SRC-549

Solar Power Satellite Concept Evaluation Activities Report, Volume II - Detailed Report (progress report, July 1976-June 1977); NASA TM-74942; 1977

Commissioned by National Aeronautics and Space Administration, Washington, D.C.; in-house report, no contract number printed. Who paid for a study is recorded because it bears on how its conclusions should be read, not because it makes them wrong.

Published claims resting on this source

• CLM-1089 The higher industrial band would have shrunk the receiving field to a fifth or a third of its size, at the price of a satellite that could not shed its heat, a bigger electricity bill, and a beam that rain could knock out. Every time the programme costed it the answer was the same and 2.45 GHz stayed.
• CLM-1409 A 1977 NASA study of how to hold up the receiving station's panels was told the ground underneath had to stay farmable, with a metal mesh of small diamond-shaped holes. It compared eleven ways of building it, some raised about 5 metres, high enough for farm machines underneath, and found the more usable the land below, the more the structure costs.
• CLM-1486 A 1977 NASA study of how receiving stations would join the US power grid looked at two kinds of shadow. For about six weeks around each equinox, the Earth would shade each satellite once a night near midnight; the study judged this easy to cover, because demand then is about half its peak. If more than a hundred satellites were built, they would also shade each other each morning and evening, close to peak demand. By the study's table, that would cut the number of five-gigawatt receiving stations the US grids could take in 2025 from about 360 to about 60. The study added that direct-current links between the regional grids would largely remove the problem, but gave no figures for that.
• CLM-1487 In Britain, the amount of fast back-up power kept ready depends mainly on the biggest single block of power that could be lost at once; the rules do not set it by fuel. So a space solar station would need about the same fast back-up as a gas power station whose biggest single loss is the same size. A 2 GW space plant would be a bigger single loss than the 1,800 MW Britain now plans for, if one fault could take all of it. A satellite in geostationary orbit also passes through the Earth's shadow each night for about six weeks around each spring and autumn equinox, for up to about 70 minutes. Those times can be predicted exactly, and other power stations would have to cover them.

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