After a rescue mission failed to save NASA’s Neil Gehrels Swift Observatory, the doomed spacecraft is due to plummet back to Earth in a blaze of fire this week. Most of Swift should burn up in the atmosphere, but experts believe some of its internal components could survive reentry.
“That wouldn’t be surprising,” Jonathan McDowell, an astrophysicist and honorary professor at Durham University who has spent decades tracking objects in orbit, told Gizmodo. “It’s about a ton-and-a-half spacecraft, and satellites of that size often have some fraction—like 10%—survive reentry.”
That’s especially true for astronomy satellites like Swift, which tend to have dense telescope mirror equipment and other components, McDowell said. “It wouldn’t be surprising if at least 100 kilograms [220 pounds] or so survive reentry.”
Tracking Swift’s descent
Swift spent nearly 22 years in orbit studying gamma-ray bursts, the most powerful explosions in the cosmos. Launched in November 2004, the mission was only supposed to last two years. Over the course of its surprisingly long career, the telescope observed more than 2,000 gamma-ray bursts, 1,400 supernovae, and other cosmic phenomena that have led to about 7,000 published papers, according to NASA.
All good things must come to an end, however. Swift has gradually lost altitude over the last two decades, as all satellites do, but recent spikes in solar activity helped accelerate its orbital decay. In September 2025, NASA tapped Katalyst Space Technologies of Flagstaff, Arizona, to launch a mission to boost Swift’s orbit and extend its operational lifespan.
That mission, called LINK, launched in July but was later derailed by attitude control issues. As of October 23, Swift’s orbit had decayed to an altitude of less than 171 miles (275 kilometers) above Earth’s surface, according to NASA. Based on the latest tracking data from the U.S. Space Force, McDowell said the satellite should reenter the atmosphere sometime between Tuesday and Wednesday this week.
Given the uncertainty of that timing and the unpredictability of an uncontrolled descent, it’s extremely difficult to forecast Swift’s reentry point, let alone where any surviving pieces of the spacecraft could land. Swift’s orbit extends about 20 degrees north and south of the equator, meaning debris could fall anywhere between those latitudes.
“Obviously a lot of that latitude band is ocean,” McDowell said. That’s where any surviving components of Swift are most likely to land, but there are land masses—and densely populated communities—within the reentry zone, including swaths of Africa, Australia, India, Southeast Asia, and Central and South America.
To be clear, the chances of a falling piece of Swift damaging infrastructure or injuring someone are extremely low. “Typically when you do the detailed calculations, it comes out to a one in 10,000 chance that someone will get hurt,” McDowell said. “But at this point, since Sputnik, we’ve had about 10,000 reentries. So, one of these days, our luck is going to run out.”
The growing risk of orbital reentries
As Earth’s orbit has rapidly grown more crowded, the amount of space junk falling back to Earth has increased drastically in the last several years. While there have been reports of debris crashing through roofs, into farm fields, and other populated areas, these incidents are still exceptionally rare.
“Should you be worried that you are going to get hit by space junk? No,” McDowell said. “As a government, should you be worried that someone might be hit by space junk? Yes. So, it is a policy issue. We shouldn’t have these uncontrolled reentries.”
Observing the demise of Swift and other reentering spacecraft can help researchers assess the risks to people and infrastructure. Gaining a better understanding of which components tend to melt and which tend to survive the extreme temperatures of reentry could lead to safer satellite design.
“We also need to understand what the melted stuff does to the chemistry of the upper atmosphere, because there’s an emerging concern that we may be screwing the climate and the ozone layer with all of these reentries,” McDowell said.
So while it’s highly unlikely that Swift’s return to Earth will pose a danger to people and property, it will present a valuable opportunity that could help scientists mitigate future risks. This event will also mark the end of one of the most successful astronomy campaigns NASA has ever launched.
“We’re all going to pour one out for Swift,” McDowell said.
