Thousands of small satellites are being launched into the “lower orbit” of space, just above the stratosphere, by companies like SpaceX, OneWeb, Amazon’s proposed Project Kuiper and more — devices that can provide internet service among other uses. Because the number will soon reach many tens of thousands, concern is growing among atmospheric scientists about how they may harm the protective ozone layer that shields life on Earth from dangerous radiation from the sun.

Most of these low-earth-orbit satellites, sometimes called LEO constellations, are propelled by rockets that are fueled by kerosene. The satellites are mostly made of aluminum and contain numerous electronic parts, batteries, carbon fiber, epoxies and metals, including titanium, cadmium, lithium, nickel and cobalt — materials that may contribute to ozone depletion as they continuously disintegrate in space and descend into the stratosphere.

A recent report published by the U.S. Government Accountability Office said at least 5,500 such satellites are in orbit, but it also questioned why these systems are not subject to environmental scrutiny by the Federal Communications Commission, which licenses such systems in the United States, even as the agency is reviewing applications involving tens of thousands of new satellites.