Swift expected to re-enter Earth's atmosphere on 4 November

The Swift space observatory is expected to enter Earth's atmosphere on Wednesday, 4 November 2026. In its release of 2 November, NASA cites a forecast from the US Space Force of approximately 9.30 a.m. Swiss time, with an uncertainty of eleven hours. An exact impact location is therefore not yet established.

For Switzerland, the announcement contains a clear geographical limit: according to NASA, surviving fragments can only come down between 20.6 degrees south and 20.6 degrees north latitude. Switzerland lies outside this belt. That is not a pinpoint prediction for other countries, but it already narrows the possible area considerably.

Some components are likely to survive re-entry

According to NASA, Swift weighs about 3200 pounds, roughly 1.45 tonnes. The agency expects most of it to burn up in the atmosphere. Individual components, however, are likely to survive re-entry. Where these could reach the ground depends on when the spacecraft reaches the decisive altitude.

NASA puts the probability that a person somewhere on Earth is harmed at about one in 2100. This global risk estimate is not the probability for any single individual. Nor is it the probability that any debris reaches the ground at all. The agency expressly expects such surviving components.

NASA and the Space Force intend to keep monitoring the orbit and update their forecasts. The time given in Monday's release is therefore a provisional calculation, not a return fixed to the minute.

The sun changes the braking effect of the atmosphere

Even in a low Earth orbit, space is not completely empty of air. The thin upper layers of the atmosphere slow satellites down and cause their orbits to sink. The US space weather service NOAA explains that active solar phases can increase density at these altitudes. This raises the braking effect.

According to NASA, precisely this development accelerated Swift's loss of altitude. A commercial attempt to move the observatory to a higher orbit ended in August without carrying out the orbit raise. Afterwards, Swift resumed its scientific observations.

On 20 October, the satellite reached an altitude of about 275 kilometres. It could no longer compensate sufficiently for the stronger braking effect and went into safe mode. The operations team at Pennsylvania State University then sent the command that ended operations ahead of the imminent re-entry.

The European Space Agency ESA explains why the timing cannot simply be derived from the known trajectory, using natural re-entries as an example: the future density of the atmosphere can only be predicted to a limited extent. The orientation of the satellite and the area it presents to the thin air add further variables. The longer the remaining flight, the more such differences can affect the location of the return.