Dying satellites are changing the chemistry of our upper atmosphere

When a satellite reaches the end of its life, it is programmed to dive into the atmosphere and incinerate. While this prevents space junk from cluttering our orbit, it creates a new chemical footprint roughly 75 kilometers above the Earth. At this altitude, the intense heat of reentry vaporizes aluminum and exotic composites into a fine metallic mist. These particles act as seeds for noctilucent clouds—electric-blue ribbons of ice that glow long after sunset—altering the delicate balance of the upper atmosphere in ways that have no historical precedent.