in snow removal costs alone. There would also be large savings in energy consumed for heating and cooling because of the drastically reduced surface area of the city. If the receiving antenna were to be integrated into a roof structure over a city, several advantages and possibilities appear: no new land would be consumed by the rectenna nor would long-distance transmission lines be necessary, with the city receiving its power from the satellite directly. Tidal marshes and similar coastal wetlands have been suggested as possible sites for a receiving antenna, on the grounds that these are “waste” of little economic value. However, the extremely great ecological importance of such sites effectively prohibits this or any other use of them. The existence of offshore fisheries is wholly dependent on continued unimpaired functioning of such coastal wetlands. Unlike a meadow or a field of crops, these wetlands could be severely disturbed by the disruption associated with construction of a receiving antenna, which would require deep footings, and might even entail dredging. Even minor amounts of travel for example, through, a salt marsh for the purpose of routine maintainence or inspection could have a serious cumulative negative effect. Furthermore, the presence of the antenna structures and the associated RF screening would certainly reduce the light intensity on the ground; reductions of up to 20% are possible, and these would result in corresponding — and intolerable — reductions in overall productivity. Open land under the antenna could be used for a variety of compatible agricultural purposes. The lowering of light intensity would generally have an adverse effect on the agricultural value of the land, although there are some crops which do not thrive in full sunlight (for example, shade-grown tobacco). For other kinds of crops, a lowered overall productivity might be tolerated. Stratospheric Pollution with Shuttle Vehicle Exhaust Products. - a. Introduction Considerable attention has recently been paid to the potentially harmful effects of supersonic transport (SST) exhausts in the stratosphere, although current opinion seems to hold that these may have been overestimated at first. The potential hazards of SST operation which have received the greatest attention include: (1) The injection of particulate matter or gases which combine to produce particulate matter which may either reduce solar insolation by increasing the population of scattering particles, or increase the temperature of the atmosphere by increasing the population of particles which absorb solar radiation. Comparisons of the maximum possible effects of SST's with the effects of volcanic explosions have shown the former to be very small compared to the latter (54).
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