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4
Right: The fir~....~.. f Six hundred million people
an earthling ..~....~er
..................... ~ r. r ~ ~ ~ ,
celestial body are rim.. in nearly one-tlit. :1 at the world . S
..,~.,,~,,,,.,., ,, ,.,., ~ ~ ~' . ~.population watched on
. . ~
~lSlOn In JU. .y lamp as an
earthling first set foot onto
another celestial body. With
that step, human conscious-
ness leaped a quarter million
miles into space, expanding
mankind's vision to a degree
unequalled since Columbus's
voyage to the New World.
"The astronauts didn't just
go to the moon," said one
observer. "All our minds went
to the moon."
Looking back from the moon, people
saw white wispy clouds and blue sparkling
water covering a planet framed by immense ~1
darkness. Earth appeared as a highly
integrated unit, not just a collection of I
isolated oceans and continents. And it was
strikingly obvious how small, fragile, and
beautiful our planet really is, a precious oasis
in the vastness of space.
The Apollo program sent nine spacecraft
to the moon from 1968 to 1972, landing a
dozen astronauts at six different sites. The
rocks and scientific information they brought
~ ~ I - ~
In - ena
back revealed that the moon was formed at
I the same time and of the same elements as
earth but that it lacks water, atmosphere, and
life. The astronauts also left instruments to
gather data on ground tremors and other
phenomena. A laser reflector left by Apollo 11
astronauts is still being used to measure the
earth-to-moon distance and study the
movement of continents.
The feat of landing men on the moon
and returning them safely home ranks the
Apollo project with the Egyptian pyramids,
the Panama Canal, and the Manhattan
Project as outstanding engineering achieve-
ments of all time. It stands alone for the
advances in size and sophistication it made
over prior technology. Apollo required a
E N G ~ N E E R ~ N G A N ~ T ~ E A ~ VA N C E M E N ~ O F H ~ M ~ N W E ~ FA R E
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rocket 15 times more powerful, a navigation
I system far more reliable, a unique lunar
landing craft, and improved space suits
capable of withstanding a very hostile
environment. In addition, the program
demanded a novel, comprehensive manage-
ment system to ensure that thousands of
government and industrial organizations
worked together well enough so that
millions of parts would arrive where they
should on schedule and would fit and
function properly.
The Saturn/Apollo system was com-
posed of an Apollo spacecraft, a lunar lander,
1
M O O N L A N ~ I N G I
Apollo ~ 7 is readied for a
nighttime launch toward the
moon, peeking out from the
clouds beyond. The spacecraft
carried the first scientist to
the moon and was the only
one launched at night in the
Apollo series.
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and a three-stage Saturn V rocket, which
I launched them toward the moon. Once in
lunar orbit, the spacecraft released the two-
stage lander, which carried two of the three
astronauts to the surface. The lander's ascent
stage later returned them to the spacecraft
and was abandoned. lust before they
reentered the atmosphere, the astronauts
jettisoned the large service unit that supplied
An Apollo ~ ~ astronaut
unpacks a scientific
experiment to measure
ground tremors on the moon.
The small laser reflector, on
the ground behind the
astronaut, is still being used
for laser measurements of the
distance between the earth
and moon.
6
power, water, and oxygen and returned to
earth in the small command capsule of the
spacecraft.
Buildings shook and the ground trem-
bled when a Saturn V rocket roared skyward
with the first trio of astronauts heading for
lunar orbit in December 1968. The rocket
developed roughly enough thrust to hurl a
small house into earth orbit. Thirty-six stories
tall and weighing as much as a good-sized
Navy destroyer, the Saturn/Apollo vehicle
used the biggest, most powerful rocket ever
built.
The first stage of the three-stage Saturn
V dwarfed the largest rockets of its day. An
Atlas ballistic missile, for instance, produced I
360,000 pounds of thrust. The first-stage
engines of the Saturn V, however, each
produced 1.5 million pounds, and there were
five. Together they burned 3 tons of kerosene
and liquid oxygen per second. Building
reliability into such monstrous engines was a
monumental challenge. Yet, all 12 Saturn V
rockets launched in the Apollo series suc-
ceeded.
To fuel the second and third stages,
engineers chose liquid hydrogen, which gave
40 percent more thrust per pound of fuel
burned than kerosene. The second stage was
a cluster of five engines, while the third had
just one. But unlike those in lower stages, the
third-stage engine had to be restartable in
order to push the spacecraft toward the
moon after coasting an hour and a half in
earth orbit.
Building a rocket of such size and design
required many new and advanced engineer-
ing techniques. The field of fracture mechan-
ics, for example, advanced greatly in answer-
ing questions raised during construction of
the second-stage fuel tank, which was 65 feet
long, 33 feet in diameter, and held liquid
hydrogen at -423 degrees F. The aluminum
tank was pieced together with literally miles I
of welds, which could contain a few tiny
cracks. But how big could the cracks be
before they began to weaken the tank? By
analyzing aluminum with similar cracks,
engineers calculated the amount of pressure
the metal could stand before cracks of
various sizes begin to grow and thus become
dangerous. To ensure its safety, they tested
each second-stage tank by loading it with
liquid hydrogen at a pressure 5 percent
higher than the maximum required for flight.
If cracks did not grow at that pressure, they
would not grow at the lower pressure during
flight.
The Apollo flights would have been
impossible without inertial navigation,
I which was developed in the 1950s and was
just being installed in the early 1960s on
aircraft, submarines, and ballistic missiles.
Radio navigation from earth was impractical
during the final minutes of a landing
approach to the moon. The time radio signals
take to travel that distance is too long for the
immediate reactions needed to land a craft
safely. Radio navigation was also useless for
flights behind the moon because it requires
line-of-sight transmission from earth.
~ N G I N E E R I ~ G ~ N ~T ~ E ~ D VA N C E M E N ~O ~H U M A N W E ~ FA R E ~
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~. l
Apollo's navigation the rocket,
spacecraft, and lunar lander each had a
separate system included gyroscopes and
accelerometers, which sensed change In
direction and speed. They were combined in
single subsystems, called inertial measure-
ment units, or IMUs, which measured
movement along, as well as off, the desired
course due to rocket thrust or atmospheric
resistance. When leaving or approaching the
earth or moon, IMUs were critical for making
quick guidance decisions. Gravitational
influences of the earth and moon were
calculated before flight and added to
onboard guidance computers. This informa-
tion and the IMU data permitted control
systems to keep the craft almost exactly on
course. During the flight, astronauts used a
sextant in calculating midcourse corrections.
In practice, however, ground radar stations
usually performed this time-consuming task
and radioed up commands to correct
deviations.
The two-stage lander that ferried
astronauts to the lunar surface was the first
manned vehicle designed to fly solely in
space. Its structure could be extremely
lightweight, since the moon's gravity is only
one-sixth that of earth. And aerodynamics
did not need to be considered, since there is
no air on the moon. The lander was essential-
ly built inside out. Its thin aluminum pres-
surized cabin was inside, wiring and tubing
surrounded that, and a patchwork of black
or golden ~nsulahng materials covered the
outside. These materials absorbed or reflect-
ed light, depending on whether that part of
the lander needed protection from cold or
heat. Its four spiderlike legs with wide foot
pads could keep the lander upright, whether
it touched down on a slope, in deep dust, or
under any of 500 other combinations of
terrain and landing conditions anticipated by
the engineers. !
One of the most critical parts of the
lander was the small ascent engine. Once the
astronauts landed, they were completely
dependent on this engine to return them to
the mother ship. There was no backup. The
basic portion of the flight engine had been
briefly test-fired on earth. Its fuel system,
however, had not previously been exposed
to the highly corrosive propellants for fear of
weakening its seals and corroding its valves.
So engineers ground-tested ascent-eng~ne
prototypes for every failure they could
The five first-stage engines of
the mighty Saturn V rocket lift
Apollo ~ ~ off the launch pad
anal start the spacecraft
toward the moon. Astronauts
are in the conical command
capsule atop the rocket. Just
below the capsule is the
cylindrical service unit. Below
that, the lunar lander is
packed in another cylinder
just above the rocket's third
stage.
-
M O O N L A N D I N G
7
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required more than 450 persons in the launch
I control center and nearly 7,000 others on 9
ships, in 54 aircraft, and at stations around
I the world. At its peak, 400,000 people were
working on Apollo at three major space
centers and 20,000 contractor sites. The
people who managed Apollo pioneered
techniques that remain the model for
operating a massive, well-run engineering
program. In 1961 NASA estimated that the
project would cost $20 billion and would put
a man on the moon before 1970. The space
agency actually spent $25.4 billion for all the
Apollo flights. And two Apollo 11 astronauts
stepped onto the moon on July 20, 1969.
On the planning and control side of the
program, the Apollo managers created a
monitoring system that gave them enough
information to ensure that the millions of
pieces for the project were coming together at I
the right time and place, in the right engi
neering configuration, and for the right price.
To do this, they identified a few hundred
critical milestones such as "rocket first
stage complete" or "stage shipped to Cape
Kennedy" for each program area. Once a
month, contractors reported their progress to
the three NASA centers, who reported to the
_ Apollo managers. The managers, in turn,
identified projects that were falling
The lunar lander, seen from imagine that might happen in flight. None behind-most of them did-and devised
the Apollo ~ ~ spacecraft, ~ did. solutions to bring them back on schedule.
heads for a landing on the
Astronauts who walked on the moon For instance when a tragic fire killed three
moon. The descent stage, ,
with outstretched legs and wore a three-piece space suit and backpack astronauts during a ground test of their
protruding rocket nozzle, will of life-support equipment for up to four spacecraft, managers swiftly reviewed the
remain on the moon when the hours outside the lander. The ensemble safety of nearly the entire Saturn/Apollo
upper ascent stage brings the weighed q.90 pounds on earth but only a system, redesigned the spacecraft and space
mother ship sixth of that on the moon. The first piece was suit, and brought the program back on
a cooling undergarment of knitted nylon- schedule in little more than a year.
spandex with a network of plastic tubes
Right: Dressed in a three- filled with water circulating from the
piece space suit, an Apollo T ~backpack. The next piece was the basic suit, a
astronaut climbs down a leg rubber_cOated nylon bladder sandwiched ~
of the lunar lander and hops I s - __
onto the hard, dusty surface between a cloth lining and a nylon cover to
of the moon. His life~support shape the suit. The third piece was a protec
back pack carried enough live outer garment of 17 layers, including 6
oxygen for, a 4-hour tour layers of Beta cloth. This is a fireproof fabric
outside the lander of fiberglass threads coated with Teflon to _
prevent itching. The outfit was completed by ~ --~'':._. I
a helmet, boots, gloves, and the backpack, _ ~ . . TIC
which also carried a radio and antenna. _- ~/~
The Apollo program was probably the ~ .` :~
most complex and ambitious engineering . . If- ~ I_
project ever attempted. A moon flight , ~ 3
!
E N G ~ N E E R ~ N G A N D T H E h ~ VA N C E M E N T O F H U M A N W E L FA R E
_ ~_ .
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On the technical side, the great challenge
was to create a management system that
would ensure the precise interface among
millions of pieces the Saturn V alone had
6 million manufactured by thousands of
contractors. Careful records were kept of
specifications for all the parts and the
interfaces between them. This documenta-
tion was especially valuable when, for
instance, during the unmanned second
Apollo flight, the first-stage engines began to
flicker, a piece of an aluminum panel fell off,
and two second-stage engines quit early. By
comparing flight instrument data with the
documentation, engineers were able to find
the problems, simulate them on the ground,
and correct them with enough confidence to
go ahead with the next flight the first with
astronauts aboard.
astronauts traveled over the lunar surface
in a motorized rover to gather rocks and
conduct scientific experiments. Apollo 17, the
last of the program, carried the first scientist
a geologist to the moon in December 1972.
Since the inception of the Apollo
program, nearly all the known planets in our
solar system and many of their moons have
I been visited by unmanned spacecraft.
Between them, the United States and the
Soviet Union have sent automated probes to
Earth's two neighbors, Mars and Venus, as
well as to Mercury, the planet nearest the
sun. U.S. probes have journeyed to all the
other planets except Pluto. The most cele-
brated unmanned spacecraft, Voyager 2, left
Earth in 1977, rendezvoused with [upiter in
1979 and then with Saturn, Uranus, and
finally Neptune in 1989. Yet, it was man's
.
_ hi
_ -
_y!
~ ;7_- ~ ~
I Apollo Is astronauts explore
the moon in a lunar rover,
which was packed aboard the
lander and unfolded on the
lunar surface. It carried the
astronauts 1 7.5 miles during
three exploratory tours and
helped them collect 170
pounds of moon rocks for the
return to earth.
The first two moon flights Apollo 8 and
10 put astronauts into lunar orbit; Apollo 11
and 12 put them on the moon. An exploding
oxygen tank in the service unit crippled
Apollo 13, whose astronauts took temporary
shelter in the lunar lander during the
emergency return to earth. Apollo 14 went
smoothly. During the next three missions,
landing on the moon that truly captured the
world's imagination, an engineering achieve-
ment that has extended the human domain
far beyond the boundaries of earth.
MOON LANDING I
The earth, like a sparkling
jewel against black velvet,
rises above a barren lunar
landscape to greet the Apollo
~ ~ astronauts 240,000 miles
out in space.
9
Representative terms from entire chapter:
lunar surface
