What's Falling
Back to Earth?

What is a satellite reentry?

When a satellite or rocket body runs out of altitude-maintaining propellant — or was never capable of station-keeping — atmospheric drag gradually slows it down. As it descends into denser atmosphere, drag increases, the orbit decays faster, and eventually the object enters the upper atmosphere at orbital velocity.

Most objects burn up completely during reentry. Larger, denser objects — particularly rocket bodies with thick metal components — may survive partial reentry and reach the ground. The majority of surviving fragments land in oceans, which cover about 71% of Earth's surface.

How accurate are reentry predictions?

Reentry prediction is notoriously difficult. The primary variables — atmospheric density, solar activity, and the object's attitude (tumbling vs stable) — all fluctuate and compound into large timing uncertainties. A prediction made a week out might carry a window of ±2 days. Even 24 hours before reentry, the window is typically ±hours.

Because Earth rotates under a decaying orbit, a ±1 hour timing error translates to roughly ±27,000 km of ground track uncertainty. This is why precise reentry location predictions are essentially impossible until the final orbit.

Is reentry debris dangerous?

The statistical risk to any individual from falling satellite debris is extremely low — estimated at roughly 1-in-several-trillion per person per year. No confirmed human fatality from orbital debris has ever been recorded.

However, debris does reach the ground regularly. In 2024, a piece of hardware from a SpaceX Dragon trunk section landed near a farm in Saskatchewan, Canada. NASA hardware has been identified in Florida. ESA maintains active public reentry watch programmes for their larger objects.

The main concern is uncontrolled reentries of large rocket bodies — particularly Chinese Long March upper stages, which have historically been left in low orbits without passivation or deorbit capability.

How does Space Command track reentries?

The 18th Space Defense Squadron continuously monitors all tracked objects in the Space-Track catalogue. For objects predicted to reentry within 30 days, they publish decay predictions including estimated reentry window, object identity, and uncertainty bounds.

Confirmed reentries are recorded in the catalogue with a DECAY date once the object can no longer be tracked — indicating it has reentered. OrbitalNodes pulls both prediction and confirmation data directly from Space-Track every 2 hours.