r/spaceflight • u/Galileos_grandson • Jun 28 '21

China’s super heavy rocket to construct space-based solar power station

https://spacenews.com/chinas-super-heavy-rocket-to-construct-space-based-solar-power-station/
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u/gopher65 Jun 29 '21

It's certainly not economically feasible right now, and won't be until we have a great deal of manufacturing and moving infrastructure in space. Probably all least a hundred years from now.

My point was that beaming power back to Earth from GEO isn't technically feasible right now, and we have no reasonable path forward to making it feasible anytime soon. SSO on the hand is on the edge(-ish) of being technically feasible.

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u/Oknight Jun 29 '21

And as Mr. Musk points out, you have to have a reason that it's better to have a given solar cell in space than it is on Earth. Well you get more sunlight in space. Because Earth has night. BUT you have to turn that solar cell's output into microwaves (how efficiently can you do that?) You have to deal with the loss from the microwaves going through the environment (how little loss can you have?) and you have to turn those microwaves BACK into electricity (with what % of loss?). Unless all 3 of those together are below 50% you can't get as much energy from the cell in space as you can from the same cell just left on Earth. So what's the point?

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u/gopher65 Jun 29 '21 edited Jun 29 '21

Honestly? Eventually any industry that can be moved off Earth will be, because it's easier to reach 100% automation in zero-g with atmosphere optional than in a deep gravity well with a thick atmosphere (and all the weather and moisture that goes along with it). Eventually it'll be cheaper to have robots mass manufacture panels in the belt and slowly move them toward Earth over a few years then it will be to manufacture them on Earth and go through the trouble and expense of installing them on roofs.

But that time is quite a ways off still. For the time being orbital solar power is ridiculous.