Satellite reentry
Every object in orbit is on a one-way ticket. When a satellite's orbit decays far enough, it plunges into the atmosphere and burns up — and with tens of thousands of objects now tracked, reentries are a routine part of the space environment.
How reentry works
// the physicsReentry is the end of orbital decay. A satellite in low Earth orbit constantly loses a little speed to atmospheric drag. As its orbit shrinks, the air gets denser and the drag grows — until the object can no longer maintain orbit and falls into the atmosphere, heating to thousands of degrees as it compresses the air ahead of it.
Most of it never reaches the ground. The vast majority of a reentering satellite burns up completely high in the atmosphere. Larger pieces can survive — rocket stages, dense components — which is why agencies track reentry windows and aim uncontrolled reentries over oceans or sparsely populated areas where the risk is negligible.
Predictions are probabilistic, not exact. Reentry timing depends on solar activity (which heats and expands the upper atmosphere, increasing drag), the object's shape, and its tumbling. That is why you see reentry predictions given as windows — "within 12 hours" — that tighten as the object gets lower. This site's alerts reflect exactly that process: early wide windows, narrowing as the end approaches.
Why it is more common now. Modern mega-constellations are designed for short service lives — a few years, not decades — and deorbit deliberately at end of life. Add the natural reentry of old hardware and debris, and the catalogue records thousands of reentry events, with new ones appearing every week.