Project Mercury in the context of "Apollo program"

The National Aeronautics and Space Administration (NASA /ˈnæsə/) is an independent agency of the US federal government responsible for the United States' civil space program and for research in aeronautics and space exploration. Headquartered in Washington, D.C., NASA operates ten field centers across the United States and is organized into mission directorates for Science, Space Operations, Exploration Systems Development, Space Technology, Aeronautics Research, and Mission Support. Established in 1958, NASA succeeded the National Advisory Committee for Aeronautics (NACA) to give the American space development effort a distinct civilian orientation, emphasizing peaceful applications in space science. It has since led most of America's space exploration programs, including Project Mercury, Project Gemini, the 1968–1972 Apollo program missions, the Skylab space station, and the Space Shuttle.

The agency maintains major ground and communications infrastructure including the Deep Space Network and the Near Space Network. NASA's science division is focused on better understanding Earth through the Earth Observing System; advancing heliophysics through the efforts of the Science Mission Directorate's Heliophysics Research Program; exploring bodies throughout the Solar System with advanced robotic spacecraft such as New Horizons and planetary rovers such as Perseverance; and researching astrophysics topics, such as the Big Bang, through the James Webb Space Telescope, the four Great Observatories (including the Hubble Space Telescope), and associated programs. The Launch Services Program oversees launch operations for its uncrewed launches.

Human spaceflight (also referred to as crewed spaceflight, or more historically manned spaceflight) is spaceflight with a crew or passengers aboard a spacecraft, often with the spacecraft being operated directly by the onboard human crew. Spacecraft can also be remotely operated from ground stations on Earth, or autonomously, without any direct human involvement. People trained for spaceflight are called astronauts (American or other), cosmonauts (Russian), or taikonauts (Chinese); and non-professionals are referred to as spaceflight participants or spacefarers.

The first human in space was Soviet cosmonaut Yuri Gagarin, who launched as part of the Soviet Union's Vostok program on 12 April 1961 at the beginning of the Space Race. On 5 May 1961, Alan Shepard became the first American in space, as part of Project Mercury. Humans traveled to the Moon nine times between 1968 and 1972 as part of the United States' Apollo program, and have had a continuous presence in space for 25 years and 30 days on the International Space Station (ISS). On 15 October 2003, the first Chinese taikonaut, Yang Liwei, went to space as part of Shenzhou 5, the first Chinese human spaceflight. As of December 2025, humans have not traveled beyond low Earth orbit since the Apollo 17 lunar mission in December 1972.

Project Gemini (IPA: /ˈdʒɛmɪni/) was the second United States human spaceflight program to fly. It was conducted after the first American crewed space program, Project Mercury, while the Apollo program was still in early development. Gemini was conceived in 1961 and concluded in 1966. The Gemini spacecraft carried a two-astronaut crew. Ten Gemini crews and 16 individual astronauts flew low Earth orbit (LEO) missions during 1965 and 1966.

Gemini's objective was the development of space travel techniques to support the Apollo mission to land astronauts on the Moon. In doing so, it allowed the United States to catch up and overcome the lead in human spaceflight capability the Soviet Union had obtained in the early years of the Space Race, by demonstrating mission endurance up to just under 14 days, longer than the eight days required for a round trip to the Moon; methods of performing extravehicular activity (EVA) without tiring; and the orbital maneuvers necessary to achieve rendezvous and docking with another spacecraft. This left Apollo free to pursue its prime mission without spending time developing these techniques.

The Vostok programme (/ˈvɒstɒk, vɒˈstɒk/ VOST-ok, vost-OK; Russian: Восток, IPA: [vɐˈstok] , lit. 'East') was a Soviet human spaceflight project to put the first Soviet cosmonauts into low Earth orbit and return them safely. Competing with the United States Project Mercury, it succeeded in placing the first human into space, Yuri Gagarin, in a single orbit in Vostok 1 on April 12, 1961. The Vostok capsule was developed from the Zenit spy satellite project, and its launch vehicle was adapted from the existing R-7 Semyorka intercontinental ballistic missile (ICBM) design. The name "Vostok" was treated as classified information until Gagarin's flight was first publicly disclosed to the world press.

The programme carried out six crewed spaceflights between 1961 and 1963. The longest flight lasted nearly five days, and the last four were launched in pairs, one day apart. This exceeded Project Mercury's demonstrated capabilities of a longest flight of just over 34 hours, and of single missions.

Alan Bartlett Shepard Jr. (November 18, 1923 – July 21, 1998) was an American astronaut. In 1961, he became the second person and the first American to travel into space and, in 1971, he became the fifth and oldest person to walk on the Moon, at age 47.

A graduate of the United States Naval Academy at Annapolis, Shepard saw action with the surface navy during World War II. He became a naval aviator in 1947, and a test pilot in 1950. He was selected as one of NASA's original Mercury Seven astronauts in 1959, and in May 1961 he made the first crewed Project Mercury flight, Mercury-Redstone 3, in a spacecraft he named Freedom 7. His craft entered space, but was not capable of achieving orbit. He became the second person, and the first American, to travel into space. In the final stages of Project Mercury, Shepard was scheduled to pilot the Mercury-Atlas 10 (MA-10), which was planned as a three-day mission. He named Mercury Spacecraft 15B Freedom 7 II in honor of his first spacecraft, but the mission was canceled.

The John F. Kennedy Space Center (KSC, originally known as the NASA Launch Operations Center), located on Merritt Island, Florida, is one of the National Aeronautics and Space Administration's (NASA) ten field centers. Since 1968, KSC has been NASA's primary launch center of American spaceflight, research, and technology. Launch operations for the Apollo, Skylab and Space Shuttle programs were carried out from Kennedy Space Center Launch Complex 39 and managed by KSC. Located on the east coast of Florida, KSC is adjacent to Cape Canaveral Space Force Station (CCSFS). The management of the two entities work very closely together, share resources, and operate facilities on each other's property.

Though the first Apollo flights and all Project Mercury and Project Gemini flights took off from the then-Cape Canaveral Air Force Station, the launches were managed by KSC and its previous organization, the Launch Operations Directorate. Starting with the fourth Gemini mission, the NASA launch control center in Florida (Mercury Control Center, later the Launch Control Center) began handing off control of the vehicle to the Mission Control Center in Houston, shortly after liftoff; in prior missions it held control throughout the entire mission.

A launch escape system (LES) or launch abort system (LAS) is a crew-safety system connected to a space capsule. It is used in the event of a critical emergency to quickly separate the capsule from its launch vehicle in case of an emergency requiring the abort of the launch, such as an impending explosion. The LES is typically controlled by a combination of automatic rocket failure detection, and a manual activation for the crew commander's use. The LES may be used while the launch vehicle is on the launch pad, or during its ascent. Such systems are usually of three types:

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  A solid-fueled rocket, mounted above the capsule on a tower, which delivers a relatively large thrust for a brief period of time to send the capsule a safe distance away from the launch vehicle, at which point the capsule's parachute recovery system can be used for a safe landing on ground or water. The escape tower and rocket are jettisoned from the space vehicle in a normal flight at the point where it is either no longer needed, or cannot be effectively used to abort the flight. These have been used on the Mercury, Apollo, Soyuz, and Shenzhou capsules.
• The crew are seated in seats that eject themselves (ejection seats) as used in military aircraft; each crew member returns to Earth with an individual parachute. Such systems are effective only in a limited range of altitudes and speeds. These have been used on the Vostok and Gemini capsules, and Space Shuttle Columbia during its testing phase.
• Thrusters integrated in the capsule or its detachable service module having the same function as an escape tower, as in the case of Crew Dragon, Starliner and New Shepard.