In the subsections that follow, the specific construction approach and status of the solar-photovoltaic concept is first discussed, followed by a similar discussion for the solar-thermal approach. A summing up of general considerations and overall requirements is then provided. (1) Solar-Photovoltaic Concept The implementation approach under consideration for this concept would utilize solar cell blankets with concentrators, and an aluminum structure with a rotary joint for power transfer and antenna pointing. All assembly would be in LEO (250 nautical miles-463 km) although activities in an intermediate orbit (~7,000 nmi-13,000 km) outside the Van Allen belts have been considered and are still apparently not ruled out. Trade-offs between assembly using ground-based remote control, space-based teleoperators, and manned extra-vehicular activities (EVA) have been considered. Some combination of these assembly approaches is said to be most likely to evolve, including establishment of a space factory. Since lift vehicles may be more volume than weight restricted, a space factory would utilize flat-rolled stock in combination with automated manufacturing techniques to form beams, girders, etc. These would then be welded or mated to produce the required modules. With respect to the state-of-the-art, Ref. All states: • Manufacturing modules: The specific technology for manufacturing modules in space is not known at this time. It is believed, however, that the technology should be relatively straightforward to develop once the basic design and materials have been established for the items to be manufactured in space. The major items for manufacture are structural elements and slotted waveguides for the subarrays. • Remote manipulators: The specific technology for remote manipulation modules is not known at this time. However, some investigations have been conducted in associated control systems. To advance the state-of-the-art and derive a more definitive approach to construction, Ref. All proposes a series of "near term" studies, where "near term" would extend up to the time the Shuttle becomes
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