In the past year, I've covered two different proposals on using space technology to create some sort of "shade" for the entire planet that would save us from global warming. In covering those stories, words like "radical" and even "outlandish" seemed appropriate.

Now, NASA has actually funded a more thorough study of a third "sunshade" proposal. Should I be worried that the government is actually thinking they need some sort of space-based fallback plan for the global warming problem?

If you'd like to see the past proposals, take a look at the single giant concave fresnel lens at L1 solution and the space ring girdles the Earth solution.

The new (third!) sunshade solution is proposed by University of Arizona Steward Observatory optics expert Roger Angel. He suggests that we launch trillions of tiny (0.6 meters across) screens. The screens would be thin transparent disks with little 0.1 meter protruding fins with solar energy-gathering capabilities for position adjustment. The disks would essentially be lenses that would take a small amount of the sun's light (energy) and focus it away from Earth.

They would be sent to the inner Lagrange point L1, the point (or relatively small area) between the sun and the Earth where the orbital period of any object becomes exactly equal to the Earth's orbital period. In other words, all of the trillions of tiny "lenses" could stay there forever without expending extra energy, shielding the Earth from about 1.8% of the sun's radiation, according to Dr. Angel.

According to Dr. Angel's paper, just published in Proceedings of the National Academy of Sciences, there would have to be a cloud of lenses about 100,000 kilometers long. To accomplish this, we would need to launch an 800,000 unit stack of these every five minutes for ten years. Angel suggests that this could be done with electromagnetic rail launchers powered (preferably) by some sort of renewable power source like hydroelectric or wind.

As Dr. Angel puts it "...if there's nothing you can do except shade the planet, you may want to think about it."

Now that we are getting more comfortable with large-scale space construction projects, take a look at the giant fresnel lens and the space ring. Also, read more about Dr. Angel's solution in A Sunshade for Planet Earth and Space Sunshade Might Be Feasible in Global Warming Emergency.

(This Science Fiction in the News story used with permission from Technovelgy.com - where science meets fiction.)