anthropogenic pollution on a global scale. It is, however, a serious local concern in the vicinity of launch test sites and deserves further investigation.

A plan is needed to provide an array of engines with a range of thrust levels and propulsion system capabilities for all stages of future launch vehicles. The proposed STME can be used for first stages of future launch vehicles. In addition, the Rocketdyne F-1A and the current Russian RD-170 engines should be evaluated for liquid booster applications. Hybrid engine technology should be investigated to determine its suitability with new launch systems. The propulsion system technology for second-and third-stage applications should emphasize low system cost and high reliability as in the initial booster stage. Revival of the Rocketdyne J-2 or upgrading of the Pratt & Whitney RL10 liquid-oxygen/liquid-hydrogen engines could provide upper-stage engines fitting the range of desired propulsion capabilities.

The modern Space Transportation Main Engine (STME) is the beneficiary of a significant investment in the underlying technologies, including fabrication methodologies, advanced materials, and revised design procedures aimed at improving the reliability and cost of a production engine. Development and qualification of the Space Transportation Main Engine (STME) should proceed immediately and vigorously. The initial use of the STME is to propel the NLS vehicles, and its development is crucial.

In addition, it is the Committee's recommendation that the STME development team invest in demonstrating a prototype of the 650,000-pound thrust engine concept for the 20,000-pound payload vehicle. The design philosophy should reinforce the robustness aspects of the engine, and should include health monitoring and control technology.

The Space Shuttle will remain the centerpiece of the U.S. manned presence in space well into the first decade of the next century. The Committee believes that efforts underway to improve reliability, reduce the cost, and simplify production and refurbishment of the SSME should be continued and that investment should be made in maintaining the operating integrity and effectiveness of all aspects of the propulsion system.

Front Matter (R1-R10)

List of Figures and Tables (1-2)

Summary of Key Findings and Recommendations (3-8)

Terms, Acronyms, and Abbreviations (9-10)

1 Introduction (11-14)

2 A Path to a Desirable National Space Launch System (15-21)

3 Projected Launch Requirements (22-25)

4 Launch Vehicle Options (26-39)

5 Propulsion Capabilities for Earth-to-Orbit Launch Vehicle (40-61)

6 Technology Development (62-71)

Biographical Sketches of Committee Members (72-76)

Appendix A An Approach to Space Infrastructure (77-83)

Appendix B List of Participants (84-87)

Appendix C Bibliography (88-92)