University of Pennsylvania researchers got a pair of small plastic plates to levitate in a vacuum chamber using only light. The two little Mylar pieces hovered off the energy from a set of bright LEDs. The feat was a breakthrough because nobody has ever been able to cause an object that large to float using light alone.
Mohsen Azadi, a UPenn engineering doctoral candidate, told Wired:
When the two samples lifted, there was a gasp between all four of us.
This doesn’t mean there will be light-powered magic carpets flying around someday soon.
The technology is intended for use in researching the mesosphere – a distant region of the atmosphere that’s notoriously complicated to study.
Igor Bargatin, a UPenn professor of mechanical engineering, said:
Sometimes it’s called ignorosphere, in-joke. We just don’t have access to it. You can send a rocket for a few minutes at a time, but that’s very different from doing measurements using airplanes or balloons.
The team is looking to develop a flight system that uses light-powered hovering technology to carry tiny sensors into the mesosphere. The sensor-equipped levitation devices would roam like balloons or floating ocean sensors gathering data. The sensors could hang from the levitator, like a parachute, to keep the system upright in the face of the wind.
Bargatin said:
Another approach is to develop a smart flyer that gives you control over where you actually go.
The researchers ran simulations that found that a 6-centimeter plate could carry an estimated ten milligrams of cargo into the mesosphere under natural light. Granted, a single drop of water is five times heavier than ten milligrams.
Fortunately, silicon chips today have been reduced to minuscule dust-sized sensors thanks to engineering advances. Meaning, a cube only one millimeter in diameter can contain “small dust” systems that house wireless communications, power, and data collection sensors. (One drop of water is 0.50 millimeters.)
Bargatin said:
Researchers can do a lot by giving 1 cubic millimeter of silicon. And one cubic millimeter of silicon weighs a few milligrams.
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There is a downside to their vacuum chamber tests: After around 30 seconds, the photophoretic force caused the discs to curl and eventually collapse. This is because the material (mylar with a carbon nanotube shag) isn’t strong enough to stand the force of fast molecular collisions over time. Bargatin said they are working on developing a lightweight frame.
Paul Newman, the Chief Scientist of Earth Sciences at NASA’s Goddard Institute for Space Flight, is enthusiastic about the technology’s possible applications. However, he does acknowledge that facing mesospheric winds will be a major technical challenge for the device.
Newman said:
[Mesospheric clouds are] another sign of climate change, and we need the information to show it. That’s why these may be really cool to get data on atmospheric composition.
NASA is also interested in the technology’s potential applications in Mars research. The pressure in the atmosphere there is similar to Earth’s mesosphere. So, if the device works here, it’s likely it could also help collect composition and temperature data on the Red Planet.
Newman said:
You can just take off once per day and go up and then come back down and land on your little Martian lander. We don’t have that information on Mars. That would be fantastic.
For now, NASA has a small space helicopter under development called Ingenuity. It’s expected to take flight on the Martian surface soon, but it’s still in the test flight stage, and the science mission isn’t ready yet.
