Article URL: https://spectrum.ieee.org/space-debris-atmosphere-burn-up Comments URL: https://news.ycombinator.com/item?id=49062120 Points: 35 # Comments: 9

Tereza Pultarova is a London-based journalist specializing in aerospace and defense technologies. Researchers in Germany are simulating in the lab a satellite’s reentry into the atmosphere—revealing new dangers posed by many more reentries to come from today’s growing fleets of satellite constellations. Researchers in Germany are melting chunks of satellites in high-temperature plasma wind tunnels to simulate how space debris burns up in Earth’s atmosphere. These tests are revealing in relation to trends about satellite reentry as the population of objects in low Earth orbit swells today. Only a handful of facilities around the world are capable of conducting reentry simulation tests like the German researchers are performing. In particular, the researchers raise concern that ashes from reentry that remain in the upper atmosphere could increase ozone depletion and alter the atmosphere’s thermal balance in the process. Three or more large satellites or used rocket stages burn up in Earth’s atmosphere every day, according to the European Space Agency’s Space Environment Report published last year. Every year, hundreds of tons of human-made objects reenter the atmosphere and evaporate, leaving behind clouds of microscopic ash along with some fragments that happen to fall all the way to the ground. Researchers say the amount of satellite ash and the number of human-made objects hitting Earth so far is relatively low. However, the rapidly increasing numbers of launches to low Earth orbit now threaten to increase the levels of space junk reentering the atmosphere. As of June, according to the ESA, some 18,000 operational and defunct satellites orbit the planet. And companies like SpaceX and Blue Origin have ambitions to launch hundreds of thousands of satellites, including giant orbiting data centers, in the next decade. China, too, is targeting up to 140 launches this year, and filing ambitious plans with the International Telecommunication Union for more launches toward its own megaconstellation of satellites and its own orbiting data-center fleets. Since most satellites are currently designed to be replaced every five years with newer technology, tens of thousands of tonnes of old spacecraft could be vaporizing in Earth’s atmosphere in the foreseeable future.