The Complete Book of Spaceflight: From Apollo 1 to Zero Gravity

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whose main task was guidance and navigation, although
he also sometimes flew the craft. On a lunar
mission, the CM pilot remained in the CM while his
two companions descended to the Moon’s surface.
In the right-hand couch was the LM pilot, who was
mainly responsible for managing the spacecraft’s
subsystems.
The CM had five windows: two forward-facing for
use during docking with the LM and three others for
general observation. A hatch opposite the center
couch was used to enter and leave the CM on the
ground. The aft section contained 10 reentry
thrusters, their fuel tanks, and the heat-shield.
COMMAND MODULE FACTS
Height: 3.2 m
Diameter (at base): 3.9 m
Weight
At launch, including crew: 5,900 kg
At splashdown: 5,300 kg
Apollo Command Service Module and Lunar Module A
comparison of the Apollo CSM and the LM; schematic diagram.
NASA
Service Module (SM)
An aluminum alloy cylinder at the end of which was
the main engine used to place Apollo into lunar orbit
and begin the return to Earth. The SM carried
the hypergolic (self-igniting) propellants for the
main engine, the systems (including fuel cells) used
to generate electrical power, and some of the lifesupport
equipment. At four locations on the SM’s
exterior were clusters of attitude control jets. On the
Apollo 15, 16, and 17 missions, the SM also contained
a Scientific Instrument Module (SIM) with
cameras and other sensors for studying the Moon
from orbit.
SERVICE MODULE FACTS
Diameter: 3.9 m
Length: 7.5 m
Engine thrust: 91,000 N
Propellants: hydrazine, UDMH, nitrogen tetroxide
Command and Service Module (CSM)
The combined CM and SM. The CSM orbited the
Moon, while the LM conveyed two astronauts to and
from the lunar surface and subsequently provided the
means of returning to Earth.
Lunar Module (LM)
The part of the Apollo spacecraft in which two astronauts
could travel to and from the Moon’s surface;
it was the first manned spacecraft designed for
use exclusively outside Earth’s atmosphere. Built by
Grumman Aircraft, the LM was a two-stage vehicle
consisting of an ascent stage and a descent stage.
During descent to the lunar surface and while the
astronauts were on the Moon, these stages acted as a
single unit. The descent stage contained the components
used to de-orbit and land the LM, including
the main engine, propellants, and landing gear. Its
engine was the first in the American space program
that could be throttled, providing a thrust range of
4,890 to 43,900 N, and could swing through 6
degrees from vertical in two planes to give the vehicle
maneuverability in landing. The ascent stage,
equipped with its own engine of 15,600-N thrust,
separated at the start of the climb back to lunar orbit
and used the descent stage as a launch platform.
Given that every kilogram of the LM had to be paid
for with 70 kg of launch vehicle and fuel from Earth,
the LM was made as light as possible. Its main
cladding was a paper-thin skin of aluminum alloy
fixed to aluminum alloy stringers. The ascent stage
also had several skins of Mylar to serve as heat and
micrometeoroid shields. The ladder enabling the
astronauts to climb to the lunar surface was so
flimsy that it could only support a man’s weight in
the one-sixth gravity of the Moon. Weight limita-