Value chain · CLM-0101
In plain terms
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.
The claim as recorded
The 1978 Duncan and Gordon contract task set 2 to 3 degrees RMS as the level of heated-ionosphere phase perturbation on the uplink pilot beam above which methods to minimise the error shall be reported; NASA RP-1076 separately records that the existing error budget allows a single 10 degree overall phase error for the phase control system in pointing and focusing the beam; and the 0.0005 degree pointing accuracy, about 300 metres at the rectenna from geostationary orbit, is stated by the 2007 URSI White Paper for a model system, the 1978 Reference System Report leaving beam pointing as To Be Determined.
Scope and limits
The allocation is a design budget, not a measurement. Modelled quiet mid-latitude phase jitter of about 1 degree at 2.45 GHz sits inside it, and modelled disturbed equatorial and auroral values of 15 degrees sit far outside it, but both those figures are modelled rather than measured and the validating experiment was never completed. SRC-100 states that natural scintillation will be present at all power densities, so it is a baseline load independent of the beam. The existing framing of the allocation as a design budget rather than a measurement is correct and stands. The 2 to 3 degree figure is a contract-task REPORTING THRESHOLD, not an allocation inside a stated budget, and no source held states a total-system budget as a range; NASA RP-1076 states a single 10 degree overall phase error. On the 1978 scans the degree symbol does not survive text extraction and is returned as the digit 0, so a text search of SRC-108 for a degree figure returns FALSE NEGATIVES and these pages must be image-rendered to be read.
What it assumes
No assumptions are recorded against this claim.
Where it comes from
Phase allocation from SRC-108, the Duncan and Gordon contract task. Total budget from SRC-107, Dietz, Arndt and Leopold. Every reviewed design uses a retrodirective array, including SRC-085 1978, SRC-107 1981, SRC-100 2007 and the CASSIOPeiA description.
Related records
- Answers question
- QST-009 not published in this release
Cite this
energyaperture.com/c/clm-0101
CLM-0101, Energy Aperture, as of 1978-1981; pointing figure 2007.
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-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...CLM-0182When two different research teams assessed the exact same 1978 space solar power design, the older accounting method (which spreads...More on the source page.
- Also from SRC-100
- CLM-0032In 2007 the international radio science union published a white paper saying that nobody had measured this heating effect from the ground...CLM-0047Heating falls with the square of frequency. In 2007 no ground-based measurement of it was available at gigahertz frequencies, and...CLM-0048An international scientific body reviewed the proposed figures, found them ranging from 230 to 1,000 watts per square metre, and chose 300...CLM-0049The 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...CLM-0067According to a 2007 international report, Japanese designs of the time chose their beam strength on cost and land grounds; the report does...CLM-0079The 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...CLM-0083The 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...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...More on the source page.
- 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-0160A 1978-81 NASA design study calculated that simply pointing the satellite's structure accurately enough, without any electronic correction...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.
- Also from SRC-108
- CLM-0043The study the 1978 reference system cites put the level where the beam may start to disturb the ionosphere at about 20 milliwatts per...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-0066The figure adopted in 1978 was higher than each of the lower figures in the studies it cited, though those figures were themselves...CLM-0072The 1978 study gives 12 milliwatts per square centimetre for runaway, give or take a factor of two, and says no threshold can be set in the...CLM-0082The formula is the right one for the conditions space solar power would create. It was written for this case, not borrowed from a different...CLM-0083The 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...CLM-0085The 1978 formula does not give a threshold. It relates threshold power to the width of the plasma structures produced, so getting a single...CLM-0132A 1978 NASA-funded study calculated that a beam of about 12 milliwatts per square centimetre at 2.45 GHz would be the point where the...More on the source page.