- Tiny devices propelled by sunlight have been tested for the first time in conditions akin to those in Earth’s upper atmosphere, potentially revolutionizing atmospheric science.
- These lightweight membranes are made of aluminum oxide and a layer of chromium and utilize a phenomenon known as photophoresis, where the difference in temperature on either side of the membrane creates motion.
- A recent experiment demonstrated that 0.4-inch-wide (1 cm) membranes could float in a vacuum chamber under light that’s about 55% as intense as natural sunlight.
- This success suggests that these devices could operate effectively in the mesosphere and lower thermosphere, regions of the atmosphere that remain largely unexplored due to their inaccessibility.
Why it matters: Accurate data from the ignorosphere, which spans altitudes between 30 and 53 miles (50 to 85 kilometers) in the mesosphere and extends up to 100 miles (160 km) in the lower thermosphere, could significantly enhance global climate models.
What they’re saying:
- “Being able to send something out there would enable us to take more precise data than we currently can,” said Ben Schafer, the lead author and a researcher at the Harvard John A. Paulson School of Engineering and Applied Sciences.
- “It opens up an entirely new class of device: one that’s passive, sunlight-powered, and uniquely suited to explore our upper atmosphere,” said David Keith, a professor of applied physics who inspired Schafer’s work.
The potential: Schafer envisions multiple applications for the technology, including atmospheric studies and even communication networks. “If you were to put small communications packages on board these devices and loft them into the mesosphere, you could rival data rates of low-Earth-orbit constellations,” he said.
What’s next: To achieve practical applications, future iterations of the device would need to be around 2.4 inches (6 cm) wide, capable of lofting tiny sensors and antennas to collect atmospheric data. Schafer and colleague Angela Feldhaus have spun off a company, Rarefied Technologies, from Harvard SEAS to commercialize this technology.
