NASA - Measuring Up to a Solar Sail

So far, I can't quite get my head around something 40 to 100 times thinner than writing paper, generally about as large as a football field, that can propel a spacecraft. But I'd love to see one.

Solar sails.

The idea of using these large, reflective structures to "sail" through space is nothing new. In fact, it's been around for a long time -- first suggested nearly 400 years ago by the German astronomer Johannes Kepler, after he "discovered" comet tails being blown by what he believed to be a kind of solar breeze. Kepler suggested ships could possibly move through space using large sails to capture this "breeze" from the Sun, much the way the wind pushes sailboats across water on Earth.

Fast forward to today, and NASA has taken the solar sail idea past the drawing board and into development and testing.

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