Value chain · CLM-0160
In plain terms
A 1978-81 NASA design study calculated that simply pointing the satellite's structure accurately enough, without any electronic correction, would miss the ground target by 10 to 30 kilometres - which is why the system needs a self-correcting radio-steering mechanism, and that mechanism's own error budget keeps beam losses under 3% and keeps the beam within a quarter of a kilometre of its target 99% of the time.
The claim as recorded
Dietz, Arndt and Leopold (1981) state that mechanical pointing accuracy alone (about 1 arcminute for the 1 km spacetenna, about 3 arcminutes for individual subarrays) would leave a potential ground miss distance of 10 to 30 km from GEO against a roughly 10 km-class rectenna, which is why active retrodirective phase control is required; the design's overall system phase-error budget is 10 degrees RMS, at which main-beam power loss stays under 3% and beam-pointing error stays under +-250 m at 99% probability.
Scope and limits
A 1978-81 MODELLED design figure; never validated with a flown SPS-scale system. The 3% power-loss and 250 m pointing-error figures are themselves modelled consequences of the budget, not independently measured. THE `support` TEXT WAS PRESENTED AS A DIRECT QUOTATION AND THE WORDING IS INVENTED (VER-1065, 2026-09-06). It is now marked as a paraphrase rather than a quotation, and the invented string is not reproduced. The MEANING is faithful and EVERY NUMBER in this claim is correct, which is precisely why it survived: an invented quotation whose sense is right reads as evidence and checks out on every value a reviewer would test. Do not quote this record. Anything needing verbatim text must be re-read from NASA RP-1076 directly - and note that document's text layer renders the DEGREE SYMBOL AS A PRIME, so an extracted '10 deg rms phase error' reads as ten arcminutes, a factor of 60. Render the page as an image before taking any figure from it. The support page numbers p.92, p.57 and p.93 are PDF indices for printed 63, 28 and 64 (the offset of 29 holds across the volume), and the title page lists more than three authors (R. H. Dietz, G. D. Arndt, J. W. Seyl and others), so "Dietz, Arndt and Leopold" is a short form (VER-1340 CONFIRMED 2026-09-19).
What it assumes
The 1 km transmit aperture, 10 km-class rectenna and GEO orbit of the 1978 DOE/NASA reference design are the basis for these figures; a different-sized system would need its own version of this calculation.
Where it comes from
Dietz, Arndt and Leopold (1981), NASA RP-1076, p.92 (mechanical tolerances, ref.26); p.57, p.93 ([PARAPHRASE, NOT A QUOTATION - wording invented, removed 2026-09-06; see limits]).
Basis: arcminutes (mechanical tolerance); km (ground miss distance); degrees RMS (phase budget); metres and percent (pointing error and power loss)
Related records
- Answers question
- QST-001 not published in this release
Cite this
energyaperture.com/c/clm-0160
CLM-0160, Energy Aperture, as of 1981.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-107
- CLM-0033 (low confidence)Apart from a 1981 NASA review that found no evidence for the number and suggested a higher one, nobody was found to have revisited it, and...CLM-0060In 1981 a NASA review panel said the 230 watts per square metre figure rested on an obsolete theory with no experimental support, and made...CLM-0061The experiments were done. They found heating two or three times stronger than normal, not the tenfold effect predicted, no irregularities...CLM-0062By 1981 the theory was being revised to a steeper frequency dependence, which would raise the permitted power density.CLM-0063NASA suggested in 1981 that 550 to 600 watts per square metre might be reasonable, roughly two and a half times the figure still in use...CLM-0101The 1978 contract required the researchers to report fixes if ionospheric disturbance pushed the pilot-beam phase error past 2 to 3...CLM-0420NASA's 1981 report says the experiments found nothing supporting the 23 milliwatt limit, that the measured heating was two or three times...CLM-0901Each antenna must hold its position along the line to the receiver within about three millimetres for a tenth of a decibel. The whole 1970s...More on the source page.