Comment by mlyle
20 hours ago
I doubt half the power is to the transmitter, and radio efficiency is poor -- 20% might be a good starting point.
20 hours ago
I doubt half the power is to the transmitter, and radio efficiency is poor -- 20% might be a good starting point.
Is the SpaceX thin-foil cooling based on graphene real? Can experts check this out?
"SmartIR’s graphene-based radiator launches on SpaceX Falcon 9" [1]. This could be the magic behind this bet on heat radiation through exotic material. Lot of blog posts say impossible, expensive, stock pump, etc. Could this be the underlying technology breakthrough? Along with avoiding complex self-assembly in space through decentralization (1 million AI constellation, laser-grid comms).
[1] https://www.graphene-info.com/smartir-s-graphene-based-radia...
This coating looks like it can selectively make parts of the satellite radiators or insulators, as to regulate temperature. But I don't think it can change the fundamental physics of radiating unwanted heat and that you can't do better than black body radiation.
Indeed, graphene seems capable of .99 of black body radiation limit.
Quote: "emissivity higher than 0.99 over a wide range of wavelengths". Article title "Perfect blackbody radiation from a graphene nanostructure" [1]. So several rolls of 10 x 50 meters graphene-coated aluminium foil could have significant cooling capability. No science-fiction needed anymore (see the 4km x 4km NVIDIA fantasy)
[1] https://opg.optica.org/oe/fulltext.cfm?uri=oe-21-25-30964
10 replies →
Entirely depends on band, at 10GHz more like 40%, at lower frequencies more, for example FM band can even go to 70%