A 22-year-old space telescope is losing its fight against gravity and is predicted to come crashing down to Earth on the morning of Nov. 4, 2026. The Neil Gehrels Swift Observatory had been the go-to telescope for observing astrophysical events that happen quickly, such as supernovas . Its onboard instruments allowed it to contribute greatly to many subfields of science.
Author
- Mary Ogborn
Ph.D. Candidate in Astrophysics, Penn State
Swift was not classified as a flagship observatory, like the Hubble Space Telescope or Chandra X-Ray Observatory , but it left behind a legacy that will not swiftly be forgotten.
The Swift Observatory first came onto the scene in 2004 when NASA launched it into low Earth orbit . Originally called the Swift Gamma-Ray Burst Explorer, its purpose was to move quickly to follow up on explosive events called gamma-ray bursts and their afterglows using its three onboard telescopes.
Swift's name is not an acronym. Instead, it refers to its speed and likens the observatory to the bird . It could rotate and move quickly to observe transient events , which are events that happen quickly and fade away.
Watching for gamma-ray bursts
Gamma-ray bursts are the most explosive and energetic events in the universe. Scientists theorize they come from the explosions of large stars or mergers of a very dense type of star called neutron stars . Gamma-ray bursts, as the name implies, release large bursts of gamma-rays, but as these explosions fade, they lose energy. Scientists can spot remnants of gamma-ray bursts by looking for X-rays and optical light as the gamma rays themselves fade.
Swift's burst alert telescope could see light in the gamma-ray portion of the electromagnetic spectrum , so it searched directly for gamma-ray bursts. Its X-ray telescope and ultraviolet-optical telescope could measure the resulting afterglow of X-ray and UV light these events produced as they faded.
What set Swift apart was its ability to do what's called slewing: In order to follow up on transient events, it swiveled its telescopes around quickly and could cover 50 degrees in less than 75 seconds . Comparatively, it takes Hubble about 15 minutes to turn 90 degrees .
By 2015, just 10 years after science operations started, Swift detected its 1,000th gamma-ray burst .
Beyond gamma-ray bursts
Swift's ability to slew quickly allowed it to detect more than just gamma-ray bursts. Its onboard instruments could detect anything that changes quickly in the sky, including supernovae and X-ray flares from binary stars , which are two stars bound by gravity that tend to interact with each other. It could also detect the electromagnetic counterparts to gravitational waves , which result from large distortions in space-time, such as the merger of dense objects such as black holes and neutron stars.
In 2008, when observing another supernova, Swift by chance detected a slight rise in X-rays , which preceded a supernova explosion. This initial increase in X-rays represented the earliest phase of supernova evolution ever observed. Swift's extensive alert network notified astronomers all over the world who were able to point other space- and ground-based telescopes at the supernova to follow up and obtain even more data.
Then in 2017, when the IceCube Neutrino Observatory - whose principal investigator Francis Halzen won the 2026 Nobel Prize in physics - detected high-energy neutrinos , Swift was able to help localize their source. Neutrinos are massless particles that do not interact with most matter. This property makes it hard for physicists to detect them and pinpoint their source. Scientists know that astrophysical events can emit them, and they used Swift to connect these neutrinos to a very energetic supermassive black hole at the center of its galaxy .
In 2025, Swift detected a compound called hydroxyl on the interstellar object 3I/ATLAS , indicating the presence of water. This result may help answer the question of how Earth obtained water on its surface. Some theories propose that comets and interstellar objects bombarded the Earth in the early solar system and deposited water.
A failed recovery mission
Swift's journey took a turn in 2024 and 2025, as the Sun became more active . These years were in a period known as a solar maximum , when more solar flares, or explosions on the surface of the Sun, released matter and high-energy particles that hit Earth's atmosphere .
Because of this increase in space weather, many people as far south as Pennsylvania were able to see the northern lights. While this activity produced jaw-dropping views, it also exerted pressure on satellites. Solar particles can exert a small force on whatever they hit, and when there are many, that force multiplies.
This force pushed against Swift, which lived in low Earth orbit at about 373 miles (600 kilometers) above Earth's surface. The telescope is soon set to start reentering the atmosphere, where drag will pull it down toward Earth.
NASA partnered with a company called Katalyst Space Technologies and launched a mission to boost Swift back into its orbit on July 3, 2026.
Unfortunately, this mission failed, and Swift will reenter and burn up in Earth's atmosphere in early November. The observatory likely won't hit the surface fully intact. Instead, it will mostly burn up on its way in.
The loss of such an observatory is a tough blow to the astronomical community, which was gearing up to use the satellite in conjunction with the new Vera C. Rubin Observatory . However, astronomers will continue to remember Swift's team and their countless accomplishments and discoveries.
Mary Ogborn receives funding from the National Science Foundation and the Pennsylvania Space Grant Consortium. She is currently a member of the American Astronomical Society.
