Tranquility Base () is the site on the

Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...

where, in July 1969, humans landed and walked on a

celestial body An astronomical object, celestial object, stellar object or heavenly body is a naturally occurring physical entity, association, or structure that exists within the observable universe. In astronomy, the terms ''object'' and ''body'' are of ...

other than

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

for the first time. On July 20, 1969,

Apollo 11 Apollo 11 was a spaceflight conducted from July 16 to 24, 1969, by the United States and launched by NASA. It marked the first time that humans Moon landing, landed on the Moon. Commander Neil Armstrong and Lunar Module pilot Buzz Aldrin l ...

crewmembers

Neil Armstrong Neil Alden Armstrong (August 5, 1930 – August 25, 2012) was an American astronaut and aerospace engineering, aeronautical engineer who, in 1969, became the Apollo 11#Lunar surface operations, first person to walk on the Moon. He was al ...

and

Buzz Aldrin Buzz Aldrin ( ; born Edwin Eugene Aldrin Jr.; January 20, 1930) is an American former astronaut, engineer and fighter pilot. He made three extravehicular activity, spacewalks as pilot of the 1966 Gemini 12 mission, and was the Lunar Module Eag ...

landed their

Apollo Lunar Module The Apollo Lunar Module (LM ), originally designated the Lunar Excursion Module (LEM), was the lunar lander spacecraft that was flown between lunar orbit and the Moon's surface during the United States' Apollo program. It was the first crewed sp ...

Eagle Eagle is the common name for the golden eagle, bald eagle, and other birds of prey in the family of the Accipitridae. Eagles belong to several groups of Genus, genera, some of which are closely related. True eagles comprise the genus ''Aquila ( ...

'' at approximately 20:17:40 UTC. Armstrong exited the spacecraft six hours and 39 minutes after touchdown, followed 19 minutes later by Aldrin. The

astronauts An astronaut (from the Ancient Greek (), meaning 'star', and (), meaning 'sailor') is a person trained, equipped, and deployed by a List of human spaceflight programs, human spaceflight program to serve as a commander or crew member of a spa ...

spent two hours and 31 minutes examining and photographing the lunar surface, setting up several scientific experiment packages, and collecting of 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'' landed. It is located in the south-western corner of the dark lunar plain

Mare Tranquillitatis Mare Tranquillitatis (Latin for Sea of Tranquillity or Sea of Tranquility) is a lunar mare that sits within the Tranquillitatis basin on the Moon. It contains Tranquility Base, the first location on another celestial body to be visited by huma ...

("Sea of Tranquility"). The U.S. states of

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

and

New Mexico New Mexico is a state in the Southwestern United States, Southwestern region of the United States. It is one of the Mountain States of the southern Rocky Mountains, sharing the Four Corners region with Utah, Colorado, and Arizona. It also ...

have registered Tranquility Base as a heritage site associated with them, but

Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...

, the U.S.

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, and

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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 The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

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 Surveying or land surveying is the technique, profession, art, and science of determining the terrestrial two-dimensional or three-dimensional positions of points and the distances and angles between them. These points are usually on the ...

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 , was the Sea of Tranquility site ultimately chosen. Since a precision landing was not expected on the first mission, the target area was an ellipse measuring east and west by north and south. On the landing, a combination of thrust from residual pressure in the docking tunnel that connected the Lunar Module with the command module '' 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 , and thus the computer-targeted landing spot about , downrange (west) of the planned target. The automated targeting system was taking ''Eagle'' toward what Armstrong described as a " 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. The landing was still within the target ellipse.

Name

Armstrong named the site at 20:17:58 UTC, approximately 18 seconds after his and Aldrin's successful landing, as he announced:

Houston Houston ( ) is the List of cities in Texas by population, most populous city in the U.S. state of Texas and in the Southern United States. Located in Southeast Texas near Galveston Bay and the Gulf of Mexico, it is the county seat, seat of ...
, Tranquility Base here. The ''
Eagle Eagle is the common name for the golden eagle, bald eagle, and other birds of prey in the family of the Accipitridae. Eagles belong to several groups of Genus, genera, some of which are closely related. True eagles comprise the genus ''Aquila ( ...
'' has landed.

During training, Armstrong and Aldrin had exclusively used the callsign "Eagle" in simulated ground conversations, both before and after landing.''Failure is Not an Option''.

History History is the systematic study of the past, focusing primarily on the Human history, human past. As an academic discipline, it analyses and interprets evidence to construct narratives about what happened and explain why it happened. Some t ...

, 24 August 2003. Armstrong and Aldrin decided on using "Tranquility Base" just before the flight, telling only Capsule Communicator Charles Duke before the mission, so Duke would not be taken by surprise. Author's note on page 206. The name has become a permanent designation for the site. Although the name was designated by the Apollo astronauts, the

International Astronomical Union The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...

officially recognizes the designation "Tranquility Base". It is listed on lunar maps as ''Statio Tranquillitatis'', conforming to the standard use of

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

for lunar place names.

Status

About 100 artificial objects, as well as footprints left by Armstrong and Aldrin, remain at Tranquility Base, and Armstrong commented that during the launch of ''Eagles ascent stage he could see "

Kapton file:Kaptonpads.jpg, Kapton insulating pads for mounting electronic parts on a heat sink Kapton is a polyimide film used in flexible printed circuits (flexible electronics) and space blankets, which are used on spacecraft, satellites, and variou ...

and other parts on the LM staging scattering all around the area for great distances." The descent stage of the Lunar Module remains at the original point of landing. According to Aldrin (with apparent confirmation from later

Lunar Reconnaissance Orbiter The Lunar Reconnaissance Orbiter (LRO) is a NASA robotic spacecraft currently orbiting the Moon in an eccentric Polar orbit, polar mapping orbit. Data collected by LRO have been described as essential for planning NASA's future human and robotic ...

photos), the US flag planted at the site during their moonwalk was blown over by the ascent rocket exhaust, but remains on the surface of the Moon. A laser reflector was placed at the site to allow precise ongoing measurements of the distance to the Moon from Earth. A solar-powered

seismometer A seismometer is an instrument that responds to ground displacement and shaking such as caused by quakes, volcanic eruptions, and explosions. They are usually combined with a timing device and a recording device to form a seismograph. The out ...

was also left to measure moonquakes, 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 In astronomy and spaceflight, a lunar orbit (also known as a selenocentric orbit) is an orbit by an object around Earth's Moon. In general these orbits are not circular. When farthest from the Moon (at apoapsis) a spacecraft is said to be at apo ...

. As the site of the first human landing on an extraterrestrial body, Tranquility Base has cultural and historic significance. The U.S. states of

and

have listed it on their

heritage register This list is of heritage registers, inventories of cultural properties, natural and human-made, tangible and intangible, movable and immovable, that are deemed to be of sufficient heritage value to be separately identified and recorded. In ma ...

s, since their laws require only that listed sites have some association with the state.

has not granted similar status to the site, despite the location of Mission Control in

Houston Houston ( ) is the List of cities in Texas by population, most populous city in the U.S. state of Texas and in the Southern United States. Located in Southeast Texas near Galveston Bay and the Gulf of Mexico, it is the county seat, seat of ...

, as its

historic preservation Historic preservation (US), built heritage preservation or built heritage conservation (UK) is an endeavor that seeks to preserve, conserve and protect buildings, objects, landscapes or other artifacts of historical significance. It is a philos ...

laws limit such designations to properties located within the state. The U.S.

has declined to grant it

National Historic Landmark A National Historic Landmark (NHL) is a National Register of Historic Places property types, building, district, object, site, or structure that is officially recognized by the Federal government of the United States, United States government f ...

status to avoid violating the

Outer Space Treaty The Outer Space Treaty, formally the Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies, is a Multilateralism, multilateral treaty that forms the bas ...

's prohibition on any nation claiming sovereignty over any extraterrestrial body. It has not been proposed as a

World Heritage Site World Heritage Sites are landmarks and areas with legal protection under an treaty, international treaty administered by UNESCO for having cultural, historical, or scientific significance. The sites are judged to contain "cultural and natural ...

since the

United Nations Educational, Scientific and Cultural Organization The United Nations Educational, Scientific and Cultural Organization (UNESCO ) is a List of specialized agencies of the United Nations, specialized agency of the United Nations (UN) with the aim of promoting world peace and International secur ...

(UNESCO), which oversees that program, limits nations to submitting sites within their own borders. 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 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 from the site. In 2020, the ''One Small Step to Protect Human Heritage in Space Act'' was enacted, protecting Tranquility Base and other Apollo landing sites from damage from US-licensed space activity.

Gallery

File:Apollo 11 landing site 5076 med.jpg,

Lunar Orbiter 5 Lunar Orbiter 5, the last of the "Lunar Orbiter series", was designed to take additional Project Apollo, Apollo and Surveyor program, Surveyor landing site photography and to take broad survey images of unphotographed parts of the Moon's far sid ...

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 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 km × 25 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 crater and is about 190 m in diameter. File:Apollo11-LRO-March2012.jpg,

photo taken March 7, 2012. The Lunar Module descent stage, Laser Ranging RetroReflector, and Early Apollo Scientific Experiments Package can be clearly seen. The craters Little West (at right) and

Double Double, The Double or Dubble may refer to: Mathematics and computing * Multiplication by 2 * Double precision, a floating-point representation of numbers that is typically 64 bits in length * A double number of the form x+yj, where j^2=+1 * A ...

(left of LM) are also shown. File:Buzz Aldrin's bootprint on the Moon, AS11-40-5877 (21472308758).jpg,

's footprint at Tranquility Base (photograph by Aldrin) File:Double aldrin huggin stich2.jpg, Composite image of Double crater, a few meters from ''Eagle''. Photos by Aldrin. File:Little west Crater composite.jpg, Composite image of 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 Apollo 15 (July 26August 7, 1971) was the ninth crewed mission in the Apollo program and the fourth Moon landing. It was the first List of Apollo missions#Alphabetical mission types, J mission, with a longer stay on the Moon and a greate ...

showing the landing site just below center. The bright crater is Moltke.

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 ''From the Earth to the Moon: A Direct Route in 97 Hours, 20 Minutes'' () is an 1865 novel by Jules Verne. It tells the story of the Baltimore Gun Club, a post-American Civil War society of weapons enthusiasts, and their attempts to build an en ...

'', the 2015 series '' The Astronaut Wives Club'', and the 2018 film '' First Man''. Tranquility Base is referenced in " Boat on the River" (". . . all roads lead to Tranquility Base...") by the American Rock band Styx, from their 1979 album ''

Cornerstone A cornerstone (or foundation stone or setting stone) is the first stone set in the construction of a masonry Foundation (engineering), foundation. All other stones will be set in reference to this stone, thus determining the position of the entir ...

.'' Tranquility Base is referenced in

indie rock Indie rock is a Music subgenre, subgenre of rock music that originated in the United Kingdom, United States and New Zealand in the early to mid-1980s. Although the term was originally used to describe rock music released through independent reco ...

band

Arctic Monkeys Arctic Monkeys are an English Rock music, rock band formed in Sheffield in 2002. They comprise lead singer Alex Turner, drummer Matt Helders, guitarist Jamie Cook and bassist Nick O'Malley. The co-founder and original bassist Andy Nicholson ...

' 2018 album, '' Tranquility Base Hotel & Casino'', as the location of a hotel and casino.

Notes

External links

Surface panorama of landing site
(by Armstrong), Lunar and Planetary Institute
USGS Planetary Gazetteer EntryPhoto Number IV-085-H1
Digital Lunar Orbiter Photographic Atlas of the Moon, showing the Apollo 11 landing site and vicinity {{Authority control Apollo 11 Apollo program Exploration of the Moon LQ12 quadrangle Geological type localities Buzz Aldrin Neil Armstrong 1969 on the Moon Articles containing video clips Space archaeology Historical footprints