The Earth-Sun L1 (LaGrange) point is a point of stability for orbiting objects that is between the earth and sun, approximately 4 lunar-orbit-radii from earth. Spacecraft positioned there actually move in something called a halo orbit.
By using a solar sail to control a daily trajectory of an L1 vicinity spacecraft, a shadow could (in)conveniently be placed on virtually any place on earth. The daily trajectory would cover a roughly linear path going from West to East during a 10 hour interval. Thus a single square solar sail, with an edge of 1 km, could cast a slight shadow, on, say, Kabul.
Orchestrating several hundred might markedly diminsh sunlight on a small city. Ambitious efforts to float 10,000 such solar sails between sun and an adversary could drop temperatures, wither crops, and generally be a nuisance, but without that nasty nuclear fallout.
When the U.S. is done with the 'cold-sholder', we might lease out the space-shade to locations like Phoenix, Arizona, and other places where the airconditioning bill in summer is just too high.-- pathetic, Sep 18 2001 There seems to be a bit of discussion surrounding what nasty things we can do to people. This is a novel idea, and (to my limited technical knowledge,) a workable one to boot. But it won't get my croissant because it simply does nothing to stop the atrocities that have occurred in the US (or anywhere else, let's not forget) from happening again elsewhere.
Do you really think that simultaneously spanking Bin Laden to death and pissing off countless Moslems living in desperate poverty all around the world will stop others from going nuts and ramming passenger liners into the side of very tall buildings?-- sdm, Sep 18 2001 What, and end a perfectly fine drought?-- thumbwax, Sep 18 2001 Hm... I'll stay neutral on this one. It's an ingenious idea, but I can't say I approve of tampering further with the environment, nor of more foolish military action.
I do like this idea as a weapon though! It's a great invention! Reminds me of Mr. Burns's sun-blocker >:-)-- Crazy Bastard, Apr 26 2002 random, halfbakery