Author Topic: Massive Solar Mirror To Bring Light at Night  (Read 1782 times)

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Offline cdev

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Re: Massive Solar Mirror To Bring Light at Night
« Reply #25 on: November 06, 2018, 12:01:12 am »
Fusion? This sounds like nuclear fusion.

Please no more fission, (Earth's last generation's nuclear) its an accident waiting to happen.

Or we could pursue the technology which would provide endless power, next gen nuclear.  With next gen nuclear There is no long lived radioactive waste, a Chernobyl size accident would be habitable in 25 years and we have a universe of fuel.   Unlike, solar or wind nuclear power provides electricity day and night.  And we don’t have to do any silly engineering like a mirror in space or transmit gig-watts of electricity thousands of miles and over land and through the oceans,
"What the large print giveth, the small print taketh away."
 

Offline cdev

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Re: Massive Solar Mirror To Bring Light at Night
« Reply #26 on: November 06, 2018, 12:07:16 am »
Lots of other things to worry about before then. I agree.

But: "space elevator"


I am going to prod you a little further.  My estimate, based on childhood ant burning experiments is that the diameter of the mirror would have to about 100 times larger than the diameter of the city you were burning. (There are relatively easy ways to get better estimates.  Solar power density is well known.  Reflectances and transmission can be estimated accurately.  Heat density to start fires is also obtainable, or you could do some backyard experiments.)

Small cities are 10 miles in diameter.  Large cities are 100 miles or more in diameter.  So your mirror would be 1000 to 10,000 miles in diameter.  Now google mylar film and figure the mass of such a disk.  Compare it to the launch capacity of Musk's BFR .  It should give you some idea how long we have before we have to worry about stupidity.  If that time is short enough to worry you, throw in a somewhat heavier rim for spin forming, some mass for a deployment mechanism, think about the time constant of something that scale (for the initial waves and ripples to die out) and it should buy you enough time to let the grandkids worry  about it.

This is indeed what I do worry about, despite not having any children. I'm worried about disinvestment in society as jobs vanish, "why educate expensive workers when you can rent cheap workers instead"  Seriously. That is what we are facing.
In which case the most prudent thing for you to do is not to worry about this, but to worry about your kid's education so that their kids are well enough educated to not do this, or if they don't control everyone, to toss a load of gravel up to rip the thing to shreds before it stabilizes.
"What the large print giveth, the small print taketh away."
 

Offline DougSpindler

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Re: Massive Solar Mirror To Bring Light at Night
« Reply #27 on: November 06, 2018, 01:15:58 am »
You are mixing up next iteration nuclear with next generation nuclear.  What exactly is your issue with next generation nuclear?
 

Offline Red Squirrel

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Re: Massive Solar Mirror To Bring Light at Night
« Reply #28 on: November 08, 2018, 03:10:48 am »
If it's geostationary it could in theory be setup to focus the light in one spot on earth.  The precision involved would have to be quite insane though.  This would make it viable to generate power via thermal solar.  I use the word viable very loosely here, because a ground based system is probably going to be way cheaper and easier to manage and can be built much bigger/powerful with less effort.

From a tech perspective the idea of a giant mirror in space sounds cool but I think it's a bad idea for many reasons already mentioned here.
 
 

Offline vk6zgo

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Re: Massive Solar Mirror To Bring Light at Night
« Reply #29 on: November 08, 2018, 10:38:18 am »
Already happening in the UK and Germany with there big tall glass office building melting cars parked on the street.

When is it sunny enough in the UK for this to happen? ;D
OK, Germany has decent Summers, but I'm still very doubtful.
Plenty of big tall glass buildings in Australia, & it doesn't happen.
 

Offline cdev

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Re: Massive Solar Mirror To Bring Light at Night
« Reply #30 on: November 08, 2018, 11:34:24 am »
Are you talking about fusion power or fission?

Fusion I think we will eventually figure out. Fission IMHO is dangerous due to the spent fuel and loss of the ultimate heat sink issues. We should concentrate on improving other forms of energy generation.

Or we could pursue the technology which would provide endless power, next gen nuclear.  With next gen nuclear There is no long lived radioactive waste, a Chernobyl size accident would be habitable in 25 years and we have a universe of fuel.   Unlike, solar or wind nuclear power provides electricity day and night.  And we don’t have to do any silly engineering like a mirror in space or transmit gig-watts of electricity thousands of miles and over land and through the oceans,
"What the large print giveth, the small print taketh away."
 

Offline DougSpindler

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Re: Massive Solar Mirror To Bring Light at Night
« Reply #31 on: November 09, 2018, 10:52:03 am »
If it's geostationary it could in theory be setup to focus the light in one spot on earth.  The precision involved would have to be quite insane though.  This would make it viable to generate power via thermal solar.  I use the word viable very loosely here, because a ground based system is probably going to be way cheaper and easier to manage and can be built much bigger/powerful with less effort.

From a tech perspective the idea of a giant mirror in space sounds cool but I think it's a bad idea for many reasons already mentioned here.

Never going to happen based on an international treaty to not weaponize space.  (Although the Russians already did.)  I think this was before the treaty, but not sure.

A giant mirror could be used as a weapon to destroy cities Dresden style. 

AstroSpies is the story of other astronaut program the US had and the weaponsizing space.  Well worth watching if you spy, space and the story of the Hubble Spy, errrr space  telescope story.  Sorry this is too good to be science fiction.


 

Offline Clear as mud

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Re: Massive Solar Mirror To Bring Light at Night
« Reply #32 on: November 27, 2018, 08:44:42 am »
Already happening in the UK and Germany with there big tall glass office building melting cars parked on the street.

When is it sunny enough in the UK for this to happen? ;D

I don't live there, but I've heard about this.  London has a building with a mirror-like finish and curved surface, such that it focuses the light from much of the side of the building onto just a small area.  Because of climate change, they have an increasing number of days hotter than the previous record heat, and the extra sunlight from that building can really damage things and hurt people.  I assume there's a similar building somewhere in Germany, but I haven't heard of that one.
 

Offline DougSpindler

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Re: Massive Solar Mirror To Bring Light at Night
« Reply #33 on: November 27, 2018, 01:33:23 pm »
In the UK the glass building that melts cars is in London and the one in Germany is in Frankfurt.  There might be others.
 


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