Researchers at the California Institute of Technology (Caltech) say they have found way to produce and propel objects using only light – though, for the time being, the work remains theoretical.
They hope the technique could be used for "trajectory control of ultra-light spacecraft and even laser-propelled light sails for space exploration," according to a paper published in the journal Nature Photonics Monday. That means no fuel needed – just a powerful laser fired at a spacecraft from back on Earth.
The Caltech scientists devised the so-called "photonic levitation and propulsion" system by designing a complex pattern that could be etched into an object's surface. The way the concentrated light beam reflected from the etching causes the object to "self-stabilize," they say, as it attempts to stay inside the focused laser beam.
The first breakthrough that laid the groundwork for the new research was the development of "optical tweezers" ̵
Ognjen Ilic, post-doctoral scholar and first author of the new study, puts the two concept and its limitations in much simpler terms: “One can levitate a ping pong ball using a steady stream of air from a hair dryer, ”he said in a statement. "But it wouldn't work if the ping pong ball was too big, or if it was too far away from the hair dryer, and so on."
From Micrometers to Meters
In the paper, the Caltech researchers argue that their light manipulation theoretically could work with an object of any size, from micrometers to spaceship size.
Though the theory is still untested in the real world, the researchers say that if it pans out, it could send a spacecraft to the nearest solar system in just 20 years.
"There is an interesting application to use this technique as a means of propulsion of a new generation of spacecraft," said Harry Atwater, professor at the Caltech Division of Engineering and Applied Science. “We're a long way from actually doing that, but we are in the process of testing out the principles.”