Tiny light‑driven 'metajets' enable steerable sails for interstellar travel

Context Light sails rely on photon momentum to push huge, thin sheets through space. Until now, scientists could only push them straight; changing direction required mechanical tilting or separate thrusters. A team at Texas A&M inverted the usual approach: instead of shaping light with a metasurface, they let light shape the metasurface’s motion.

Key Facts The metajet is about 0.01 millimetres across, roughly a tenth the width of a human hair. Made of silicon pillars, it redirects incoming laser light via refraction, generating sideways force. In water tests, the device levitated and moved horizontally, reaching a top speed of roughly 0.07 millimetres per second.

What It Means Demonstrating controllable momentum transfer opens a path to steerable light sails without moving parts. Researchers plan to tune the metasurface for broader wavelengths, including sunlight, to make the technology viable for interstellar probes. Next, watch for outdoor tests in air or vacuum and attempts to scale the metajet to sail‑size arrays.