For interstellar travel, light-sail craft would depend on extremely large-scale constructions such as huge solar-power relays around Mercury and enormous Fresnel zones in the outer Solar System. Since light applies pressure to surfaces, the stream of photons can be used for propulsion in a near-frictionless environment. This concept is the background for light (or solar) sails. It is a method of space travel that would negate the need for on-board fuel. Sails using the solar wind or only the light from stars are less efficient at larger distance from the Sun. Read more at SOLARIPEDIA.com
