The Apollo program, also known as Project Apollo, was the United States human spaceflight program carried out by the National Aeronautics and Space Administration (NASA), which succeeded in preparing and landing the first men on the Moon in 1969. It was first conceived in 1960 during President Dwight D. Eisenhower's administration as a three-person spacecraft to follow the one-person Project Mercury, which put the first Americans in space. 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 Congress on May 25, 1961. It was the third US human spaceflight program to fly, preceded by the two-person Project Gemini conceived in 1961 to extend spaceflight capability in support of Apollo.
Apollo 9 was the third human spaceflight in NASA's Apollo program. Flown in low Earth orbit, it was the second crewed Apollo mission that the United States launched via a Saturn V rocket, and was the first flight of the full Apollo spacecraft: the command and service module (CSM) with the Lunar Module (LM). The mission was flown to qualify the LM for lunar orbit operations in preparation for the first Moon landing by demonstrating its descent and ascent propulsion systems, showing that its crew could fly it independently, then rendezvous and dock with the CSM again, as would be required for the first crewed lunar landing. Other objectives of the flight included firing the LM descent engine to propel the spacecraft stack as a backup mode, and use of the portable life support system backpack outside the LM cabin.
The Apollo Lunar Module, originally designated the Lunar Excursion Module (LEM), was the lunar lander spacecraft that was flown between lunar orbit and the Moon's surface during the United States' Apollo program. It was the first crewed spacecraft to operate exclusively in the airless vacuum of space, and remains the only crewed vehicle to land anywhere beyond Earth.
The Agena Target Vehicle, also known as Gemini-Agena Target Vehicle (GATV), was an uncrewed spacecraft used by NASA during its Gemini program to develop and practice orbital space rendezvous and docking techniques, and to perform large orbital changes, in preparation for the Apollo program lunar missions. The spacecraft was based on Lockheed Aircraft's Agena-D upper stage rocket, fitted with a docking target manufactured by McDonnell Aircraft. The name 'Agena' derived from the star Beta Centauri, also known as Agena. The combined spacecraft was a 26-foot (7.92 m)-long cylinder with a diameter of 5 feet (1.52 m), placed into low Earth orbit with the Atlas-Agena launch vehicle. It carried about 14,000 pounds (6,400 kg) of propellant and gas at launch, and had a gross mass at orbital insertion of about 7,200 pounds (3,300 kg).
John Watts Young was an American astronaut, naval officer and aviator, test pilot, and aeronautical engineer. He became the 9th person to walk on the Moon as commander of the Apollo 16 mission in 1972. He is the only astronaut to fly on four different classes of spacecraft: Gemini, the Apollo command and service module, the Apollo Lunar Module and the Space Shuttle.
Gemini 8 was the sixth crewed spaceflight in NASA's Gemini program. It was launched on March 16, 1966, and was the 14th crewed American flight and the 22nd crewed spaceflight overall. The mission conducted the first docking of two spacecraft in orbit, but also suffered the first critical in-space system failure of a U.S. spacecraft which threatened the lives of the astronauts and required an immediate abort of the mission. The crew returned to Earth safely.
Gemini 11 was the ninth crewed spaceflight mission of NASA's Project Gemini, which flew from September 12 to 15, 1966. It was the 17th crewed American flight and the 25th spaceflight to that time. Astronauts Pete Conrad and Dick Gordon performed the first direct-ascent rendezvous with an Agena Target Vehicle, docking with it 1 hour 34 minutes after launch; used the Agena rocket engine to achieve a record high-apogee Earth orbit; and created a small amount of artificial gravity by spinning the two spacecraft connected by a tether. Gordon also performed two extra-vehicular activities for a total of 2 hours 41 minutes.
The Constellation program was a crewed spaceflight program developed by NASA, the space agency of the United States, from 2005 to 2009. The major goals of the program were "completion of the International Space Station" and a "return to the Moon no later than 2020" with a crewed flight to the planet Mars as the ultimate goal. The program's logo reflected the three stages of the program: the Earth (ISS), the Moon, and finally Mars—while the Mars goal also found expression in the name given to the program's booster rockets: Ares. The technological aims of the program included the regaining of significant astronaut experience beyond low Earth orbit and the development of technologies necessary to enable sustained human presence on other planetary bodies.
Nova was a series of NASA's rocket designs that were proposed both before and after the Saturn V rocket used in the Apollo program. Nova was NASA's first large launcher proposed in 1958, for missions similar to what Saturn V was subsequently used for. The Nova and Saturn V designs closely mirrored each other in basic concept, power, size, and function. Differences were minor but practical, and the Saturn was ultimately selected for the Apollo program, largely because it would reuse existing facilities to a greater extent and could make it to the pad somewhat earlier.
Project Gemini was the second United States human spaceflight program to fly. 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.
A space rendezvous is a set of orbital maneuvers during which two spacecraft, one of which is often a space station, arrive at the same orbit and approach to a very close distance. Rendezvous requires a precise match of the orbital velocities and position vectors of the two spacecraft, allowing them to remain at a constant distance through orbital station-keeping. Rendezvous may or may not be followed by docking or berthing, procedures which bring the spacecraft into physical contact and create a link between them.
Direct ascent is a method of landing a spacecraft on the Moon or another planetary surface directly, without first assembling the vehicle in Earth orbit, or carrying a separate landing vehicle into orbit around the target body. It was proposed as the first method to achieve a crewed lunar landing in the United States Apollo program, but was rejected because it would have required developing a prohibitively large launch vehicle.
Lunar orbit rendezvous (LOR) is a process for landing humans on the Moon and returning them to Earth. It was utilized for the Apollo program missions in the 1960s and 1970s. In a LOR mission, a main spacecraft and a lunar lander travel to lunar orbit. The lunar lander then independently descends to the surface of the Moon, while the main spacecraft remains in lunar orbit. After completion of the mission there, the lander returns to lunar orbit to rendezvous and re-dock with the main spacecraft, then is discarded after transfer of crew and payload. Only the main spacecraft returns to Earth.
The Altair spacecraft, previously known as the Lunar Surface Access Module or LSAM, was the planned lander spacecraft component of NASA's cancelled Constellation program. Astronauts would have used the spacecraft for landings on the Moon, which was intended to begin around 2019. The Altair spacecraft was planned to be used both for lunar sortie and lunar outpost missions.
Thomas Dolan was an American engineer who proposed the first fully developed concept of Lunar orbit rendezvous for the Apollo program while working at Vought Astronautics.
The Ares V was the planned cargo launch component of the cancelled NASA Constellation program, which was to have replaced the Space Shuttle after its retirement in 2011. Ares V was also planned to carry supplies for a human presence on Mars. Ares V and the smaller Ares I were named after Ares, the Greek god of war.
The Atlas-Agena was an American expendable launch system derived from the SM-65 Atlas missile. It was a member of the Atlas family of rockets, and was launched 109 times between 1960 and 1978. It was used to launch the first five Mariner uncrewed probes to the planets Venus and Mars, and the Ranger and Lunar Orbiter uncrewed probes to the Moon. The upper stage was also used as an uncrewed orbital target vehicle for the Gemini crewed spacecraft to practice rendezvous and docking. However, the launch vehicle family was originally developed for the Air Force and most of its launches were classified DoD payloads.
The Saturn C-2 was the second rocket in the Saturn C series studied from 1959 to 1962. The design was for a four-stage launch vehicle that could launch 21,500 kg (47,300 lb) to low Earth orbit and send 6,800 kg (14,900 lb) to the Moon via Trans-Lunar Injection.
The C-2 design concept was for a proposed crewed circumlunar flight and the Earth orbit rendezvous (EOR) missions. It was initially considered for the Apollo lunar landing at the earliest possible date (1967).
The Saturn C-3 was the third rocket in the Saturn C series studied from 1959 to 1962. The design was for a three-stage launch vehicle that could launch 45,000 kilograms (99,000 lb) to low Earth orbit and send 18,000 kilograms (40,000 lb) to the Moon via trans-lunar injection.
Advanced Gemini was a series of proposals that would have extended the Gemini program by the addition of various missions, including crewed low Earth orbit, circumlunar and lunar landing missions. Gemini was the second crewed spaceflight program operated by NASA, and consisted of a two-seat spacecraft capable of maneuvering in orbit, docking with uncrewed spacecraft such as Agena Target Vehicles, and allowing the crew to perform tethered extra-vehicular activities.
