The
Apollo spacecraft was designed as part of
the
Apollo Program,
by the United States in the early 1960s to land
men on the
moon
before 1970 and return them safely to earth.
This goal was set forth by President Kennedy
after the first flight of the
Mercury Space Program.
The spacecraft was made up of multiple units or
stages that worked together to perform the
mission of
landing
on the moon and returning safely to earth. The
main components of the Apollo spacecraft were
(going from top to
bottom) the launch escape system, the Command
module, the
Service Module,
the Lunar Module
and the lunar module adapter. These stages
together would sit atop the launch vehicle.
The
principle was
Lunar Orbit Rendezvous:
A rocket would launch the spacecraft to the
moon. The spacecraft would fly to the moon and
orbit it. A smaller portion of the spacecraft
would land on the moon and return to lunar
orbit.
Then a portion of the spacecraft would return to
earth.
Launch Escape System (LES)
The
purpose of the Apollo
launch escape system
was to pull the Command Module (which contained
the crew cabin) away from the launch vehicle in
an abort situation.
The
emergency could be a pad fire, exploding launch
vehicle or a launch vehicle going off course.
The Launch
Escape System would work automatically (or
through manual activation) to fire a solid fuel
escape rocket and open a canard system to direct
the Command Module away from, and off the path
of, a launch vehicle in trouble. The Launch
Escape System would then jettison and the
Command Module would land with its parachute
recovery system.
If the
emergency happened on the launch pad, the Launch
Escape System would lift the Command Module to a
sufficient height to allow the recovery
parachutes to deploy safely before coming in
contact with the ground.
Major Components of
the Launch Escape System (LES)
Nose Cone and Q-Ball—The nosecone of the
LES contained sensors to sense
aerodynamic pressure
("Q"), and thereby determine the angle of
attack, airspeed, and attitude of the
spacecraft and launch vehicle. This
structure, known as the Q-ball, relayed this
information to the command module and the
launch vehicle guidance system.
Q-Ball cover—The Q-ball's pitot tubes,
which could easily be clogged by debris,
were protected by a styrofoam cover that was
removed a few seconds before launch. The
Q-ball cover was split in half vertically
and held together by a 2 inch rubber band. A
razor blade was positioned behind the rubber
band, pinched between the halves of the
cover. A wire
rope was connected to the top and bottom of
the razor blade and to both halves of the
cover. The wire rope was routed through a
pulley on the hammerhead crane at the top of
the launch umbilical tower (LUT) down to a
tube on the right side of the 360 foot level
of the LUT. The wire rope was connected to a
cylindrical weight inside a tube. The weight
rested on a lever controlled by a pneumatic
solenoid valve. When the valve was actuated
from the Launch Control Center (LCC), the
pneumatic pressure of 600 PSI GN2 (nitrogen
gas) rotated the lever down allowing the
weight to drop down the tube. The dropping
weight pulled the wire rope, which pulled
the blade cutting the rubber band, and the
wire rope pulled the halves of the Q-Ball
away from the launch vehicle. The apparent
overengineering of this simple system was
due to the fact that the launch escape
system, which depended on the Q-ball data,
was armed 5 minutes before launch, so
retraction of the Q-ball cover was a
life-critical part of a possible pad abort.
Canard Assembly and Pitch Motor—These
worked in combination to direct the Command
Module off a straight path and to the side
during an emergency. This would direct the
Command Module off the flight path of an
exploding launch vehicle. It would also
direct the Command Module to land off to the
side of any launch pad fire and not in the
middle of it.
Tower Jettison Motor—A smaller solid
fuel motor that jettisons the Launch Escape
System after it is no longer needed. This
usually happens after second stage ignition.
Launch Escape Motor—The main
solid fuel rocket
motor that,
firing through four rocket nozzles, pulls
the Command Module rapidly away from a
launch emergency.
Launch Escape Tower—Assembly that
attaches the Launch Escape System rocket
motors to the Command Module.
Boost Protective Cover—Hollow conical
structure that fits over the Command Module
during launch. It protects the Command
Module heat shield and windows during ascent
through the atmosphere. It also protects the
Command Module from rocket exhaust should
the Launch Escape System have to be used.
Specifications
Total
Length: 10.2 m
Diameter: 0.66 m
Total
mass: 9,200 lb (4,170 kg)
Thrust: 155,000 lbf (689 kN)
Abort Tests
Pad
Abort Test-1—Launch Escape System (LES)
abort test from launch pad with Apollo
Boilerplate
BP-6.
Pad
Abort Test-2—LES pad abort test of near
Block-I CM with Apollo Boilerplate B-23A.
Little
Joe II—In-air LES abort tests.
Command Module (CM)
The
Command Module was the control
center for the Apollo spacecraft
and living quarters for the
crew. It contained the
pressurized main crew cabin,
crew couches, control and
instrument panel,
optical
and electronic guidance systems,
communications systems,
environmental control system,
batteries,
heat
shield,
reaction control system, forward
docking hatch, side hatch, five
windows and the parachute
recovery system.
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 Equipment Mass:
505 kg
Telemetry 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
Misc.
Contingency Mass: 200 kg
RCS
Thrust: 12 x 420 N
RCS
Propellants: N2O4/UDMH
RCS
Engine Propellants: 75 kg
RCS
Specific Impulse Isp:
290 s (2.84 kN·s/kg)
RCS
Impulse: 257 kN·s
Electric System Batteries:
20.0 kW·h, 1000 A·h
Service Module (SM)
The Service
Module was a
portion of the
spacecraft that
was
unpressurized
and contained
fuel cells,
batteries, high
gain antenna,
radiators,
water, oxygen,
hydrogen,
reaction control
system and
propellant to
enter and leave
lunar orbit, and
service
propulsion
systems. On
Apollo 15, 16
and 17 it also
carried a
scientific
instrument
package, mapping
camera and a
small
sub-satellite to
study the moon.
A major portion
of the service
module was taken
up by propellant
and the main
rocket engine
that placed the
Apollo
spacecraft into
and out of lunar
orbit. The main
rocket engine
was also used
for mid-course
corrections
between the
earth and the
moon. It was
capable of
multiple
restarts. During
Apollo 13,
a tank heater
thermostat fused
closed, causing
gases in an
oxygen tank to
vaporize and
melted the
casing on the
wires to the
tank stirring
fan. During
flight when the
tank fan was
turned on, a
spark from short
caused the gas
to ignite. It
remained
attached to the
Command Module
throughout the
mission. It was
jettisoned just
prior to reentry
into the earth's
atmosphere.
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 × 440 N
Propellants:
N2O4/UDMH
RCS Specific
Impulse Isp:
290 s (2.84
kN·s/kg)
RCS Impulse:
3,517 kN·s
Service
Propulsion
Engine (SPS)
Engine Mass:
3,000 kg
SPS Engine
Specific
Impulse Isp:
314 s (3.08
kN·s/kg)
Spacecraft
Delta-V:
2.804 km/s
Electrical
System: Fuel
Cells
Electric
System: 6.30
average kW,
670 kW·h
Lunar Module
(LM)
The Lunar Module was the portion of the Apollo spacecraft that landed on the moon and returned to lunar orbit. It is divided into two major parts, the Descent Module and the Ascent Module. It was designed specifically for flight in space. It supplied life support systems for two astronauts for a total of four to five days. The spacecraft was designed and manufactured by the Grumman Aircraft Company led by Tom Kelly.
The Descent Module contains the landing gear, landing radar antenna, descent rocket engine, and fuel to land on the moon. It also had several cargo compartments used to carry among other things, the Apollo Lunar Surface Experiment Packages ALSEP, Mobile Equipment Cart (a hand pulled equipment cart - Apollo 14) the Lunar Rover (moon car - Apollo 15, 16 and 17), surface television camera, surface tools and lunar sample collection boxes.
The Ascent Module contains the crew cabin, instrument panels, overhead hatch/docking port, forward hatch, optical and electronic guidance systems, reaction control system, radar and communications antennas, ascent rocket engine and fuel to return to lunar orbit and rendezvous with the Apollo Command and Service Modules.
Descent Engine Engine Specific Impulse Isp: 311 s (3.05 kN·s/kg)
Descent Stage Delta-V: 2.47 km/s
Electric System Batteries: 33 kW·h, 1,600 A·h
Spacecraft Lunar Module Adapter (SLA)
The Spacecraft Lunar Module Adapter (SLA) was a conical aluminum structure which supported the Service Module above the Saturn S-IVB rocket stage. It protected the Lunar Module, the Service Propulsion System engine nozzle, and the launch vehicle to Service Module umbilical during launch and ascent through the atmosphere.
The SLA was composed of four fixed seven foot long panels bolted to the Instrument Unit on top of the S-IVB stage, which were connected via hinges to four twenty-one foot long panels which would open from the top similar to flower petals.
The SLA was made from 1.7 inch (42.5 mm) thick aluminum honeycomb material.The exterior of the SLA was covered by a thin (0.03–0.2 inch, 1–5 mm) layer of cork and painted white to minimize thermal stresses during launch and ascent.
The Service Module was bolted to a flange at the top of the longer panels, and power to the SLA multiply-redundant pyrotechnics was provided by an umbilical. Because a failure to separate from the S-IVB stage could leave the crew stranded in orbit, the separation system used multiple signal paths, multiple detonators and multiple explosive charges where the detonation of one charge would set off another even if the detonator on that charge failed to function.
Once in space, the astronauts pressed the 'CSM/LV Sep' button on the control panel to separate the Command and Service Module from the launch vehicle. Detonating cord was ignited around the flange between the Service Module and SLA, and along the joints between the four SLA panels, releasing the Service Module and blowing apart the connections between the panels. Dual-redundant pyrotechnic thrusters at the lower end of the SLA panels then fired to rotate them around the hinges at 30-60 degrees per second.
On the Apollo 7 flight the SLA panels were retained on the S-IVB, but concerns about collision between the CSM and the SLA panels when docking with the Lunar Module led to a decision that the Saturn V launches would release the panels during the separation process. When they opened to an angle of approximately 45 degrees the hinges connecting the moving panels to the fixed panels disengaged, and springs pushed the panels away from the S-IVB at a velocity of around five miles per hour. Hence by the time the astronauts had rotated the Command/Service Module through one hundred and eighty degrees in preparation for docking, the panels were a safe distance away with no chance of a collision occurring.
The Lunar Module was connected to the SLA at four points around the lower panels. After the astronauts docked the CSM to the LEM, they blew charges to separate those connections and a guillotine severed the LEM to Instrument Unit umbilical. After the charges fired, springs pushed the LEM away from the S-IVB and the astronauts were free to continue their trip to the Moon.
Specifications
Height: 8.5 m (28 ft)
Apex Diameter: 3.9 m (12 ft 10 in) Service Module end
bottom) the launch escape system, the Command
module, the
Service Module,
the Lunar Module
and the lunar module adapter. These stages
together would sit atop the launch vehicle.
rope was connected to the top and bottom of
the razor blade and to both halves of the
cover. The wire rope was routed through a
pulley on the hammerhead crane at the top of
the launch umbilical tower (LUT) down to a
tube on the right side of the 360 foot level
of the LUT. The wire rope was connected to a
cylindrical weight inside a tube. The weight
rested on a lever controlled by a pneumatic
solenoid valve. When the valve was actuated
from the Launch Control Center (LCC), the
pneumatic pressure of 600 PSI GN2 (nitrogen
gas) rotated the lever down allowing the
weight to drop down the tube. The dropping
weight pulled the wire rope, which pulled
the blade cutting the rubber band, and the
wire rope pulled the halves of the Q-Ball
away from the launch vehicle. The apparent
overengineering of this simple system was
due to the fact that the launch escape
system, which depended on the Q-ball data,
was armed 5 minutes before launch, so
retraction of the Q-ball cover was a
life-critical part of a possible pad abort.
