The nearest star system to our own, Alpha Centauri, is well over four light-years away — tens of trillions of lonely miles that could take hundreds, if not thousands, of Earth years to reach using contemporary rocket propulsion methods.
But there may be a way to cut the length of the journey down significantly. As detailed in a new paper published in the journal Newton, a team of researchers at Texas A&M University say they’ve demonstrated an exciting new approach, which uses lasers to propel and steer objects from a distance, without physical contact.
They claim lasers could one day push entire spacecraft, accelerating them to the point where the trip to Alpha Centauri will only take around 20 years. While that may still sound like a long time, it’d be a major upgrade over having to send a generation ship built to survive thousands of years.
That’s if the concept can effectively be scaled up, of course. For their research, the scientists developed micron-scale devices, called “metajets,” which are smaller than the width of a human hair, and which move when a laser light is pointed at them.
These metajets feature minuscule “metasurfaces,” or intricate patterns that change how the light behaves, not unlike a lens. These etchings allow the researchers to move the metajets in all three dimensions, which they claim is a world’s first.
In a press release, Texas A&M assistant professor and corresponding author Shoufeng Lan compared the effect to ping pong balls bouncing off a surface. When light reflects from a surface, it can transfer momentum to it.
Shining light on an object may not exert a huge amount of force, but in the microgravity of space, a small cumulative effect can be significant. Case in point, previous experiments involving solar sails have demonstrated that rays of the Sun alone could provide enough propulsion power for specialized spacecraft to move.
Earlier this month, scientists at the European Space Agency also suggested that lasers could one day steer solar sails and even adjust a satellite’s position using graphene aerogels, an ultralight and highly porous material.
The latest research takes the basic concept of light propulsion a step further, enabling “full three-dimensional maneuverability.”
“When illuminated by a normally incident beam, these free-standing devices simultaneously translate laterally and lift vertically, enabling 3D motion not accessible with conventional optical manipulation methods,” the researchers’ paper reads.
They also say the idea could be scaled up beyond a microscopic demonstration, since the power exerted depends on the power of the light itself and not the size of the device.
In other words, given enough optical power, a much larger device could be propelled from a distance. According to their paper, the concept could work on anything from “microrobots, to large settings, including interstellar light sails for space travel.”
Yet plenty of questions remain surrounding the concept’s feasibility. While the researchers’ experiments were carried out in a “fluid environment” to offset the effects of gravity, they’re hoping to get external funding to test the concept in the microgravity of space as well.
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