Apollo Command/Service Module

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Apollo Command/Service Module

The Command/Service Module (CSM) was a spacecraft

Spacecraft

A spacecraft is a Craft or machine designed for spaceflight. On a sub-orbital spaceflight, a spacecraft enters outer space then returns to the Earth....
built for NASA

NASA

The National Aeronautics and Space Administration is an agency of the Federal government of the United States, responsible for the nation's public list of space agencies....
by North American Aviation

North American Aviation

North American Aviation was a major United States aircraft manufacturer, responsible for a number of historic aircraft, including the T-6 Texan trainer, the P-51 Mustang fighter aircraft, the B-25 Mitchell bomber, the F-86 Sabre jet aircraft fighter, and the X-15 rocket plane, as well as Apollo Apollo spacecraft, the second stage of the Satu...
. It was one of the two spacecraft that were utilized for the Apollo program, along with the Lunar Module

Apollo Lunar Module

The Apollo Lunar Module was the Lander portion of the Apollo spacecraft built for the United States Apollo program by Grumman to achieve the transit from cislunar orbit to the surface and back....
, to land astronauts on the Moon

Moon

The Moon is Earth's only natural satellite and the List of natural satellites by diameter satellite in the Solar System. The average centre-to-centre distance from the Earth to the Moon is km, about thirty times the diameter of the Earth....
. Together they were called the Apollo spacecraft

Apollo spacecraft

The Apollo spacecraft was designed as part of the Project Apollo, by the United States in the early 1960s to land men on the moon before 1970 and return them safely to earth....
. After the conclusion of the Apollo program, the CSM saw service as a ferry for the Skylab

Skylab

Skylab was the first space station the United States launched into orbit, and the second space station ever visited by a human crew. The 100 ton space station was in Earth's orbit from 1973 to 1979, and it was visited by crews three times in 1973 and 1974....
program and for the Apollo-Soyuz Test Project

Apollo-Soyuz Test Project

mission_name = ASTP Apollo|insignia = ASTPpatch.png|crew_size = 3|command_module = CMmass |spacecraft_mass = total...
where a CSM rendezvoused in orbit

ORBit

ORBit is a Common Object Request Broker Architecture 2.4 compliant Object Request Broker . It features mature C , C++ and Python bindings, and less developed bindings for Perl, Lisp , Pascal , Ruby , and Tcl....
with a Soviet

Soviet Union

The Union of Soviet Socialist Republics was a Constitution of the Soviet Union socialist state that existed in Eurasia from 1922 to 1991.The name is a translation of the , romanization of Russian Soyuz Sovetskikh Sotsialisticheskikh Respublik, abbreviated ????, SSSR....
Soyuz spacecraft

Soyuz spacecraft

Soyuz ; English: Union) is a series of spacecraft designed for the Soviet space program by the S.P. Korolev Rocket and Space Corporation Energia....
.

The spacecraft, as its name suggests, consisted of two segments, the command module (reentry capsule

Reentry capsule

A reentry capsule is the portion of a spacecraft which returns to Earth following a space flight. The shape is determined partly by aerodynamics; a capsule is aerodynamically stable falling blunt end first, which allows only the blunt end to require a heat shield for atmospheric reentry....
) which housed the crew and the equipment needed for re-entry

Re-Entry

"Re-Entry" was the second album released by United Kingdom R&B / Hip hop music collective Big Brovaz. After the album was delayed in May 2006, the band finally release the follow-up to "Nu Flow" on 9 April, 2007....
and splashdown

Splashdown (spacecraft landing)

Splashdown is the method of landing a spacecraft by parachute in a body of water. It was used by American manned spacecraft prior to the Space Shuttle program....
, and a service module
Service module

A service module is a spacecraft compartment containing a variety of support systems used for spacecraft operations, but not any habitable area....
that provided propulsion, electrical power and storage for various consumables required during a mission.

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Encyclopedia

The Command/Service Module (CSM) was a spacecraft

Spacecraft

A spacecraft is a Craft or machine designed for spaceflight. On a sub-orbital spaceflight, a spacecraft enters outer space then returns to the Earth....
built for NASA

NASA

North American Aviation

Apollo Lunar Module

Moon

Apollo spacecraft

Skylab

Apollo-Soyuz Test Project

mission_name = ASTP Apollo|insignia = ASTPpatch.png|crew_size = 3|command_module = CMmass |spacecraft_mass = total...
where a CSM rendezvoused in orbit

ORBit

Soviet Union

Soyuz spacecraft

Reentry capsule

Re-Entry

Splashdown (spacecraft landing)

Command Module (CM)

The Command Module was a truncated cone measuring 10 feet 7 inches (3.2 m) tall and having a diameter of 12 feet 10 inches (3.9 m) across the base. The forward compartment

Compartment

In heraldry, a compartment is a design placed under the Shield , usually rocks, a grassy mount, or some sort of other landscape upon which the supporters are depicted as standing....
contained two reaction control engines

Thruster

A thruster is a small spacecraft propulsion used by spacecraft and watercraft for Orbital stationkeeping, attitude control, or long duration low thrust acceleration....
, the docking tunnel, and the components of the Earth Landing System. The inner pressure vessel housed the crew accommodations, equipment bays, controls and displays, and many spacecraft

Spacecraft

A spacecraft is a Craft or machine designed for spaceflight. On a sub-orbital spaceflight, a spacecraft enters outer space then returns to the Earth....
systems. The last section, the aft compartment, contained 10 reaction control engines and their related propellant

Propellant

A propellant is a material that is used to move an object. This will often involve a chemical reaction. It may be a gas, liquid, Plasma , or, before the chemical reaction, a solid....
tanks, fresh water tanks, and the CSM umbilical cables.

Construction

The command module's inner structure was an aluminum "sandwich" consisting of a welded aluminum inner skin, a thermally bonded honeycomb

Honeycomb

A honeycomb is a mass of hexagonal waxcells built by honey bees in their beehive to contain their larva and stores of honey and pollen.beekeeping may remove the entire honeycomb to harvest honey....
core, and a thin aluminum "face sheet". The central heat shield

Heat shield

A heat shield is a protective layer on a spacecraft or ballistic missile that is designed to protect it from the high temperature of atmospheric entry, on a body with an atmosphere, such as Earth, Mars and Venus....
consisted of 40 individual panels interspersed with several holes and openings for the reaction control engines and after-compartment equipment access. The central compartment structure consisted of an inner aluminum face sheet with a steel honeycomb core, a glass-phenolic ablative

Ablative armor

Ablative armor is armor designed to negate damage by itself being damaged or destroyed through the process of ablation. In contemporary spacecraft, ablative plating is most frequently seen as an ablative heat shield for a vehicle that must enter atmosphere from orbit, such as on nuclear warheads, or space vehicles like the Mars Pathfinder pro...
honeycomb heat shield, a layer of q-felt fibrous insulation

Thermal insulation

The term thermal insulation can refer to materials used to reduce the rate of heat transfer, or the methods and processes used to reduce heat transfer....
, a pore seal, a moisture barrier, and a layer of aluminized PET film

PET film (biaxially oriented)

Biaxially-oriented polyethylene terephthalate polyester film is used for its high tensile strength, chemical stability and Shape strength of materials, Transparency , reflective, gas and aroma barrier properties and electricity Electrical insulation....
thermal strips.

The aft heat shield consisted of four brazed honeycomb panels, four spot-welded sheet metal fairings, and a circumferential ring. The fairing segments were attached to the honeycomb panels and ring with conventional fasteners. The steel honeycomb core and outer face sheets were then thermally bonded to the inner skin in a giant autoclave

Autoclave

An autoclave is a pressure vessel designed to heat aqueous solutions above their boiling point at normal atmospheric pressure to achieve sterilization ....
. The aft heat shield is nearly identical to the central, with the exception of the outer alluminized PET film

PET film (biaxially oriented)

Earth landing system

The components of the ELS were housed around the forward docking tunnel. The forward compartment was separated from the central by a bulkhead and was divided into four 90-degree wedges. The ELS consists of three main parachute

Parachute

A parachute is a device used to slow the motion of an object through an atmosphere by creating Drag .Parachutes are made out of cloth, most commonly nylon....
s, three pilot parachutes, two drogue parachute motors, three upright bags, a sea recovery cable, a dye marker, and a swimmer umbilical.

The CM's center of mass was offset a foot or so from the center of pressure (along the symmetry axis). This provided a rotational moment during reentry, angling the capsule and providing some lift (a lift to drag ratio of about 0.368). The capsule was then steered by rotating the capsule using thrusters; when no steering was required, the capsule was spun slowly, and the lift effects cancelled out. This system greatly reduced the g-force

G-force

The g-force of an object is its acceleration relative to free-fall. The unit of measure used is informally but commonly known as the "gee" , symbolized as g . An acceleration of 1 g is generally considered as equal to standard gravity , which is defined as precisely metre per second square...
experienced by the astronauts, permitted a reasonable amount of cross range and allowed the capsule to be targeted within a few miles.

At 24,000 feet (7.3 km) the forward heat shield was jettisoned using four pressurized-gas compression springs. The drogue parachutes were then released and slowed the spacecraft to 125 miles per hour (201 km/h). At 10,700 feet (3.3 km) the drogues were jettisoned. The pilot parachutes were deployed, which pulled out the mains. These slowed the CM to 22 miles per hour (35 km/h). The Apollo CM can safely parachute to an ocean landing with at least two parachutes (as it happened on Apollo 15

Apollo 15

Apollo 15 was the ninth manned mission in the Apollo program and the fourth mission to land on the Moon. It was the first of what were termed "J missions", long duration stays on the Moon with a greater focus on science than had been possible on previous missions....
), as the third parachute acted as a safety precaution.

Reaction control system

The Command Module attitude control system consisted of 12 x 93 lbf (414 N) maneuvering jets; 10 were located in the aft compartment, and 2 pitch motors in the forward compartment. Four tanks stored 122 kg of N₂O₄ oxidizer and MMH

Monomethylhydrazine

Monomethylhydrazine is a Volatility hydrazine with the chemical formula CarbonHydrogen3Nitrogen2Hydrogen3. It is used as a rocket fuel in bipropellant rocket engines....
fuel. They were pressurized by 0.5 kg of helium

Helium

Helium is a colorless, odorless, tasteless, non-toxic, inert monatomic chemical element that heads the noble gas group in the periodic table and whose atomic number is 2....
stored at 28.6 MPa in two tanks.

Hatches

The forward docking hatch was mounted at the top of the docking tunnel. It was 30 inches (760 mm) in diameter and weighed . It was constructed from two machined rings that were weld-joined to a brazed honeycomb panel. The exterior side was covered with a of insulation and a layer of aluminum foil. It was latched in six places and operated by a pump handle. At the center was a pressure equalization

Equalization

Equalization, equalisation or EQ is the process of using passive or active electronic elements or digital algorithms for the purpose of altering the frequency response characteristics of a system....
valve

Valve

A valve is a device that regulates the flow of a fluid by opening, closing, or partially obstructing various passageways. Valves are technically pipe Piping and plumbing fittings, but are usually discussed as a separate category....
, used to equalize the pressure in the tunnel and lunar module before the hatch was removed.

The Unified Crew Hatch (UCH) measured high, 34 inches (864 mm) wide, and weighed . It was operated by a pump handle, which drove a ratchet

Ratchet

A ratchet may refer to:* Ratchet , a mechanical device for controlling rotational motion* Socket wrench, a tool that makes use of the above mechanical device...
mechanism to open or close fifteen latches simultaneously.

Docking assembly

The docking probe allowed the command and lunar modules to "link up" and maintain a pressure-tight seal during the mission. It was mounted to the docking tunnel in three places, and was designed to fold easily for storage.

The docking probe consisted of three shock attenuators, three tension linkages, a retractable and extendable probe, and two power umbilicals. Before docking, a crewman in the CM extended the probe. When it came in contact with the drogue, three capture latches in the probe head held the two modules together. The probe was retracted, pulling the CM and LM together. Twelve latches attached to the forward docking ring automatically activated to form an air-tight seal.

At LM separation, the probe and forward docking ring were pyrotechnically separated leaving all docking equipment with the lunar module.

Cabin interior arrangement

The central pressure vessel of the command module was its sole habitable compartment. It had an interior volume of 210 cubic feet (5.9 m³) and housed the main control panels, crew seats, guidance and navigation systems, food and equipment lockers, the waste management system, and the docking tunnel.

Dominating the forward section of the cabin was the crescent-shaped main display panel measuring nearly seven feet (2.1 m) wide and three feet (0.9 m) tall. It was arranged into three panels, each emphasizing the duties of each crew member. The mission commander’s panel (left side) included the velocity

Velocity

In physics, velocity is defined as the Derivative of Position vector. It is a vector physical quantity; both speed and direction are required to define it....
, attitude

Attitude

Attitude may refer to:...
, and altitude

Altitude

Altitude has multiple uses depending on the context in which it is used . As a general definition, altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object....
indicators, the primary flight controls, and the main FDAI (Flight Director Attitude Indicator).

The CM pilot’s panel (middle) included the Guidance and Navigation computer

Apollo Guidance Computer

The Apollo Guidance Computer was the first recognizably modern embedded system, used in Real-time computing by astronaut pilot to collect and provide flight information, and to automatically control all of the navigational functions of the Apollo spacecraft....
controls, the caution and warning indicator panel, the event timer, the service propulsion system and RCS controls, and the environmental control system controls.

The LM pilot’s panel (right) included the fuel cell

Fuel cell

A fuel cell is an Electrochemistry conversion device. It produces electricity from fuel and an Oxidizing agent , which react in the presence of an electrolyte....
gauges and controls, the electrical and battery

Battery (electricity)

In electronics, a battery or voltaic cell is a combination of one or more electrochemical cell Galvanic cells which store chemical energy that can be converted into electric potential energy, creating electricity....
controls, and the communications controls.

Flanking the right side of the main panel were sets of smaller control panels. On the left side were a circuit breaker

Circuit breaker

A circuit breaker is an automatically-operated Electricity switch designed to protect an Electrical network from damage caused by Overcurrent or short circuit....
panel, audio controls, and the SCS power controls. On the right were additional circuit breakers and a redundant audio control panel, along with the environmental control switches. In total, the command module panels included 24 instruments, 566 switches, 40 event indicators, and 71 lights.

The three crew couches were constructed from hollow steel

Steel

Steel is an alloy consisting mostly of iron, with a carbon content between 0.2% and 2.14% by weight , depending on grade. Carbon is the most cost-effective alloying material for iron, but various other alloying elements are used such as manganese, chromium, vanadium, and tungsten....
tubing and covered in a heavy, fireproof cloth, known as Armalon. The leg pans of the two outer couches could be folded in a variety of positions, while the hip pan of the center couch can be disconnected and laid on the aft bulkhead. One rotational and one translation hand controller was installed on the armrests of the commander’s couch. The LM pilot and CM pilot couches had rotational controllers only. The couches rested on eight shock attenuation struts to ease the impact of splashdown.

There are a total of six equipment bays in the cabin:

*The lower equipment bay, which houses the guidance and control telescope

Telescope

A telescope is an instrument designed for the observation of remote objects by the collection of electromagnetic radiation. The first known practically functioning telescopes were invented in the Netherlands at the beginning of the 17th century....
, various communications beacons, the SCS gyro

Gyro

Gyro may refer to:*An abbreviation for autogyro, a type of rotary-wing aircraft*Gyros, a Greek pita sandwich or the rotisseried meat it contains...
assemblies, the command module computer

Computer

A computer is a machine that manipulates Data according to a list of Code .The first devices that resemble modern computers date to the mid-20th century , although the computer concept and various machines similar to computers existed earlier....
, medical stores, the audio center, the S-band power amplifier, etc.

The left-hand forward equipment bay, containing four food storage compartments, the cabin heat exchanger
Exchanger

Exchanger may refer to:* Digital currency exchanger, a market maker which exchanges fiat currency for electronic money* Exchanger , an integral membrane protein that is involved in active transport of two or more different molecules or ions...
, pressure suit
Pressure suit

A pressure suit is a protective suit worn by high-altitude pilots who may fly at altitudes where the air pressure is too low for an unprotected person to survive, even breathing pure oxygen at positive pressure....
connector, potable water
Water

Water is a common chemical substance that is essential for the survival of all known forms of life. In typical usage, water refers only to its liquid form or States of matter, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam....
supply, and G&N telescope eyepiece
Eyepiece

An eyepiece, or ocular lens, is a type of lens that is attached to a variety of optical devices such as Optical telescopes and microscopes....
s.
The right-hand forward equipment bay, housing two survival kit
Survival kit

A survival kit is a package of basic tools and supplies prepared in advance as an aid to survival skills in an emergency. Military aircraft, lifeboat s, and spacecraft are equipped with survival kits....
containers, a data card kit, flight data books and files, and other mission documentation.
The left hand intermediate equipment bay, housing the oxygen
Oxygen

Oxygen no O2 produced; 2) O2 produced, but absorbed in oceans & seabed rock; 3) O2 starts to gas out of the oceans, but is absorbed by land surfaces and formation of ozone layer; 4-5) O2 sinks filled and the gas accumulates]]...
surge tank, the water delivery system, food supplies, the cabin pressure relief valve controls, and the ECS package.
The right hand intermediate equipment bay, which contained the bio instrument kits, the waste management system, food and sanitary supplies, and a waste storage compartment.
The aft storage, compartment, behind the crew couches. This housed the 70 mm camera
Camera

A camera is a device that records images, either as a still photograph or as moving images known as videos or movies. The term comes from the camera obscura , an early mechanism of projecting images where an entire room functioned as a real-time imaging system; the modern camera evolved from the camera obscura....
equipment, the astronaut’s garments, tool sets, storage bags, a fire extinguisher
Fire extinguisher

A fire extinguisher is an active fire protection device used to extinguish or control small fires, often in emergency situations. It is not intended for use on an out-of-control fire, such as one which has reached the ceiling, endangers the user , or otherwise requires the expertise of a fire department....
, CO₂
Carbon dioxide

Carbon dioxide is a chemical compound composed of two oxygen atoms covalent bond to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state....
absorbers, sleep restraint ropes, spacesuit maintenance kits, the 16mm camera equipment, and the contingency lunar sample container.

The CM had five windows. The side windows measured 13 inches (330 mm) square and were installed to the side of the left and right-hand couches. The triangular rendezvous windows measured 8 by 13 inches (204 by 330 mm) and were used to aid in docking and rendezvous

Rendezvous

Rendezvous may refer to:...
maneuvers. The hatch window was 9 inches (229 mm) in diameter and was directly over the cm pilot’s couch. Each window assembly consisted of three thick panes of glass. The inner two panes, which were made of aluminosilicate,made up part of the capsules pressure vessel, the fused silica outer pane served as both a debris shield and as part of the capsules heat shield. Each pane had an anti-reflective coating and a blue-red reflective coating on the inner surface.

Specifications

Crew: 3
Crew cabin volume: 6.17 m³
Length: 3.47 m
Diameter: 3.90 m
Mass: 5,806 kg
Structure mass: 1,567 kg
Heat shield mass: 848 kg
RCS mass: 400 kg
Recovery equipment mass: 245 kg
Navigation
Navigation

Navigation is the process of reading, and controlling the movement of a craft or vehicle from one place to another. It is also the term of art used for the specialized knowledge used by navigators to perform navigation tasks....
equipment mass: 505 kg
Telemetry
Telemetry

Telemetry is a technology that allows the remote measurement and reporting of information of interest to the system designer or operator. The word is derived from Greek language roots tele = remote, and metron = measure....
equipment mass: 200 kg
Electrical equipment mass: 700 kg
Communications systems mass: 100 kg
Crew couches and provisions mass: 550 kg
Environmental control system mass: 200 kg
Mis. contingency mass: 200 kg
RCS thrust: 12 x 410 N
RCS propellants: N₂O₄/UDMH
RCS engine propellants: 122 kg
Drinking water capacity: 15 kg
Waste water capacity: 26.5 kg
Atmosphere cleanser: lithium hydroxide
Lithium hydroxide

Lithium hydroxide is a corrosive alkali hydroxide. It is a white hygroscopic crystalline material. It is soluble in water, and slightly soluble in ethanol....
Odor absorber: activated charcoal
Electric system batteries: three 40 ampere-hour silver zinc batteries, two 0.75 ampere-hour silver zinc pyrotechnic batteries
Parachutes: two 5 meter conical ribbon drogue parachutes, three 2.2 meter ringshot pilot parachutes, three 25.45 meter ringsail main parachutes

Service Module (SM)

The Service Module was an unpressurized cylindrical structure, measuring 24 feet 7 inches (7.5 m) long and 12 feet 10 inches (3.9 m) in diameter. It housed the service propulsion system and its propellants, the fuel cell power system, four maneuvering thruster quads, the S-band antenna for communication with Mission Control, and storage tanks for water and air. On Apollo 15, 16 and 17 it also carried a scientific instrument package. It was connected to the Command module using three tension ties and six compression pads. The tension ties were stainless steel

Stainless steel

In metallurgy, stainless steel is defined as a steel alloy with a minimum of 10% chromium content by mass. Stainless steel does not stain, corrode, or rust as easily as ordinary steel , but it is not stain-proof....
straps bolted to the CM's aft heat shield.

The 91.2 kN Service Propulsion System (SPS) was used to place the Apollo spacecraft into and out of lunar orbit, and for mid-course corrections between the Earth and Moon. The SPS used a single AJ10-137 engine.

The Service module remained attached to the Command Module throughout the mission. It was jettisoned just prior to re-entry into the earth's atmosphere.

The Service Module was a simple structure consisting of a center section and six pie-shaped sectors. The basic components were the forward bulkhead and fairing, six radial beams, four honeycomb panels, and the aft bulkhead and heat shield.

The forward fairing measured 2 feet 10 inches (864 mm) long and included the RCS computer, umbilical connection, power distribution block, ECS controller, separation controller, and components for the high-gain antenna. The umbilical housing contained the main electrical and plumbing connections from the SM. At SM jettison, the connections were cut using a pyrotechnic-activated guillotine

Guillotine

The guillotine consists of a tall upright frame from which a long, smooth, heavy blade is suspended. This blade is raised with a rope and then allowed to drop, severing the victim's head from his or her body....
assembly.

Four clusters of reaction control jets were installed around the upper section of the SM every 90 degrees. Each thruster generated approximately 445 N of thrust, and used MMH for fuel and N204 as oxidizer. Each quad assembly measures 8 by 3 feet (2.4 by 0.9 m) and has a single fuel tank, an oxidizer tank, and its associated valves and regulators.

The central tunnel housed the service propulsion engine and its two helium pressurant tanks. The engine used Aerozine 50

Aerozine 50

Aerozine 50 is a 50/50 mix of hydrazine and unsymmetrical dimethylhydrazine . Originally developed in the late 1950s by Aerojet General Corporation as a storable, high-energy, hypergolic fuel for the Titan II ICBM rocket engines, Aerozine continues in wide use as a rocket fuel, typically with dinitrogen tetroxide as the oxidizer, with w...
(hydrazine

Hydrazine

Hydrazine is a chemical compound with the chemical formula N2H4. It is a colourless liquid with an ammonia-like odor and is derived from the same industrial chemistry processes that manufacture ammonia....
/UDMH

UDMH

Unsymmetrical dimethylhydrazine is a toxic volatile hygroscopic clear liquid, with a sharp, fishy, ammoniacal smell typical for organic amines....
) fuel and nitrogen tetroxide oxidizer and had a maximum thrust of 20,500 lbf (91.2 kN). It is 152.82 inches (3.882 m) long and 98.48 inches (2.501 m) wide at the base.

Service Module sectors

The Service Module was divided into six sectors:

Sector 1 was usually filled with ballast
Sailing ballast

Ballast is used in sailboats to provide moment to resist the lateral forces on the sail. Insufficiently ballasted boats will tend to tip, or heel, excessively in high winds....
to maintain the SM's center-of gravity. On Apollo 15-17, it housed a Scientific Instrument Module (SIM) for lunar study. The equipment included a panoramic camera, gamma ray
Gamma ray

Gamma rays are a form of electromagnetic radiation produced by atom particle interactions, such as electron-positron annihilation or radioactive decay....
spectrometer
Spectrometer

A spectrograph is an optical instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify materials....
, mapping camera, laser altimeter
Altimeter

An altimeter is an instrument used to measure the altitude of an object above a fixed level. The measurement of altitude is called altimetry, which is related to the term bathymetry, the measurement of depth underwater....
, mass spectrometer, and lunar sub-satellite. It required an EVA to retrieve the film.
Sector 2 contained the oxidizer sump tank, from which oxidizer was fed to the engine. It was 51 inches (1.3 m) wide, 153.8 inches (3.9 m) high, and contained 6,315 kilograms of oxidizer.
Sector 3 held the main oxidizer storage tank, which was 154.47 inches (3.924 m) high, 45 inches (1.14 m) wide, and held 5,118 kilograms (11,283 lb) of oxidizer.
Sector 4 contained most of the electrical power subsystem. Two oxygen tanks contained 290 kilograms of liquid oxygen
Liquid oxygen

Liquid oxygen is a form of the element oxygen. It has a pale blue color and is strongly paramagnetism. Liquid oxygen has a density of 1.141 g/cm? and is moderately cryogenics ...
, and two hydrogen tanks carrying 25 kilograms of hydrogen. The oxygen tanks supplied the environmental control system and fuel cells, and the hydrogen tanks the fuel cells only. The fuel cells combine the two elements to generate electrical power for the spacecraft, along with a small amount of drinking water. Each fuel cell weighed 112 kilograms.
Sector 5 housed the fuel sump tank. It was the same size as the oxidizer tank and held 3,950 kilograms of propellant. Feed lines connected the tank to the SPS.
Sector 6 contained the main fuel tank, also the same size as the oxidizer tank. It held 3,201 kilograms of fuel.

Mounted on the top of the aft bulkhead was the S-band high-gain antenna

Antenna (radio)

An 'antenna' is a transducer designed to transmitter or receive Electromagnetic radiations. In other words, antennas convert electromagnetic waves into electrical currents and vice versa....
. This was used for deep space communications, and was composed of 4 x 31 inch (787 mm) diameter reflectors and a single 11 inch (279 mm) square reflector. During launch, it was folded down parallel to the main engine. After launch, it deployed at a right angle to the SM.
Also on the SM exterior were a retractable forward-facing spotlight

Spotlight

Spotlight can refer to several types of lighting:* a searchlight* a Followspot, a light used in theatre* several types of stage lighting instrument#Spotlights...
, an EVA floodlight

Floodlight

A floodlight is an artificial light providing even illumination across a wide area.* High-intensity discharge lamp, the class of lamp itself* Stage lighting instrument#Floodlights, the types associated with Stage productions...
, and a flashing rendezvous beacon

Beacon

A Beacon is an intentionally conspicuous device designed to attract attention to a specific location.Beacons help guide navigation to their destinations....
visible from 100 kilometers away. Following jettison, the SM translation jets automatically fired aft to distance it from the CM. The roll jets were fired for five seconds to ensure faster break-up on re-entry.

Specifications

Length: 7.56 m
Diameter: 3.90 m
Mass: 24,523 kg
Structure mass: 1,910 kg
Electrical equipment mass: 1,200 kg
RCS thrust: 16 x 446 N
Propellants: N₂O₄/UDMH
Service Propulsion (SPS) engine mass: 3,000 kg
SPS engine thrust: 91.2 kN
SPS engine propellants: N₂O₄/Aerozine 50
Aerozine 50

Aerozine 50 is a 50/50 mix of hydrazine and unsymmetrical dimethylhydrazine . Originally developed in the late 1950s by Aerojet General Corporation as a storable, high-energy, hypergolic fuel for the Titan II ICBM rocket engines, Aerozine continues in wide use as a rocket fuel, typically with dinitrogen tetroxide as the oxidizer, with w...
(UDMH/N₂H₄)
SPS engine propellants: 18,413 kg
SPS ISP: 314 s (3100 m/s)
Spacecraft delta v: 2,804 m/s
Electrical System: three 1.4 kW dc/30-volt fuel cells

Apollo Command/Service Module

Command Module (CM)

Construction

Earth landing system

Reaction control system

Hatches

Docking assembly

Cabin interior arrangement

Specifications

Service Module (SM)

Service Module sectors

Specifications

CSMs produced

See also