Tranquility Base

Tranquility Base 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 47.5lb 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.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, east of the craters Sabine and Ritter, north of the crater Moltke, and near a rille unofficially called "U.S. Highway Number 1".Site selectionFor 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, 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 11.5mi east-west by 3.0mi north-south.