Editing Tranquility Base

{{Short description|Landing site of Apollo 11 on the Moon}}
{{Infobox historic site
| name                 = Tranquility Base
| type                 = Extraterrestrial landing site
| image                = Aldrin Looks Back at Tranquility Base - GPN-2000-001102.jpg
| caption              = Astronaut [[Buzz Aldrin]] with [[Lunar Module Eagle|Apollo Lunar Module ''Eagle'']] at Tranquility Base; photo taken by [[Neil Armstrong]]
| location             = [[Mare Tranquillitatis]], [[Moon]]
| area                 =
| beginning_label      = Named and founded
| beginning_date       = {{Date and age|July 20, 1969}}
| governing_body       = [[California]], [[New Mexico]]
| image_map            = Apollo 11 photo map.svg
| image_map_caption    = Map of Tranquility Base
| coordinates          = {{coord|00|41|15|N|23|26|00|E|globe:moon|format=dms|display=inline,title}}
| founder              = [[Neil Armstrong]] and [[Buzz Aldrin]]
<!-- | locmapin          = {{Location map|Moon}}   Can't get this to work... -->
| designation1         = 
| designation1_offname = 
| designation1_date    = 
| designation1_number  = 
}}
{{Apollo11series}}
'''Tranquility Base''' ({{langx|la|'''Statio Tranquillitatis'''}}) is the site on the [[Moon]] where, in July 1969, humans landed and walked on a [[celestial body]] other than [[Earth]] for the first time. On July 20, 1969, [[Apollo 11]] crewmembers [[Neil Armstrong]] and [[Buzz Aldrin]] landed their [[Apollo Lunar Module]] ''[[Lunar Module Eagle|Eagle]]'' at approximately 20:17:40 [[Universal Coordinated Time|UTC]]. Armstrong exited the spacecraft six hours and 39 minutes after touchdown, followed 19 minutes later by Aldrin. The [[astronauts]] spent two hours and 31 minutes examining and photographing the lunar surface, setting up several scientific experiment packages, and collecting {{convert|47.5|lb|kg}} of [[Moon rocks|dirt and rock samples]] for return to Earth. They lifted off the surface on July 21 at 17:54 UTC.

Tranquility Base was named by Aldrin and Armstrong, and first announced by Armstrong when the [[Lunar Module Eagle|Lunar Module ''Eagle'']] landed. It is located in the south-western corner of the dark lunar plain [[Mare Tranquillitatis]] ("Sea of Tranquility").<ref>{{citation |title=The Eagle Has Landed – 1969; Video Transcript for Archival Research Catalog (ARC) Identifier 45017 |year=1969 |access-date=Nov 27, 2015 |publisher=[[National Archives and Records Administration]] |url=https://www.archives.gov/files/social-media/transcripts/transcript-eagle-has-landed-1969-45017.pdf}}</ref> The U.S. states of [[California]] and [[New Mexico]] have registered Tranquility Base as a heritage site associated with them, but [[Texas]], the U.S. [[National Park Service]], and [[United Nations Educational, Scientific and Cultural Organization|UNESCO]] have declined to do so, due to the technicality that it is not located within their borders.

==Site selection==
For more than two years, [[NASA]] planners considered a collection of 30 potential sites for the first crewed landing. Based on high-resolution photographs taken by the [[Lunar Orbiter]] spacecraft, and photos and data taken by the uncrewed [[Surveyor Program|Surveyor]] landers, this list was narrowed down to five sites located near the lunar equator. They ranged between 45 degrees east and west, and 5 degrees north and south of the center of the Moon's facing side. They were numbered 1 to 5, going from east to west. Site number 2, centered at {{coord|0|42|50|N|23|42|28|E|globe:moon}}, was the Sea of Tranquility site ultimately chosen.<ref>{{cite press release
 | title = Apollo 11 Lunar Landing Mission Press Kit
 | publisher = [[NASA]]
 | date = July 6, 1969
 | pages = 82–85
 | url = https://history.nasa.gov/alsj/a11/A11_PressKit.pdf
 }}
</ref> Since a precision landing was not expected on the first mission, the target area was an ellipse measuring {{convert|11.5|mi|km}} east and west by {{convert|3.0|mi|km}} north and south.<ref name="chaikin_88">{{Cite book |author=Chaikin, Andrew |title=A Man on the Moon: The Triumphant Story Of The Apollo Space Program |date=2007|publisher=[[Penguin Group]] |location=New York |page=88|isbn=978-0-14-311235-8}}</ref>

On the landing, a combination of thrust from residual pressure in the docking tunnel that connected the Lunar Module with the [[Apollo command and service module|command module]] ''[[Command module Columbia|Columbia]]'' in orbit, and an imperfect understanding of the Moon's uneven gravitational field, resulted in navigation errors which pushed the powered descent initiation point about {{convert|3|mi|km}}, and thus the computer-targeted landing spot about {{convert|4|mi|km}}, downrange (west) of the planned target.<ref>{{cite web| url=http://www.history.nasa.gov/alsj/a11/a11.landing.html| last=Jones| first=Eric M.| title=The First Lunar Landing, time 102:36:21| publisher=Apollo Lunar Surface Journal| via=NASA| access-date=2013-08-09| archive-date=2017-12-25| archive-url=https://web.archive.org/web/20171225232200/https://history.nasa.gov/alsj/a11/a11.landing.html| url-status=dead}}</ref> The automated targeting system was taking ''Eagle'' toward what Armstrong described as a "[[American football field|football-field]] sized crater, with a large number of big boulders and rocks for about one or two crater diameters around it", which he avoided by assuming manual control and flying a bit farther downrange.<ref>{{cite web| url=http://www.history.nasa.gov/alsj/a11/a11.postland.html| last=Jones| first=Eric M.| title=Post-landing Activities, time 102:55:16| publisher=Apollo Lunar Surface Journal| via=NASA| access-date=2013-08-23| archive-date=2021-04-18| archive-url=https://web.archive.org/web/20210418132829/https://history.nasa.gov/alsj/a11/a11.postland.html| url-status=dead}}</ref> The landing was still within the target ellipse.

==Name==
[[File:AP11 FINAL APPROACH.ogv|thumb|Armstrong pilots the [[Lunar Module Eagle|Apollo Lunar Module ''Eagle'']] and lands on the Moon, July 20, 1969, creating Tranquility Base]]
Armstrong named the site at 20:17:58 [[Universal Coordinated Time|UTC]], approximately 18 seconds after his and Aldrin's successful landing, as he announced:
<blockquote>[[Christopher C. Kraft Jr. Mission Control Center|Houston]], Tranquility Base here. The ''[[Lunar Module Eagle|Eagle]]'' has landed.<ref>{{cite web|url=http://www.hq.nasa.gov/alsj/a11/a11.landing.html|title=Apollo 11 Lunar Surface Journal: The First Lunar Landing|last=Jones|first=Eric M.|publisher=Apollo Lunar Surface Journal|via=NASA|date=1995|access-date=2009-07-15|archive-date=2016-12-27|archive-url=https://web.archive.org/web/20161227230604/http://www.hq.nasa.gov/alsj/a11/a11.landing.html|url-status=dead}}</ref>
</blockquote>

During training, Armstrong and Aldrin had exclusively used the callsign "Eagle" in simulated ground conversations, both before and after landing.<ref name="failure">''Failure is Not an Option''. [[History (U.S. TV channel)|History]], 24 August 2003.</ref> Armstrong and Aldrin decided on using "Tranquility Base" just before the flight, telling only [[Capsule communicator|Capsule Communicator]] [[Charles Duke]] before the mission, so Duke would not be taken by surprise.<ref name="chaikin_206">{{Cite book |author=Chaikin, Andrew |title=A Man on the Moon: The Triumphant Story Of The Apollo Space Program |date=2007|publisher=[[Penguin Group]] |location=New York |page=637|isbn=978-0-14-311235-8}} Author's note on page 206.</ref>

The name has become a permanent designation for the site. Although the name was designated by the Apollo astronauts, the [[International Astronomical Union]] officially recognizes the designation "Tranquility Base". It is listed on lunar maps as ''Statio Tranquillitatis'', conforming to the standard use of [[Latin]] for lunar place names.

==Status==
[[Image:Apollo 11 plaque closeup on Moon.jpg|right|thumb|The [[Lunar plaque|plaque left at Tranquility Base]] on the Lunar Module Descent Stage which commemorates the first crewed lunar landing (photographed by Neil Armstrong)]]

About [[List of artificial objects on the Moon|100 artificial objects]], as well as footprints left by Armstrong and Aldrin, remain at Tranquility Base, and Armstrong commented that during the launch of ''Eagle'''s ascent stage he could see "[[Kapton]] and other parts on the LM staging scattering all around the area for great distances."<ref>[https://history.nasa.gov/afj/ap11fj/21day6-tei.html Apollo 11 Flight Journal – Day 6 part 4: Trans-Earth Injection]. History.nasa.gov (15 March 2011). Retrieved on 2012-04-28.</ref> The [[Apollo Lunar Module#Descent stage|descent stage of the Lunar Module]] remains at the original point of landing.  According to Aldrin (with apparent confirmation from later [[Lunar Reconnaissance Orbiter]] photos<ref name="Space.com Apollo Flag Status Story">{{cite news|last=Moskowitz|first=Clara|publisher=[[Space.com]]|title=Apollo Moon Landing Flags Still Standing, Photos Reveal|url=http://www.space.com/16798-american-flags-moon-apollo-photos.html|access-date=2015-07-21}}</ref>), the [[Lunar Flag Assembly|US flag]] planted at the site during their [[List of spacewalks and moonwalks 1965–1999|moonwalk]] was blown over by the [[Ascent Propulsion System|ascent rocket]] exhaust, but remains on the surface of the Moon.  A [[Lunar Laser Ranging Experiment|laser reflector]] was placed at the site to allow precise ongoing measurements of the distance to the Moon from Earth. A solar-powered [[seismometer]] was also left to measure [[moonquake]]s, but this stopped functioning after 21 days. A disc containing the [[Apollo 11 goodwill messages]] was left at the site, and various gear that was no longer needed for the return phase of the mission—including Aldrin's boots—was left behind to lighten the craft for return to [[lunar orbit]].<ref name=smithsonian>{{cite web|title=NASA Looks to Protect Historic Sites on the Moon|url=http://www.smithsonianmag.com/science-nature/nasa-looks-to-protect-historic-sites-on-the-moon-47186092/|publisher=[[Smithsonian (magazine)|Smithsonian Magazine]]|first1=Michael|last1=Milstein|access-date=July 22, 2013}}</ref>

As the site of the first human landing on an extraterrestrial body, Tranquility Base has cultural and historic significance. The U.S. states of [[California]] and [[New Mexico]] have listed it on their [[heritage register]]s, since their laws require only that listed sites have some association with the state.<ref>{{cite web|url=http://www.parks.ca.gov/pages/1054/files/winter10.pdf|title=One Small Step for Man, One Giant Leap for Preservation|last1=Donaldson|first1=Milford Wayne|publisher=California State Parks|date=Winter 2010|volume=3|issue=1|page=2|access-date=June 30, 2019}}</ref> [[Texas]] has not granted similar status to the site, despite the location of Mission Control in [[Houston]], as its [[historic preservation]] laws limit such designations to properties located within the state.<ref name="NYT lunar preservation story">{{cite news|last=Chang|first=Kenneth|title=To Preserve History on the Moon, Visitors Are Asked to Tread Lightly|url=https://www.nytimes.com/2012/01/10/science/space/a-push-for-historic-preservation-on-the-moon.html|newspaper=[[The New York Times]]|date=January 10, 2012|access-date=January 11, 2012}}</ref>  The U.S. [[National Park Service]] has declined to grant it [[National Historic Landmark]] status to avoid violating the [[Outer Space Treaty]]'s prohibition on any nation claiming sovereignty over any extraterrestrial body. It has not been proposed as a [[World Heritage Site]] since the [[United Nations Educational, Scientific and Cultural Organization]] (UNESCO), which oversees that program, limits nations to submitting sites within their own borders.<ref name="NYT lunar preservation story" />

Interest in according the site some formal protection grew in the early 21st century with the announcement of the [[Google Lunar X Prize]] for private corporations to successfully build spacecraft and reach the Moon; a $1 million bonus was offered for any competitor that visited a historic site on the Moon. One team, led by [[Astrobotic Technology]], announced it would attempt to land a craft at Tranquility Base. Although it canceled those plans, the [[Google Lunar X Prize#Objections to the Heritage Bonus Prizes|ensuing controversy]] led NASA to request that any other missions to the Moon, private or governmental, human or robotic, keep a distance of at least {{convert|75|m|sp=us}} from the site.<ref name="NYT lunar preservation story" />

In 2020, the ''One Small Step to Protect Human Heritage in Space Act''<ref>''One Small Step to Protect Human Heritage in Space Act'' {{USStatute|116|275|134|3357|2020|12|31}}</ref> was enacted, protecting Tranquility Base and other Apollo landing sites from damage from US-licensed space activity.<ref>{{cite news |last1=Engel |first1=Currie |title=Inside the Fight to Save the Moon's Historic Sites |url=https://time.com/5627640/moon-historic-sites/ |access-date=July 19, 2019 |magazine=Time |date=July 18, 2019 |language=en}}</ref>

==Gallery==
<gallery heights="240px" mode="packed">
File:Apollo 11 landing site 5076 med.jpg|[[Lunar Orbiter 5]] image from 1967, cropped to show the vicinity of the landing site of Apollo 11, used in mission planning.  The image is centered precisely on a small crater called [[West (lunar crater)|West crater]] (190 m in diameter), and the lunar module ''Eagle'' touched down about 550 m west of West Crater. The area shown is approximately 25&nbsp;km × 25&nbsp;km across.
File:Apollo 11 landing site 5076 h3.jpg|High-resolution Lunar Orbiter 5 image cropped to show the landing site of Apollo 11.  The landing site is indicated by a red dot.  The prominent crater at right is called [[West (lunar crater)|West crater]] and is about 190 m in diameter.
File:Apollo11-LRO-March2012.jpg|[[Lunar Reconnaissance Orbiter]] photo taken March 7, 2012. The Lunar Module descent stage, [[Lunar Laser Ranging experiment|Laser Ranging RetroReflector]], and [[Early Apollo Scientific Experiments Package]] can be clearly seen.  The craters [[Little West (lunar crater)|Little West]] (at right) and [[Double (lunar crater)|Double]] (left of LM) are also shown.
File:Buzz Aldrin's bootprint on the Moon, AS11-40-5877 (21472308758).jpg|[[Buzz Aldrin]]'s footprint at Tranquility Base (photograph by Aldrin)
File:Double aldrin huggin stich2.jpg|Composite image of [[Double (lunar crater)|Double crater]], a few meters from ''Eagle''. Photos by Aldrin.
File:Little west Crater composite.jpg|Composite image of [[Little West (lunar crater)|Little West Crater]], app. 60 meters from ''Eagle''. Photos by Armstrong.
File:Apollo 15 Hasselblad image from film magazine 97 O - lunar orbit view.jpg|Orbital photo from [[Apollo 15]] showing the landing site just below center.  The bright crater is [[Moltke (crater)|Moltke]].
</gallery>

== In popular culture ==
Tranquility Base has been depicted in many books, films and television shows, such as in the 1996 novel ''[[The Tranquillity Alternative]]'' by [[Allen Steele]], the 1998 mini-series ''[[From the Earth to the Moon (miniseries)|From the Earth to the Moon]]'', the 2015 series ''[[The Astronaut Wives Club]]'', and the 2018 film ''[[First Man (film)|First Man]]''.

Tranquility Base is referenced in "[[Boat on the River]]" (". . . all roads lead to Tranquility Base...") by the American Rock band [[Styx (band)|Styx]], from their 1979 album ''[[Cornerstone (Styx album)|Cornerstone]].''

Tranquility Base is referenced in [[indie rock]] band [[Arctic Monkeys]]' 2018 album, ''[[Tranquility Base Hotel & Casino]]'', as the location of a hotel and casino.<ref name="StereogumEvaluation">{{cite web|title=Premature Evaluation: Arctic Monkeys Tranquility Base Hotel & Casino|url=https://www.stereogum.com/1995502/premature-evaluation-arctic-monkeys-tranquility-base-hotel-casino/franchises/premature-evaluation|last=Breihan|first=Tom|work=[[Stereogum]]|date=May 10, 2018|access-date=May 12, 2018}}</ref>

==See also==
*[[Apollo 11 lunar sample display]]
*[[Apollo 11 in popular culture]]
*[[List of archaeological sites beyond national boundaries]]
*[[Moonbase]]
*[[Space archaeology]]
*[[Mare Cognitum#Statio Cognitum|Statio Cognitum]], the [[Apollo 12]] landing site
*[[Tranquility (ISS module)|''Tranquility'' (ISS module)]], namesake

== Notes ==
{{reflist}}

==External links==
*[http://www.lpi.usra.edu/resources/apollopanoramas/pans/?pan=JSC2007e045375 Surface panorama of landing site] (by Armstrong), Lunar and Planetary Institute
*[http://planetarynames.wr.usgs.gov/jsp/FeatureNameDetail.jsp?feature=65853 USGS Planetary Gazetteer Entry]
*[http://www.lpi.usra.edu/resources/lunar_orbiter/images/aimg/iv_085_h1.jpg Photo Number IV-085-H1], Digital [[Lunar Orbiter]] Photographic Atlas of the Moon, showing the Apollo 11 landing site and vicinity

{{Apollo landing sites|state=expanded}}
{{Apollo program}}

{{Authority control}}

[[Category:Apollo 11]]
[[Category:Apollo program]]
[[Category:Exploration of the Moon]]
[[Category:LQ12 quadrangle]]
[[Category:Geological type localities]]
[[Category:Buzz Aldrin]]
[[Category:Neil Armstrong]]
[[Category:1969 on the Moon]]
[[Category:Articles containing video clips]]
[[Category:Space archaeology]]
[[Category:Historical footprints]]