A space telescope weighing nearly 1.5 tons is about to fall back to Earth, with no one able to choose where it will land.
The U.S. Swift observatory is expected to enter Earth's atmosphere this Wednesday, November 4, 2026. According to forecasts published by NASA on November 2, reentry is expected around 9:30 a.m. Paris time.
Illustration of the Swift observatory
NASA image
This estimate includes a margin of 11 hours before or after that time. The exact location therefore remains unknown, and at the time of publication, we are right in the middle of the predicted window for the fall.
Should we be concerned about the fall of such a heavy object? As it passes through increasingly dense layers of air, Swift will undergo intense heating. Most of its structure should burn up. Some more resistant components could nevertheless reach the ground or ocean.
NASA estimates the risk of someone, somewhere on Earth, being injured at approximately one in 2,100.
One thing is already known: any debris cannot fall just anywhere. Swift's orbit takes it over a band near the equator. The areas concerned lie between 20.6 degrees north and south latitude.
Why is this satellite falling back now? Even several hundred kilometers above Earth, space is not completely empty. There are still enough air particles to gradually slow down an object in orbit. Solar activity can expand the upper layers of the atmosphere and increase this drag. Swift has therefore lost altitude over time.
A rescue operation had nevertheless been considered. A small robotic probe was supposed to rendezvous with Swift and push it into a higher orbit. The attempt did not succeed. Having become too low to keep its instruments properly oriented, the observatory ceased scientific operations in October.
Launched in November 2004 for an initial two-year mission, Swift ultimately worked for nearly 22 years. Its instruments notably observed gamma-ray bursts, very brief emissions of extremely energetic light originating in space. It could quickly change direction and alert other telescopes so they could examine the same events.
NASA and the U.S. Space Force are now continuing to track its trajectory. New measurements should reduce the uncertainty surrounding the reentry time. Only as it approaches its passage through the atmosphere will the impact area be estimated more precisely.