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Darken the sky

With mylar! And railguns!
  (+10, -5)
(+10, -5)
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against]

I have been pondering the idea of fighting the greenhouse effect with nuclear winter (previous idea - linked). It is sloppy. However the idea still seems valid - if you can decrease incident radiation, you can cool the earth. Doing so by suspending particles in the atmosphere is a reversable way to achieve cooling.

Rather than blowing up bombs in the Antarctic, the same end could be more cleanly achieved with railguns. A railgun operation with a dedicated powerplant would launch small payloads up to the appropriate level in the atmosphere. Once there they would detonate, releasing microparticle mylar. These particles would do a better job at reflecting than random dirt launched by a volcano or bomb. They would do no harm on settling down to the earth over months or years. Also, the railgun could be run continuously for incremental darkening of the sky. Mistakes would not be calamatous - a $100 5 kg undetonated mylar projectile falls into the ocean, or the railgun malfunctions and must be repaired. If it turns out that dark skies are bad, give it a year or two and it will revert to normal!

Another idea about railguns - it seems like arcing and melting of the rails is a big problem. If the rails were superconducting, would this still be a problem? My understanding of a superconductor is that they do not lose energy to heat. It is heat that melts the rails and requires the gun to go offline for resurfacing. Would superconductivity avoid this? How about surfacing with carbon fiber? It does not melt, but vaporizes, which would avoid globs of congealed rail matter gumming up your rail.

bungston, Dec 21 2005

Railgun hobbyist http://www.powerlabs.org/railgun2.htm
Donate now! If railgun research stops, the terrorists win! [bungston, Dec 21 2005]

[link]






       You had me at railguns. Though I imagine there's an easier solution - mylar balloons.
Worldgineer, Dec 21 2005
  

       Would they go high enough? Would they cover as much sky area as mylar powder? Would they scare people?
bungston, Dec 21 2005
  

       Yes. About 1/2 as much by weight. Some people, but this will likely be dwarfed by those that are pleased.   

       Actually, the balloons have brought up an interesting question. They will still be reflective when they land. Will mylar dust still be reflective when it lands? Likely, which might be a problem. Though I guess eventually it'll get covered in dust, so perhaps it's not that big of an issue.
Worldgineer, Dec 21 2005
  

       What do you think about superconducting / carbon fiber railguns, [World]?
bungston, Dec 21 2005
  

       With current superconductive materials, wouldn't the friction of the projectile heat the rails to such a temperature that they lose superconductivity?
Laimak, Dec 21 2005
  

       My (extremely limited) understanding of railguns is that it is arcing current that "spotwelds" the rails. If the rails were big and cold and the projectile small and smooth, I bet friction would not play a big part in heating the rails. You would need to let it cool off in between shots. Kind of like a cannon!
bungston, Dec 21 2005
  

       [bun]gston, great idea for its use.
DesertFox, Dec 21 2005
  

       I am (controversially) boning this, because I worry that all these particles are going to make it impossible to launch stuff into space without having your rocket shredded by high-velocity mylar particles.
moomintroll, Dec 21 2005
  

       [+] The basic premise seems quite sound.   

       But, instead of railguns or balloons, just leak a bit of dust out of airplanes that are already flying around.   

       I'm not sure why you'd need mylar, though. Any powder should do. Yes, mylar reflects light, but it's not like they are all going to be oriented to reflect it back into space. It will have random orientations and thus be just as effective as other dust to absorb or scatter, right?   

       This would give you flexibility to optimize your dust based on factors of residence time, environmental impact (both in air, land, sea), cost, and most importantly in mitigating inevitable unintended consequences.   

       I'm also not sure the quantities you'd need, as we've got thousands of tons of particulate in the air over cities that are not cooling down (Bagdad, Los Angelas, etc)   

       Overall, great premise of controlled, temporary cooling.
sophocles, Dec 21 2005
  

       //What do you think about superconducting / carbon fiber railguns, [World]?//   

       I think highly of them both. I know little about either, but think highly of them.   

       Do you have any links about the heat issues involved in railguns? I'm feeling Google lazy today.
Worldgineer, Dec 21 2005
  

       mylar is too messy. What about ice crystals?
Sendra, Apr 01 2009
  

       Mylar is reflective when coated with aluminium. Do you have a link where mylar powder is described as reflective too? Coated mylar is only reflective on one side, so the mylar would have to be coated on both sides, which in turn means you are mostly shooting aluminium into the atmosphere, which might devalue the // They would do no harm on settling down to the earth over months or years // -part
loonquawl, Apr 01 2009
  

       Ice crystals would quickly sublimate into worthless vapor once in space.
bungston, Apr 01 2009
  

       // I am (controversially) boning this, because I worry that all these particles are going to make it impossible to launch stuff into space without having your rocket shredded by high-velocity mylar particles. //   

       They aren't in orbit. They're floating in the atmosphere. Your rocket can plow through them like it does other airborne dust.   

       On the other hand, this idea is basically one to deliberately produce and release a huge amount of microplastic pollution, so [-].
notexactly, Apr 11 2019
  

       we currently have the ability to make cluds/rain but there are curretnyl some porlicial. issues with it. If you cool the earh it might be good for you but not so great for people in an already cold area. a little more rain would be good in the desert, but not so good in the areas that would then flood. etc.
bob, Apr 12 2019
  

       Errm, if you have the railgun oomph then go zap the moon, assuming the strike gives enough velocity to the zapped bits to leave the moon's gravity.   

       Would work better if the railgun was in space, and don't ask me what the Selenite's are going make of it...and that secret Nazi base on the dark side...
not_morrison_rm, Apr 13 2019
  
      
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