Economic benefits due to higher payload fraction are not expected because the expenditure for development is substantially higher and the operational costs are, due to extensive ground stations, not less than the costs for a conventional system. A rough estimate has shown, that for the reference scenario a conventional launch system yields no significant ozone change [7], Thus, a conventional launch system is (subject to detailed atmosphere-chemical analysis) preferred. Infrastructure and Logistics Due to its magnitude and complexity the considered scenario is to be realized in an international framework. The decisions concerning the launch base and infrastructure will be driven by policy more than by technical considerations. At present, only some technical requirements can be placed. Assuming 11 launches per day, then a minimum of 7 to 8 launch bases are required. The personnel transport may be separated from the cargo transport. For maximum efficiency, launch bases near the equator are necessary for cargo transport. It should be analyzed, whether artificial islands in international waters are suitable and can be built at justifiable costs. If the proposed launch vehicle is capable of cruise, launch- and landing, the location of the bases is nearly arbitrary. The most relevant aspect of logistics is the information transfer between the international partners, because a complex system like this needs a very carefully planned coordination. It is advisable to develop all systems in an international framework to get a standardization and avoid duplication of effort. The production of technical components , payloads and propellants might be dine in national programs. Summary The technological problems are mainly in development, production and operation of the proposed HDCF. Particularly the energy transfer by laser and the extremely high temperature of the combustion chamber lead to nearly insurmountable problems. Due to the environmental compatibility, the selection of the stabilizing medium is of special significance. Analysis showed that only oxygen or argon seems to be suitable for the externally supplied vehicle. However, these stabilizing media lead to the highest requirements on technology. The utilization of a conventional launch system equipped with a chemical propulsion system seems to be more favorable. With the required technology, based on existing systems like Energia, problems concerning environment are not expected. If there are no other negative findings concerning environmental compatibility, this launch system is preferred. Another additional issue is the extremely high launch rate of approximately 4000 launches per year. In comparison to the other problems in connection with the discussed transportation scenario, this seems not to be an insurmountable problem. 1. BIBLIOGRAPHY [1] "Globales Sonnenenergiekonzept (GSEK)" MBB Ottobrunn/Bremen, Dec. 1988
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