From the Abstract:

"The main propulsion requirements for the fully reusable Space Shuttle are reviewed, and the engine concept under study to meet these requirements is presented and discussed. New approaches to engine development and testing are presented in the context of low cost hardware, low cost development, and low cost operation. High specific impulse to meet payload needs, and hardware lifetime to satisfy reusability and minimum maintenance are major goals of this engine development. An engine development program that is fully responsive to the viable technological needs of the Space Shuttle vehicle is fundamental to the attainment of a low cost, economical space transportation system."