What can a solar sail be used for?
Solar sails can be used to boost or decrease the orbits of spacecraft, hold a spacecraft in position to monitor the Sun for solar storms, provide stable Earth observation platforms, travel between the planets within our solar system, and someday take us to worlds around other stars. However, once you get much beyond the orbit of Jupiter, energy from sunlight is too weak to keep you accelerating. Far away from the Sun, the highly focused beams of lasers can be directed at the sails to boost them onto interstellar trajectories.
