North American Rockwell Apollo Command/Service Module
North American Rockwell · Three-Seat Crewed Lunar Transfer Capsule · USA · Early Jet (1946–1969)
The Apollo Command and Service Module (CSM) was the U.S. spacecraft that carried 24 astronauts to the Moon — and its lunar mission profile remains unique and returned them to Earth between 1968 and 1972 — the only piloted spacecraft to ever leave low Earth orbit. Built by North American Rockwell (now Boeing) under NASA contract starting in 1961, the CSM consisted of two parts: the Command Module (the conical capsule that returned astronauts to Earth) and the Service Module (the cylindrical engine-and-propellant section that carried the CSM to lunar orbit and back). 19 CSMs flew across the Apollo, Apollo-Soyuz, and Skylab programmes.
The Command Module was a 3.9 m (12.8 ft) wide bell-shaped conical capsule with crew capacity of three astronauts. The Service Module behind it was 7.6 m (25 ft) long and 4.0 m (13 ft) diameter, carrying the AJ-10 main engine (91 kN), reaction control system thrusters, fuel and oxidizer tanks, and the consumables (oxygen, water, electrical generation) needed for two-week-long lunar missions. Total CSM mass: about 28-29 tonnes fully loaded. Combined Command Module + Service Module + Lunar Module + Saturn V rocket put Apollo astronauts on the lunar surface for nine missions (Apollo 11 through Apollo 17, except Apollo 13).
The CSM was the spacecraft that almost killed the Apollo 11 mission and almost saved the Apollo 13 mission. On 27 January 1967 the Apollo 1 crew (Grissom, White, Chaffee) was killed in a launchpad fire during a ground test, attributable to a flammable atmosphere and electrical short in the Command Module — leading to extensive Block II redesign of the CSM that delayed the lunar-landing programme by 21 months but produced a much-safer spacecraft. On Apollo 13 (April 1970), an oxygen-tank rupture in the Service Module 56 hours into the mission required the crew to use the Lunar Module as a lifeboat, returning to Earth via free-return trajectory using the LM's life-support systems while the CSM was powered down. All three crew members returned safely.
The CSM made its last crewed flight on the Apollo-Soyuz Test Project (15-24 July 1975), where Stafford, Brand, and Slayton docked with a Soviet Soyuz capsule in the first international crewed-spacecraft rendezvous. Subsequent Apollo CSMs scheduled for crewed flight were converted into Skylab ferry vehicles (3 missions in 1973-1974) before the programme ended. Several original CSMs survive in museums: Apollo 11 (Smithsonian), Apollo 13 (Cosmosphere), Apollo 14 (Kennedy Space Center), Apollo 17 (Johnson Space Center), Apollo Skylab 4 (Smithsonian Udvar-Hazy), and Apollo-Soyuz Test Project (California Science Center).
For Kids — a shorter, friendlier version
The Apollo Command Module is the spacecraft that took American astronauts to the Moon and brought them home safely. It looked like a giant silver Hershey's Kiss — a cone shape about 11 feet tall, just big enough for three people squeezed together.
From 1968 to 1972, eleven Apollo missions used these modules. Six of them landed on the Moon. The most famous was Apollo 11 in July 1969, when Neil Armstrong stepped onto the Moon and said, "That's one small step for man, one giant leap for mankind."
The Command Module was strong but very small inside. Three astronauts had to live and work in a space smaller than a minivan for almost two weeks. They slept in hammocks tied to the walls, ate freeze-dried food from plastic bags, and used special toilets that didn't need gravity.
When the astronauts came home, the Command Module was the only part that returned to Earth. The bigger part (called the Service Module) burned up in the atmosphere, and the Command Module came down like a meteor — moving 25,000 miles per hour. A heat shield on the bottom protected it from the heat. Three giant parachutes opened in the last few minutes, and it splashed down in the ocean. Today you can see real Apollo Command Modules in museums across America.
Fun Facts
- The Apollo Command Module flew over a million times faster than a person can walk.
- Three astronauts squeezed into a space smaller than the inside of a family van for up to 12 days.
- The heat shield got hotter than 5,000°F coming back to Earth — hotter than the surface of the sun's outer layer.
- Astronauts couldn't take showers — they used wet wipes for 12 days straight.
- The Command Module had no toilet seat. Astronauts strapped themselves to a tube that sucked everything away in zero gravity.
- Apollo computers had less power than a modern pocket calculator, but they still flew people to the Moon.
- Twelve different astronauts walked on the Moon between 1969 and 1972. Six Command Modules brought them all home safely.
Kids’ Questions
Why did astronauts go to the Moon?
In the 1960s, the United States and the Soviet Union (Russia) were in a race to see who could reach the Moon first. It was called the Space Race, and going to the Moon was seen as proof of which country had better science and technology. President John F. Kennedy promised in 1961 that America would land on the Moon by the end of that decade — and Apollo 11 did it with five months to spare in 1969.
Has anyone walked on the Moon recently?
Not yet — the last astronaut walked on the Moon in December 1972. After Apollo, the U.S. focused on the Space Shuttle and the International Space Station instead. But NASA is now working on a new program called Artemis, which plans to send astronauts back to the Moon. The first crewed Artemis flight is scheduled for 2025, and the next Moon landing for 2026 or 2027.
Variants
- Block I CSM
- Original 1965-1967 design. Killed Grissom, White, and Chaffee in the Apollo 1 launchpad fire on 27 January 1967. The Block I design used a flammable pure-oxygen atmosphere and unsealed wiring; never flew crewed.
- Block II CSM
- Post-Apollo 1 redesign with non-flammable atmosphere, sealed wiring, and outward-opening hatch. Flew all 11 Apollo crewed missions (Apollo 7-17), three Skylab ferry missions, and the Apollo-Soyuz Test Project.
Notable Operators
- NASA
- Mission sponsor and operator. Mission control at NASA Houston (Mission Control). Launches from Kennedy Space Center on Saturn V (lunar missions) or Saturn IB (Skylab + ASTP).
Frequently Asked Questions
How many Apollo CSMs were built?
19 CSMs flown across all programmes: Apollo 7-17 (11 lunar+Earth-orbit missions, Apollo 7 + 9 + 10 in Earth orbit, Apollo 8 + 10-17 in lunar orbit), Skylab 2/3/4 (three crewed Skylab missions in 1973-1974), and the Apollo-Soyuz Test Project (1975). The Apollo 1 capsule was a Block I airframe destroyed in the 1967 launchpad fire.
What is the difference between Command Module and Service Module?
The Command Module is the conical 3.9 m capsule that astronauts ride in and that returns to Earth on a parachute. The Service Module is the cylindrical 7.6 m engine-and-propellant section behind it that carries the CSM into lunar orbit and back. The Service Module is jettisoned shortly before re-entry; only the Command Module returns to Earth.
What happened on Apollo 13?
An oxygen tank in the Service Module ruptured 56 hours into the flight (13 April 1970), crippling the CSM. The crew (Lovell, Swigert, Haise) used the Lunar Module as a lifeboat for life support, navigated by free-return trajectory back to Earth, and powered the CSM up only briefly for re-entry. All three returned safely on 17 April 1970. The cause was traced to thermostat failure during a ground test; the Apollo 14 CSM had additional safeguards.
Did the Apollo CSM go to the Moon's surface?
No — the CSM stayed in lunar orbit. The Lunar Module (LM) descended to the surface and ascended back to dock with the CSM. The CSM provided the trans-Earth injection burn to leave lunar orbit and return home. Mike Collins on Apollo 11 was the first astronaut to remain alone in lunar orbit while his crewmates explored the surface.
Are any Apollo CSMs preserved?
Yes — most are: Apollo 11 (Smithsonian NASM), Apollo 12 (Virginia Air and Space Center), Apollo 13 (Cosmosphere, Kansas), Apollo 14 (Kennedy Space Center), Apollo 15 (USAF Museum), Apollo 16 (Hutchinson Cosmosphere), Apollo 17 (Johnson Space Center), Skylab 4 (Smithsonian Udvar-Hazy), and ASTP (California Science Center).
Sources
See Also
- Saturn V — Launch vehicle for lunar Apollo missions
- Mercury Capsule — Predecessor U.S. crewed spacecraft (single-seat)
- Soyuz spacecraft — Soviet counterpart crewed spacecraft (Apollo-Soyuz Test Project partner)
- Space Shuttle Orbiter — U.S. successor crewed reusable spacecraft
- SpaceX Crew Dragon — Modern U.S. crewed-capsule descendant