operation should be as small as possible to enclose the mass to be delivered to orbit. The automatic fabrication of structure in space results in high density packaging. Solar cell blankets, concentrator membranes and power distribution busses also can be densely packaged. The antenna waveguides are lightweight, precision hardware. See figure A-34 for nominal densities of various components. Early concepts tolerated lightly-loaded HLLV's to avoid manufacture of waveguides in orbit. However, more recent studies have shown that by mixing low- density components with high-density components on individual flights, packing densities approaching 100 kg/m can be achieved, thereby avoiding a relatively difficult space manufacturing activity for antenna subarrays while maintaining high launch vehicle payload density. Figure A-35 illustrates a typical component mix to reduce the number of launches. Space Construction Personnel - The number of construction personnel required for building the SPS is a function of the degree of automation, the ratio of direct monitoring of operations to remote monitoring, the rate of construction and the amount of maintenance anticipated on the facility equipment. Once estimates of construction workers are made, the requirements for support personnel are derived. There has been little fluctuation in the construction crew requirements during the SPS studies. Table A-6 provides a chronology of the estimates that have been made. Construction Equipment and Construction Support Equipment - For the purpose of developing construction concepts and costing, the categories of construction equipment and construction support equipment were established. Generally, the construction equipment is designed for a specific function such as solar cell blanket deployment, fabrication of structural elements, or power distribution system installation. The construction support equipment performs a variety of tasks or more universal function such as the facility proper, logistics vehicles, work stations, or remote manipulators. A primary requirement in space construction is providing a means of positioning construction equipment so it can perform its function. The construction facility or base is a space frame with support points, guides and
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