a picture of satellite
Two small discs ascend into the air, floating in midair while a brilliant light shines on them. Mohsen Azadi said, “I see it!” He and many other Ph.D. students burst out laughing. They had assisted in the discovery of a new way to fly.
The discs could not be lifted since there were no engines or propellers. The bright light had done the job. It was the first time science utilized light to lift things large enough to see unaided eyes. The two floating discs rotated and passed each other. “It looked like a dance,” Azadi of the University of Pennsylvania in Philadelphia says.
According to Igor Bargatin, his team’s innovation might pave the way for a new approach to investigate the mesosphere, a region of Earth’s upper atmosphere. He spearheaded the latest research as an engineer at the University of Pennsylvania.
He claims that there is “not enough air for airplanes or balloons, but too much air for satellites” in the mesosphere. Rockets can pass through, but they only stay for a few seconds before falling back to Earth. Scientists know virtually little about this location since it is so difficult to investigate. According to Bargatin, it is referred to as the “ignorosphere” by some.
He, Azadi, and the rest of the crew flew their discs in a room with the same air concentration as the mesosphere. That thin air also happens to be ideal for light levitation. The team published its findings in Science Advances on February 12th.
Heat and Energy
“There is a mystical element to levitation,” adds Bargatin. It appears miraculous that light can lift anything, even something as light as a feather. This is feasible because light particles carry energy in the form of heat. The photophoretic (Foh-toh-phoh-RET-ik) effect occurs when heat causes movement.
The effect is also responsible for spinning the paddles inside a toy known as a light mill. A light mill on a shelf in his lab prompted Bargatin to experiment with making discs float.
The photophoretic effect could only lift very light objects. But his staff was already working on it. They’d spent years focusing on creating incredibly light yet stiff structures. “They are the lightest items you have ever seen,” Bargatin adds. Some are as thin as soap bubbles. “Invention or creativity is not a mystical or magical process,” explains Bargatin. “It is the act of integrating previously known concepts in novel ways.” The team questioned what might happen if they employed the photophoretic effect on fragile, lightweight materials in this situation.
Mylar is a transparent plastic sheet that was used to make the discs (MY-lar). They utilized the thinnest mylar they could find. It’s only around half a micron thick. That is one-twice the thickness of a human hair. When you attempt to hold a portion of it, it “simply coils up and rests on your finger,” explains Azadi.
Carbon nanotubes were painted on the bottom side of each mylar disc by the researchers. They operate “like a shaggy carpet,” according to Bargatin, and assist the disc in maintaining its form. They also aid in its takeoff.