  Laser sails propelled by gigawatt-scale ground-based laser arrays have the
potential to reach relativistic speeds, traversing the solar system in hours
and reaching nearby stars in years. Here, we describe the danger interplanetary
dust poses to the survival of a laser sail during its acceleration phase. We
show through multi-physics simulations how localized heating from a single
optically absorbing dust particle on the sail can initiate a thermal-runaway
process that rapidly spreads and destroys the entire sail. We explore potential
mitigation strategies, including increasing the in-plane thermal conductivity
of the sail to reduce the peak temperature at hotspots and isolating the
absorptive regions of the sail which can burn away individually.
