Twenty
Years On Orbit: The Space Shuttle Legacy
By
Roger D. Launius
NASA
History Office
NASA
Headquarters
On
the anniversary of the Space Shuttle Columbias first
flight into space on 12 April 1981, and after more than one hundred
orbital missions, it is most assuredly appropriate to reflect on
the legacy of this vehicles twenty years of operations. Indeed,
from the first flight to the present, the Space Shuttle has been
an important symbol of this nations technological capability,
universally recognized as such by both the American people and the
larger international community. After two decades, NASAs Space
Shuttle remains the most highly visible symbol of American technological
capability worldwide. There are several important legacies from
the Space Shuttle program that should be considered on the twentieth
anniversary of that first orbital flight.
First,
and certainly most significant, the Space Shuttle is a magnificent
machine. No other nation on the face of the Earth had the technological
capability to build such a sophisticated vehicle during the 1970s.
Few could do so today. A massively complex systemwith more
than 200,000 separate components that must work in synchronization
with each other and to specifications more exacting than any other
technological system in human historythe Space Shuttle must
be viewed as a triumph of engineering and excellence in technological
management. As such, it has been an enormously successful program.
The research, development, and operation of the Space Shuttle represent
a worthy follow-on to the spectacularly successful Apollo program
of the 1960s and early 1970s. Any assessment of the program that
fails to recognize this unique accomplishment is incomplete and
inaccurate.
Because
of its technological magnificence, the Space Shuttle has become
an overwhelmingly commanding symbol of American excellence for the
world community. Ask almost anyone outside the United States what
ingredients they believe demonstrate Americas superpower status
in the world, and they will quickly mention the Space Shuttleas
well as NASAs larger space exploration programas a constant
reminder of what Americans can accomplish when we put our minds
to it.
Indeed,
if there is one hallmark of the American people, it is their enthusiasm
for technology and what it can help them to accomplish, and this
fact is never lost on observers around the globe. Since the birth
of the republic, this has been a nation of technological system
builders who used their abilities to create great machines of wonder,
and the components of their operation. Without question, the Space
Shuttle is one of those machines. Perceptive foreigners might be
enamored with American political and social developments, with democracy
and pluralism, but they are often even more taken with U.S. technology.
The United States is not just the nation of George Washington, Thomas
Jefferson, Abraham Lincoln, Frederick Douglas, and Elizabeth Cady
Stanton, but also of Thomas Edison, Henry Ford, Neil Armstrong,
the Tennessee Valley Authority, and NASA. These have reinforced
the belief everywhere that the United States is the technological
giant of the world. NASAs Space Shuttle and its accomplishments
have symbolized our technological creativity more than any other
invention or program in modern America. It is because of this that
every perceived NASA failure raises the question of American technological
virtuosity, damaging the image of the United States far in excess
of what the failure should actually warrant.
Second,
the Space Shuttle has been remarkably reliable over the course of
its operational history. One exceptionally catastrophic accident,
the Challenger explosion that killed the crew of seven on
28 January 1986, ruins an otherwise excellent reliability record.
Without minimizing that tragic accident, one is compelled to conclude
that the vehicle has been significantly improved since 1986 as NASA
engineers worked to correct design flaws and develop more effective
operational procedures. Upgrades to many components of the Space
Shuttle and organizational changes to the management system have
led to the implementation of a strikingly more reliable vehicle
than was flying in 1986. The Shuttle is the most reliable launch
system now in service anywhere in the world, with a success-to-failure
ratio of greater than .99.
As
an even greater challenge than its rate of operational failure,
the Space Shuttle has been called upon to launchwithin a window
of less than fifteen minuteson-schedule flights to the International
Space Station. This is an enormously challenging operational environment
that has never even been considered a possibility for other launch
vehicles. Not even the vaunted Apollo flights to the Moon placed
operational demands on their launch personnel anywhere approaching
those required of current Space Shuttle operators. Thus far, the
program has been remarkably successful in meeting these requirements,
and we now have an International Space Station with a crew aboard
largely because of the success of the Shuttle in meeting those demanding
operational requirements.
Third,
the Space Shuttle is also a mature system at this point in its career,
and that is an important factor in the quality of its performance
over the last several years. At the beginning of the twenty-first
century, the Space Shuttle appropriately enjoys many of the same
plaudits and suffers from some of the same criticisms that have
been made clear since not long after the program first began. It
remains the only vehicle in the world with the dual capability to
deliver and return large payloads to and from orbit. The design,
now more than two decades old, is still state-of-the-art in many
areas, including computerized flight control, airframe design, electrical
power systems, thermal protection system, and main engines.
The
individuals who operate the vehicle also have a finely honed sense
of what the Space Shuttle can and cannot do. Twenty years of operational
data, refinements over time in system parameters, and a workforce
that understands the vehicle and its limits ensure that the Space
Shuttle will remain an overwhelmingly significant force in the ability
of the United States to reach orbit for the foreseeable future.
Even so, it is important always to understand that the Space Shuttle
remains an experimental rather than an operational vehicle and must
be treated as such.
Fourth,
the Space Shuttle has proven itself one of the most flexible space
vehicles ever flown. Most assuredly, the range of possibilities
for operations on orbit expanded dramatically with the launch of
Columbia in 1981. With its large payload bay, satellite deployment,
capture and return to Earth, and repair and redeployment all became
possibilities for the first time once the Shuttle flew. Requirements
to perform these tasks have ensured that the crew of every Shuttle
mission has a much broader range of required activities than the
pioneering astronauts of the Mercury, Gemini, Apollo, and even Skylab
programs. President Richard M. Nixon, who approved the Shuttle development
effort in 1972, was much enamored with this flexibility. He was
especially impressed with the Shuttles potential for secret
military missions, even believing that it would be useful in capturing
and recovering both American and Soviet reconnaissance satellites.
The
ability to carry diverse payloads, to accomplish a myriad of tasks
on orbit, and to deploy and retrieve satellites are attributes that
need to be considered in any effort to develop a follow-on system
once the Shuttles operational life comes to an end. The concepts
under consideration for a successor to the Space Shuttle must approach
the same level of flexibility that this vehicle has demonstrated,
and it is important to consider the uniqueness of the orbiters
capabilities in planning for the future.
No
flights demonstrate the flexibility of the Space Shuttle more effectively
than the three Hubble Space Telescope servicing missions. After
it was launched in 1990, many believed that a spherical aberration
in the mirror of the telescope would cripple the instrument. Because
of the difficulties with the mirror, NASA launched the shuttle Endeavour
on a dramatic repair mission in December 1993 to insert corrective
lenses into the telescope and to service other instruments. During
a weeklong mission, Endeavours astronauts conducted
a record five spacewalks and successfully completed all programmed
repairs to the spacecraft. The first reports from the Hubble spacecraft
after the servicing showed that the images were more than an order
of magnitude crisper than those obtained before. For this outstanding
effort, NASAs Hubble Space Telescope Recovery Team received
the Robert J. Collier Trophy for outstanding leadership, intrepidity,
and the renewal of public faith in Americas space program
by the successful orbital recovery and repair of the Hubble Space
Telescope. Two additional successful servicing missions have
extended the capabilities of the telescope into the first decade
of the twenty-first century.
Fifth,
the Space Shuttle has served as a marvelous testbed for scientific
inquiry. While the program was not conceptualized as a science effortrather,
it was a technology demonstrator and workhorse for space accessit
has been used as an exemplary platform for all manner of microgravity
and space science enterprises. President Nixon, announcing the decision
to build the Space Shuttle on 5 January 1972, minimized its scientific
role. Instead, he argued that it was the right step for America
to take, in moving out from our present beach-head in the sky to
achieve a real working presence in spacebecause the Space
Shuttle will give us routine access to space.
Even
so, the Space Shuttle has been a remarkable instrument in the hands
of scientists. Each of its more than one hundred flights has undertaken
some scientific experiments ranging from the deployment of important
space probes to other planets, through the periodic flight of the
European-built Spacelab science module, to a dramatic
set of Earth observations over a twenty-year period. One example
of an extremely momentous science experiment, among others that
might be offered, is the flight of the Italian Tethered Satellite
System designed to investigate new sources of spacecraft power and
ways to study Earths upper atmosphere on STS-75 in 1996. It
demonstrated that tethered systems might be used to generate thrust
to compensate for atmospheric drag on orbiting platforms such as
the International Space Station. Deploying a tether towards Earth
could place movable science platforms in hard-to-study atmospheric
zones. Tethers also could be used as antennas to transmit extremely
low-frequency signals able to penetrate land and seawater, enabling
communications not possible with standard radio. In addition, non-electrical
tethers can be used to generate artificial gravity and to boost
payloads to higher orbits.
Finally,
the Space Shuttle program, while an enormous achievement, has wrought
something of a divided legacy for NASA. In fundamental ways it may
be viewed as both a triumph and a tragedy. As a symbol of American
technological excellence and as a reliable, mature, flexible system
on which stunning scientific experiments may be conducted, it receives
high marks. However, the program failed to achieve one of its core
objectives: lowering the cost of reaching Earth orbit. In fact,
President Nixon stated in 1972 that the Shuttles resulting
economies may bring operating costs down as low as one-tenth of
those present launch vehicles. Granted, this is an extraordinarily
elusive goal, but disappointment over not achieving it has plagued
NASA and hampered space flight advocacy ever since. It remains a
goal that must be emphasized in the development of any new vehicle
that might eventually replace the Space Shuttle, still one of the
most successful and impressive technology development efforts in
American history.


Updated
April 5, 2001
Steven J. Dick, NASA Chief Historian
Steve Garber, NASA History Web Curator
For further information, e-mail histinfo@hq.nasa.gov
Designed
by Douglas Ortiz and edited by Lisa Jirousek
NASA Printing and
Design
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