Space Flight by Light (Solar Sail)

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The Planetary Society is preparing to launch a tiny satellite into orbit later this month as the first phase in testing a solar sail as a means of spacecraft propulsion — an idea that has been kicking around in the science (and science-fiction) literature for at least a century.

The satellite, LightSail, no larger than a loaf of bread, is contained within the somewhat larger Prox-1 satellite developed by the Georgia Institute of Technology. It is scheduled to liftoff aboard an Atlas V rocket on May 20.

The concept states that if a large enough, kite-like "sail" can be deployed in space, the pressure exerted by particles streaming from the the Sun (known as the "solar wind") could be used to push a spacecraft along, much the same way that a sailing vessel is propelled when heading downwind.

The first LightSail won't reach a high enough orbit to try out the sail in the solar wind, but it should be able to test the mechanism for deploying the 345-square foot tissue-thin Mylar sail. A mission set for next year should put a second LightSail in a high enough orbit to fully test the concept.

A decade ago, the Planetary Society, the non-profit founded by the late Carl Sagan and now headed by Bill Nye ("The Science Guy"), made its first attempt to launch a solar sail, but the satellite was lost when the Russian launch vehicle it was on failed to reach orbit."



http://www.npr.org/blogs/thetwo-way/2015/05/09/405506717/planetary-society-set-to-launch-solar-sail-experiment