Dust grain damage to interstellar laser-pushed lightsail

Lightsails pushed by laser beams to velocities around 0.1c have been propos ed as propulsion systems for interstellar travel. These lightsails will und ergo high-energy collisions with small (similar to 1-mu m) dust grains in t he interstellar environment. For a very thin beryllium sail, the grains pas s through the sail with only 10(-4) of the energy coupled into the sail. Th e resulting damaged area is not significantly larger than the cross section of the dust grain. Only a small fraction (10(-6)-10(-4)) of the sail will be destroyed by these 1-mu m-sized grains during the sail acceleration. For thick sails or larger grains, the damage can be more significant.