Tranquility Base (Latin: 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 ModuleEagle 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 spent two hours and 31 minutes examining and photographing the lunar surface, setting up several scientific experiment packages, and collecting 47.5 pounds (21.5kg) 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 ("Sea of Tranquility").[1] 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 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 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 0°42′50″N23°42′28″E / 0.71389°N 23.70778°E / 0.71389; 23.70778, was the Sea of Tranquility site ultimately chosen.[2] Since a precision landing was not expected on the first mission, the target area was an ellipse measuring 11.5 miles (18.5km) east and west by 3.0 miles (4.8km) north and south.[3]
On the landing, a combination of thrust from residual pressure in the docking tunnel that connected the Lunar Module with the command moduleColumbia 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 3 miles (4.8km), and thus the computer-targeted landing spot about 4 miles (6.4km), downrange (west) of the planned target.[4] 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.[5] The landing was still within the target ellipse.
Name
Armstrong pilots the Apollo Lunar Module Eagle and lands on the Moon, July 20, 1969, creating Tranquility Base
Armstrong named the site at 20:17:58 UTC, approximately 18 seconds after his and Aldrin's successful landing, as he announced:
During training, Armstrong and Aldrin had exclusively used the callsign "Eagle" in simulated ground conversations, both before and after landing.[7] Armstrong and Aldrin decided on using "Tranquility Base" just before the flight, telling only Capsule CommunicatorCharles Duke before the mission, so Duke would not be taken by surprise.[8]
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
The plaque left at Tranquility Base on the Lunar Module Descent Stage which commemorates the first crewed lunar landing (photographed by Neil Armstrong)
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 Eagle's ascent stage he could see "Kapton and other parts on the LM staging scattering all around the area for great distances."[9] 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 photos[10]), 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 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.[11]
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 registers, since their laws require only that listed sites have some association with the state.[12]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.[13] 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.[13]
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 75 meters (246ft) from the site.[13]
In 2020, the One Small Step to Protect Human Heritage in Space Act[14] was enacted, protecting Tranquility Base and other Apollo landing sites from damage from US-licensed space activity.[15]
Gallery
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 crater (190 m in diameter), and the lunar module Eagle touched down about 550 m west of West Crater. The area shown is approximately 25km × 25km across.
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.
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.
↑ Failure is Not an Option. History, 24 August 2003.
↑ Chaikin, Andrew (2007). A Man on the Moon: The Triumphant Story Of The Apollo Space Program. New York: Penguin Group. p.637. ISBN978-0-14-311235-8. Author's note on page 206.
Apollo 11 was a spaceflight conducted by the United States from July 16 to July 24, 1969. It marked the first time in history that humans landed 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, and Armstrong became the first person to step onto the Moon's surface six hours and 39 minutes later, on July 21 at 02:56 UTC. Aldrin joined him 19 minutes later, and they spent about two and a quarter hours together exploring the site they had named Tranquility Base upon landing. Armstrong and Aldrin collected 47.5 pounds (21.5 kg) of lunar material to bring back to Earth as pilot Michael Collins flew the Command Module Columbia in lunar orbit, and were on the Moon's surface for 21 hours, 36 minutes, before lifting off to rejoin Columbia.
Apollo 10 was the fourth human spaceflight in the United States' Apollo program and the second to orbit the Moon. NASA, the mission's operator, described it as a "dress rehearsal" for the first Moon landing. It was designated an "F"mission, intended to test all spacecraft components and procedures short of actual descent and landing.
Apollo 12 was the sixth crewed flight in the United States Apollo program and the second to land on the Moon. It was launched on November 14, 1969, by NASA from the Kennedy Space Center, Florida. Commander Charles "Pete" Conrad and Lunar Module Pilot Alan L. Bean performed just over one day and seven hours of lunar surface activity while Command Module Pilot Richard F. Gordon remained in lunar orbit.
Buzz Aldrin is an American former astronaut, engineer and fighter pilot. He made three spacewalks as pilot of the 1966 Gemini 12 mission, and was the Lunar Module Eagle pilot on the 1969 Apollo 11 mission. He was the second person to walk on the Moon after mission commander Neil Armstrong. Following the death of Michael Collins in 2021, he is the last surviving Apollo 11 crew member.
Moon landing conspiracy theories claim that some or all elements of the Apollo program and the associated Moon landings were hoaxes staged by NASA, possibly with the aid of other organizations. The most notable claim of these conspiracy theories is that the six crewed landings (1969–1972) were faked and that twelve Apollo astronauts did not actually land on the Moon. Various groups and individuals have made claims since the mid-1970s that NASA and others knowingly misled the public into believing the landings happened, by manufacturing, tampering with, or destroying evidence including photos, telemetry tapes, radio and TV transmissions, and Moon rock samples.
Oceanus Procellarum is a vast lunar mare on the western edge of the near side of the Moon. It is the only one of the lunar maria to be called an "Oceanus" (ocean), due to its size: Oceanus Procellarum is the largest of the maria ("seas"), stretching more than 2,500 km (1,600 mi) across its north–south axis and covering roughly 4,000,000 km2 (1,500,000 sq mi), accounting for 10.5% of the total lunar surface area.
Mare Tranquillitatis 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 humans.
Mare Cognitum is a lunar mare located in a basin or large crater which sits in the second ring of Oceanus Procellarum. To the northwest of the mare is the Montes Riphaeus mountain range, part of the rim of the buried crater or basin containing the mare. Previously unnamed, the mare received its name in 1964 in reference to its selection as the target for the successful impact probe Ranger 7, the first American spacecraft to return closeup images of the Moon's surface.
Aldrin is a small impact crater located on the southern part of the Mare Tranquillitatis, to the east of Sabine. It is located about 50 kilometers to the northwest of the Apollo 11 landing site, Tranquility Base. Named after Edwin Buzz Aldrin, the crater is the westernmost of a row of three craters named in honor of the Apollo 11 crew members. About 30 kilometers to the east is the landing site of the Surveyor 5 lunar probe.
Armstrong is a small lunar impact crater located in the southern part of the Mare Tranquillitatis. It lies about 50 kilometers to the northeast of the Apollo 11 landing site, Tranquility Base. Named after American astronaut Neil Armstrong, the crater is the easternmost of the row of three craters named in honor of the Apollo 11 crew members. To the north is the Ranger 8 impact site.
Collins is a tiny lunar impact crater located on the southern part of the Mare Tranquillitatis. It is located about 25 kilometers to the north of the Apollo 11 landing site, Tranquility Base. Named after American astronaut Michael Collins, the crater is the central member of the row of three craters named in honor of the Apollo 11 crew members. About 15 kilometers to the west-northwest is the landing site of the Surveyor 5 lunar probe.
Sabine is a lunar impact crater that forms a nearly matching pair with Ritter to the northwest. The two rims are separated by a distance of only a couple of kilometers. To the west is the bowl-shaped crater Schmidt, and farther to the north are Manners and Arago. Its diameter is 30 km. It was named after Irish physicist and astronomer Edward Sabine.
A Moon landing or lunar landing is the arrival of a spacecraft on the surface of the Moon, including both crewed and robotic missions. The first human-made object to touch the Moon was Luna 2 in 1959.
Tranquillity Park is a municipal park in Houston, Texas.
Third-party evidence for Apollo Moon landings is evidence, or analysis of evidence, about the Moon landings that does not come from either NASA or the U.S. government, or the Apollo Moon landing hoax theorists. This evidence provides independent confirmation of NASA's account of the six Apollo program Moon missions flown between 1969 and 1972.
West crater is a small crater in Mare Tranquillitatis on the Moon, east of the Apollo 11 landing site, which is known as Tranquility Base. The name of the crater was formally adopted by the IAU in 1973.
Little West is a small crater in Mare Tranquillitatis on the Moon, east of the Apollo 11 landing site known as Tranquility Base.
Double is a small crater in Mare Tranquillitatis on the Moon, within the Apollo 11 landing site known as Tranquility Base.
Lunar Module Eagle (LM-5) is the spacecraft that served as the crewed lunar lander of Apollo 11, which was the first mission to land humans on the Moon. It was named after the bald eagle, which was featured prominently on the mission insignia. It flew from Earth to lunar orbit on the command module Columbia, and then was flown to the Moon on July 20, 1969, by astronaut Neil Armstrong with navigational assistance from Buzz Aldrin. Eagle's landing created Tranquility Base, named by Armstrong and Aldrin and first announced upon the module's touchdown.
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