Legendary astronomer Carl Sagan once envisioned a solar sailer, a spaceship that uses sunlight radiation to push itself through the solar system much like a boat relies on the wind. Decades later, his project is about to become a practical reality. The Planetary Society (which was co-founded by Sagan) has scheduled the first test flight for just such a solar vehicle, the LightSail, on May 20th. This initial run will see if the craft can successfully deploy its four Mylar sails. It won't be in a high-enough orbit to harvest the Sun's energy, but the experiment should pave the way for an honest-to-goodness sailing test in April 2016.