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The Evolution
of the Space Shuttle |
Dr. von
Braun with the V2 rocket |
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Low-Earth Orbit |
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| In the 1960's, the Mercury,
Gemini,
and Apollo
programs brought the first Americans to low-Earth
orbit and then on to the Moon. The Space
Shuttle and its partner, the space
station, were promoted by Dr.
Werner von Braun, NASA engineer and rocket designer,
with the help of Walt Disney who produced a series
of television films entitled, "Man
in Space," "Man and the Moon," and
"Mars and Beyond" in 1955 and 1956.
An estimated 42 million people saw the first show
in the Disney "science factual" series.
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Walt
Disney and Dr. von Braun
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In the series
Dr. von Braun described a winged Shuttle launched
on a liquid-fueled rocket that would return to Earth
as a glider and be completely reusable.
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Dr. von Braun also described for the
American public a majestic
250-foot-wide wheel space station that would
orbit 1,075 miles above Earth and would rotate to
provide artificial gravity, similar to the station
visualized in the movie "2001: A Space Odyssey."
In addition, the Cold War with the Soviet Union
led the race to be the first country to land a man
on the Moon. |
Rockets got increasingly
larger and more complex as time went on, using more
fuel and bigger engines. They were, therefore, capable
of carrying heavier payloads. Click
here for a timeline of rockets through history.
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Click
here to read about Dr. von Braun's experience
with rocketry as a boy.
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Dr. von Braun's original
plans for a low-Earth orbit Space Shuttle transportation
system laid much of the groundwork for what was
to become the Space Shuttle program. In the early
1970's, following the Apollo lunar missions and
the Skylab space station programs, NASA was looking
towards the future__and to Mars.
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Parallel
to the development of Dr. von Braun's rocket designs
in the 1950's and 1960's, was a series of experimental
aircraft or X-planes.
The military and NASA both wanted to fly jets higher
and faster than ever before and, to do so, they
had to understand much more about the aerodynamics
of high speed flight.
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M2-F1,
M2-F2 |
X-1 |
This series of high-performance
jet and rocket aircraft provided some of earliest
models for the Space Shuttle: a spacecraft that
launches into space on a rocket and then returns
and lands on a traditional runway like a glider.
In
the 1950's and 1960's a variety of designs were developed
by NASA and the U.S. Air Force for a maneuverable reentry
vehicle. These led to a lifting-body design which used
small fins for maneuvering and had a rounded, blunt
nose. Landing on an airstrip would eliminate the expense
of oceangoing recovery forces needed for the re-entry
capsules in the Mercury, Gemini, and Apollo Programs.
The Space Shuttle would marry rocket and airplane technologies
together in a vehicle that would become the first high-tech
transportation method to and from space. |
| The Cold
War lessened somewhat when President Nixon visited the
Soviet Union to meet with their leader, Leonid Brezhnev
in 1973. In 1975, NASA and the Soviet Union participated
together in the Apollo-Soyuz
Program, which docked an American spacecraft with a
Soviet spacecraft for the first time in history. No
longer were we in a full-fledged space race with the
Soviets. This had been a major part of the impetus behind
the massive funding of the Apollo Program. |
Leonid Brezhev and
Richard Nixon
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McDonnell
Douglas/Martin Marietta Shuttle design |
When NASA decided to
build the Space Shuttle in the late 1960's and early
1970's, many designs were considered. Dr. von Braun's
design used a rocket powered by only liquid fuel,
and another design included booster rockets that
could fly back to the ground. The cost of developing
a purely liquid rocket Shuttle (like the Saturn
V rocket used to go to the Moon) was considered
too prohibitive. A liquid-fueled rocket has the
advantage of being able to be controlled, and it
can be shut down if necessary in an emergency.
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In
1969, NASA began soliciting proposals for the Space
Shuttle in earnest. In response to a request for proposals,
government-funded studies and studies funded with
private contractor money looked at designs for a fully
reusable vehicle that would be launched vertically
and land horizontally. The Shuttle
had to have a 15' x 60' payload bay and be capable
of lifting 65,000 pounds. The missions had to
last seven days, and there was to be a two-week turnaround
on the ground. Click
here to review the original Space Shuttle
requirements.
In
1970, the Manned Spacecraft Center or MSC (now the
Johnson
Space Center) began looking at ways to use
existing technology in the Shuttle design. The
vehicle would be more economical, be safer, and have
a shorter development time. These designs were called
the 'MSC designs', and there were over 50 of them
proposed over the next few years. Then in 1971,
a partially reusable design was introduced that would
reduce cost even further. This design used reusable
solid rocket boosters (SRBs) and an expendable external
fuel tank.
In March of 1972, NASA selected the parallel burn
approach in which both liquid-fuel engine and solid-fuel
booster would burn during ascent; and in July of that
year, the Agency selected the Rockwell Corporation's
proposal for development.
Beginning
in 1973, the Space Shuttle main engines (SSMEs) were
tested at the Marshall
Space Flight Center in Huntsville , Alabama
(where Dr. von Braun had designed and tested all of
the previous rocket engines). Click
here for a chronology of the Space Shuttle
Program in development.
The first
Space Shuttle was named the Enterprise
(after the Star Trek spaceship, following a write-in
campaign by the American public). It was destined
not to fly in space. It was built and used only for
landing tests from 1973 to 1976.
The final
design of the Shuttle uses a combination of liquid
rocket engines and solid rocket boosters. The solid
rocket boosters are less expensive to build, although
they are more dangerous to fly. Once ignited, solid
rockets cannot be shut down. It was tested extensively
in wind tunnels and under water at NASA Centers ,
but the actual configuration was never tested until
the first launch in 1981.
The weight
of the external tank (ET) was reduced in 1974 with
a redesign; and beginning with the third mission,
NASA elected not to paint the tank white, saving even
more weight (about 15,000 pounds). This weight savings
would allow for more payload to be carried on board.
Tests of the SRBs began in 1976 and vibration tests
on the mated configuration (the Shuttle, boosters,
and tank bolted together) began in 1977. In
1981 the first Space Shuttle, Columbia
, which launched from the Kennedy
Space Center orbited for 2 days. It
was commanded by John Young and piloted by Robert
Crippen. The Space Shuttle program had truly
begun. |
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Since
1981, the Space Shuttle has provided a platform for
launching a variety of payloads into space including:
interplanetary spacecraft like Galileo,
space telescopes like the Hubble
, the Compton
Gamma Ray Observatory , and the Chandra
telescope . Many types of communications
satellites for the U.S. and other countries have also
been carried; and for several years, it deployed a
variety of secret military hardware.
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More
importantly, for every dollar spent in the space program,
studies have shown that the return investment here
on Earth is approximately seven dollars. These
dollars are represented in the form of new technologies,
medical processes, technological advancements, and
the development of new materials. The space
program does indeed benefit people here on Earth!
Spinoffs
from the space program do not include just
Tang and personal computers. They also include Kevlar,
pacemakers, CT scans, and MRIs. Hundreds of
discoveries and inventions have resulted from space
program research: from miniature electronics
to advancements in recycling techniques, and from
improvements in airplane control systems to better
firefighter suits. Safety, which is a NASA priority,
has led the way to the development of a variety of
emergency procedures and safety equipment with applications
in many professions outside of the space program.
Questions
to think about:
- Why did the Cold War inspire people to fund the
space program?
- Which design of the Space Shuttle would have been
the safest?
- Which design would have been the most expensive?
- Which design of the Space Shuttle did you find
the most interesting? Why?
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