SRC-100

URSI White Paper on Solar Power Satellite Systems (clean full text, 194 pp)

Published claims resting on this source

• CLM-0032 In 2007 the international radio science union published a white paper saying that nobody had measured this heating effect from the ground at these frequencies, and only calculations existed. The 1978 figure was repeated not in that white paper but in the longer report attached to it, which is a separate document.
• CLM-0047 Heating falls with the square of frequency. In 2007 no ground-based measurement of it was available at gigahertz frequencies, and theoretical estimates at 3 gigahertz said a rise in electron temperature from 200 K to 1000 K in the E layer might occur at 500 watts per square metre.
• CLM-0048 An international scientific body reviewed the proposed figures, found them ranging from 230 to 1,000 watts per square metre, and chose 300 on health grounds, with 10 at the edge of the receiving site.
• CLM-0049 The stated design intent in a 2007 URSI white paper is that the beam would be shaped to fall to 10 watts per square metre by the edge of the receiving site, which the paper gives as the human safety limit in most countries.
• CLM-0067 According to a 2007 international report, Japanese designs of the time chose their beam strength on cost and land grounds; the report does not give the ionosphere as the reason.
• CLM-0079 The 1978 paper modelled both a ground facility and a satellite case, and its 500 watts per square metre figure is a power flux for a given temperature rise, not a power rating.
• CLM-0083 The formula is the right type but nobody has said how far it can be pushed, and at space solar power frequencies the wave is about 200 times the plasma frequency. The field's own 2007 review says the case is unclear.
• CLM-0101 The 1978 contract required the researchers to report fixes if ionospheric disturbance pushed the pilot-beam phase error past 2 to 3 degrees, and a 1981 NASA report allowed 10 degrees of phase error for the whole pointing system. The requirement to hit the receiver within about 300 metres from geostationary orbit was stated in 2007, not in the 1978 design, which left that number open.
• CLM-0137 In four major space solar power studies from 1978 to 2007, none put a number on how much of the beam's energy would be lost if the beam sets up fine stripes of uneven density in the upper atmosphere; they mention the concern but do not measure or calculate it.
• CLM-0164 Two international radio-regulation reports and a radio-science white paper on beaming power from space never mention GPS-type satellite navigation in connection with heating the upper atmosphere, and none of them gives a figure in metres for how far off such navigation could be thrown.
• CLM-0460 The URSI working group's report proposes about 250 watts per square metre on bird-welfare grounds, and says the figure does not change with frequency.
• CLM-1467 (low confidence) Keeping people out of the area where the beam is strong is a plausible way for a strong beam to meet the 2020 international limit for public exposure, and international exposure guidance accepts limiting access as a way to comply. Other designs have worked this out: a 2013 Japanese review plans a no-entry area 3.5 kilometres across, and a 2007 international study sizes a 4-kilometre receiver this way. A 1977 US study set aside 204 square kilometres for one receiving site, without saying in its cost table what fixed that size, and costed buying and preparing that land. A 2026 international radio report that takes CASSIOPeiA as its example says the beam can be designed to fall below the public limit at the edge of the receiving site, with a safety zone matching the beam's footprint, about 3.5 to 6.5 by 7 to 13 kilometres in the UK. A diagram in it shows the receiving site taking 245 watts per square metre, but the report gives no figure for the beam's strength at the edge and no cost for the zone. A 2021 UK cost model for a CASSIOPeiA design includes the land for the receiving site but names no safety zone.
• CLM-1482 A 2007 report by the international radio science union, answering whether a power satellite would be safe, says government rules let a microwave oven leak up to 5 milliwatts per square centimetre, and that Japan allows 1 milliwatt per square centimetre measured 5 centimetres from the oven.

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