Value chain · CLM-1117
In plain terms
The 1977 study found the cheapest way to keep a silicon satellite at full power was to heal the radiation damage in place rather than build it bigger, that healing works best without mirrors because mirrors cannot be healed, and that a cheaper cell mattered more than a better one. That is why the reference system went to flat arrays and an annealing plan.
The claim as recorded
Boeing's 1977 trade of ways to hold 10 GW for 30 years against silicon degradation found that initial oversizing "is a severe penalty" (253.1 km2, 120.5 km2 active, 105,794 t against the beginning-of-life reference's 146 km2, 70 km2, 64,883 t), that adding array at five-year intervals captured most of the gain (238.3 km2, 86,295 t), and that "Annealing provides the least-cost approach" (182.2 km2, 86.4 km2, 76,075 t); that with annealing the concentration-ratio trade "strongly favors" CR 1 (106.5 km2, 71,728 t for GEO assembly) because the CR 2 reflectors also degrade and cannot be annealed; that for LEO assembly with self-powered transfer the transfer blankets are "severely degraded (about 50%, depending on coverglass thickness and transfer time)", which again favours CR 1 with annealing (73,177 t against 78,821 t); and that dropping the cell from 18 to 14 per cent in 2-point steps made no dramatic change in mass or cost, so "achieving low cell costs is much more important than maximizing efficiency". Its summary: "Annealing is a critically important technology".
Evidence behind this: T3-contractor trade study, its conclusions stated in its own words and its configuration masses tabulated on figure sheets.
Scope and limits
A 1977 TRADE ON A 10 GW TWO-ANTENNA SATELLITE WITH A PROJECTED 18 PER CENT CELL; the array-addition and LEO masses are read at zoom-6 and zoom-8 crops where the layer garbles them, and two figure sheets print different initial masses for the same configuration (86,295 against 80,589 t for array addition; 78,821 against 78,515 t for the LEO annealed CR 2 satellite), carried here as printed. The annealing option assumes the feasibility CLM-1118 and CLM-1119 test; the cost figures on the figure sheets are not carried here.
What it assumes
The report's gross cost model (section 3.7, not read) for the cost ordering; the 10 GW at two rectennas of the Part I sizing; masses exclude the 50 per cent growth allowance the mass tables carry.
Where it comes from
PDF 39 / printed 33, raw: "Annealing is a critically important technology"; normalised: "high promise for the eventual success of annealing"; raw: the simpler satellite at CR 1 "is preferable" (fragment); normalised: "Silicon also is less sensitive to cell performance than supposed". PDF 44 / printed 38, raw: "does not meet the requirement of" maintaining rated output over 30 years; "blankets and the reflectors degrade"; "Annealing is the most attractive"; the page's three options, initial oversizing, annealing and array addition (render reading), with "Initial oversizing is the least attractive option" (normalised). PDF 53 / printed 49: "Initial oversizing is a severe penalty" and "there are better solutions" (normalised and raw). PDF 55 / printed 51, raw: "Annealing provides the least-cost approach"; "trade strongly favors" CR 1 with annealing; "starting from a reference figure of" 18 per cent; normalised: "dropping 2 points per step"; "Even at 14% efficiency there is not a dramatic change in either mass or cost"; raw: "low cell costs is much" more important than maximizing efficiency; the reflector-degradation reason and the "about 50%" transfer degradation are render readings. Figure sheets (layer, PDF 56-58): Figure 3.2-13 "REFERENCE SILICON CR=2 10 GW BOL TOTAL AREA: 146 Km2 ACTIVE ARRAY AREA: 70 KM2 TOTAL MASS: 64,883 MT" and "10 GW FOR 30 YRS. VIA INITIAL OVERSIZE TOTAL AREA: 253.1 Km2 ACTIVE ARRAY AREA: 120.5 Km2 TOTAL MASS: 105,794 MT"; Figure 3.2-14 array addition 238.3 km2, 90.3 km2 (113.3 EOL), 86,295 MT (100,480 EOL), the mass read at a zoom-8 crop where the layer garbles it, annealing 182.2 km2, 86.4 km2, 76,075 MT; Figure 3.2-16 CR 1 with annealing, GEO assembly, 106.5 km2, 71,728 MT against CR 2's 182.2 km2, 76,075 MT; Figure 3.2-18 LEO assembly with annealing, CR 1 106.5 km2, 73,177 MT against CR 2 182.2 km2, 78,821 MT, both read at a zoom-6 crop; Figure 3.2-17 prints the same LEO annealed CR 2 satellite at 78,515 MT with the same costs, and Figure 3.2-15 prints the array-addition satellite at 79.8 km2 active and 80,589 MT initial against Figure 3.2-14's 90.3 km2 and 86,295 MT, with the same end-of-life 113.3 km2 and 100,480 MT. Recomputed: 71,728 / 76,075 = 0.943, a 5.7 per cent mass saving for CR 1 with annealing at GEO; 73,177 / 78,821 = 0.928 for LEO assembly; 105,794 / 64,883 = 1.63 for oversizing; 253.1 / 146 = 1.73 in area.
Basis: km2 of total and active array area; metric tons of satellite mass (excluding growth); 10 GW minimum ground output for 30 years
Cite this
energyaperture.com/c/clm-1117
CLM-1117, Energy Aperture, as of 1977-07.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-475
- CLM-1114The 1977 silicon design assumed an 18 per cent cell that did not yet exist, doubled the sunlight on it with cheap plastic mirrors, and got...CLM-1115Mirrors that doubled the light only added 40 per cent to the output, because the cells ran hot and the mirrors were not flat; after thirty...CLM-1116Thirty years of radiation behind a hair-thin glass cover was expected to take a third of the cell's power; a cover three times thicker...CLM-1118In 1977 five radiation-damaged cells were healed with a laser or an electron gun, getting back between a fifth and a half of what they had...CLM-1120In 1977 the gallium arsenide option rested on a 20 per cent cell nobody had made, an assumption that it would still be near 20 per cent...CLM-1121Half a kilogram per square metre for the working blanket, about half of it the silicon itself; per kilowatt delivered on the ground the...CLM-1468The basic idea, a solar power satellite climbing to its final orbit on electric engines run by solar panels it carries, with no separate...