8 Space Transportation_____________ Space transportation is usually the single most expensive service used by a space program. In view that about 25 to 40% of the cost is spent for as little as a 10 minute service, for a project that lasts many years, it is clear that special attention has to be given to this topic. In each step of a Space Solar Power Program development plan, different types of space transportation are needed. The first demonstration missions are envisaged as being near term, small in size —a few kW—and can utilize current launch systems. The first operational missions are larger in size —100 kW—and may be 10-15 years away. The missions would profit by using systems under development or updated versions of today's launchers. The future commercial missions are yet larger, 1-100 MW, and 1-10 GW. These missions are dependent on more future, reliable, inexpensive and dedicated transportation. In the first and second space transportation section (8.1, 8.2) the basic data is given for the launchers and upper stages (OTV) that are operational or under development. This is primarily used as basic data upon choosing a transport for the different first demonstration missions of the stepped evolution of the Space Solar Power Program. The third section (8.3) covers the launch systems under development today and informs the reader of what is available for the first operational space based solar power satellites in the first years of the 21 th century. The fourth section (8.4) summarizes the space transportation envisaged by previous “SPS” studies. Especially all the future transportation concept of the NASA/DOE studies in the late 1970's are reviewed. The four following chapters look into the next generation of available space transportation systems. 8.5 discusses perceived SPS customer requirements. Specific suggestions are made for preferred new transportation systems and their possible changed characteristics. Not only cost but also reliability, availability and resiliency are addressed. Section 8.6 describes different technologies that could improve all types of space transportation systems. In specific improved propellants, new materials and nuclear and laser power is discussed, section 8.7 goes into more detail about the technical options and possible systems used for future lunar transportation. The final section 8.8 discusses the development schedule of the space transportation for the stepped Space Solar Power Program development program. 8.1 Operational Space Transportation Systems This section will discuss the world's current orbital launch and piggy-back capability. 8.1.1 Review and Analysis of Earth To Orbit Launchers This section will examine the current 1992 launcher market. Any space power demonstrations will be launched on one of the vehicles discussed below. The discussion starts with a review of operational launchers, This is followed by a market analysis. The section finishes with a discussion of costs. Review of Operational Launchers Modern operational launchers can be organized into categories according to payload lift capabilities and orbit that payload is placed into. For the purposes of this review, we will use the following classification system: System Classification Payload to leq Payload to GTQ Small Below 1000 kg N/A Medium 1001 kg to 10,000 kg 500 kg to 5000 kg Large 10001 kg to 20,000 kg 5001 kg to 8000 kg Heavy Lift Above 20,000 kg Above 8000 kg
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