NASA’s Neil Gehrels Swift Observatory has ended its science mission after nearly 22 years, NASA said on Oct. 23. Atmospheric drag had pulled the spacecraft below 171 miles (275 kilometers), too low for its telescopes to gaze steadily at their targets, and the agency expects it to re-enter the atmosphere in the next few weeks.

Swift made its final observation on Oct. 20. That day the observatory reached 171 miles, could no longer compensate for the increased drag and entered safe mode, according to a Swift mission blog post. The operations team at Penn State in University Park, Pennsylvania, then sent a command that effectively ended Swift’s operations to prepare it for re-entry. NASA said drag intensified by recent solar activity had caused the spacecraft to sink rapidly.

A rescue that never reached Swift

NASA had tried a commercial fix. In September 2025 it contracted Katalyst Space, based in Flagstaff, Arizona, which had around one year to design, build, test and launch a satellite that would meet, grab and lift Swift, according to a NASA review of lessons learned. That spacecraft, a robotic servicer called LINK, lifted off from Kwajalein Atoll in the Republic of the Marshall Islands in July 2026 aboard a Northrop Grumman Pegasus XL rocket.

After reaching orbit, LINK began experiencing intermittent communications losses and developed problems with its orientation control. NASA and Katalyst agreed to scale back the mission: LINK would no longer try to grab or boost Swift and would instead attempt a series of technology demonstrations, including tests of its xenon propulsion system and three robotic arms. NASA formally concluded its involvement on Sept. 3, and LINK re-entered the atmosphere on Sept. 25.

Swift’s operators also tried to buy time. In December 2025 they began swapping around 25% of science targets for points on the sky that would minimize drag when the telescope was pointed at them, and by February they had switched to that approach entirely. NASA’s planning hinged on predictions that Swift would sink to a “point of no return” of around 185 miles (300 kilometers) in fall 2026. The team later paused science observations to reduce drag and then restarted them, and Swift observed hundreds of targets before the extra drag from resumed observations sent it sinking rapidly again.

What Swift leaves behind

Swift launched on Nov. 20, 2004, for a two-year primary mission and operated more than 10 times that long. “Swift was designed as a satellite dedicated to studying gamma-ray bursts,” said S. Bradley Cenko, the mission’s principal investigator at NASA’s Goddard Space Flight Center. To do that it had to detect and locate the bursts, send their positions to other observatories and turn its own telescopes to image them, which typically took about a minute, he said. It could schedule up to 75 independent targets per day.

By NASA’s count, Swift observed more than 2,000 gamma-ray bursts, the most powerful explosions in the universe, studied more than 1,400 supernova explosions and contributed data to about 7,000 published papers. In May 2005 it caught GRB 050509B, a burst lasting 0.03 seconds, and detected 11 X-ray photons from it, making it the first short burst with a detected afterglow. Those observations supported long-standing models in which short bursts come from mergers of two neutron stars. Swift also witnessed stars being torn apart by black holes, monitored active galaxies, carried out an all-sky X-ray survey and studied comets and asteroids, including water from the interstellar comet Borisov. The observatory was renamed in 2018 to honor Neil Gehrels.

Why it matters

Swift’s ability to swing quickly toward short-lived events is what NASA now has to replace. “Swift delivered an incredible, lasting return on investment for the nation,” said Shawn Domagal-Goldman, director of NASA’s Astrophysics Division. NASA said it will continue to prioritize finding new options to react rapidly to cosmic events, using current missions to help fill the gap in the meantime. Domagal-Goldman said the agency is exploring how to use and augment its existing space telescopes, from fast-to-orbit commercial capabilities to new missions.

The data remain available to researchers. The archive holds nearly 22 years of brightness measurements, multiwavelength spectra and more than 1.5 million images from Swift’s Ultraviolet/Optical Telescope, about 12 terabytes in all. NASA has also presented the boost attempt as a gain for industry, with Domagal-Goldman crediting it with advancing U.S. spacecraft servicing technology.

What to watch

NASA has not given a re-entry date beyond “the next few weeks.” NASA’s statements so far describe options under study rather than a named successor to Swift’s rapid-response role.

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