Burned-Up Satellites Threaten Earth's Atmosphere and Deplete Ozone Layer

The increasing number of satellites, especially from entities like SpaceX’s Starlink, Amazon, and China, urgently raises concerns about atmospheric pollution created by satellite re-entries. For example, a failed launch of 20 Starlink satellites by a SpaceX Falcon 9 rocket on July 11 resulted in immediate fallbacks into Earth’s atmosphere, leading to their combustion, similar to meteor showers initiated by human activity. Concerning both deliberate deorbits to prevent space debris and unintended ones like this, researchers now intensely study the long-term atmospheric impact. This is prepared by SSP.

Environmental Impact of Satellites: Re-Entries

Historically, the number of satellite re-entries was minimal—just a few hundred per year—and little attention was paid to ensuing environmental impacts on Earth’s stratosphere, which spans from approximately 10 to 50 kilometers above the ground. Staple in many satellites, aluminum emerges as the most worrisome component because if it forms aluminum oxide or hydroxide on disintegration, it may catalyze reactions its various hydrogen chloride in the stratosphere to form aluminum chloride, freeing chlorine to damage the ozone layer, raising significant concerns about rising concentrations of metal particles that might dwindle the protective layer.

From weather forecasting to navigation, satellites enrich many systems we take for granted. Joeseph Wang and colleagues at the University of Southern California simulated these satellite disruptions, finding that aluminum oxide nanoparticles not only form during re-entries but also potentially amplify reactions between ozone and chlorine. A 250 kg satellite re-entering can generate about 30 kg of aluminum oxide nanoparticles. Based on this, 2022 alone saw 17 metric tons of such compounds from satellite re-entries. By 2023, observable alterations in stratospheric composition stemming from re-entries, detected by NASA’s airborne laser mass spectrometer showing significant spikes in elements like lithium, aluminum, copper, and lead; mean lower-bound estimates still strain relative natural inputs from meteors, were reported.

Impending High-Volume Impact

Future mega-constellation ventures could exacerbate the situation, highlighting a grave trajectory toward vastly scaled environmental perturbation. Comparatively minor, recent figures like SpaceX’s application for 30,000 more launched satellites forecast unprecedented future proliferation. Researchers estimate the disposal rate could mushroom to 10,000 satellites annually, dramatically raising pollutant concentrations, with a significant annual forecast of 360 metric tons of aluminum oxide in the era of such mega-constellations. Researchers stress the urgency of establishing ample understanding and regulatory foundations before this proliferates further, as satellites represent a legitimate environmental challenge within Earth's atmospheric territory.

Sustainable Solutions

Industry prediction models call for exploring synthetic solutions such as recycling, repair, refueling of satellites right in orbit, and using less contaminating materials as imperative measures before adverse milestones cement physical and chemical cumulative repercussions on Earth's stratosphere and ozone-safe qualitative measures from being easily quantified prior. Experts press on providing detailed guidance to the industry and regulators emphasizing inter-cooperation to investigate and understand this interdisciplinary overlap significantly.