Researchers explore using light to levitate discs in the mesosphere  February 15, 2021
To improve weather prediction sensors need to be sent to mesosphere. The satellites and rockets currently used have problems as the air is too thick and friction and heat would make long-duration flights impractical. Researchers at the University of Pennsylvania constructed and demonstrated light-driven levitation of macroscopic polymer films with nanostructured surface as candidates for long-duration near-space flight. The disks were made of 0.5-micron-thick mylar film coated with carbon nanotubes on one side. When illuminated with light intensity comparable to natural sunlight, the polymer disk heats up and interacts with incident gas molecules differently on the top and bottom sides, producing a net recoil force. They demonstrated the levitation of 6-mm-diameter disks in a vacuum chamber controlling the flight of the disks using a shaped light field that optically trapped the levitating disks. The experimentally validated theoretical model predicts that the lift forces can be many times the weight of the films, allowing payloads of up to 10 milligrams for sunlight-powered low-cost microflyers at altitudes of 50 to 100 km…read more. Open Access TECHNICAL ARTICLE¬†

Experimental data and theoretical prediction. Credit: Science Advances 12 Feb 2021: Vol. 7, no. 7, eabe1127

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