Apollo 12 in the context of Canceled Apollo missions

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.

The NASA Astronaut Corps is a unit of the United States National Aeronautics and Space Administration (NASA) that selects, trains, and provides astronauts as crew members for U.S. and international space missions. It is based at Johnson Space Center in Houston, Texas.

Richard Francis "Dick" Gordon Jr. (October 5, 1929 – November 6, 2017) was an American naval officer and aviator, test pilot, and NASA astronaut, and a football executive. He was one of 24 people to have flown to the Moon, as command module pilot of the Apollo 12 mission, which orbited the Moon 45 times. Gordon had already flown in space as the pilot of the 1966 Gemini 11 mission.

Charles "Pete" Conrad Jr. (June 2, 1930 – July 8, 1999) was an American NASA astronaut, aeronautical engineer, naval officer, aviator, and test pilot who commanded the Apollo 12 mission, on which he became the third person to walk on the Moon. Conrad was selected for NASA's second astronaut class in 1962.

Conrad was born in Philadelphia, Pennsylvania. Despite having dyslexia, he earned his Bachelor of Science degree in aeronautical engineering from Princeton University—being the first Ivy League astronaut—and joined the U.S. Navy. In 1954, Conrad received his naval aviator wings, served as a fighter pilot and, after graduating from the U.S. Naval Test Pilot School (Class 20), as a project test pilot. In 1959, he was an astronaut candidate for Project Mercury.

A wrinkle ridge is a type of feature commonly found on lunar maria, or basalt plains. These features are low, sinuous ridges formed on the mare surface that can extend for up to several hundred kilometers. Wrinkle ridges are tectonic features created after the lava cooled and solidified. They frequently outline ring structures buried within the mare, follow circular patterns outlining the mare, or intersect protruding peaks. They are sometimes called veins due to their resemblance to the veins that protrude from beneath the skin.