An anonymous reader writes: This morning Japanese space agency, JAXA, successfully unfurled a solar sail in space for the first time. Solar sails offer the best hope for deep space exploration because they eliminate the need to carry fuel. The Japanese spacecraft IKAROS created centrifugal force by spinning, allowing it to launch the
.0003-inch-thick sail. While deployment is a challenge in a zero gravity environment, spacecraft — unlike airplanes — don’t have to contend with drag, so with each photon of light that hits the sail, the spacecraft could gather speed.