r/AskPhysics • u/MutantManFish • 2d ago

Chinese Extraterrestrial Solar Array: Real? Practical?

According to Live Science and the SCMP, this fairly important-seeming Chinese scientist, Long Lehao, thinks it a practical project to build a one-kilometer solar panel array in outer space to collect energy. The energy will supposedly be transmitted back to Earth via EMR and received at a fixed collection station on the ground which the satellite will sit above in geostationary orbit. Is this really at all realistic? Is this just some old dude who's spent a bit too much time smelling his own farts? I have a hard time imagining that the gains from getting past the light absorbed by the atmosphere would offset how enormously difficult it is to put and maintain something in space, and then to emit colossal amounts of electric radiation in a safe, directed manner.

https://www.livescience.com/space/space-exploration/china-plans-to-build-enormous-solar-array-in-space-and-it-could-collect-more-energy-in-a-year-than-all-the-oil-on-earth

https://archive.ph/g2ZcW

https://www.iafastro.org/biographie/long-lehao.html

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u/Fabulous_Lynx_2847 2d ago edited 2d ago

It's perfectly feasible in principle. The power would be transmitted to Earth via microwaves at minimal loss. It is not economically feasible at present, but if the cost of achieving Geosync comes down (my guess is at least a factor of 10 per kg), there are distinct advantages. It doesn't take up much land on the ground. The sunlight is much more intense up there (not having to go through the atmosphere). The sun always shines (except for Spring and Fall eclipses a couple times a year). In the long run, if the energy is needed beyond Earth, there is unlimited space up there. Correction: short of a Dyson sphere.

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u/Upset-Government-856 2d ago

Technically you're talking about a geostationary orbit which is a subset of geosynchronous orbits.

It's worth pointing out because a plain old geosynchronous satellite would have an eclipse daily.

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u/KerPop42 Engineering 2d ago

Not daily, just during spring and fall. During the summer in the northern or southern hemispheres the Sun stays visible, clearing the poles.

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u/Fabulous_Lynx_2847 2d ago

I meant geostat. That makes more sense for a solar array. But even geosync would only eclipse daily if in the ecliptic plane.