Tranquility Base ( la, Statio Tranquillitatis) is the site on the

Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width ...

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 in the observable universe. In astronomy, the terms ''object'' and ''body'' are often us ...

other than

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surf ...

for the first time. On July 20, 1969,

Apollo 11 Apollo 11 (July 16–24, 1969) was the American spaceflight that first landed humans on the Moon. Commander Neil Armstrong and lunar module pilot Buzz Aldrin landed the Apollo Lunar Module ''Eagle'' on July 20, 1969, at 20:17 UTC, a ...

crewmembers

Neil Armstrong Neil Alden Armstrong (August 5, 1930 – August 25, 2012) was an American astronaut and aeronautical engineer who became the first person to walk on the Moon in 1969. He was also a naval aviator, test pilot, and university professor. ...

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 spacewalks as pilot of the 1966 Gemini 12 mission. As the Lunar Module ''Eagle'' pilot on the 1969 ...

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 s ...

Eagle Eagle is the common name for many large birds of prey of the family Accipitridae. Eagles belong to several groups of genera, some of which are closely related. Most of the 68 species of eagle are from Eurasia and Africa. Outside this area, j ...

'' 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 human spaceflight program to serve as a commander or crew member aboard a spacecraft. Although generally r ...

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 ''tranquillitātis'', the Sea of Tranquillity or Sea of Tranquility; see spelling differences) is a lunar mare that sits within the Tranquillitatis basin on the Moon. It is the first location on another world to ...

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

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the ...

and

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe, New Mexico, Santa Fe , LargestCity = Albuquerque, New Mexico, Albuquerque , LargestMetro = Albuquerque metropolitan area, Tiguex , Offi ...

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

Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...

, the U.S.

National Park Service The National Park Service (NPS) is an List of federal agencies in the United States, agency of the Federal government of the United States, United States federal government within the United States Department of the Interior, U.S. Department of ...

, and

UNESCO The United Nations Educational, Scientific and Cultural Organization is a specialized agency of the United Nations (UN) aimed at promoting world peace and security through international cooperation in education, arts, sciences and culture. I ...

have declined to do so, due to the technicality that it is not located on Earth or within their borders.

Site selection

For more than two years,

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeedi ...

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. A land surveying professional is c ...

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 Columbia may refer to: * Columbia (personification), the historical female national personification of the United States, and a poetic name for America Places North America Natural features * Columbia Plateau, a geologic and geographic region in ...

'' 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 Texas, the Southern United States#Major cities, most populous city in the Southern United States, the List of United States cities by population, fourth-most pop ...
, Tranquility Base here. The ''
Eagle Eagle is the common name for many large birds of prey of the family Accipitridae. Eagles belong to several groups of genera, some of which are closely related. Most of the 68 species of eagle are from Eurasia and Africa. Outside this area, j ...
'' 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 (derived ) is the systematic study and the documentation of the human activity. The time period of event before the History of writing#Inventions of writing, invention of writing systems is considered prehistory. "History" is an umbr ...

, 24 August 2003. Armstrong and Aldrin decided on using "Tranquility Base" just before the flight, telling only

Capsule Communicator Flight controllers are personnel who aid space flight by working in such Mission Control Centers as NASA's Mission Control Center or ESA's European Space Operations Centre. Flight controllers work at computer consoles and use telemetry to m ...

Charles Duke Charles Moss Duke Jr. (born October 3, 1935) is an American former astronaut, United States Air Force (USAF) officer and test pilot. As Lunar Module pilot of Apollo 16 in 1972, he became the tenth and youngest person to walk on the Moon, at ...

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; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach ...

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 branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power ...

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 Structure of poly-oxydiphenylene-pyromellitimide 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 spa ...

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 mapping orbit. Data collected by LRO have been described as essential for planning NASA's future human and robotic missions to ...

photos), the

US flag The national flag of the United States of America, often referred to as the ''American flag'' or the ''U.S. flag'', consists of thirteen equal horizontal stripes of red (top and bottom) alternating with white, with a blue rectangle in the c ...

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 noises and shaking such as caused by earthquakes, volcanic eruptions, and explosions. They are usually combined with a timing device and a recording device to form a seismograph. The outp ...

was also left to measure

moonquake A quake is the result when the surface of a planet, moon or star begins to shake, usually as the consequence of a sudden release of energy transmitted as seismic waves, and potentially with great violence. The types of quakes include: Earthquak ...

s, but this stopped functioning after 21 days. A disc containing the

Apollo 11 goodwill messages The Apollo 11 goodwill messages are statements from leaders of 73 countries around the world on a disc about the size of a 50-cent piece made of silicon that was left on the Moon in 1969 by the Apollo 11 astronauts. The disc also carried names ...

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, lunar orbit (also known as a selenocentric orbit) is the orbit of an object around the Moon. As used in the space program, this refers not to the orbit of the Moon about the Earth, but to orbits by spacecraft around the Moon. T ...

. 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 man-made, tangible and intangible, movable and immovable, that are deemed to be of sufficient heritage value to be separately identified and recorded. In many i ...

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 Texas, the Southern United States#Major cities, most populous city in the Southern United States, the List of United States cities by population, fourth-most pop ...

, 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 building, district, object, site, or structure that is officially recognized by the United States government for its outstanding historical significance. Only some 2,500 (~3%) of over 90,000 places listed ...

status to avoid violating the

Outer Space Treaty russian: link=yes, Договор о космосе es, link=yes, Tratado sobre el espacio ultraterrestre , long_name = Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moo ...

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

World Heritage Site A World Heritage Site is a landmark or area with legal protection by an international convention administered by the United Nations Educational, Scientific and Cultural Organization (UNESCO). World Heritage Sites are designated by UNESCO for ...

since the

United Nations Educational, Scientific and Cultural Organization The United Nations Educational, Scientific and Cultural Organization is a specialized agency of the United Nations (UN) aimed at promoting world peace and security through international cooperation in education, arts, sciences and culture. It ...

(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 The Google Lunar XPRIZE (GLXP), sometimes referred to as Moon 2.0, was a 2007–2018 inducement prize space competition organized by the X Prize Foundation, and sponsored by Google. The challenge called for privately funded teams to be the ...

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 Astrobotic Technology is an American privately held company that is developing space robotics technology for lunar and planetary missions. It was founded in 2007 by Carnegie Mellon professor Red Whittaker and his associates with the goal of w ...

, 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 Apollo and Surveyor landing site photography and to take broad survey images of unphotographed parts of the Moon's far side. It was also equipped to colle ...

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 West Crater is a small lava dome with associated lava flows in southern Washington, United States. Located in Skamania County, it rises to an elevation of , and forms part of the Cascade Volcanic Arc. It is also part of the Marble Mountain- ...

(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

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 A double is a look-alike or doppelgänger; one person or being that resembles another. Double, The Double or Dubble may also refer to: Film and television * Double (filmmaking), someone who substitutes for the credited actor of a character * Th ...

(left of LM) are also shown. File:AldrinFootprint.jpg,

's footprint at Tranquility Base (photograph by Aldrin) File:AS15-97-13284 (22007031822).jpg, Orbital photo from

Apollo 15 Apollo 15 (July 26August 7, 1971) was the ninth crewed mission in the United States' Apollo program and the fourth to land on the Moon. It was the first J mission, with a longer stay on the Moon and a greater focus on science than ea ...

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

Moltke The House of Moltke is the name of an old German noble family. The family was originally from Mecklenburg, but apart from Germany, some of the family branches also resided throughout Scandinavia. Members of the family have been noted as pigfarme ...

In popular culture

Tranquility Base has been depicted in many films and television shows, such as in the 1998 mini-series ''

From the Earth to the Moon ''From the Earth to the Moon: A Direct Route in 97 Hours, 20 Minutes'' (french: De la Terre à la Lune, trajet direct en 97 heures 20 minutes) is an 1865 novel by Jules Verne. It tells the story of the Baltimore Gun Club, a post-American Civil W ...

'', the 2015 series ''

The Astronaut Wives Club ''The Astronaut Wives Club'' is a 2015 American period drama television series developed by Stephanie Savage for ABC. It is based on Lily Koppel's 2013 book of the same name. The series tells the story of the wives of the Mercury Seven—Ameri ...

'', and the 2018 film '' First Man''. Tranquility Base is referenced in "

Boat on the River "Boat on the River" is a 1979 song by Styx, from their album ''Cornerstone''. It was released as a single in 1980 in various countries, but not in the band's native United States, where " Borrowed Time" was released instead. It was popular in s ...

" (". . . all roads lead to Tranquility Base...") by the American Rock band

Styx In Greek mythology, Styx (; grc, Στύξ ) is a river that forms the boundary between Earth (Gaia) and the Underworld. The rivers Acheron, Cocytus, Lethe, Phlegethon, and Styx all converge at the centre of the underworld on a great marsh, ...

, from their 1979 album ''

Cornerstone The cornerstone (or foundation stone or setting stone) is the first stone set in the construction of a masonry foundation. All other stones will be set in reference to this stone, thus determining the position of the entire structure. Over ti ...

.'' Tranquility Base is referenced in

indie rock Indie rock is a Music subgenre, subgenre of rock music that originated in the United States, United Kingdom and New Zealand from the 1970s to the 1980s. Originally used to describe independent record labels, the term became associated with the mu ...

band

Arctic Monkeys Arctic Monkeys are an English rock band formed in Sheffield in 2002. The group consists of Alex Turner (lead vocals, guitar, keyboards), Jamie Cook (guitar, keyboards), Nick O'Malley (bass guitar, backing vocals), and Matt Helders (drums, ...

' 2018 album, ''

Tranquility Base Hotel & Casino ''Tranquility Base Hotel & Casino'' is the sixth studio album by English rock band Arctic Monkeys, released on 11 May 2018 by Domino Recording Company. It was written by band frontman Alex Turner in 2016 on a Steinway Vertegrand piano in his ...

'', 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