Neil Armstrong in the context of "Tranquility Base"

A planetary surface is where the solid or liquid material of certain types of astronomical objects contacts the atmosphere or outer space. Planetary surfaces are found on solid objects of planetary mass, including terrestrial planets (including Earth), dwarf planets, natural satellites, planetesimals and many other small Solar System bodies (SSSBs). The study of planetary surfaces is a field of planetary geology known as surface geology, but also a focus on a number of fields including planetary cartography, topography, geomorphology, atmospheric sciences, and astronomy. Land (or ground) is the term given to non-liquid planetary surfaces. The term landing is used to describe the collision of an object with a planetary surface and is usually at a velocity in which the object can remain intact and remain attached.

In differentiated bodies, the surface is where the crust meets the planetary boundary layer. Anything below this is regarded as being sub-surface or sub-marine. Most bodies more massive than super-Earths, including stars and giant planets, as well as smaller gas dwarfs, transition contiguously between phases, including gas, liquid, and solid. As such, they are generally regarded as lacking surfaces.

The Apollo program, also known as Project Apollo, was the United States human spaceflight program led by NASA, which landed the first humans on the Moon in 1969. Apollo was conceived during Project Mercury and executed after Project Gemini. It was conceived in 1960 as a three-person spacecraft during the presidency of Dwight D. Eisenhower. Apollo was later dedicated to President John F. Kennedy's national goal for the 1960s of "landing a man on the Moon and returning him safely to the Earth" in an address to the U.S. Congress on May 25, 1961.

Kennedy's goal was accomplished on the Apollo 11 mission, when astronauts Neil Armstrong and Buzz Aldrin landed their Apollo Lunar Module (LM) on July 20, 1969, and walked on the lunar surface, while Michael Collins remained in lunar orbit in the command and service module (CSM), and all three landed safely on Earth in the Pacific Ocean on July 24. Five subsequent Apollo missions also landed astronauts on the Moon, the last, Apollo 17, in December 1972. In these six spaceflights, twelve people walked on the Moon.

Apollo 11 was the first spaceflight to land humans on the Moon, conducted by NASA from July 16 to 24, 1969. Commander Neil Armstrong and Lunar Module Pilot Edwin "Buzz" Aldrin landed the Lunar Module Eagle on July 20 at 20:17 UTC, and Armstrong became the first person to step onto the surface about six hours later, at 02:56 UTC on July 21. Aldrin joined him 19 minutes afterward, and together they spent about two and a half hours exploring the site they had named Tranquility Base upon landing. They collected 47.5 pounds (21.5 kg) of lunar material to bring back to Earth before re-entering the Lunar Module. In total, they were on the Moon’s surface for 21 hours, 36 minutes before returning to the Command Module Columbia, which remained in lunar orbit, piloted by Michael Collins.

Apollo 11 was launched by a Saturn V rocket from Kennedy Space Center in Florida, on July 16 at 13:32 UTC (9:32 am EDT, local time). It was the fifth crewed mission of the Apollo program. The Apollo spacecraft consisted of three parts: the command module (CM), which housed the three astronauts and was the only part to return to Earth; the service module (SM), which provided propulsion, electrical power, oxygen, and water to the command module; and the Lunar Module (LM), which had two stages—a descent stage with a large engine and fuel tanks for landing on the Moon, and a lighter ascent stage containing a cabin for two astronauts and a small engine to return them to lunar orbit.

The physical exploration of the Moon began when Luna 2, a space probe launched by the Soviet Union, made a deliberate impact on the surface of the Moon on 14 September, 1959. Prior to that the only available means of lunar exploration had been observations from Earth. The invention of the optical telescope brought about the first leap in the quality of lunar observations. Galileo Galilei is generally credited as the first person to use a telescope for astronomical purposes, having made his own telescope in 1609. The mountains and craters on the lunar surface were among his first observations.

Human exploration of the Moon since Luna 2 has consisted of both crewed and uncrewed missions. NASA's Apollo program has been the only program to successfully land humans on the Moon, which it did six times on the near side in the late 20th century. The first human landing took place in 1969, when the Apollo 11 astronauts Buzz Aldrin and Neil Armstrong touched down on the surface in the region of Mare Tranquillitatis, leaving scientific instruments upon the mission's completion and returning lunar samples to Earth. All lunar missions had taken place on the lunar near side until the first soft landing on the far side of the Moon was made by the CNSA robotic spacecraft Chang'e 4 in early 2019, which successfully deployed the Yutu-2 robotic lunar rover. On 25 June 2024, CNSA's Chang'e 6 conducted the first lunar sample return from the far side of the Moon.

A test pilot is an aircraft pilot with additional training to fly and evaluate experimental, newly produced and modified aircraft with specific maneuvers, known as flight test techniques.

The Apollo/Skylab space suit (sometimes called the Apollo 11 Spacesuit because it was most known for being used in the Apollo 11 Mission) is a class of space suits used in Apollo and Skylab missions. The names for both the Apollo and Skylab space suits were Extravehicular Mobility Unit (EMU). The Apollo EMUs consisted of a Pressure Suit Assembly (PSA) aka "suit" and a Portable Life Support System (PLSS) that was more commonly called the "backpack". The A7L was the PSA model used on the Apollo 7 through 14 missions.

The subsequent Apollo 15-17 lunar missions, Skylab, and Apollo–Soyuz used A7LB pressure suits. Additionally, these pressure suits varied by program usage. For the Skylab EMU, NASA elected to use an umbilical life support system named the Astronaut Life Support Assembly.

Buzz Aldrin (/ˈɔːldrɪn/ AWL-drin; born Edwin Eugene Aldrin Jr.; January 20, 1930) is an American former astronaut, aeronautical 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 deaths of Armstrong in 2012 and pilot Michael Collins in 2021, he is the last surviving Apollo 11 crew member. Following Jim Lovell's death in 2025, Aldrin became the oldest living astronaut.

Born in Glen Ridge, New Jersey, Aldrin graduated third in the class of 1951 from the United States Military Academy at West Point with a degree in mechanical engineering. He was commissioned into the United States Air Force and served as a jet fighter pilot during the Korean War. He flew 66 combat missions and shot down two MiG-15 fighter jets.

Extravehicular activity (EVA) is any activity done by an astronaut in outer space outside a spacecraft. In the absence of a breathable Earthlike atmosphere, the astronaut is completely reliant on a space suit for environmental support. EVA includes spacewalks and lunar or planetary surface exploration (commonly known from 1969 to 1972 as moonwalks). In a stand-up EVA (SEVA), an astronaut stands through an open hatch but does not fully leave the spacecraft. EVAs have been conducted by the Soviet Union/Russia, the United States, and China; astronauts from Canada, Japan, the United Arab Emirates, and the European Space Agency have also participated in EVAs conducted by those nations.

On March 18, 1965, Alexei Leonov became the first human to perform a spacewalk, exiting the Voskhod 2 capsule for 12 minutes and 9 seconds. On July 20, 1969, Neil Armstrong became the first human to perform a moonwalk, outside his lunar lander on Apollo 11 for 2 hours and 31 minutes. In 1984, Svetlana Savitskaya became the first woman to perform a spacewalk, conducting EVA outside the Salyut 7 space station for 3 hours and 35 minutes. On the last three Moon missions, astronauts also performed deep-space EVAs on the return to Earth, to retrieve film canisters from the outside of the spacecraft. American Astronauts Pete Conrad, Joseph Kerwin, and Paul Weitz also used EVA in 1973 to repair launch damage to Skylab, the United States' first space station.

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.

In 1969, Apollo 11 was the first crewed mission to land on the Moon. There were six crewed landings between 1969 and 1972 and numerous uncrewed landings. All crewed missions to the Moon were conducted by the Apollo program, with the last departing the lunar surface in December 1972. After Luna 24 in 1976, there were no soft landings— landings without significant damage—on the Moon until Chang'e 3 in 2013. All soft landings took place on the near side of the Moon until January 2019, when Chang'e 4 made the first landing on the far side of the Moon.