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I wonder what the logistical challenges would be to adding an hour of actual daylight to a medium-sized U.S. city around dusk by means of orbital mirrors? Sunl
by elihu 6y ago
I wonder what the logistical challenges would be to adding an hour of actual daylight to a medium-sized U.S. city around dusk by means of orbital mirrors?
Sunlight irradiance is about 1000 watts per square meter if the sun is straight up. We'll say that a city center is about 10 square km, and that 300 watts per square meter is an acceptable afternoon-evening light level. So, if I did the math right, that's 3 billion watts if we wanted to illuminate electrically with 100% efficient bulbs, or 3 million kwhs to provide one evening of light, which would be $300,000 per night at 10 cents per kwh.
On the other hand, a giant sheet of mylar in space, correctly positioned, might have a similar effect with no recurring energy cost. I imagine the orbital mechanics and optics situation would be challenging, but could at least be fun and interesting to talk about.
- matsemann 6y agoSounds like the Norwegian town Rjukan that doesn't get any sunlight during winter, so they put a huge mirror on a mountain top. https://www.theguardian.com/world/2013/nov/06/rjukan-sun-norway-town-mirrors https://www.theguardian.com/world/2013/nov/06/rjukan-sun-nor...
- elihu 6y agoI like that kind of problem solving.
- _Microft 6y agoWhat environmental impacts would you expect?
- elihu 6y agoConfused animals. Also, the mirror would cause shading on whatever part of the Earth they passed over, which all things considered is probably a good thing. (If the mirror is big enough and close enough, some people might get to see a full eclipse.) There'd be local heating in the target city though, which could be good or bad. If the mirror is only used in the winter, it could be a net positive and reduce icy road conditions and heating bills somewhat.