Apollo command and service module in the context of AS-202

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 7 (October 11–22, 1968) was the first crewed flight in NASA's Apollo program, and saw the resumption of human spaceflight by the agency after the fire that had killed the three Apollo 1 astronauts during a launch rehearsal test on January 27, 1967. The Apollo 7 crew was commanded by Walter M. Schirra, with Command Module Pilot Donn F. Eisele and Lunar Module pilot R. Walter Cunningham (so designated even though Apollo 7 did not carry a Lunar Module).

The three astronauts were originally designated for the second crewed Apollo flight, and then as backups for Apollo 1. After the Apollo 1 fire, crewed flights were suspended while the cause of the accident was investigated and improvements made to the spacecraft and safety procedures, and uncrewed test flights made. Determined to prevent a repetition of the fire, the crew spent long periods monitoring the construction of their Apollo command and service modules (CSM). Training continued over much of the 21-month pause that followed the Apollo 1 disaster.

The Apollo Lunar Module (LM /ˈlɛm/), 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 space, and remains the only crewed vehicle to land anywhere beyond Earth.

Structurally and aerodynamically incapable of flight through Earth's atmosphere, the two-stage Lunar Module was ferried to lunar orbit attached to the Apollo command and service module (CSM), about twice its mass. Its crew of two flew the Lunar Module from lunar orbit to the Moon's surface. During takeoff, the spent descent stage was used as a launch pad for the ascent stage which then flew back to the command module, after which it was also discarded.

The Apollo spacecraft was composed of three parts designed to accomplish the American Apollo program's goal of landing astronauts on the Moon by the end of the 1960s and returning them safely to Earth. The expendable (single-use) spacecraft consisted of a combined command and service module (CSM) and an Apollo Lunar Module (LM). Two additional components complemented the spacecraft stack for space vehicle assembly: a spacecraft–LM adapter (SLA) designed to shield the LM from the aerodynamic stress of launch and to connect the CSM to the Saturn launch vehicle and a launch escape system (LES) to carry the crew in the command module safely away from the launch vehicle in the event of a launch emergency.

The design was based on the lunar orbit rendezvous approach: two docked spacecraft were sent to the Moon and went into lunar orbit. While the LM separated and landed, the CSM remained in orbit. After the lunar excursion, the two craft rendezvoused and docked in lunar orbit, and the CSM returned the crew to Earth. The command module was the only part of the space vehicle that returned with the crew to the Earth's surface.

The Saturn V is a retired American super heavy-lift launch vehicle developed by NASA under the Apollo program for human exploration of the Moon. The rocket was human-rated, had three stages, and was powered by liquid fuel. Flown from 1967 to 1973, it was used for nine crewed flights to the Moon and to launch Skylab, the first American space station.

As of 2025, the Saturn V remains the only launch vehicle to have carried humans beyond low Earth orbit (LEO). The Saturn V holds the record for the largest payload capacity to low Earth orbit, 140,000 kg (310,000 lb), which included unburned propellant needed to send the Apollo command and service module and Lunar Module to the Moon.

Skylab 2 (also SL-2 and SLM-1) was the first crewed mission to Skylab, the first American orbital space station. The mission was launched on an Apollo command and service module by a Saturn IB rocket on May 25, 1973, and carried NASA astronauts Pete Conrad, Joseph P. Kerwin, Paul J. Weitz to the station. The name Skylab 2 also refers to the vehicle used for that mission. The Skylab 2 mission established a twenty-eight-day record for human spaceflight duration. Its crew was the first space station occupants ever to return safely to Earth – the only previous space station occupants, the crew of the 1971 Soyuz 11 mission that had crewed the Salyut 1 station for twenty-four days, died upon reentry due to unexpected cabin depressurization.

The crewed Skylab missions were officially designated Skylab 2, 3, and 4. Miscommunication about the numbering resulted in the mission emblems reading "Skylab I", "Skylab II", and "Skylab 3" respectively.

Skylab 3 (also SL-3 and SLM-2) was the second crewed mission to the first American space station, Skylab. The mission began on July 28, 1973, with the launch of NASA astronauts Alan Bean, Owen Garriott, and Jack Lousma in the Apollo command and service module on the Saturn IB rocket, and lasted 59 days, 11 hours and 9 minutes. A total of 1,084.7 astronaut-utilization hours were tallied by the Skylab 3 crew performing scientific experiments in the areas of medical activities, solar observations, Earth resources, and other experiments.

The crewed Skylab missions were officially designated Skylab 2, 3, and 4. Miscommunication about the numbering resulted in the mission emblems reading "Skylab I", "Skylab II", and "Skylab 3" respectively.

Skylab 4 (also SL-4 and SLM-3) was the third crewed Skylab mission and placed the third and final crew aboard the first American space station.

The mission began on November 16, 1973, with the launch of Gerald P. Carr, Edward Gibson, and William R. Pogue in an Apollo command and service module on a Saturn IB rocket from the Kennedy Space Center, Florida, and lasted 84 days, one hour and 16 minutes. A total of 6,051 astronaut-utilization hours were tallied by the Skylab 4 astronauts performing scientific experiments in the areas of medical activities, solar observations, Earth resources, observation of the Comet Kohoutek and other experiments.

Command module Columbia (CM-107) is the spacecraft that served as the command module during Apollo 11, which was the first mission to land humans on the Moon. Columbia is the only spacecraft of the 1969 Apollo 11 mission that returned to Earth.

Apollo–Soyuz was the first crewed international space mission, conducted jointly by the United States and the Soviet Union in July 1975. Millions watched on television as an American Apollo spacecraft docked with a Soviet Soyuz capsule. The mission and its symbolic "handshake in space" became an emblem of détente during the Cold War.

The Americans referred to the flight as the Apollo–Soyuz Test Project (ASTP), while the Soviets called it Experimental flight "Soyuz"–"Apollo" (Russian: Экспериментальный полёт «Союз»–«Аполлон», romanized: Eksperimentalniy polyot "Soyuz"–"Apollon") and designated the spacecraft Soyuz 19. The unnumbered Apollo vehicle was a leftover from the canceled Apollo missions program and was the final Apollo module to fly.

Apollo 13 (April 11–17, 1970) was the seventh crewed mission in the Apollo space program and would have been the third Moon landing. The craft was launched from Kennedy Space Center on April 11, 1970, but the landing was aborted after an oxygen tank in the service module (SM) exploded two days into the mission, disabling its electrical and life-support system. The crew, supported by backup systems on the Apollo Lunar Module, instead looped around the Moon in a circumlunar trajectory and returned safely to Earth on April 17. The mission was commanded by Jim Lovell, with Jack Swigert as command module (CM) pilot and Fred Haise as Lunar Module (LM) pilot. Swigert was a late replacement for Ken Mattingly, who was grounded after exposure to rubella.

A routine stir of an oxygen tank ignited damaged wire insulation inside it, causing an explosion that vented the contents of both of the SM's oxygen tanks to space. Without oxygen, needed for breathing and for generating electrical power, the SM's propulsion and life support systems could not operate. The CM's systems had to be shut down to conserve its remaining resources for reentry, forcing the crew to transfer to the LM as a lifeboat. With the lunar landing canceled, mission controllers worked to bring the crew home alive.

The Apollo program was a United States human spaceflight program carried out from 1961 to 1972 by the National Aeronautics and Space Administration (NASA), which landed the first astronauts on the Moon. The program used the Saturn IB and Saturn V launch vehicles to lift the Command/Service Module (CSM) and Lunar Module (LM) spacecraft into space, and the Little Joe II rocket to test a launch escape system which was expected to carry the astronauts to safety in the event of a Saturn failure. Uncrewed test flights beginning in 1966 demonstrated the safety of the launch vehicles and spacecraft to carry astronauts, and four crewed flights beginning in October 1968 demonstrated the ability of the spacecraft to carry out a lunar landing mission.

Apollo achieved the first crewed lunar landing on the Apollo 11 mission, when Neil Armstrong and Buzz Aldrin landed their LM Eagle in the Sea of Tranquility and walked on the lunar surface, while Michael Collins remained in lunar orbit in the CSM Columbia, and all three landed safely on Earth on July 24, 1969. Five subsequent missions landed astronauts on various lunar sites, ending in December 1972 with 12 men having walked on the Moon and 842 pounds (382 kg) of lunar rocks and soil samples returned to Earth, greatly contributing to the understanding of the Moon's composition and geological history.

The Boeing Starliner (or CST-100) is a spacecraft designed to transport crew to and from the International Space Station (ISS) and other low-Earth-orbit destinations. Developed by Boeing under NASA's Commercial Crew Program (CCP), it consists of a reusable crew capsule and an expendable service module.

Slightly larger than the Apollo command module or SpaceX Crew Dragon, but smaller than the Orion capsule, the Starliner can accommodate a crew of up to seven, though NASA plans to fly no more than four. It can remain docked to the ISS for up to seven months and is launched on an Atlas V N22 rocket from Cape Canaveral Space Launch Complex 41 in Florida.

Alexei Arkhipovich Leonov (30 May 1934 – 11 October 2019) was a Soviet and Russian cosmonaut and aviator, Air Force major general, writer, and artist. On 18 March 1965, he became the first person to conduct a spacewalk, exiting the capsule during the Voskhod 2 mission for 12 minutes and 9 seconds. He was also selected to be the first Soviet person to land on the Moon although the project was eventually cancelled.

In July 1975, Leonov commanded the Soyuz capsule in the Apollo–Soyuz mission, which docked in space for two days with an American Apollo capsule.

Apollo 1, initially designated AS-204, was planned to be the first crewed mission of the Apollo program, the American undertaking to land the first man on the Moon. It was planned to launch on February 21, 1967, as the first low Earth orbital test of the Apollo command and service module. The mission never flew; a cabin fire during a launch rehearsal test at Cape Kennedy Air Force Station Launch Complex 34 on January 27 killed all three crew members—Command Pilot Gus Grissom, Senior Pilot Ed White, and Pilot Roger B. Chaffee—and destroyed the command module (CM). The name Apollo 1, chosen by the crew, was made official by NASA in their honor after the fire.

Immediately after the fire, NASA convened an Accident Review Board to determine the cause of the fire, and both chambers of the United States Congress conducted their own committee inquiries to oversee NASA's investigation. The ignition source of the fire was determined to be electrical, and the fire spread rapidly due to combustible nylon material and the high-pressure pure oxygen cabin atmosphere. Rescue was prevented by the plug door hatch, which could not be opened against the internal pressure of the cabin. Because the rocket was unfueled, the test had not been considered hazardous, and emergency preparedness for it was poor.

AS-201 (Also known as SA-201, Apollo 1-A, or Apollo 1 prior to the 1967 pad fire, flown February 26, 1966, was the first uncrewed test flight of an entire production Block I Apollo command and service module and the Saturn IB launch vehicle. The spacecraft consisted of the second Block I command module and the first Block I service module. The suborbital flight was a partially successful demonstration of the service propulsion system and the reaction control systems of both modules, and successfully demonstrated the capability of the command module's heat shield to survive re-entry from low Earth orbit.