Metajet Enables Precise Light‑Sail Steering and Heat‑Free Drug Delivery

Light sails rely on photons bouncing off a large, reflective sheet to generate thrust for interstellar travel. Until now, the thrust direction could not be altered without mechanical adjustments. Researchers at Texas A&M University have built a 0.01 mm‑wide metajet that uses light refraction—bending light through tiny pillars—to control both the magnitude and direction of photon momentum.

In laboratory tests, the silicon‑based device levitated in water while a laser illuminated it. The metajet moved horizontally at a peak speed of about 0.07 mm s⁻¹, demonstrating that light can both lift and propel the structure without contact. The researchers achieved this by designing the pillar pattern to steer incoming photons, turning the metasurface into an active propulsor rather than a passive reflector.

“While any light or laser can impart momentum, we can now control its direction,” said Kaushik Kudtarkar, lead author. He added that redesigning the metasurface geometry could enable arbitrary steering paths, a capability that could be transferred to full‑scale light sails. Future versions aim to operate with broader wavelengths, including sunlight, to match the spectrum used in proposed solar‑sail missions.

Beyond space travel, the metajet offers a biomedical advantage. Conventional laser‑driven drug delivery heats the target area, risking molecular damage. Kudtarkar explained that the metajet can push drug particles to exact locations without exposing them to laser heat, because the momentum transfer occurs through the metasurface rather than direct photon absorption.

The breakthrough suggests two parallel development tracks. In aerospace, steerable light sails could reduce mission complexity and fuel requirements for deep‑space probes. In medicine, non‑thermal micro‑propulsion may enable targeted therapies with minimal collateral damage. Both applications hinge on scaling the technology and adapting it to different light sources.

What to watch next: Researchers will test metajets with solar‑like spectra and explore dynamic metasurfaces that reshape in real time, a step that could turn sci‑fi concepts into operational tools for space and health.