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Introduction

THE TASK

The Committee on Science, Space and Technology of the U.S. House of Representatives and the Committee on Commerce, Science and Transportation of the U.S. Senate requested that the National Research Council (NRC) assess the requirements, benefits, technological feasibility, and roles of Earth-to-orbit transportation systems and options that could be developed in support of future national space programs. The NRC was asked to examine transportation requirements, including those for Mission-to-Planet Earth, Space Station Freedom assembly and operation, human exploration of space, space science missions, and other major civil space missions. These requirements were to be compared with existing, planned, and potential launch capabilities, including expendable launch vehicles (ELVs), the Space Shuttle, the National Launch System (NLS), and new launch options.

In addition, the NRC was asked to examine propulsion systems in the context of various launch vehicles. These included the Advanced Solid Rocket Motor (ASRM), the Redesigned Solid Rocket Motor (RSRM), the Solid Rocket Motor Upgrade (SRMU), the Space Shuttle Main Engine (SSME), the Space Transportation Main Engine (STME), existing expendable launch vehicle engines, and liquid-oxygen/hydrocarbon engines. Consideration was to be given to systems that have been proposed to accomplish the national interests in relatively cost effective ways, with the recognition that safety and reliability contribute to cost-effectiveness. The NRC was also asked to assess, to some degree, related resources, including propulsion test facilities and manufacturing capabilities.

APPROACH

The NRC formed the Committee on Earth-to-Orbit Transportation Options, which met on October 23–24, November 13–16, and December 16–18, 1991; January 22–25 and February 3–4, 1992. The Committee heard extensive briefings by representatives from many government



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From Earth to Orbit: An Assessment of Transportation Options 1 Introduction THE TASK The Committee on Science, Space and Technology of the U.S. House of Representatives and the Committee on Commerce, Science and Transportation of the U.S. Senate requested that the National Research Council (NRC) assess the requirements, benefits, technological feasibility, and roles of Earth-to-orbit transportation systems and options that could be developed in support of future national space programs. The NRC was asked to examine transportation requirements, including those for Mission-to-Planet Earth, Space Station Freedom assembly and operation, human exploration of space, space science missions, and other major civil space missions. These requirements were to be compared with existing, planned, and potential launch capabilities, including expendable launch vehicles (ELVs), the Space Shuttle, the National Launch System (NLS), and new launch options. In addition, the NRC was asked to examine propulsion systems in the context of various launch vehicles. These included the Advanced Solid Rocket Motor (ASRM), the Redesigned Solid Rocket Motor (RSRM), the Solid Rocket Motor Upgrade (SRMU), the Space Shuttle Main Engine (SSME), the Space Transportation Main Engine (STME), existing expendable launch vehicle engines, and liquid-oxygen/hydrocarbon engines. Consideration was to be given to systems that have been proposed to accomplish the national interests in relatively cost effective ways, with the recognition that safety and reliability contribute to cost-effectiveness. The NRC was also asked to assess, to some degree, related resources, including propulsion test facilities and manufacturing capabilities. APPROACH The NRC formed the Committee on Earth-to-Orbit Transportation Options, which met on October 23–24, November 13–16, and December 16–18, 1991; January 22–25 and February 3–4, 1992. The Committee heard extensive briefings by representatives from many government

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From Earth to Orbit: An Assessment of Transportation Options agencies, industry, and other experts in space transportation issues. These included the National Aeronautics and Space Administration (NASA), Department of Defense, National Space Council, Department of Transportation, Office of Technology Assessment, Department of Energy, American Institute of Aeronautics and Astronautics, independent research organizations, and many representatives from launch vehicle and propulsion companies. During this process, the Committee familiarized itself with launch traffic databases; civil, defense, and commercial mission models, requirements, and cost modeling; the capability, availability, and environmental effects of liquid, hybrid, and solid rocket motors; and various launch systems. These systems included the Space Shuttle and the National Launch System, international systems, recently decommissioned ballistic missiles, and other past and proposed systems. The Committee also reviewed the technological status of proposed concepts such as the National Aero-Space Plane (NASP) and other single-stage-to-orbit concepts. In addressing its task, the Committee decided that it would be useful first to determine the attributes of an effective national space launch system and its accompanying infrastructure. In subsequent chapters, existing, planned, and proposed vehicle and propulsion systems are evaluated, including the potential roles of non-U.S. systems. Recommendations are presented with supporting arguments. The importance of technology development as an investment in the future cannot be overemphasized, and Chapter 6 examines the Committee's views regarding some technology priorities that could lead to more adequate space launch and infrastructure systems. Because of the intense concern expressed during the study regarding the development of adequate infrastructure (i.e., launch pads and processes) to support modern vehicles, the Committee has devoted Appendix A to a discussion of the major considerations and appropriate design elements for a more efficient and reliable launch infrastructure system. ECONOMIC ENVIRONMENT Realizing that the current restrictive budgetary environment may continue into the future, the Committee made every effort in its recommendations to delay expenditures of a noncritical nature and, where possible, to phase in the more critical elements as funding permits. Although no cost or future budgetary estimates have been proposed, the approach taken was to establish the necessary space transportation elements for the nation and to let future funding levels define the progress in achieving this goal. The Committee focused on propulsion capabilities and applications to the first stages of potential launch vehicles, recognizing that upper stages, payloads, a cargo transfer vehicle (CTV), a crew return vehicle (CRV), and eventually replacement for the Orbiter will all place demands on future budgets. Avoiding the historically uneconomical approach of starting and stopping major programs is crucial to the success of any new programs. Funding will vary, but it will be necessary to maintain the long-term objective of improving space infrastructure and vehicle capabilities (with

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From Earth to Orbit: An Assessment of Transportation Options adequate supportive research) to permit incorporation of more distant goals such as space exploration. NATIONAL POLICY CONSIDERATIONS U.S. space activities are conducted by three separate and distinct sectors: civil, national security, and commercial. In considering Earth-to-orbit launch systems and infrastructure, the Committee took into account national policy objectives, which are to: 1) provide safe and reliable access to, transportation in, and return from space, 2) reduce the costs of space transportation and related services, thus encouraging expanded space activities, 3) exploit the unique attributes of manned and unmanned launch and recovery systems, and 4) encourage, to the maximum extent feasible, the development and growth of U.S. private sector space transportation capabilities which can compete internationally.1 The national policy objectives apply to all three sectors.2 In the past, the United States had a near monopoly on the commercial space launch business. However, in recent years other nations have placed high priority on acquiring this market. They have developed new launch vehicles, streamlined launch processes, and brought to bear pricing policies that are based on factors other than costs, i.e., they have applied policies to achieve larger market share by employing creative financing arrangements or subsidies for various phases of development or production. The major competitor to the U.S. commercial sector is the French firm, Arianespace, which in 1991 launched 11 out of the 16 commercial satellites that were launched in the world.3 Many of the commercial payloads, such as communications satellites, require equatorial orbits, and Arianespace enjoys an advantage in launching from Guiana Space Center in Kourou, French Guiana. In addition to a close proximity to the equator, this site is sparsely populated with a wide opening on the ocean allowing all inclination missions. In the future, the Japanese, the Chinese, and the former Soviet Union are also potential competitors. Thus, in addition to providing more reliable and less costly launch services, the United States may need to reexamine its own policies regarding innovative financing and various forms of subsidies and support for U.S. industry in order to enable it to compete successfully. 1   National Space Council. July 10, 1991. National Space Policy. Directive 4. 2   National Space Council. February 12, 1991. Memorandum. 3   "Market Trends." February 1992. Arianespace. No. 63.

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From Earth to Orbit: An Assessment of Transportation Options ACKNOWLEDGMENTS In addition to the many formal briefings mentioned above, the Committee received valuable input from Admiral Richard H. Truly; Dr. Mark J. Albrecht, Executive Director of the National Space Council; Lt. Gen. Thomas P. Stafford, U.S. Air Force (ret.) and chairman of the report America at the Threshold; and several NASA associate administrators (AAs), including Mr. Arnold D. Aldrich, AA for Space Systems Development; Dr. William D. Lenoir, AA for Operations, Office of Space Flight; and Dr. Michael D. Griffin, AA for Exploration. The Committee would like to thank Mr. Edward A. Gabris and Mr. James Taylor for arranging briefings and responding to Committee requests throughout the study. In addition, Dr. Eugene Sevin served as the Committee's liaison with the Department of Defense and was very helpful in obtaining relevant information and briefings. The Committee also benefitted from the work of numerous previous study groups, and a list of key reports appears in Appendix C. In addition to the many helpful briefings, the Committee requested a large number of written responses concerning various issues and wishes to thank all of the contributors from NASA and its contractors; the Departments of Defense, Transportation, and Energy; individual aerospace companies; and independent research organizations for their cooperation in providing existing information and in researching some of the areas that arose.