SRC-169

Modular Multirotary Joints SPS Concept - Challenges and Design Considerations. IEEE Transactions on Aerospace and Electronic Systems, vol. 61 no. 1. Received 13 March 2024, accepted 5 August 2024, published 12 August 2024, version of record 11 February 2025.

Commissioned by China Academy of Space Technology per author affiliation, not independently confirmed. Who paid for a study is recorded because it bears on how its conclusions should be read, not because it makes them wrong.

Published claims resting on this source

• CLM-0141 A Chinese government-linked design study calculated that, outside the main beam of its proposed satellite, stray sidelobe power on the ground would fall to about 22 watts and then 7.5 watts per square metre.
• CLM-0142 A major Chinese government-linked design paper on a specific space solar power concept does not mention the upper atmosphere at all, and does not reference any of the classic Western physics papers on beam-ionosphere interaction.
• CLM-0501 A 2024 Chinese satellite design concept plans to beam down microwaves twice as strong as CASSIOPeiA's own typical figure, and its designers do not appear to have considered the upper-atmosphere stability question at all.
• CLM-0687 The Chinese design says how it gets to orbit. Rockets carry the parts to a low orbit. A reusable space tug then moves each part up to the high orbit, where they are put together. The paper says that assembling it high up lowers the risk of hitting space debris, because there is much less debris there. The tug comes back down to be refuelled and to have its solar panels swapped. The design does not say whether the tug burns fuel or uses electric thrusters.
• CLM-0688 The Chinese design shields the satellite parts from radiation during the climb to high orbit, using the tug itself as the shield. It also plans to replace the tug's own solar panels in low orbit, along with refuelling it, so that the tug can be reused.
• CLM-0689 The Chinese team published its own cost figures for a one-gigawatt system: about 17.3 billion US dollars over 30 years, which they put at about 6.6 US cents per kilowatt-hour. They say this is more than 30 per cent cheaper than their previous design.
• CLM-0692 The Chinese design's own summary table adds up: the parts weigh what the total says they weigh. Its claimed 12.3 per cent efficiency is sunlight-to-grid, which checks out against the area of the panels and the strength of sunlight in space. The antenna is a long thin strip, 100 metres by 10.5 kilometres, at 5.8 gigahertz.
• CLM-0697 The Chinese 6.6 cent figure ignores the cost of money. Once you charge interest on the capital, the same numbers give about 10 cents at a low interest rate and 21 cents at a high one. Even so, NASA's own figures stay between about 2 and 16 times more expensive, depending which of NASA's cases you pick.
• CLM-0698 The Chinese cost table states a transport price of 1,000 dollars per kilogram in its column heading, but its own numbers only work out at about 482 dollars per kilogram. Every row shows the same mismatch, so it is not a rounding error. Either way the figure is far below NASA's assumed 11,050 dollars per kilogram - between 11 and 23 times below, depending which of the two you use.
• CLM-0879 The only two full satellite designs here that say what voltage they run at disagree eight-fold, and the newer, smaller one runs at the lower voltage. The newer design's paper says its modular layout keeps the cables short, about 310 metres, and that this allows the lower voltage.
• CLM-0880 The Chinese design runs its solar panels at about 500 volts and steps up to a 5,000 volt main bus. It is the only modern satellite power distribution architecture recorded here.
• CLM-0888 Cable mass rises with the square of distance and falls with the square of voltage. The Chinese design says it can use a low five thousand volts because it is built as fifty modules, each sending its power only about 310 metres. The 1978 design sends all five gigawatts across the satellite as one system, and its report says it chose forty thousand volts to save conductor and equipment mass.

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