The Planetary Society is planning to launch a solar-propelled space craft in 2010 after its first attempt landed in the ocean four years ago. The LightSail-1 would run on the pressure of light hitting its four triangular-shaped Mylar sails. The society sees the project as a way to achieve long space flights with slow, continuous acceleration that eventually leads to high speeds. The society's executive director imagines flights of many years reaching speeds of 100,000 mph where the craft could leave the solar system in five years instead of 25. The spacecraft will be composed of three Cubesats, small cubes that contain the electronics and controls modules and the sails. When the craft hits the target altitude the sails will unfurl to resemble a kite. The LightSail-1 will "piggyback" on another mission's rocket (the exact one is yet to be determined) and then orbit at an altitude of around 500 miles for a few days to test sunlight as a means of propulsion. If it's successful, the...