<P> Tranquility Base (Latin: Statio Tranquillitatis) is the site on the Moon where, in 1969, humans landed and walked on another celestial body for the first time . On July 20, 1969, Apollo 11 crewmembers Neil Armstrong and Buzz Aldrin landed their Apollo Lunar Module Eagle at approximately 20: 17: 40 UTC . Six hours later, the two astronauts exited the spacecraft and spent 2 hours 31 minutes on the lunar surface, examining and photographing it, setting up some scientific experiment packages, and collecting 47.5 pounds (21.5 kg) of dirt and rock samples for return to Earth . They lifted off the surface on July 21 at 17: 54 UTC . Tranquility Base has remained unvisited since then . </P> <P> Its lunar coordinates are 00 ° 41 ′ 15" N, 23 ° 26 ′ 00" E, in the south - western corner of the lunar lava - plain called Mare Tranquillitatis ("Sea of Tranquility"), east of the craters Sabine and Ritter, north of the crater Moltke, and near a rille unofficially called "U.S. Highway Number 1". </P> <P> For more than two years, NASA planners considered a collection of 30 potential sites for the first manned landing . Based on high - resolution photographs taken by the Lunar Orbiter spacecraft, and photos and data taken by the unmanned Surveyor landers, this list was narrowed down to five sites located near the lunar equator, ranging between 45 degrees east and west, and 5 degrees north and south of the center of the Moon's facing side; these were numbered 1 to 5 going from east to west . Site number 2, centered at 0 ° 42 ′ 50" N 23 ° 42 ′ 28" E ﻿ / ﻿ 0.71389 ° N 23.70778 ° E ﻿ / 0.71389; 23.70778, 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 11.5 miles (18.5 km) east - west by 3.0 miles (4.8 km) north - south . </P> <P> On the actual landing, a combination of thrust from residual pressure in the docking tunnel that connected the Lunar Module with the Command Module 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 (4.8 km), and thus the computer - targeted landing spot about 4 miles (6.4 km), 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 further downrange . Thus the landing was still within the target ellipse . </P>

Houston tranquility base here. the eagle has landed