconds.{{sfn|Orloff & Harland 2006|p=335}}

Four possible geologic traverses had been planned, the variable being where the LM might set down. Conrad had landed it between two of these potential landing points, and during the first EVA and the rest break that followed, scientists in Houston combined two of the traverses into one that Conrad and Bean could follow from their landing point.{{sfn|Phinney 2015|p=106}} The resultant traverse resembled a rough circle, and when the astronauts emerged from the LM some 13 hours after ending the first EVA, the first stop was [[Head (crater)|Head crater]], some {{convert|100|yard}} from the LM. There, Bean noticed that Conrad's footprints showed lighter material underneath, indicating the presence of ejecta from [[Copernicus (lunar crater)|Copernicus crater]], {{convert|230|mi}} to the north, something that scientists examining overhead photographs of the site had hoped to find. After the mission, samples from Head allowed geologists to date the impact that formed Copernicus{{sfn|Chaikin 1995|pp=272–274}}—according to initial dating, some 810,000,000 years ago.{{sfn|Harland 2011|p=339}}

[[File:Apollo AS12-47-6897.jpg|thumb|upright=1.3|right|Conrad with the U.S. flag]]

The astronauts proceeded to [[Bench (crater)|Bench crater]] and [[Sharp-Apollo (crater)|Sharp crater]] and past [[Halo (crater)|Halo crater]] before arriving at [[Surveyor (crater)|Surveyor crater]], where the Surveyor 3 probe had landed.{{sfn|Lattimer 1985|p=74}} Fearing treacherous footing or that the probe might topple on them, they approached Surveyor cautiously, descending into the shallow crater some distance away and then following a contour to reach the craft, but found the footing solid and the probe stable. They collected several pieces of Surveyor, including the television camera, as well as taking rocks that had been studied by television. Conrad and Bean had procured an automatic timer for their [[Hasselblad]] cameras, and had brought it with them without telling Mission Control, hoping to take a [[selfie]] of the two of them with the probe, but when the time came to use it, could not locate it among the lunar samples they had already placed in their Hand Tool Carrier.{{sfn|Chaikin 1995|pp=277–279}} Before returning to the LM's vicinity, Conrad and Bean went to [[block (crater)|Block crater]], within [[Surveyor (crater)|Surveyor crater]].{{sfn|Mission Report|p=3-26}} The second EVA lasted 3 hours, 49 minutes, 15 seconds, during which they traveled {{convert|4300|ft}}. During the EVAs, Conrad and Bean went as far as {{convert|1350|ft}} from the LM, and collected {{convert|73.75|lb}} of samples.{{sfn|Orloff & Harland 2006|p=336}}

=== Lunar orbit solo activities ===
[[File:Astronaut Richard F. Gordon Jr. during training.jpg|thumb|right|Gordon in the CM simulator]]

After the LM's departure, Gordon had little to say as Mission Control focused on the lunar landing. Once that was accomplished, Gordon sent his congratulations and, on the next orbit, was able to spot both the LM and the Surveyor on the ground and convey their locations to Houston. During the first EVA, Gordon prepared for a [[Orbital inclination change|plane change maneuver]], a burn to alter the CSM's orbit to compensate for the rotation of the Moon, though at times he had difficulty communicating with Houston since Conrad and Bean were using the same communications circuit. Once the two moonwalkers had returned to the LM, Gordon executed the burn,<ref name="orbit1">{{cite web |url=https://history.nasa.gov/afj/ap12fj/15day5_csm_rev14_24.html |title=Day 5: Yankee Clipper Rev 14 to 24 |date=April 6, 2020|editor-last=Woods |editor-first=W. David |editor-last2=Waugh |editor-first2=Lennox J. |work=Apollo 12 Flight Journal |publisher=NASA |access-date=January 27, 2021 |df=mdy-all }}</ref> which ensured he would be in the proper position to rendezvous with the LM when it launched from the Moon.{{sfn|Chaikin 1995|p=269}}

While alone in orbit, Gordon performed the Lunar Multispectral Photography Experiment, using four Hasselblad cameras arranged in a ring and aimed through one of the CM's windows. With each camera having a different color filter, simultaneous photos would be taken by each, showing the appearance of lunar features at different points on the [[spectrum]]. Analysis of the images might reveal colors not visible to the naked eye or detectable with ordinary color film, and information could be obtained about the composition of sites that would not soon be visited by humans. Among the sites studied were contemplated landing points for future Apollo missions.{{sfn|Press Kit|p=43}}{{sfn|Mission Report|p=9-26}}

===Return===
[[File:Apollo 12 view of Solar Eclipse (5052129615).jpg|thumb|A solar eclipse seen from Apollo 12]]

LM ''Intrepid'' lifted off from the Moon at mission time 143:03:47.78, or 14:25:47 UTC on November 20, 1969; after several maneuvers, CSM and LM docked three and a half hours later.{{sfn|Orloff & Harland 2006|p=358}} At 147:59:31.6, the LM ascent stage was jettisoned, and shortly thereafter the CSM maneuvered away. Under control from Earth, the LM's remaining propellant was depleted in a burn that caused it to impact the Moon {{convert|39|nmi}} from the Apollo 12 landing point.{{sfn|Orloff & Harland 2006|p=358}}  The seismometer the astronauts had left on the lunar surface registered the resulting vibrations for more than an hour.<ref name = "a12" >{{cite web|date=July 8, 2009|title=Apollo 12|access-date=January 27, 2021|url=https://www.nasa.gov/mission_pages/apollo/missions/apollo12.html|publisher=[[NASA]]}}</ref>

The crew stayed another day in lunar orbit taking photographs of the surface, including of candidate sites for future Apollo landings. A second plane change maneuver was made at 159:04:45.47, lasting 19.25 seconds.{{sfn|Orloff & Harland 2006|pp=336–337}}

The trans-Earth injection burn, to send the CSM ''Yankee Clipper'' towards home, was conducted at 172:27:16.81 and lasted 130.32 seconds. Two short midcourse correction burns were made en route. A final television broadcast was made, the astronauts answering questions submitted by the media.{{sfn|Orloff & Harland 2006|p=338}} There was ample time for rest on the way back to Earth.{{sfn|Chaikin 1995|p=282}} One event was the photography of a solar eclipse that occurred when the Earth came between the spacecraft and the Sun; Bean described it as the most spectacular sight of the mission.<ref>{{cite news|newspaper=[[The New York Times]]|title=Moon film and rocks are viewed|url=https://timesmachine.nytimes.com/timesmachine/1969/11/28/79439729.pdf?pdf_redirect=true&ip=0|url-access=subscription|date=November 28, 1969}}</ref>

===Splashdown===
''Yankee Clipper'' returned to Earth on November 24, 1969, splashing down in the South Pacific Ocean southeast of [[Samoa]] at 244:36:25 (20:58:24&nbsp;UTC, 10:58:24{{nbsp}}am{{nbsp}}[[Hawaii–Aleutian Time Zone|HST]], local time at the landing site). The landing was hard, resulting in a camera becoming dislodged and striking Bean in the forehead. After recovery by {{USS|Hornet|CV-12|6}}, they entered the [[Mobile Quarantine Facility]] (MQF), while lunar samples and Surveyor parts were sent ahead by air to the [[Lunar Receiving Laboratory]] (LRL) in Houston. Once the ''Hornet'' docked in Hawaii, the MQF was offloaded and flown to [[Ellington Air Force Base]] near Houston on November 29, from where it was taken to the LRL, where the astronauts remained until released from quarantine on December 10.{{sfn|Orloff & Harland 2006|pp=338–339}}<ref>{{cite web|access-date=January 27, 2021|publisher=[[NASA]]|date=November 25, 2019|title=50 Years Ago: Apollo 12 Return to Houston|url=https://www.nasa.gov/feature/50-years-ago-apollo-12-return-to-houston}}</ref>