Heres part of a article I read about this...
http://msnbcmedia.msn.com/i/msnbc/Compo ... eld_02.jpg
If all goes as planned, the spacecraft will unfurl its eight triangular sails, each nearly 50 feet long and just a quarter of the thickness of a trash bag. Controlled flight, achieved by rotating each blade to change its pitch, would be attempted early next week.
Solar sails are seen as a means for achieving interstellar flight by using the gentle push from the continuous stream of light particles known as photons. Though gradual, the constant light pressure should allow a spacecraft to build up great speed over time, and cover great distances.
Such a craft would not have to carry chemical fuel to propel itself through space, and, according to advocates, would eventually achieve greater speed than a traditional spacecraft.
Cosmos 1 was expected to orbit Earth once every 101 minutes and operate for at least a month.