SRC-516

Workshop on Satellite Power Systems (SPS) Effects on Optical and Radio Astronomy; CONF-7905143; published April 1980, workshop held May 1979

Commissioned by U.S. Department of Energy, Office of Energy Research, Satellite Power System Project Division; Under Contract No. KD-03-82029. 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-0988 The rule that radio astronomers hold the satellite to is a specific international report, and its limit near the satellite's frequency is 87 dB, about five hundred million times, below the noise the 1975 transmitter design would put on the ground. The rule also says nothing about noise just outside the protected bands, which is where most of a wideband transmitter's noise would fall.
• CLM-0989 The same figure, minus 160, appears in two 1970s papers meaning two different things: in one it is the noise reaching the ground, in the other it is the noise of a single tube compared with its own signal, which after adding up ninety thousand tubes and the distance to the ground comes out 27 decibels lower. Anyone quoting "minus 160" has to say which.
• CLM-0990 The extra twenty decibels of noise suppression for a fleet assumes a hundred satellites. The government's reference plan was sixty, which needs about eighteen decibels; the hundred was a convenient round figure that the workshop papers used and said so.
• CLM-0991 In 1978 the frequency band the satellite was to use was an industrial free-for-all band in the West, where users must put up with each other's interference, but the Eastern bloc had its equivalent band shifted 75 MHz lower, so the satellite's frequency was not inside it there.
• CLM-0992 The receiving field on the ground makes its own harmonics: the diodes that turn microwaves into electricity also generate signals at two, three and four times the frequency and send some of it back out. Early measurements put the strongest of these at about three hundred times weaker than the main beam.
• CLM-1091 The people running the programme said 2.45 GHz was sensible and also said, in the same breath, that nobody international had agreed to it and the choice was open. Their own account of the 1979 world radio conference is that no frequency was given and one might be, if the environmental case were made.
• CLM-1222 The fourth paper the 1978 design cites for its beam limit also calls the limit a theory that had not been tested. The one experiment it reports, at Arecibo in 1977, heated the upper atmosphere less strongly than the satellite would and found nothing, so it did not test the limit.

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