Thursday, June 29, 2006

Thinking Outside the Van Allen Belts

Tuesday's Times Science section had the good judgement to publish an article about one of my favorite engineering proposals of all time: regulating the Earth's climate by building a giant diverging Fresnel lens at the Earth-Sol system's L1 Lagrange point. By rotating the lens you can control what percent (up to a maximum of maybe .01%, depending on just how big and how divergent this lens is) of incident sunlight gets bent away from the Earth's surface. This of course would obviate the need to worry about things like carbon dioxide emissions, since any increase in the greenhouse effect could be compensated for by limiting the amount of sunlight hitting the Earth. I've never seen a particularly detailed engineering proposal for this, but I can't imagine it would be that hard to build once the first space elevator goes up and reduces lift costs to transatlantic flight levels. There's some other stuff in there about seeding cloud decks with sulfur to increase reflectivity, but clearly massive orbiting lenses are the most politically viable of our options at this stage.


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