A New Kind of Light Sail Brings Interstellar Travel One Step Closer

The idea of sending tiny spacecraft to another star system, not with rocket engines, but by riding a beam of light, may once have been science fiction, but new research published in Nature Communications is illuminating how the idea could become reality.

Led by Matthew Campbell, Research Assistant Professor in Mechanical Engineering and Applied Mechanics (MEAM), Igor Bargatin, Associate Professor in MEAM, and Deep Jariwala, Peter and Susanne Armstrong Distinguished Scholar and Associate Professor in Electrical and Systems Engineering, along with collaborators at the California Institute of Technology (Caltech) and UCLA, the research team leveraged a surprisingly simple driving force to power these light sails.

Just as wind fills the sails of a boat, photons (particles of light) carry momentum. If enough laser light is directed at a highly reflective, ultralight sail, those photons can push a spacecraft to extraordinary speeds, potentially reaching one-fifth the speed of light. At that pace, a mission to Alpha Centauri, the closest star system to our own, could take about 20 years, with data returning to Earth within a human lifetime. In contrast, this journey could take anywhere from 75,000 to 165,000 years using current spacecraft.

“The idea of laser photons has been around for a while,” says Campbell. “The question is: what material could actually survive the journey?”

Now, these researchers have demonstrated a new class of ultrathin “light sails” that brings that question closer to an answer. Their prototype combines exceptional reflectivity, mechanical strength and extremely low weight — three properties that have proven difficult to achieve simultaneously in previous designs.

The work represents an important step toward laser-driven spacecraft capable of traveling at relativistic speeds while also opening new possibilities for exploring our own solar system.

Penn Engineering’s research team from left to right: Jason Lynch, Matthew Campbell, Deep Jariwala and Igor Bargatin.

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