Value chain · CLM-0870
In plain terms
Recomputing the 1978 design from its own stated parameters reproduces its beam, its power and its own intercept figure of 95 per cent; the 88 per cent quoted elsewhere in the same report matches a different term in another breakdown of the same losses, and on the knowledge base's arithmetic the two breakdowns agree to about 0.3 per cent.
The claim as recorded
The 1978 DOE/NASA reference downlink's three headline values are all reproduced by independent forward computation, and the inconsistency between them is INTERNAL TO THE DOCUMENT rather than a disagreement with it. Three implementations sharing no code place 94.72, 94.14 and 94.80 per cent of radiated power inside a 5 km radius perpendicular to boresight, against the "Intercept Efficiency 0.95" that the document's own Table B-1 lists as a separate row - agreement to within one point. The approximately 88 per cent stated in the p.37 prose matches the 0.88 that Figure A-9 at PDF p.125 gives for Rectenna Energy Collection, a term in a different decomposition; on our arithmetic the two chains agree to 0.31 per cent, 0.965 x 0.956 x 0.981 x 0.95 = 0.85976 against 0.98 x 0.88 = 0.86240, on a pairing of terms that is ours and not the document's (see limits).
Evidence behind this: Forward computation of the downlink from the source's own stated design parameters, run by three implementations sharing no code, the first of them blind to all prior work on the question. CALC-088.
Scope and limits
THE FINDING IS ABOUT SRC-085'S INTERNAL CONSISTENCY, NOT ABOUT ANY OF ITS NUMBERS BEING WRONG. Its p.37 prose sentence and its two efficiency tables describe the same system in different decompositions, and the prose sentence states the chain term where a reader takes it for a beam-geometry fact. The 0.003 per cent shape agreement reported by the first computation is NOT reproducible as stated: it uses that route's own radiated power and peak rather than the source's stated pair, which give 0.17 per cent, and the ratio depends on a range the source never states. Use 0.17 per cent, with the range attached, or do not use it. No computation here modelled the omitted error terms, so none of these figures is a prediction of what the built system would have delivered. AN OPEN QUESTION AGAINST THIS CLAIM, RAISED 2026-09-06 AND NOT RESOLVED HERE. A second reading of the page found that Table B-1 has NO Rectenna Energy Collection row at all, and that its own brace groups Intercept Efficiency 0.95 with Ideal Beam 0.965, Inter-Subarray Errors 0.956 and Intra-Subarray Errors 0.981 to a printed 0.86 - 0.965 x 0.956 x 0.981 x 0.95 = 0.85976, which has been checked arithmetically. If that reading holds, THE COMPARABLE AGGREGATE in Table B-1 against the figures' collection term is 0.86 and not 0.95, and a reconciliation setting 0.95 against 0.88 compares an intercept term to a collection term. It would NOT overturn this claim's central comparison, which sets our computed intercept against Table B-1's intercept row, but it bears on how the two decompositions were reconciled. Table B-1 has NOT been rendered and the question is recorded rather than settled. ANSWERED 2026-09-06, IN THE DIRECTION THE QUESTION ANTICIPATED, AND THE CLAIM STANDS. Table B-1 was rendered at 600 dpi per block. Only one combination reproduces the printed 0.86 - Ideal Beam 0.965 x Inter-Subarray 0.956 x Intra-Subarray 0.981 x Intercept 0.95 = 0.85976 - and it SKIPS Atmosphere Absorp., a row the drawn brace appears to enclose. So the aggregate comparable to the figures' collection term IS 0.86 and the 0.95 IS the geometric intercept alone. Whether the document intends that grouping or drew the brace wrongly is not settled and does not need to be: both readings leave 0.95 an intercept term rather than a collection term, which is what this claim's central comparison turns on. Every product was re-checked. CALC-090 carries the brace work. The 0.31 per cent agreement rests on a pairing of terms that is ours, not the document's: it sets Table B-1's beam-quality and intercept terms, without B-1's own Atmosphere Absorp. 0.98, against Figure A-9's Average Atmosphere 0.98 times Rectenna Energy Collection 0.88, while A-9 also lists a separate Mechanical Tolerances 0.98. Other pairings of the two tables are possible and are not tested here.
What it assumes
An ideal aperture. NEITHER OF THE FIRST TWO COMPUTATIONS MODELLED THE 2 DEGREE MEAN EDGE PHASE ERROR, a defocus term that would push the computed fraction DOWN, nor the plus or minus 3 arc-minute mechanical alignment, grating lobes, ionospheric phase perturbation or a Fresnel correction; the third did not either. That omission mattered more to the ORIGINAL version of this claim, which asserted a gap against the document, than it does to this one, which asserts agreement with the document's own intercept row.
Where it comes from
This is the project's own working, shown in full:
CALC-088 carries both computations, their sabotage records and the disagreement between them. The stated values are quoted on CLM-0869 and CLM-0015. The 5 km region is confirmed circular and beam-normal by SRC-085 PDF p.37 verbatim: "88% of its energy within a 5 km radius perpendicular to boresight".
Basis: physical optics on a 1 km circular aperture, 2.45 GHz, 10 dB truncated Gaussian taper; no currency
Related records
- Answers question
- QST-001 not published in this release
Cite this
energyaperture.com/c/clm-0870
CLM-0870, Energy Aperture, as of 2026-09-06.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-085
- CLM-0013The paper that modern UK studies rely on for the beam figure calls anything below 1 kilowatt per square metre safe, with 230 watts per...CLM-0020The original 1978 design set the beam at 230 watts per square metre in the middle of the receiving site, about one twenty-third of that at...CLM-0023In the 1978 reference design, two limits set the size of the transmitter and the receiving site: how much heat the transmitter can shed...CLM-0039The 1978 report set the figure to protect radio and navigation systems from a disturbed ionosphere, called the number theoretical and...CLM-0045The apparent conflict between 12 and 23 was not an error. The underlying study gave a range, and the figure adopted sits near the top of it.CLM-0101The 1978 contract required the researchers to report fixes if ionospheric disturbance pushed the pilot-beam phase error past 2 to 3...CLM-0137In 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...CLM-0138The original 1978 government design for beaming power down from space adds up all the expected energy losses to get 63% overall efficiency...More on the source page.