Relativistic Light Sails Need to Billow

We argue that light sails with nanometer-scale thicknesses that are rapidly accelerated to relativistic velocities by lasers must be significantly curved in order to reduce their intrafilm mechanical stresses and avoid tears. Using an integrated opto-thermo-mechanical model, we show that the diameter and radius of curvature of a circular light sail should be comparable in magnitude, both on the order of a few meters, in optimal designs for gram-scale payloads. Moreover, we demonstrate that, when sufficient laser power is available, a sail's acceleration length decreases as its curvature increases. Our findings provide critical guidance for emerging light sail design programs, which herald a new era of interstellar space exploration to destinations such as the Oort cloud, the Alpha Centauri system, and beyond.

Automated summary

The study suggests that light sails with nanometer-scale thicknesses accelerated to relativistic velocities by lasers need to be significantly curved to reduce mechanical stresses and avoid tears. It shows that a circular light sail's diameter and radius of curvature should be comparable in magnitude in optimal designs for gram-scale payloads, and that sail acceleration length decreases with increasing curvature when sufficient laser power is available. These findings offer critical guidance for future light sail design programs aimed at interstellar space exploration.