Moon landing

A Moon landing is the arrival of a spacecraft on the surface of the Moon. This includes both manned and unmanned (robotic) missions. The first human-made object to reach the surface of the Moon was the Soviet Union's Luna 2 mission, on 13 September 1959.

The United States' Apollo 11 was the first manned mission to land on the Moon, on 20 July 1969. There have been six manned U.S. landings (between 1969 and 1972) and numerous unmanned landings, with no soft landings happening from 22 August 1976 until 14 December 2013.

To date, the United States is the only country to have successfully conducted manned missions to the Moon, with the last departing the lunar surface in December, 1972.

Unmanned landings

After the unsuccessful attempt by the Luna 1 to land on the moon in 1959, the Soviet Union performed the first hard (unpowered) moon landing later that same year with the Luna 2 spacecraft, a feat the U.S. duplicated in 1962 with Ranger 4. Since then, twelve Soviet and U.S. spacecraft have used braking rockets to make soft landings and perform scientific operations on the lunar surface, between 1966 and 1976. In 1966 the USSR accomplished the first soft landings and took the first pictures from the lunar surface during the Luna 9 and Luna 13 missions. The U.S. followed with five unmanned Surveyor soft landings.

Moon

The Moon (in Greek: σελήνη Selene, in Latin: Luna) is Earth's only natural satellite. It is one of the largest natural satellites in the Solar System, and, among planetary satellites, the largest relative to the size of the planet it orbits (its primary). It is the second-densest satellite among those whose densities are known (after Jupiter's satellite Io).

The Moon is thought to have formed approximately 4.5 billion years ago, not long after Earth. There are several hypotheses for its origin; the most widely accepted explanation is that the Moon formed from the debris left over after a giant impact between Earth and a Mars-sized body called Theia.

The Moon is in synchronous rotation with Earth, always showing the same face with its near side marked by dark volcanic maria that fill between the bright ancient crustal highlands and the prominent impact craters. It is the second-brightest regularly visible celestial object in Earth's sky after the Sun, as measured by illuminance on Earth's surface. Although it can appear a very bright white, its surface is actually dark, with a reflectance just slightly higher than that of worn asphalt. Its prominence in the sky and its regular cycle of phases have, since ancient times, made the Moon an important cultural influence on language, calendars, art, and mythology.

Apollo 11

Apollo 11 was the first spaceflight that landed humans on the Moon. Americans Neil Armstrong and Buzz Aldrin landed on July 20, 1969, at 20:18 UTC (46 years ago). Armstrong became the first to step onto the lunar surface six hours later on July 21 at 02:56 UTC. Armstrong spent about two and a half hours outside the spacecraft, and together with Aldrin collected 47.5 pounds (21.5 kg) of lunar material for return to Earth. The third member of the mission, Michael Collins, piloted the command spacecraft alone in lunar orbit until Armstrong and Aldrin returned to it just under a day later for the trip back to Earth.

Launched by a Saturn V rocket from Kennedy Space Center in Merritt Island, Florida, on July 16, Apollo 11 was the fifth manned mission of NASA's Apollo program. The Apollo spacecraft had three parts: a Command Module (CM) with a cabin for the three astronauts, and the only part that landed back on Earth; a Service Module (SM), which supported the Command Module with propulsion, electrical power, oxygen, and water; and a Lunar Module (LM) for landing on the Moon (which itself was composed of two parts). After being sent toward the Moon by the Saturn V's upper stage, the astronauts separated the spacecraft from it and traveled for three days until they entered into lunar orbit. Armstrong and Aldrin then moved into the Lunar Module and landed in the Sea of Tranquility. They stayed a total of about 21½ hours on the lunar surface. After lifting off in the upper part of the Lunar Module and rejoining Collins in the Command Module, they returned to Earth and landed in the Pacific Ocean on July 24.

Neil Armstrong

Neil Alden Armstrong (August 5, 1930 – August 25, 2012) was an American astronaut and the first person to walk on the Moon. He was also an aerospace engineer, naval aviator, test pilot, and university professor. Before becoming an astronaut, Armstrong was an officer in the U.S. Navy and served in the Korean War. After the war, he earned his bachelor's degree at Purdue University and served as a test pilot at the National Advisory Committee for Aeronautics (NACA) High-Speed Flight Station, where he logged over 900 flights. He later completed graduate studies at the University of Southern California.

A participant in the U.S. Air Force's Man in Space Soonest and X-20 Dyna-Soar human spaceflight programs, Armstrong joined the NASA Astronaut Corps in 1962. He made his first space flight as command pilot of Gemini 8 in March 1966, becoming NASA's first civilian astronaut to fly in space. He performed the first docking of two spacecraft, with pilot David Scott. This mission was aborted after Armstrong used some of his reentry control fuel to prevent a dangerous spin caused by a stuck thruster, in the first in-flight space emergency.

Landing

Landing is the last part of a flight, where a flying animal, aircraft, or spacecraft returns to the ground. When the flying object returns to water, the process is called alighting, although it is commonly called "landing," "touchdown" or "splashdown" as well. A normal aircraft flight would include several parts of flight including taxi, takeoff, climb, cruise, descent and landing.

Aircraft

Aircraft usually land at an airport on a firm runway or helicopter landing pad, generally constructed of asphalt concrete, concrete, gravel or grass. Aircraft equipped with pontoons (floatplane) or with a boat hull-shaped fuselage (a flying boat) are able to land on water. Aircraft also sometimes use skis to land on snow or ice.

To land, the airspeed and the rate of descent are reduced such that the object descends at a low enough rate to allow for a gentle touch down. Landing is accomplished by slowing down and descending to the runway. This speed reduction is accomplished by reducing thrust and/or inducing a greater amount of drag using flaps, landing gear or speed brakes. When a fixed-wing aircraft approaches the ground, the pilot will move the control column back to execute a flare or round-out. This increases the angle of attack. Progressive movement of the control column back will allow the aircraft to settle onto the runway at minimum speed, landing on its main wheels first in the case of a tricycle gear aircraft or on all three wheels simultaneously in the case of a conventional landing gear-equipped aircraft, commonly referred to as a "taildragger". This is known as flaring.