The Breakthrough Starshot Initiative, launched in 2016, aims to leverage the directional properties of lasers to propel ultra-light spacecraft using radiation pressure generated by the momentum of light, with the goal of reaching speeds up to 20% of the speed of light. One of the most critical technical challenges in realizing laser propulsion is developing a method to stably maintain the spacecraft at the center of the laser beam.

Various object shapes, such as spheres and cones, have been proposed to address this challenge. However, disc-shaped objects—while the most efficient at converting light momentum into thrust—are highly sensitive to tilting or misalignment with the optical axis, which causes radiation pressure to push them off-center.

In this study, the research team is developing a completely new and original method for passively controlling the position and orientation of a disc-shaped object by fabricating precisely engineered artificial nanostructures on its surface. These nanostructures generate restoring optical pressure and torque, enabling stable manipulation of the disc using light. This innovative concept—referred to as the nanostructured optical pressure actuator—represents a world-first achievement in the optical manipulation of macroscopic disc-shaped objects.

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