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Steam Power In Space

Water going through pipes on the hot side facing the sun turns to steam...
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then gets cooled on the dark side of the panel.

You've got a difference of 348 degrees, 248 degrees on the sunny side vs minus 100 degrees on the shady side of the panel. That's a big difference you could tap to turn a steam turbine to generate electricity.

Seems like you'd be able to get a heck of a lot more power than you would from a solar panel.

doctorremulac3, Feb 02 2023

Similar idea discussed on StackExchange in 2015... https://space.stack...e-for-a-space-craft
... and pretty much dismissed. [a1, Feb 02 2023]

[link]






       Riddle me this, Batman - Why has almost* every spacecraft launched so far used either solar panels or batteries (of either chemical or nuclear types) for internal power?   

       I did hedge there by saying "almost." If 8th was here he'd have the history at his fingertips but it takes me longer. I'll dig around and let you know if I find anything about space experiments with solar thermal power - Stirling engines, steam, whatever else might fall outside of "battery or solar panel" brackets.
a1, Feb 02 2023
  

       //almost*// I would guess that most of the living beings (whether Human or other) launched into space so far have not been powered by either solar panels or batteries inside them.
pocmloc, Feb 02 2023
  

       Here's why I think this hasn't been done. Why? Solar panels give you all the power you need and are a few microns of chemicals spread over plastic panels as opposed to a complicated, failure prone steam engine.   

       That being said you'd use alchohol or something with a lower boiling point.
doctorremulac3, Feb 02 2023
  

       [pocmloc] I added some important clarifying words to my earlier comment, just for you.
a1, Feb 02 2023
  

       I suspect the reason they haven't been used so far has something to do with almost all spacecraft being unmanned, and the manned ones not having much crew and their time being very expensive, driving a preference for solid state equipment that is extremely reliable. If you had an engineer on hand to fix it, the far greater efficiency of heat engines may well win out.   

       Solar thermal rockets have been proposed. Focus the sunlight, use it to heat your propellent. About 2-3x better specific impulse than the best of chemical. Whether that's a better option than solar-electric depends on your mission.   

       On Luna, you could drive a pretty efficient engine just using the lunar diurnal cycle, no concentrators needed. Given that you'd be making the thing out of steel and aluminum, readily (well, you have to smelt it) available on Luna, and the complexity of shipping a foundry up there to make solar cells, heat engines win out for in-situ energy system production.
Selky, Feb 03 2023
  

       Oh absolutely, there's no question about why this hasn't been used yet, solar panels are the simplest, lightest and most problem free electricity producing system you can make. That being said, I assume the additional power you MIGHT be able to get from these could give additional abilities to communications satellites and such. That's a pretty big temperature differential to play with.
doctorremulac3, Feb 03 2023
  
      
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