how fast can a solar sail go
In just three years, a solar sail could reach a speed of over 160,000 kilometers per hour (100,000 miles per hour). At that speed you could reach Pluto in less than five years. photon reflecting off the mirror-like surface of a solar sail gives the sail a double kick -- a push equal to twice the photon's momentum (one push from the sail stopping the photon and one from it reflecting the photon and accelerating it away).