Relativistic light sails need to billow

TL;DR

This paper demonstrates that relativistic light sails must be curved to withstand stresses, with optimal designs balancing size and curvature to enable efficient acceleration and payload capacity for interstellar exploration.

Contribution

It introduces an integrated model showing how sail curvature affects stress reduction, acceleration length, and payload capacity in relativistic laser-driven light sails.

Findings

Optimal sail diameter and curvature are on the order of meters.

Increased curvature reduces acceleration length and increases payload capacity.

Curved sails are essential for practical relativistic light sail deployment.

Abstract

We argue that light sails that are rapidly accelerated to relativistic velocities by lasers must be significantly curved in order to reduce their 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, when sufficient laser power is available, a sail's acceleration length decreases and its chip payload capacity increases as its curvature increases. Our findings provide guidance for emerging light sail design programs, which herald a new era of interstellar space exploration.