The high cost of access to space begins with the current availability of very expensive ($3,000 $5,000/lb payload to LEO) launch systems. This paper discusses and compares two distinct alternatives for making significant (nearly order-of-magnitude) reductions in launch costs. An additional benefit to dramatic reductions in the cost of space transportation would also be significant cost reductions of the payloads (i.e., spacecraft) by designing for minimum cost and not for minimum weight and maximum performance. One proposes a reusable single-stage-to-orbit and return system with high development cost but very low recurring costs leading to very low life-cycle costs. The other proposes a very simplified expendable launch vehicle with extremely low both non-recurring and recurring costs, also leading to a very low life-cycle cost and early IOC (with low risk). This paper presents physical and costbenefit arguments which result in recommending that the Ultra Low-Cost Expendable Launch Vehicle (LCELV) concept be seriously considered as the next logical step in achieving cost-effective access to space with minimum fiscal risk. Such an would greatly reduce the cost of U.S. commercial, civil and military space systems and would go a long ways towards restoring the international competitiveness of U.S. Launch Vehicles. 1TRW, Manager, Propulsion and Combustion Center, Space & Technology Division TRW, Technical Consultant 1. Background Among the various goals enunciated in the National Space Transportation Study documents (Reference 1), the statement substantial reduction in space transportation costs must be attained if the nation is to meet the demanding needs of the future is most significant and forms the basis for a redirection in the philosophy of this country should fundamentally develop and procure space hardware. During the Apollo Lunar Landing period (1968-1973) efforts were being initiated to reduce the costs of space transportation. Primary emphasis was placed on reusable systems and studies were undertaken which ultimately resulted in the development of the space shuttle. However, during that same period James Webb, who was administrator of NASA, asked the question how cheaply can build expendable launch vehicles? This question was raised because some people felt that reuse of the launch vehicle might introduce additional costs due to the demanding requirements for more durable hardware, retrieval, and rapid turnaround refurbishment. The basic concern embodied in this minority position was that a reusable vehicle might not be as cost effective as an expendable system designed for minimum cost. It must be remembered that the stable of expendable launch vehicles existing at that time was designed for minimum weight and maximum performance with costs being a derived or resulting quantity rather than minimum cost being a primary design criterion. Even in studies being conducted today, some people still feel that minimum weight and advanced equates to minimum cost. This is not the of design-for-minimum cost which guides the design to use whatever weight or gives minimum cost. In any event, the decision was made in the late 1960's to proceed with a reusable system because it was felt that a shuttle would be even more economical than the simplified expendable launch vehicle on a life-cycle basis and was better operationally when manned by astronauts. Most steadfast believers in the economics of reuse often cite the fact that we don't throw away airplanes after one use. However, the analogy with an airplane is not totally valid. The structure and control surfaces 1048 American Institute of Aeronautics and Astronautics of an airplane are always necessary and critical for an airplane mission during its entire flight operation. A launch vehicle spends less than five percent of its flight time in the atmosphere; hence, winged structures are not needed. The tanks of a simplified expendable launch vehicle merely contain the propellant and can be very inexpensive, hence expendable. In any case, the operational history of the shuttle indicates that reusability has not shown itself to be cost effective, as of this date. 2. Performance Considerations Today there is an urgent need to provide timely access to space at minimum cost. Considerations are being given to both nearterm solutions as well as long-term goals. Terms such as evolutionary approach to leap-frog technology have been used by various proponents. The various launch vehicle candidates can be grouped into four classes with the following general rationale for each: a. Low-Cost Expendable Launch Vehicle (LCELV)-See Figure 1) The emphasis here is to design the simplest minimum cost design with little reliance on advanced technology. If the design is simple, development costs will be low as well as manufacturing and operating costs. b. Fully Reusable (including Single-Stage to Orbit) (SSTO-R, TSTO-R) (See Figure 2) Development costs (and hence risk) will be high, but if done properly, recurring costs should be very low (if not the lowest). This was the thesis of the partially reusable shuttle, which has not proven itself. Proponents feel that with proper use of advanced propulsion systems and materials, this can be achieved. c. National Launch System (formerly ALS, STAS, Spacelifter) This puts great emphasis on improvements in infrastructure, reduction in operations and paperwork costs and reliance on advanced and TQM. These involve relaxing performance requirements (i.e., STME vs. SSME) while still using LOX-Hydrogen. The concepts are higher-performance oriented than the Low-Cost Expendable Launch Vehicles. This is currently on hold, as an option, because of the lack of funding and appears to be dead. d. Interim Efficiency Improvements of Existing Systems (EELV) see Figure 3) The idea here is to spend money to improve the current systems, operationally, until new systems are rendered operational, or to continue with these improved systems indefinitely (since development of new systems may prove too costly). These systems (Thor, Atlas and Titan derivatives) have been evolving over the past 35 or more years to more complicated systems and one certainly might wonder many improvements are left to evolve and at what cost effectiveness? Within each of these classes there exists a minimum-cost design option. Among all of the classes there may be a minimum-cost concept. Options a) and b) have clear-cut differences with respect to performance requirements and are discussed in the following analysis. Single-stage to earth orbit and return, for reuse, appears desirable from an operational and logistics basis, but demands minimum weight of all inert components such as tanks, structure, engines, etc., because all of these items are accelerated to orbital speed and must later return to earth. At the same time, propellant combinations such as LOXHydrogen, are used to achieve high propulsion performance (high Isp). Because of the current state-of-the art in materials and propellants, the payload percentage efficiency will be very low and requires significant and costly efforts to develop designs based upon very lightweight inert materials, which must still survive multiple reuse without major refurbishing costs or failures. When go to multiple-staged vehicles are getting rid of inert material such as tanks, structure, engines, etc., in a quantized way as use up propellant. In other words, get rid of inerts before accelerate them unnecessarily to higher speeds. The most efficient way would 1049 American Institute of Aeronautics and Astronautics
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