Characterization of a non-stationary spherical inflated light sail for ultra-fast interstellar travel by using commercial 3D codes

Spherical inflated light sails have been considered to push ultra-light nanocrafts at a significant fraction of the light speed. The light sail, which is essentially an extremely thin shell, would be subjected to extremely high accelerations and deformations. The purpose of this research is to perform a non-stationary 3D numerical analysis to study the deformed shape of a spherical inflated light sail riding on a laser beam. Common commercial codes are not specifically designed to deal with this phenomenon. A similar physical context can be found in crash events, which can be analyzed by using commercial codes. Since the development of a dedicated numerical code would require a remarkable effort, an attempt of using such commercial codes has been conducted. Moreover, the effect of changing the sail’s shell features, such as the thickness and the inflating pressure, has been considered. The model is close to a potential real case application in terms of both the acceleration given to the light sail (20000 g) and the sail’s diameter-to-thickness ratio (2 m / 0.1 μm). Particular attention has been paid to the simulation of the dynamics of the inflating gas and its effect on sail’s deformation. The inflating gas was introduced with the aim of providing a stabilizing effect on sail’s shape. Contrary to expectations, the results have shown a counterintuitive, destabilizing effect. Significant changes in the deformation mechanisms at different inflating pressure regimes were observed. All those mechanisms show the active role of the inflating gas in the destructive failure of the sail. For this reason, a solution without inflating gas has been simulated showing significant benefits. The results of this study provide significant guidelines to drive the future developments of light sails, as well as a useful input for further analysis on beam’s riding stability.