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Twenty Years On Orbit: The Space Shuttle Legacy

By Roger D. Launius
NASA History Office
NASA Headquarters

On the anniversary of the Space Shuttle Columbia’s 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 vehicle’s twenty years of operations. Indeed, from the first flight to the present, the Space Shuttle has been an important symbol of this nation’s technological capability, universally recognized as such by both the American people and the larger international community. After two decades, NASA’s 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 system—with 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 history—the 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 America’s superpower status in the world, and they will quickly mention the Space Shuttle—as well as NASA’s larger space exploration program—as 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. NASA’s 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 launch—within a window of less than fifteen minutes—on-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 Shuttle’s 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 Shuttle’s 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 orbiter’s 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, Endeavour’s 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, NASA’s Hubble Space Telescope Recovery Team received the Robert J. Collier Trophy “for outstanding leadership, intrepidity, and the renewal of public faith in America’s 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 effort—rather, it was a technology demonstrator and workhorse for space access—it 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 space—because 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 Earth’s 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 Shuttle’s “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.

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Updated April 5, 2001
Steven J. Dick, NASA Chief Historian
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